Dengiz uskunalarini tebranish diagnostikasi
Published by Nikolai Shelkovenko on
Dengiz uskunalarini tebranish diagnostikasi
A practical guide to measurement methods, signal analysis, fault detection, shaft alignment, field balancing, and condition monitoring for rotating machinery on ships and offshore installations.
At a glance
1. Texnik diagnostikaning asoslari
Tebranish tahlili nima uchun dengiz aylanuvchi mexanizmlarini monitoring qilishda yetakchi usulga aylandi — va qanday muqobil yondashuvlar mavjud.
1.1 Diagnostika tamoyillari
Texnik diagnostika — mashinaning joriy holatini baholash va bu holat vaqt o'tishi bilan qanday o'zgarishini bashorat qilish fanidir. Dengiz uskunalari uchun bu vazifa ayniqsa muhim: dengizda rejalashtirilmagan nosozlik ekipaj, yuk va kemaning o'ziga xavf tug'dirishi mumkin.
Markaziy g'oya oddiy. Har qanday aylanuvchi mexanizm o'lchanishi mumkin bo'lgan fizik signallar chiqaradi — tebranish, issiqlik, akustik emissiya, moyli ifloslanish va boshqalar. Ichki komponentlar eskirgan, yorilgan, zanglagan yoki bo'shashgan sari bu signallar odatda bashorat qilish mumkin bo'lgan tarzda o'zgaradi. Tizimli monitoring dasturi bu o'zgarishlarni erta aniqlaydi, ularni tur va og'irlik darajasi bo'yicha tasniflaydi hamda texnik xizmat ko'rsatish jadvaliga tavsiyalar kiritadi.
Key Terms
| Atama | Ta'rif | Marine Example |
|---|---|---|
| Diagnostik parametr | Uskunaning texnik holatiga bog'liq bo'lgan o'lchanadigan kattalik | Nasos podshipnik korpusidagi tebranish tezligining RMS qiymati |
| Diagnostik simptom | O'lchangan ma'lumotlardagi muayyan naqsh | Markazdan qochma nasosda parchalar o'tish chastotasida tebranishning ortishi |
| Diagnostik belgi | Muayyan holatning tanib olinadigan ko'rsatkichi | Tish eskirishini ko'rsatuvchi tishli g'ildirak chastotasi atrofidagi yon chastota komponentlari |
| Tanib olish algoritmi | O'lchangan ma'lumotlarni nosozlik toifasiga moslashtiruvchi tartib-qoida (qo'lda yoki avtomatik) | Konvert spektrida podshipnik nosozlik chastotalarini aniqlaydigan ekspert-tizim qoidalar to'plami |
Umumiy diagnostika ish jarayoni
Amaliyotda bu jarayon takroriy xarakter kasb etadi: agar naqsh biror ma'lum nosozlikka mos kelmasa, mutaxassis qayta ishlov berishni aniqlashtiradi, yangi o'lchov nuqtalarini qo'shadi yoki boshqa diagnostika usullari (termografiya, moy tahlili, ultratovush tekshiruvi) bilan solishtirib ko'radi.
Funksional va sinov stendidagi diagnostika
Funksional diagnostika mashina odatdagi yuklanish ostida ishlayotganda ma'lumot to'playdi. Bu real ish sharoitlarini aks ettiradi, lekin bajarilishi mumkin bo'lgan sinovlarni cheklaydi — masalan, asosiy dvigatelni sovutish suvini etkazib berayotgan nasosga sun'iy qo'zg'atish kiritish mumkin emas.
Sinov stendi (tester) diagnostikasi boshqariladigan qo'zg'atishni qo'llaydi — zarb bolg'asi, siljishli sinus-qo'zg'atgich yoki shunga o'xshash vositalar — odatda to'xtash paytida. Bu funksional diagnostika aniqlay olmaydigan tabiiy chastotalarni, uzatish funksiyalarini va konstruktiv xususiyatlarni aniqlaydi. Kema bortida amaliy qiyinchilik aniq: to'xtatishlar qimmatga tushadi va muhim tizimlar uchun ba'zan mutlaqo imkonsizdir.
A good shipboard programme combines both approaches. Routine functional monitoring covers the large majority of the machinery inventory, while test-bench methods are reserved for commissioning, troubleshooting, and critical systems.
Nimani kuzatish kerakligini tanlash
Kemagagi har bir mexanizm bir xil darajada e'tiborni talab qilmaydi. Qaysi uskunada qaysi parametrlarni kuzatishni tanlash — diagnostik qamrov va amaliy xarajatlar o'rtasidagi muvozanatni talab etadi. Odatdagi tanlash mezonlariga nosozlik rivojlanishiga sezgirlik, o'lchash takrorlanuvchanligi, sensor va o'rnatish narxi hamda uskunaning o'ziga xos ahamiyatlilik darajasi kiradi.
1.2 Texnik xizmat ko'rsatish strategiyalari
Dengiz sanoati to'rtta keng tarqalgan texnik xizmat ko'rsatish falsafasidan o'tgan, ularning har biri o'ziga xos xarajat–risk nisbatiga ega.
| Strategy | Approach | Strengths | Weaknesses |
|---|---|---|---|
| Reactive | Ishdan chiqqunga qadar ishlash, buzilgandan keyin ta'mirlash | Minimal dastlabki sarmoya | Oldindan aytib bo'lmaydigan turg'unlik, xavfsizlik xavfi, ikkilamchi zarar |
| Profilaktik (vaqtga asoslangan) | Holatdan qat'i nazar belgilangan oraliqda kapital ta'mirlash | Bashorat qilinadigan jadval | Haddan ziyod texnik xizmat, keraksiz ehtiyot qismlarni almashtirish |
| Holatga asoslangan (CBM) | O'lchangan parametrlar chegaradan oshganda texnik xizmat ko'rsatish | Haqiqiy ehtiyojga qarab amalga oshiriladigan aralashuvlar | Diagnostika malakasi va uskunasini talab etadi |
| Proactive / Reliability-centred | Nosozliklarning asosiy sabablarini aniqlash va bartaraf etish | Eng yuqori uzoq muddatli ishonchlilik | Yuqori dastlabki investitsiyalar, madaniy o'zgarish |
Most modern fleets use a combination. Critical propulsion and power-generation machinery gets condition-based or proactive maintenance. Auxiliary equipment may still follow time-based schedules or even run-to-failure where spares are cheap and consequences are minor. Vibration analysis is the backbone of the CBM layer.
A container ship's cooling-water pumps were previously overhauled every 3 000 operating hours. After implementing vibration-based condition monitoring the operator extended intervals to 4 500 hours while substantially reducing unplanned failures. Programmes of this kind typically pay for themselves within the first year or two of operation.
1.3 Tebranish — asosiy diagnostik signal sifatida
Tebranish tahlili dengiz sanoatida texnik holat monitoringida bir nechta o'zaro bog'liq sabablarga ko'ra yetakchi o'rinni egallaydi:
- Barcha aylanma mexanizmlar tebranish hosil qiladi — qo'shimcha qo'zg'atish talab etilmaydi.
- Nosozliklar tebranish naqshlarini yaxshi hujjatlashtirilgan, nosozlikka xos tarzda o'zgartiradi.
- O'lchashlar kontaktsiz bo'lib, mexanizm normal ish rejimida ishlayotgan paytda amalga oshirilishi mumkin.
- Oldindan ogohlantirish vaqti odatda soatlar bilan emas, balki hafta yoki oylar bilan o'lchanadi.
- Usul miqdoriy hisoblanadi — natijalar xalqaro standartlar bilan belgilangan og'irlik zonalariga to'g'ridan-to'g'ri mos keladi.
The methodology moves through six stages: baseline establishment, trend monitoring, anomaly detection, fault classification, severity assessment, and prognosis (remaining useful life). Each stage draws on a different toolbox — from simple RMS trending at the first stage to konvert tahlili, cepstrum, and machine-learning classifiers at the later ones.
Texnik holat holatlari
| State | Indicators | Tavsiya etilgan harakat |
|---|---|---|
| Good | Past, barqaror tebranish; nosozlik chastotalari yo'q | Oddiy monitoring jadvalini davom ettiring |
| Acceptable | Ko'tarilgan, ammo barqaror darajalar | Monitoring chastotasini oshiring, ildiz sababini tekshiring |
| Unsatisfactory | Yuqori darajalar yoki o'sish tendentsiyasi | Keyingi qulay imkoniyatda texnik xizmat ko'rsatishni rejalashtiring |
| Unacceptable | Juda yuqori darajalar yoki tez yomonlashuv | Darhol to'xtating yoki yukni kamaytiring; favqulodda texnik xizmat ko'rsatish |
Iqtisodiy nuqtai nazar
Kemadagi tebranish dasturlarining investitsiyadan qaytish darajasi turlicha bo'ladi, ammo adabiyotlarda ko'pincha 5:1 dan 10:1 gacha nisbatlar keltiriladi. Tejamkorlikning asosiy qismi uch manbadan kelib chiqadi: ikkilamchi halokatli zararlarning oldini olish (valga zarar yetkazgan podshipnik nosozligi), keraksiz ta'mirlash ishlarini bartaraf etish orqali komponent muddatini uzaytirish va rejalashtirilgan dok ishlariga nisbatan port chetidagi favqulodda ta'mirlash xarajatlarini kamaytirish.
2. Vibration Physics, Units and Standards
Displacement, velocity, acceleration — the three faces of vibration, and the ISO framework used to judge how much is too much.
2.1 Asosiy parametrlar
Tebranish — mexanik tizimning muvozanat holati atrofidagi tebranma haraketidir. U turli chastota diapazonlarida foydali bo'lgan o'zaro bog'liq uchta kinematik kattalik bilan tavsiflanadi.
Velocity: v(t) = A·ω · cos(ωt + φ)
Acceleration: a(t) = −A·ω² · sin(ωt + φ)
A — amplitude | ω = 2πf — angular frequency | φ — phase angle
Because velocity scales linearly with frequency (the ω factor) and acceleration scales with ω², the three parameters have very different sensitivities across the spectrum. This is the practical reason engineers choose one over another.
| Parametr | Birlik | Optimal chastota diapazoni | Dengiz sohasidagi odatiy qo'llanishlar |
|---|---|---|---|
| Siljish | μm (cho'qqidan cho'qqiga), mil | Below ≈ 10 Hz | Katta, sekin aylanadigan dizel tirqiranchlari, valmning nisbiy harakati |
| Tezlik | mm/s (RMS) | 10 Hz – 1 kHz | General machinery monitoring; ISO 20816 / legacy ISO 10816 evaluations |
| Tezlanish | m/s² yoki g (cho'qqi) | Above ≈ 1 kHz | Yuvma element podshipniklarini diagnostika qilish, tishli uzatmalar, yuqori tezlikli nasoslar |
Statistik o'lchov kattaliklari
RMS (o'rta kvadratik qiymat) samarali amplitudani ifodalaydi va tebranishning energiya mazmuni bilan bog'liq. U ISO asosidagi og'irlik darajasini baholashda standart ko'rsatkich hisoblanadi.
Peak value maksimal momentli amplitudani qayd etadi — zarbalar va o'tkinchi hodisalarni aniqlash uchun foydali.
Cho'qqidan cho'qqiga qiymat musbat cho'qqidan manfiy cho'qqigacha bo'lgan umumiy og'ishni ko'rsatadi. Ko'pincha ko'chish o'lchovlari va bo'shliqlarni tahlil qilishda qo'llaniladi.
Cho'qqi koeffitsienti is the ratio of peak to RMS. The absolute value depends on the machine type, measurement bandwidth, and operating regime — a pure sinusoid gives ≈1.4, and a healthy rotating machine commonly falls around 3–4 — so there is no single universal "normal" number. What matters diagnostically is the trend: a rising crest factor indicates growing impulsiveness, a common early sign of bearing surface defects or impacts.
Yuk nasosidagi podshipnikning qo'zg'olish koeffitsienti olti hafta ichida 3,2 dan 7,8 gacha ko'tarildi, bunda umumiy o'rta kvadratik qiymat deyarli o'zgarishsiz qoldi. Bu farq — barqaror energiya, ortib borayotgan zarbalar — podshipnik nuqsonining klassik dastlabki belgisidir. Keyingi tekshiruv tashqi halqada chuqurchaning mavjudligini tasdiqladi.
2.2 Dengiz tizimlarida tebranish turlari
Dengiz mashinalari har biri turli fizik mexanizmdan kelib chiqadigan bir necha toifadagi tebranish hosil qiladi.
Qo'zg'atuvchi manba bo'yicha
- Free vibration — sistema o'tkinchi qo'zg'atishdan (ishga tushirish, to'xtatish, zarba) keyin o'zining tabiiy chastotasida tebranadi.
- Majburiy tebranish — aylanish tezligi, qanot soni yoki elektr ta'minoti chastotasi bilan bog'liq chastotada uzluksiz qo'zg'atish. Barqaror holat tebranishlarining aksariyati majburiy tebranishdir.
- O'z-o'zini qo'zg'atuvchi vibratsiya — mexanizm ichki teskari aloqa mexanizmi orqali o'z-o'zini qo'zg'atadi: siljish podshipniklaridagi yog' aylanishi, aerodinamik flatter, ilashib-sirpanish ishqalanishi.
- Parametrik tebranish — sistemaning qattiqlik yoki so'nish ko'rsatkichi davriy ravishda o'zgarib, reaksiyaga energiya kiritadi. Har bir aylanishda tishlanish qattiqligini o'zgartiradigan yoriq tish buning tipik namunasidir.
Tezlik bilan bog'liqligi bo'yicha
- Sinxron (tartib bilan bog'liq) — frequency is an integer or simple rational multiple of shaft speed. Unbalance (1×), misalignment (2×), and looseness (many harmonics) belong here.
- Asynchronous — frequency is not an integer multiple of shaft speed. Bearing defect frequencies, electrical line-frequency harmonics, and belt-slip vibration fall in this category.
By Direction
Radial tebranish (valga perpendikulyar) aksariyat aylanadigan uskunalarda ustunlik qiladi va birinchi navbatda o'lchanadigan yo'nalish hisoblanadi. Axial tebranish (valga parallel) surilma podshipnining nosozliklarini, muftadagi muammolarni va aerodinamik kuchlarni ko'rsatadi. Torsional tebranish (val o'qi atrofida buralish) maxsus sensorlarni talab qiladi va asosan torsion rezonansi halokat keltirishi mumkin bo'lgan uzun uzatish tizimlarida kuzatiladi.
Tabiiy chastotalar va rezonans
Har bir mexanik sistema massa, qattiqlik va so'nish bilan belgilanadigan tabiiy chastotalarga ega. Qo'zg'atish chastotasi tabiiy chastotaga yaqinlashganda javob ko'rsatkichi kuchayadi — ba'zan 10 baravar va undan ham ko'proq. Aylanadigan mashinalarda bu mos kelishlar deyiladi kritik aylanish tezliklarini.
Operating speed should be separated from all identified critical speeds by at least 15–20 %. Running persistently within this margin risks resonance-driven fatigue and rapid failure.
Tebranish manbalari
Mechanical — muvozanatsizlik, nosozlik, podshipnik nuqsonlari, bo'shashish, tishli uzatma muammolari, val egilishi. Chastotalar odatda val tezligi va komponent geometriyasi bilan bog'liq.
Electromagnetic — rotor chiviqlarining nuqsonlari, stator ekssentrisiteti, ta'minot kuchlanishining muvozanatsizligi. Chastotalar tarmog' chastotasining ikki karrali qiymatiga (50 Hz ta'minot uchun 100 Hz, 60 Hz ta'minot uchun 120 Hz) va uning ko'paytmalariga to'planadi.
Gidravlik / aerodinamik — qanot o'tish chastotasi, kavitatsiya, turbulentlik, qayta aylanish. Qanot o'tish chastotasi qanotlar sonining aylanish chastotasiga ko'paytmasiga teng; kavitatsiya 1–2 kHz dan yuqorida to'plangan keng polosali tasodifiy shovqin hosil qiladi.
2.3 O'lchov birliklari va standartlar
Tebranish o'lchovlarida chiziqli va logarifmik (detsibel) shkalalar qo'llaniladi. Detsibel shakli keng dinamik diapazonlarni siqadi va nisbiy o'zgarishlarni ta'kidlaydi:
Reference values are standardised in ISO 1683: 10⁻⁹ m/s (1 nm/s) for velocity and 10⁻⁶ m/s² (1 μm/s²) for acceleration. Always state the reference when reporting levels in decibels.
ISO 20816 (formerly ISO 10816) — Vibration on Non-Rotating Parts
The ISO 10816 series was historically the most widely used framework for evaluating machinery vibration measured on non-rotating parts (bearing housings). It is being superseded by the ISO 20816 series: ISO 20816-1:2016 replaced both ISO 10816-1 and ISO 7919-1, and ISO 20816-3:2022 replaced ISO 10816-3 for industrial machinery rated above 15 kW. The four-zone evaluation logic (A through D) remains the same in both series; the numerical limits depend on machine group and support class.
The table below shows example zone boundaries for one specific classification (ISO 10816-3 / ISO 20816-3, Group 2 machines 15–300 kW, rigid support). These values are not universal — always consult the part of the standard that applies to your machine type, power range, and mounting.
| Zona | Holat | Velocity RMS (Group 2, rigid support) | Guidance |
|---|---|---|---|
| A | Good | up to 1.4 mm/s | Yangi ishga tushirilgan yoki yaqinda texnik xizmat ko'rsatilgan |
| B | Acceptable | 1.4 – 2.8 mm/s | Cheklovsiz uzoq muddatli ekspluatatsiya |
| C | Unsatisfactory | 2.8 – 4.5 mm/s | Cheklangan muddatga ekspluatatsiya; tuzatish ishlarini rejalashtirish |
| D | Unacceptable | > 4.5 mm/s | Shikastlanish ehtimoli yuqori; zudlik bilan choralar ko'rish |
Marine and Machine-Specific Standards
Beyond the general machinery series, several standards address ships and specific machine types directly:
| Standart | Scope |
|---|---|
| ISO 20283-2 | Measurement of vibration on ships — structural vibration of the hull and superstructure |
| ISO 20283-3 | Pre-installation vibration measurement of shipboard equipment |
| ISO 20283-4 | Measurement and evaluation of vibration of the ship propulsion machinery |
| ISO 20283-5 | Vibration with regard to habitability on passenger and merchant ships (crew and passenger comfort) |
| ISO 10816-6 | Reciprocating machines with power ratings above 100 kW — marine diesel engines fall in this category |
| ISO 8528-9 | Vibration measurement and evaluation of reciprocating-engine generating sets |
| ISO 7919 series | Shaft vibration measured on rotating shafts with proximity probes (its parts are progressively merged into ISO 20816) |
| API 610 | Centrifugal pumps — vibration acceptance criteria used in offshore and cargo-handling applications |
Machine Groups and Support Classes
Under the ISO 10816-3 / ISO 20816-3 framework the primary groups for industrial machinery are: Guruh 1 — large machines rated above 300 kW and up to 50 MW; Guruh 2 — medium machines rated 15–300 kW. Separate provisions exist for pumps depending on whether the driver is integrated or external. Limits are further split by support stiffness.
A support system is considered rigid when the lowest natural frequency of the machine-plus-foundation assembly is well above the principal excitation frequency — a common practical guideline is at least 25 % above. Egiluvchan supports have their lowest natural frequency below the excitation frequency, which amplifies housing vibration and is assigned more lenient acceptance limits. The distinction should be verified by measurement (impact test) rather than assumed from construction appearance alone — this matters on ships, where resiliently mounted machinery is common.
O'lchov nuqtalari
Standards prescribe measurement on bearing housings, as close to the load zone as practical, in three directions: horizontal radial, vertical radial, and axial (usually at the drive-end bearing only). Measurements should be taken under stable operating conditions — rated speed and representative load — and averaged over a period long enough to capture any cyclic variation.
Kemaning harakati, dengiz holati va yuk yuklanishi tebranish ko'rsatkichlariga ta'sir qilishi mumkin. Yaxshi amaliyot har bir o'lchov bilan birga ushbu sharoitlarni qayd etishni va qo'pol ob-havoda yig'ilgan ma'lumotlarni filtrlash yoki belgilashni o'z ichiga oladi.
3. The Marine Operating Environment
What makes vibration work on a ship different from the same work in a factory — variable speeds, a flexible steel foundation that floats, and a propeller at the end of the shaft line.
3.1 Variable Speed and Load
Unlike most industrial plant, marine propulsion machinery rarely sits at one speed. Main engines follow bridge orders, generators pick up and shed electrical load, and vessels with controllable-pitch propellers change load at constant shaft speed. For diagnostics this has two consequences:
- Spectra smear. A conventional FFT taken while speed drifts spreads each rotational component over several frequency bins. Order tracking — resampling the signal against a tachometer reference — keeps speed-related peaks sharp regardless of drift.
- Baselines must be condition-tagged. A reading taken at 85 % MCR in calm water is not comparable with one taken at 50 % load in a seaway. Every stored measurement should carry speed, load, and sea-state metadata, and trends should compare like with like.
3.2 Propeller Blade-Rate Excitation and Hull Resonances
The propeller is one of the strongest periodic exciters on the vessel. Each blade passing through the non-uniform wake field behind the hull generates a pressure pulse, producing vibration at the parchalarni o'tish chastotasi (blade rate) and its harmonics:
Z — number of blades | n — shaft speed in r/min | BPF in Hz
A four-blade propeller turning at 120 r/min: shaft frequency = 120/60 = 2 Hz; BPF = 4 × 2 = 8 Hz, with harmonics at 16 Hz, 24 Hz, and so on. These low frequencies fall exactly in the range of hull-girder and deckhouse natural frequencies.
Because the hull is a large, relatively flexible welded structure, blade-rate excitation can couple into hull-girder bending modes, local panel modes, and deckhouse modes. Symptoms range from crew discomfort in the accommodation to cracked pipe supports and fatigue in local structure. ISO 20283-2 governs the measurement of this structural vibration; ISO 20283-5 sets the framework for evaluating habitability. Remedies include propeller redesign or repair (blade damage increases wake-induced excitation), changing the number of blades, structural stiffening, and avoiding prolonged operation at resonant shaft speeds.
Elevated blade-rate vibration measured on an aft-ship machine is not necessarily that machine's fault. Always check whether the frequency matches propeller blade rate before condemning a pump or motor mounted on a vibrating foundation.
3.3 Shaft Lines and Torsional Vibration
A ship's shaft line — main engine or gearbox, intermediate shafts, stern-tube bearing, propeller — is a long, heavy rotor system whose alignment depends on the hull around it. Hull deflection changes with cargo loading, ballast condition, and temperature, so a shaft line aligned perfectly in dry dock can run misaligned at sea. Symptoms include elevated 1× and 2× vibration at intermediate bearings, stern-tube bearing overheating, and uneven wear-down readings.
Long shaft lines driven by diesel engines are also prone to burmalama tebranishni. Engine firing orders excite torsional natural frequencies of the crankshaft–shaft-line system; where a significant torsional critical falls inside the operating range, a barred speed range is defined in which continuous operation is prohibited. Torsional vibration is largely invisible to ordinary casing-mounted accelerometers — it requires dedicated instruments (torsiographs, strain gauges, encoder-based twist measurement). ISO 20283-4 covers the measurement and evaluation of propulsion-machinery vibration.
3.4 Classification Societies and Environmental Factors
Classification societies (DNV, Lloyd's Register, Bureau Veritas, ABS, and others) publish machinery and vibration guidance and offer condition-monitoring class notations under which an approved, auditable monitoring programme can substitute for parts of the fixed-interval survey regime. The specific requirements differ between societies and change over time, so the applicable rules should always be checked with the vessel's own class — but the common thread is that data quality, documented procedures, and analyst competence must be demonstrable.
Finally, the marine environment itself works against the measurement chain: salt-laden air corrodes connectors, engine-room temperatures cycle widely, and washdown areas demand appropriately protected sensors and cabling. Environmental ratings, stainless hardware, and disciplined cable maintenance are not luxuries — a corroded connector produces intermittent signals that imitate machine faults.
4. Measurement Methods and Sensors
Sensor tanlash, o'rnatish, signal konditsionerlash va kemada sifatli tebranish ma'lumotlarini yig'ishning amaliy jihatlari.
4.1 Measurement Principles
Kinematik va dinamik
Ko'pgina tebranish sensorlari faqat motion ko'chishni, tezlikni yoki tezlanishni — uni keltirib chiqaradigan kuchni miqdoriy baholamasdan o'lchaydi. Bu kinematik o'lchov hisoblanadi. Dinamik o'lchov harakat va kuch ma'lumotlarini birlashtiradi, odatda juft akselerometrlar va kuch o'lchagichlar yordamida amalga oshiriladi hamda asosan modal tahlil yoki o'tkazish funksiyasini o'lchash kabi nazorat qilinadigan sinov stendi sharoitlarida qo'llaniladi.
Mutlaq va nisbiy
Mutlaq tebranish is the motion of a point relative to an inertial reference frame. An accelerometer bolted to a bearing housing gives an absolute casing vibration measurement. Nisbiy tebranish — bu ikkita qism o'rtasidagi harakat bo'lib, odatda val va podshipnik korpusi o'rtasida o'lchanadi. Yaqinlik zondlari (proximity probe) buni ta'minlaydi va val orbita ma'lumoti zarur bo'lgan katta turbomashinalarda standart usul hisoblanadi.
| Tur | Best for | Cheklovlar |
|---|---|---|
| Mutlaq (akselerometr, tezlik sensori) | Umumiy mashinalar, yordamchi uskunalar, konstruktiv tebranish | Podshipnik ichidagi val harakatini bevosita aniqlay olmaydi |
| Nisbiy (yaqinlik zondi) | Katta turbomashinallar, sirt podshipniklari, kritik vallar | Qimmat o'rnatish, valga kirish talabi mavjud |
Kontaktli va kontaktsiz
Kontaktli sensorlar (akselerometrlar, tezlik datchiklari, deformatsiya o'lchagichlar) tebranayotgan sirtga jismonan biriktiriladi. Ular yuqori sezgirlik, keng o'tkazish kengligi va yaxshi o'rnatilgan protseduralarni taqdim etadi. Kontaktsiz sensorlar (tokovir zondlari, lazerli vibrometrlar) masofadan o'lchaydi va aylanayotgan sirtlar, yuqori haroratli zonalar hamda kontaktli sensor massasi yuki o'lchov natijalarini o'zgartirishi mumkin bo'lgan joylarda muhim ahamiyat kasb etadi.
4.2 Sensor Technologies
Piezoelektrik akselerometrlar
Dengiz vibratsiyon o'lchashlarining ishchi oti. Piezoelektrik element (kvarts yoki keramika) qo'llaniladigan kuchga proporsional elektr zaryadini hosil qiladi. Ichki elektronika (IEPE / ICP standarti) bu zaryadni past impedansli kuchlanish signaliga aylantiradi va u shovqinli mashinaxona muhitida uzun kabellar orqali ishonchli uzatiladi.
Yuqori chastotali modellar (50 kHz gacha, pastroq sezgirlik) podshipnik nuqsonlarini erta aniqlash uchun ishlatiladi. Yuqori sezgirli modellar (100–1000 mV/g, ~5 kHz gacha o'tkazish polosasi) aniq mexanizmlardagi past darajadagi vibratsiyani o'lchash uchun tanlanadi.
MEMS akselerometrlari
Mikro-elektromexanik akselerometrlar piezoelektrik qurilmalarga qaraganda kichikroq, arzonroq va kam quvvat sarflaydi. Ular muhim bo'lmagan mexanizmlarni doimiy monitoring qilish va simsiz sensor tarmoqlari uchun maqbul bo'lib qoldi. So'nggi yillarda o'tkazish polosasi va dinamik diapazon sezilarli darajada yaxshilandi, biroq piezoelektrik sensorlar yuqori chastotali ishlash ko'rsatkichlari bo'yicha hali ham yetakchilik qiladi.
Tezlik sensоrlari (seysmoakselerometrlar)
A suspended magnetic mass moves relative to a coil, generating a voltage proportional to velocity. These sensors require no external power, have robust construction, and give a direct velocity output — convenient for ISO 20816 / legacy ISO 10816 evaluation without integration. Drawbacks include limited low-frequency response (typically above 10 Hz), temperature sensitivity, and relatively large size.
Yaqinlik zondlari (Eddy-tok sensorlari)
Yuqori chastotali generator zond uchida elektromagnit maydon hosil qiladi. Yaqin joylashgan o'tkazuvchan val yuzasidagi eddy toklari impedansni o'zgartiradi, elektronika esa bu o'zgarishni bo'shliq masofasiga proporsional DC kuchlanishga aylantiradi. Har bir podshipnikda 90° burchak ostida o'rnatilgan ikkita zond orbital tahlil uchun X-Y val holati ma'lumotlarini ta'minlaydi. O'lchov aniqligi 0,1 μm tartibida bo'lib, zond DC javobi mavjud (u sekin statik siljishlarni ham, dinamik vibratsiyani ham kuzatishi mumkin).
Yaqinlik zondlari katta asosiy turbinalarda, turbokompressorlarda va reduktor vallarida standart hisoblanadi. Ular yordamchi mexanizmlar uchun deyarli hech qachon qo'llanilmaydi — o'rnatish xarajati jihozlar qiymatiga nisbatan juda yuqori.
4.3 Mounting and Calibration
O'rnatish usullari
Sensorni mashinaga mahkamlash usuli o'lchashning yuqori ishlatilishi mumkin bo'lgan chastotasini belgilaydi. Har bir usul o'rnatish rezonansini kiritadi, undan yuqori chastotalarda o'lchov ishonchsiz bo'ladi.
| Usul | Yuqori ishlatilishi mumkin bo'lgan chastota | Notes |
|---|---|---|
| Threaded stud | Up to sensor limit (often > 10 kHz) | Eng yuqori aniqlik; doimiy yoki yarim doimiy o'rnatish |
| Yupqa yopishqoq qatlam | ~5–7 kHz | Vaqtinchalik o'lchov kompaniyalari uchun qulay |
| Magnetic mount | ~2–3 kHz | Tezkor; faqat ferromagnit yuzalar uchun |
| Qo'lda tutib ishlanadigan zond | ~1 kHz | Faqat skrining; takrorlanuvchanligi past |
Podshipnik konvertining tahlili uchun (2–3 kHz dan yuqori chastotalarga asoslangan) magnit tutqichdan foydalanish noto'g'ri natijalar beradi. Shpilka yoki yupqa yopishqoq tutqich talab etiladi.
Signal konditsioneri
IEPE datchiklari doimiy tok manbasini talab qiladi (odatda 18–28 V DC da 2–4 mA). Ma'lumotlarni yig'ish qurilmasining kiritish qismi odatda bu manba bilan ta'minlangan bo'ladi. Zaryadli rejimda ishlaydigan datchiklarni alohida zaryad kuchaytirgichi talab qiladi. Har ikki holatda ham signal yo'li ekranlangan, past shovqinli kabellardan foydalanishi kerak va mashinaxona quvvat kabellaridan elektromagnit interferentsiyani kamaytirish uchun kabel uzunliklari imkon qadar qisqa bo'lishi lozim.
Kalibrlash
Datchiklarni va kanallarni kuzatiluvchi etalonga nisbatan yiliga kamida bir marta tekshirish kerak — qattiq dengiz sharoitida esa tez-tez. Belgilangan tezlanishni belgilangan chastotada (odatda 159,15 Hz da 10 m/s²) hosil qiladigan portativ kalibrlash qo'zg'atgichi standart dala qurolidir. Etalon akselerometr bilan orqa-orqaga solishtirish ishonchlilikni oshiradi va kema bortida amalga oshirilishi mumkin.
5. Signal Analysis
Xom tebranish to'lqin shaklidan diagnostik xulosalargacha — nosozliklarni aniqlashni mumkin qiladigan signal qayta ishlash zanjiri.
5.1 Signal Types
Mashinangiz qanday signal ishlab chiqarishini tushunish, foydali ma'lumotni ajratib olish uchun qaysi tahlil usullaridan foydalanish kerakligini belgilaydi.
Davriy va garmonik signallar
Bitta chastotadagi sof sinusoida eng oddiy holat hisoblanadi (amalda kamdan-kam uchraydi). Ko'pchilik aylanuvchi mashinalar ishlab chiqaradi polyharmonic signallar — asosiy chastota va uning butun son kattalari. To'rt taktli dizel yoqilg'i yonish tartibidagi garmoniklari; tishli uzatma esa tig'iz chastota va uning garmoniklari hosil qiladi.
Modulyatsiyalangan signallar
Amplituda modulyatsiyasi (AM) — the signal envelope varies periodically. A bearing inner-race defect that passes through the load zone once per revolution creates AM of the high-frequency impact response at the shaft speed. Chastota modulyatsiyasi (FM) — momentli chastota o'zgaradi. Orqa-oldinga harakatlanuvchi kompressordan kelib chiqadigan tezlik tebranishi keng tarqalgan manba hisoblanadi.
m — modulyatsiya chuqurligi | fmod — modulyatsiya chastotasi | fcarrier — tashuvchi chastota
Impulsli va o'tkinchi signallar
Short-duration, high-amplitude events that excite multiple resonances simultaneously. Rolling-element bearing defects, gear-tooth chips, and loose fasteners all produce impulsive vibration. Characteristic features: high crest factor, broad frequency content, rapid decay, and periodic repetition at the defect frequency.
Random Signals
Turbulent oqim, kavitatsiya va yuzaning ilg'or degradatsiyasi dominant davriy komponentga ega bo'lmagan tebranish hosil qiladi. Statistik jihatdan u alohida chastota cho'qqilari bilan emas, balki quvvat spektral zichligi (PSD) bilan tavsiflanadi.
5.2 Time Domain and Frequency Domain
Vaqt sohasida tahlil
Xom to'lqin shaklini o'rganish spektral tahlil yashirishi mumkin bo'lgan ma'lumotlarni ochib beradi: zarbalar vaqtini, modulyatsiya naqshlarini, assimetriyani (qisqartirish, kesish) va o'tkinchi hodisalarning mavjudligini. To'lqin shaklidan hisoblangan statistik parametrlar — RMS, crest faktor, kurtosis, asimmetriya — signal xarakterini miqdoran ifodalaydi va ko'pincha podshipnik yemirilishining birinchi ko'rsatkichlari hisoblanadi.
| Parametr | Nima aniqlanadi | Typical Guide Value (healthy) |
|---|---|---|
| RMS | Overall energy | Machine-specific (see ISO zone limits) |
| Cho'qqi koeffitsienti | Impulsiv komponent | ≈ 3 – 4 (trend matters more than the absolute value) |
| Kurtozis | Cho'qqilik / zarba tezligi | ≈ 3,0 (Gauss bazis chizig'i) |
| Skewness | To'lqin shakli assimetriyasi | ≈ 0 (simmetrik) |
Kurtosis podshipnik diagnostikasi uchun ayniqsa qimmatlidir. Sog'lom podshipnik taxminan Gauss tebranishini hosil qiladi (kurtosis ≈ 3). Rivojlanayotgan nuqsonlar umumiy RMS signal berish uchun yetarlicha oshishidan ancha oldin kurtosisni 4 dan — ba'zan 10 dan — yuqoriga ko'taradi.
Chastota sohasida tahlil (FFT)
Tez Furye o'zgarishi vaqt yozuvini chastota spektriga aylantiradi va qaysi chastotalar eng ko'p energiya tashishini ko'rsatadi. Bu asosiy diagnostika vositasi bo'lib, chunki turli nosozlik turlari turli, bashorat qilinadigan chastotalarda tebranish hosil qiladi.
Asosiy raqamli signal qayta ishlash (DSP) mulohazalari
Sampling rate qiziqish chastotasining eng yuqori qiymatidan ikki baravar oshishi kerak (Nyquist mezoni). Taxallus-filtrlash filtrlari raqamlashtirish oldidan Nyquist chastotasidan yuqori bo'lgan hamma narsani pasaytiradi. Amaliy qoida: tahlil o'tkazish polosasining 2,56 × katiga namuna olish (filtr o'tish qiyaligiga ruxsat berish uchun).
Chastota rozolishishi = 1 / T, bu yerda T yozuv uzunligi. Ikkita yaqin chastotani ajratish uchun uzunroq yozuv kerak. Tezlik biroz o'zgaradigan dengiz ilovalari uchun order kuzatish (taxometr impulsiga sinxronlashtirilgan qayta namunaviy olish) tezlik siljishidan qat'i nazar order sohasida doimiy rozolishni saqlaydi.
Oyna funksiyasini qo'llash cheklangan yozuv uzunligi sabab bo'ladigan spektral sizib chiqishni bostiradi. Hanning umumiy maqsadli standart oyna hisoblanadi; tekis tepa amplitudani eng aniq beradi (mutlaq chegaralar bilan taqqoslashda muhim); to'rtburchak faqat haqiqatan ham o'tkinchi signallar uchun maqsadga muvofiq.
| Window | Chastota Rezolyutsiyasi | Amplituda aniqligi | Use Case |
|---|---|---|---|
| Rectangular | Best | Moderate | O'tkinchi / zarbali |
| Hanning | Good | Good | Umumiy maqsadli |
| Flat-top | Poor | Best | Kalibrovka, amplituda tekshiruvlari |
5.3 Advanced Techniques
Konvert tahlili (amplituda demodulyatsiyasi)
The method of choice for rolling-element bearing diagnostics. Steps: (1) band-pass filter around a structural resonance excited by bearing impacts (typically 2–8 kHz), (2) extract the amplitude envelope via Hilbert transform or rectification + low-pass filter, (3) compute the FFT of the envelope. Podshipnik nuqsonlari chastotalari (BPFO, BPFI, BSF, FTF) then appear as distinct peaks in the envelope spectrum, clearly separated from shaft-speed harmonics and other sources.
Kepstrum tahlili
Kepstrum — log-amplituda spektrining teskari FFT'sidir. U davriy naqshlarni aniqlaydi within chastota spektrida — xuddi tishli uzatmaning tishlanish chastotasi atrofidagi yon chiziqlar yoki bo'shliqdan kelib chiqadigan garmonik oilalar hosil qiladigan naqsh. Bu usul to'g'ridan-to'g'ri FFT'ga nisbatan kamroq intuitiv bo'lsa-da, bir nechta yon chiziq oilalari bir-biriga ustma-ust tushganda alohida samarali bo'ladi.
Order Tracking
O'zgaruvchan tezlikdagi mashinalar uchun (kemada chastotali o'zgartiruvchi drayvlar yoki manevr paytida keng tarqalgan), an'anaviy FFT tezlikka bog'liq cho'qqilarni yoyib yuboradi. Order kuzatuv usuli taxometr yoki tezlik etaloni yordamida vaqt signalini qayta namunalash orqali tahlilni chastota sohasidan order sohasiga o'tkazadi. Har bir order val tezligining aniq bir butun son katlamasiga to'g'ri keladi.
Kogerentlik funksiyasi
Measures the linear relationship between two signals as a function of frequency. Coherence close to 1.0 at a given frequency means the vibration at the response point is predominantly caused by the excitation at the reference point. Useful for isolating transmission paths, verifying measurement quality, and assessing how much of a machine's vibration is transmitted to nearby structures — or, on a ship, how much of the "machine's" vibration actually arrives from the propeller through the hull.
6. Condition Monitoring Programmes
Kemadagi tebranishni monitoring qilish dasturini qurish va amalga oshirish — qabul qilish sinovlaridan trend tahlilgacha.
6.1 Acceptance Testing
Vibration acceptance testing establishes that newly installed or overhauled equipment meets its design specification before entering service. For marine equipment this is typically done in stages: factory acceptance test (FAT) at the manufacturer — ISO 20283-3 covers pre-installation vibration measurement of shipboard equipment — harbour acceptance test (HAT) after installation aboard, and sea trial at full load.
Qabul qilish sinovi nimani aniqlaydi
- Residual unbalance exceeding the specified ISO 21940-11 (formerly ISO 1940-1) balance quality grade
- Yumshoq panja — bir yoki bir nechta montaj oyog'ining poydevor bilan to'g'ri temasda emasligi
- O'rnatish jarayonida yuzaga kelgan muftaning noto'g'ri tekisligi
- Nasos yoki kompressor flantslariga uzatiladigan quvur zo'riqishi
- Foundation resonances that coincide with operating speed or propeller blade rate
Measurements during acceptance testing become the baseline for future condition monitoring. They should be taken at several load levels (typically 25 %, 50 %, 75 %, 100 %) and documented with operating parameters (speed, load, temperatures, sea state).
Yangi o'rnatilgan yuk nasosi ishga tushirilgandan so'ng darhol 4,2 mm/s RMS ko'rsatkichini qayd etdi. 100 soatlik ishdan so'ng, podshipnik yuzalari o'zaro moslashib, bo'shliqlar barqarorlashgach, ko'rsatkich 2,1 mm/s ga tushdi. Qabul sinovi o'tkazilmasdan, boshlang'ich yuqori ko'rsatkich keraksiz tekshiruvni keltirib chiqarishi mumkin edi.
6.2 Monitoring Systems
Ko'chma (marshrut asosidagi) tizimlar
Texnik xodim qo'l ma'lumot yig'uvchisidan foydalanib, belgilangan o'lchov nuqtalarida ma'lumot to'play turib, mashinalar xonasi bo'ylab oldindan belgilangan marshrutni bosib o'tadi. Quruqlikdagi yoki ofis kompyuteridagi dasturiy ta'minot ma'lumotlarni saqlaydi, tendentsiyalaydi va tahlil qiladi. Bu yondashuv doimiy monitoring zarur bo'lmagan yordamchi mexanizmlar uchun eng tejamkor usuldir.
Stasionar (onlayn) tizimlar
Sensorlar muhim uskunalarga doimiy ravishda o'rnatiladi va markaziy ma'lumotlarni yig'ish tizimiga ulangan. O'lchashlar belgilangan vaqt oraliqlarida yoki uzluksiz ravishda avtomatik tarzda amalga oshiriladi. Belgilangan chegaralar oshib ketganda signal ishga tushadi. Asosiy dvigatellar, generatorlar, ish harakati elektr motorlari va reduktor tishli uzatmalar tipik nomzodlar hisoblanadi.
Gibrid yondashuv
Zamonaviy flotlarning aksariyati ikkalasini ham birlashtiradi. Uzluksiz monitoring eng muhim 10–15 ta mashinani qamrab oladi. Marshrut asosidagi ko'chma o'lchashlar haftalik yoki choraklik tsiklda 50–200 ta yordamchi qurilmani qamrab oladi. Yagona dasturiy ta'minot ikkala ma'lumot to'plamini bitta ma'lumotlar bazasiga birlashtiradi.
A Practical Starting Point
The table below is a typical starting matrix for a merchant vessel. It is deliberately generic — criticality analysis, class requirements, and maker's instructions take precedence for any specific ship.
| Uskuna | What to Measure | Bu yerda | Typical Interval |
|---|---|---|---|
| Main propulsion engine | Broadband velocity, selective spectra; torsional monitoring per class requirements | Main bearings / frame, thrust bearing, turbocharger casings | Continuous or weekly route |
| Shaft line | Broadband velocity + 1×/2× components; bearing temperatures | Intermediate shaft bearings, stern-tube area | Continuous or monthly |
| Diesel generators | Broadband velocity (ISO 8528-9 framework), spectra on alternator bearings | Engine frame, alternator drive-end and non-drive-end bearings | Weekly – monthly |
| Sea-water / fresh-water pumps | Velocity spectra + bearing envelope | Pump and motor bearing housings, 2–3 directions | Monthly |
| Engine-room fans, blowers | Broadband velocity + 1× (unbalance builds up from deposits) | Fan and motor bearings | Monthly – quarterly |
| Compressors, purifiers, separators | Velocity spectra + high-frequency bearing parameters | Bearing housings per maker's drawing | Monthly |
Ma'lumotlar bazasi va ierarxiya
The monitoring database organises equipment in a tree: vessel → department (engine, deck, electrical) → system (propulsion, auxiliary cooling, fire-fighting) → machine → component → measurement point. Each point has defined sensor type, direction, units, alarm levels, and analysis settings. Good hierarchy design makes fleet-wide benchmarking and reporting practical.
6.3 Alarm Levels and Trend Analysis
Signal darajalarini sozlash
Uchta umumiy yondashuv mavjud bo'lib, ularni birlashtirib qo'llash mumkin.
- Standards-based — use ISO 20816 (formerly ISO 10816) or API zone boundaries directly. Simple but one-size-fits-all.
- Statistical — ogohlantirishni asosiy o'rtacha + 2–3 standart og'ish darajasida, xavf chegarasini o'rtacha + 4–6 σ darajasida belgilash. Har bir mashina uchun moslashtirilgan, ammo yetarli asosiy ma'lumotlarni talab etadi.
- Experience-based — tahlilchining muayyan mashina turi bo'yicha bilimlaridan kelib chiqib belgilanadi. Umumiy standartlar tomonidan yaxshi qamrab olinmagan g'ayrioddiy yoki juda eski uskunalar uchun ko'pincha eng samarali usuldir.
Yuzlab o'lchov nuqtalariga ega kemada noto'g'ri sozlangan signallar har bir marshrut davomida o'nlab yolg'on xabarlar yaratadi. Ekipaj ularni e'tiborsiz qoldirishni o'rganib qoladi. Boshlang'ich me'yoriy qiymatlarni to'g'ri yig'ish va signal darajalarini sozlashga vaqt ajrating — bu yangi dasturning eng yuqori samarali faoliyatidir.
Trend Analysis
Parametrni vaqt o'tishi bilan grafik ko'rinishida kuzatish nuqsonlarni signal darajasiga yetib bormasidan oldin aniqlash imkonini beradi. Trend tahlili umumiy RMS qiymati, alohida chastota komponentlari, statistik parametrlar (crest-faktor, kurtosis) va konvert asosida olingan ko'rsatkichlar uchun qo'llaniladi. Trend chizig'ining qiyaligi — va ayniqsa qiyalikdagi har qanday to'satdan o'zgarish — asosiy qaror qabul qilish omilidir.
Usullar vaqt qatorlari grafiklarini oddiy vizual ko'zdan kechirishdan tortib statistik jarayonlarni nazorat qilish (CUSUM, EWMA) va regressiyaga asoslangan qolgan foydali xizmat muddati modellarigacha bo'lgan diapazonda turadi. Muhim mexanizmlar uchun bir nechta trendli parametrlarni yagona "salomatlik indeksi"ga birlashtirish har qanday alohida parametrga qaraganda ishonchliroq umumiy tasvirni beradi.
A main-engine cooling pump showed a steady month-on-month increase in outer-race defect-frequency amplitude over six months. Bearing replacement was scheduled during a routine port call, preventing an unplanned failure that would have required diverting the vessel.
7. Fault Detection and Identification
Spektral cho'qqilar, to'lqin shakllari va statistik parametrlarni aniq nuqson diagnostikasiga aylantirishfasli.
7.1 Rolling-Element Bearing Diagnostics
Rolling-element bearings are the most commonly monitored component in marine vibration programmes. Each defect location produces a distinct characteristic frequency determined by bearing geometry and shaft speed.
Nuqson Chastotalari
BPFI = (N/2) · fshaft · (1 + d/D · cos φ)
BSF = (D/2d) · fshaft · [1 − (d/D · cos φ)²]
FTF = (1/2) · fshaft · (1 − d/D · cos φ)
N — yumaloq elementlar soni | d — element diametri
D — o'rtacha aylana diametri | φ — kontakt burchagi | fshaft — val chastotasi
The outer-race frequency is always the lower of the two race frequencies (BPFO ≈ 0.4 · N · fshaft as a rough rule) and the inner-race frequency the higher (BPFI ≈ 0.6 · N · fshaft); together they sum to N · fshaft — a convenient sanity check.
Deep-groove ball bearing with 9 balls, d = 12.7 mm, D = 58.5 mm, φ ≈ 0°, running at 1 750 r/min (fshaft = 29.17 Hz):
BPFO ≈ 4.5 × 29.17 × (1 − 0.217) ≈ 103 Hz · BPFI ≈ 4.5 × 29.17 × (1 + 0.217) ≈ 160 Hz · BSF ≈ 64 Hz · FTF ≈ 11.4 Hz
Check: BPFO + BPFI = 103 + 160 ≈ 262.5 Hz = 9 × 29.17 Hz ✓
Nuqson Rivojlanish Bosqichlari
- Onset — subtle increase in the high-frequency noise floor (ultrasonic band, > 20 kHz). No discrete peaks yet. Detectable only with specialised high-frequency techniques (acoustic emission, spike energy).
- Diskret nuqson chastotalari paydo bo'ladi — podshipnikga xos chastotalar (BPFO, BPFI va boshqalar) konvert spektrida yoki yuqori chastotali diapazon tezlanish spektrida ko'rina boshlaydi.
- Garmonikalar va yon chastotalar rivojlanadi — nuqson chastotasi garmoniklari o'sadi; podshipnik chastotalarining atrofida val tezligiga mos modulyatsion yon polosalar paydo bo'ladi.
- Kengayish va o'sish — podshipnik chastotasi diapazonida shovqin poli ko'tariladi; tezlanish va tezlik bo'yicha umumiy RMS qiymatlari oshib boradi; tasodifiy tarkib ko'payishi bilan crest-faktor pasayishi mumkin.
- Rivojlangan shikastlanish — keng polosali tasodifiy tebranish ustunlik qiladi; siljish darajalari ko'tariladi; harorat oshadi; eshitiladigan shovqin paydo bo'ladi. Nosozlik yaqin.
Konvert tahlilini qo'llash
Xom tezlanish signalini 2–8 kHz diapazonida (yoki eng yuqori podshipnik rezonansiga mos chastotada — uni zarba sinovi yoki spektrning o'zidan aniqlab oling) polosali filtr orqali o'tkazing. Hilbert-transformatsiyasi yordamida konvertni hisoblang. Konvertdan FFT oling. Agar BPFO, BPFI, BSF yoki FTF chastotalarida (va ularning garmonikalarida) cho'qqilar ko'rsangiz, podshipnik nuqsoni aniq tasdiqlangan.
7.2 Gear Faults and Shaft Problems
Tishli uzatma diagnostikasi
Asosiy tishlanish chastotasi (GMF) tishlar soni va valning aylanish chastotasi ko'paytmasiga teng. Sog'lom tishli uzatma past yon polosali toza tishlanish cho'qqisini beradi. Rivojlanayotgan nuqsonlar tishlanish amplitudasining oshishi, shikastlangan val chastotasiga mos yon polosalarning o'sishi va keyinchalik GMF ning yuqori garmonikalarining paydo bo'lishi bilan namoyon bo'ladi.
23-tooth pinion at 1 200 r/min (20 Hz) meshing with a 67-tooth wheel (6.87 Hz). GMF = 23 × 20 = 460 Hz. Sidebands at 460 ± 20 Hz indicate a developing pinion defect; sidebands at 460 ± 6.87 Hz point to the wheel.
Val va muftaning muammolari
| Nosozlik | Dominant chastota | Asosiy indikatorlar |
|---|---|---|
| Mass unbalance | 1× shaft speed | Radial tebranish; barqaror faza; amplituda ∝ tezlik² |
| Parallel noto'g'ri tekislash | 2× (+ 1×, 3×) | Yuqori radial tebranish; mufta bo'ylab 180° faza farqi |
| Burchakli noto'g'ri tekislash | 1× and 2× | Muftada yuqori aksial tebranish |
| Bent shaft | 1× and 2× | High 1× axial; 180° phase between bearings |
| Mexanik bo'shashish | 1× ning ko'plab garmonikalari | Subgarmonikalar (0,5×); beqaror faza; yo'nalishli |
| Rotor rub | Kasr garmonikalar | 0.5×, 1.5×, 2.5× etc.; truncated waveform |
Krylchatkaga / oqimga bog'liq muammolar
Blade-passing frequency (BPF) = number of blades × shaft frequency. Elevated BPF and its harmonics indicate impeller damage, diffuser–impeller gap issues, or inlet flow distortion. Cavitation produces broadband high-frequency noise — a "crackling" sound signature above 2 kHz with high kurtosis. Recirculation at low flow creates low-frequency random instability. On ships, remember that the propeller itself produces blade-rate vibration that propagates through the structure (see Section 3.2).
7.3 Severity Assessment and Prognosis
Nosozlikni aniqlash — bu ishning faqat yarmi. Texnik xizmat ko'rsatish jamoasi bilishi kerak: how fast nosozlik qanday rivojlanmoqda va how long mashina xavfsiz ishlashda davom eta oladimi.
Og'irlik ko'rsatkichlari
- Nosozlik chastotasi cho'qqisining amplitudasi uning boshlang'ich qiymatiga nisbatan
- Ushbu amplitudaning o'zgarish tezligi (trend egri chizig'ining qiyaligi)
- Garmonikalar va yon chastotalar soni hamda kuchi
- Qirra koeffitsienti va kurtosis progressiyasi
- ISO zona chegaralariga nisbatan umumiy tezlik yoki tezlanishning RMS qiymati
Prognoz usullari
Simple trending with linear or exponential extrapolation gives a rough remaining-life estimate. More sophisticated approaches include physics-based degradation models (e.g., spalling propagation under Hertzian stress) and data-driven models trained on run-to-failure datasets. In either case, predictions should carry explicit confidence intervals — a point estimate of "42 days remaining" is much less useful than "30–60 days at 90 % confidence".
| Severity Level | Tavsiya etilgan harakat | Odatiy vaqt oralig'i |
|---|---|---|
| Good | Oddiy monitoringni davom ettirish | Keyingi rejalashtirilgan o'lchov |
| Early fault | Monitoring chastotasini oshirish | Haftalik → ikki haftada bir |
| Developing | Texnik xizmat ko'rsatish bo'yicha chora-tadbirlarni rejalashtirish | Keyingi portga kirish yoki rejalashtirilgan to'xtatish |
| Advanced | Imkon qadar tezroq ta'mirni rejalashtirish | 1–2 hafta ichida |
| Critical | Yukni kamaytiring yoki to'xtating; shoshilinch ta'mirlash | Immediate |
8. Alignment and Balancing
Dengiz kemalarining aylanuvchi mexanizmlaridagi tebranish muammolarining eng katta ulushini bartaraf etadigan ikkita tuzatish chorasi.
8.1 Shaft Alignment
Ulangan vallar o'rtasidagi noto'g'ri markazlash dengiz mexanizmlaridagi tebranishning uchta asosiy sababidan biri hisoblanadi (muvozanatsizlik va podshipnik yeyilishi bilan bir qatorda). Bu podshipniklar, muhrlar va muftalar ustida haddan tashqari kuch hosil qiladi hamda 2× val aylanish tezligi bilan ajralib turadigan xarakterli tebranish spektrini vujudga keltiradi.
Noto'g'ri markazlash turlari
| Tur | Dominant tebranish | Yo'nalish | Faza belgisi |
|---|---|---|---|
| Parallel (siljish) | 2× RPM | Radial | Radial yo'nalishda mufta bo'ylab 180° siljish |
| Angular | 1× and 2× RPM | Axial | Aksial yo'nalishda mufta bo'ylab 180° siljish |
| Combined | 1× + 2× + higher | All | Murakkab; ko'p nuqtali o'lchash talab etiladi |
Statik va dinamik markazlash
Static alignment is measured when the machine is cold and at rest. Dynamic (operating) alignment can differ substantially because of thermal growth, foundation deflection under load, and piping forces that develop with temperature and pressure. A diesel generator, for instance, may grow 1–2 mm vertically at the coupling centre when the engine reaches operating temperature. On ships there is an extra layer: hull deflection with cargo and ballast condition changes shaft-line alignment between the laden and ballast voyage.
Example: 2 m steel shaft height, α = 12 × 10⁻⁶ /°C, ΔT = 50 °C → ΔL = 1.2 mm upward
Lazerli markazlash tizimlari kutilgan issiqlik uzayishini qoplash uchun sovuq holatdagi siljimalarni hisoblaydi, shunda markazlash ambient haroratida emas, balki ish haroratida to'g'ri bo'ladi.
Yumshoq tayanch
Agar bir yoki bir nechta mashina oyoqlari poydevorga to'g'ri tegmasa, mahkamlash vintini tortsangiz, rama deformatsiyalanadi, podshipniklarning markazlashi buziladi va tebranish xususiyatlari yuklanishga bog'liq tarzda o'zgaradi. "Yumshoq oyoq"ni aniqlash har qanday markazlash tartibidan oldingi birinchi qadam hisoblanadi: har bir vintni navbatma-navbat bo'shatib, dial-indikator yoki lazerli tizim yordamida siljishni o'lchang. Aniq shim plastinalari bilan tuzating.
8.2 Balancing Theory
Mass unbalance creates a centrifugal force that rotates with the shaft, producing vibration at 1× RPM. The force is proportional to ω², so a rotor that vibrates moderately at low speed may be destructive at high speed.
m — muvozanatsizlik massasi | r — radius | ω — burchak tezligi
Muvozanatsizlik turlari
- Statik — bitta og'ir nuqta; rotor pichoq qirralari ustida og'ir tomoni pastga tushgan holda to'xtaydi. Bitta tuzatish tekisligi yetarli.
- Couple — turli aksial tekisliklarda 180° burchak ostida joylashgan ikkita teng massa. Statik muvozanatsizlik yo'q, ammo rotor aylanish paytida tebranadi. Ikki tuzatish tekisligi talab etiladi.
- Dinamik — umumiy holat: statik va juftlik kombinatsiyasi. To'liq bartaraf etish uchun har doim ikki tekislikda tuzatish talab etiladi.
Balance Quality — ISO 21940-11 (formerly ISO 1940-1)
ISO 21940-11 defines permissible residual unbalance as a function of rotor mass and service speed, expressed as a balance quality grade G. The grade value equals the product euchun · ω in mm/s, where euchun is the permissible specific unbalance (displacement of the centre of mass from the shaft axis) and ω the angular velocity at service speed. In practical units:
G — balance quality grade [mm/s] | n — service speed [r/min]
| Daraja | euchun·ω (mm/s) | Typical Application (ISO 21940-11, Table 1) |
|---|---|---|
| G 0.4 | 0.4 | Gyroscopes, spindles and drives of high-precision systems |
| G 1.0 | 1.0 | Audio/video drives, grinding-machine drives |
| G 2.5 | 2.5 | Compressors, gas and steam turbines, electric motors above 950 r/min |
| G 6.3 | 6.3 | General machinery: pumps, fans, gears, electric motors, turbochargers, water turbines |
| G 16 | 16 | Drive shafts (cardan and propeller shafts), agricultural machinery, crushers |
| G 250 – G 4000 | 250 – 4000 | Crankshaft drives of large, slow marine diesel engines (grade depends on mounting and inherent balance) |
Sea-water pump rotor, mass 120 kg, service speed 2 950 r/min, specified grade G 6.3:
euchun = 9549 × 6.3 / 2950 ≈ 20.4 g·mm/kg → Uuchun = 20.4 × 120 ≈ 2 450 g·mm.
At a correction radius of 200 mm this corresponds to a residual mass of 2450 / 200 ≈ 12.2 g — the total allowed, typically split between two correction planes.
8.3 Field Balancing
Joylashmada balanslashtirish — mashinaning o'z podshipniklari va tayanch konstruktsiyalarida, real ish sharoitlarida balanssizlikni bartaraf etadi. Agar balanssizlik ishlab chiqarish nuqsonidan emas, balki foydalanish jarayonidagi ifloslangan, eroziya yoki termik deformatsiyadan kelib chiqqan bo'lsa, rotorni olib chiqib sex sharoitida balanslashtirish o'rniga joylashmada balanslashtirish deyarli doimo afzalroq hisoblanadi.
Bir tekislikda balanslashtirish tartibi (Ta'sir koeffitsienti usuli)
- 1× aylanish chastotasida dastlabki tebranish amplitudasi va fazasini o'lchang (boshlang'ich o'lchov rejimi).
- Rotorda ma'lum burchak holatida ma'lum og'irlikdagi sinov yukini mahkamlang.
- Mashinani ishga tushiring va tebranishni qayta o'lchang (sinov o'lchov rejimi).
- Ta'sir koeffitsientini hisoblang: berilgan radiusda bir birlik massa qo'yilganda tebranish qancha o'zgarishini aniqlang.
- Tebranishni nolga tushiradigan tuzatish massasi va burchagini hisoblang (vektor arifmetikasi).
- Sinov yukini olib tashlang, tuzatish yukini o'rnating va yakuniy o'lchov rejimi bilan tekshiring.
Ikki tekislikda balanslashtirish xuddi shu mantiqqa asoslanadi, ammo 2×2 ta'sir koeffitsienti tizimini yechadi va statik hamda juftlik komponentlarini bir vaqtda tuzatishga imkon beradi.
Balanset-1A — Ko'chma Balanslashtirish va Tebranish Tahlili Asbob-uskunasi
Vibromera's Balanset-1A is a portable instrument for single-plane and two-plane field balancing with built-in vibration measurement and FFT spectrum analysis: vibration velocity 0.2–80 mm/s RMS, frequency range 5–1000 Hz, laser tachometer 250–90 000 r/min, powered over USB from a laptop. It is used on fans, pumps, centrifuges, separators, shafts, and other rotating equipment in marine and industrial environments.
Dengiz sharoitiga xos muammolar
- Vessel motion — to'lqinlar va dvigateldan keladigan fon tebranishi 1× signalni yashirishi mumkin. Chora: ko'p aylanish davomida o'lchovlarni o'rtalashtirish, o'lchashni tinch sharoitda yoki portda rejalashtirish.
- Limited access — tuzatish tekisliklari korpus ichida joylashgan bo'lishi mumkin. Ko'pincha oldindan rejalashtirish va og'irlik biriktirish uchun maxsus usullar talab etiladi.
- Termik ta'sirlar — machines balanced cold may develop additional unbalance at operating temperature due to differential expansion. Ideally, verify balance at normal operating temperature.
8.4 Other Vibration Reduction Approaches
Balanslash va centerlashtirish tebranishni maqbul darajaga tushirmagan hollarda, bir nechta boshqa usullardan foydalanish mumkin.
Manba Modifikatsiyasi
Qo'zg'atuvchi kuchni kamaytirish uchun komponentni qayta loyihalash yoki modifikatsiya qilish — masalan, nasosda paqir bilan diffuzor orasidagi bo'shliqni optimallashtirish, ishlab chiqarish tolerantliklarini yaxshilash yoki kritik tezlikdan uzoqroq ish tezligini tanlash.
Qattiqlik va So'nishni O'zgartirish
Poydevorni mustahkamlash uning tabiiy chastotasini qo'zg'atuvchi chastotadan uzoqlashtiradi. So'nishni oshirish (qavatli ishlov berish, viskoelastik tayanch-amortizatorlar) rezonansdagi kuchayishni kamaytiradi. Har ikkala usul ham o'rnatilgandan keyin qo'llanilishi mumkin, ammo kemada poydevorni mustahkamlash konstruksiya massasi chegaralari bilan bog'liq.
Tebranish Izolyatsiyasi
Resilient mounts (rubber, spring, air) decouple the machine from the hull structure. Isolation becomes effective when the excitation frequency exceeds roughly √2 × the mount natural frequency. Marine isolators must also resist loads from vessel motion and tolerate corrosive atmospheres.
Sozlangan Absorberlar va Amortizatorlar
A tuned mass damper (TMD) — a small secondary mass-spring system tuned to the problem frequency — absorbs energy from the primary structure at that specific frequency. Effective for narrow-band problems such as a deck resonance excited by a generator or by propeller blade rate. The drawback is that each TMD addresses only one frequency.
9. Emerging Technologies
Dengiz tebranish diagnostikasi qayerga borayapti — simsiz sensorlar, chekka hisoblash, mashinali o'rganish va avtonom texnik xizmatga yo'l.
9.1 AI and Machine Learning
Mashinali o'rganish tebranish diagnostikasini qo'lda belgilangan qoidalar to'plamidan ma'lumotlarga asoslangan naqshlarni tanishga o'tkazmoqda. Eng dolzarb qo'llanmalar avtomatlashtirilgan nosozliklarni tasniflash va qolgan foydali xizmat muddatini bashorat qilishdir.
Classification
Yorliqli tebranish ma'lumotlari to'plamida o'qitilgan konvolyutsion neyron tarmoqlar (CNN) podshipnik, tishli uzatma, disbalans va noto'g'ri centrlash nosozliklarini tajribali tahlilchilar darajasida aniqlik bilan tasniflashi mumkin — agar o'quv ma'lumotlari haqiqiy ish sharoitlarini qamrab olsa. Transfer o'rganish va domenga moslashish sanoat ma'lumotlar to'plamida o'qitilgan modellardan boshlab va kema ma'lumotlari bilan nozik sozlash orqali cheklangan yorliqli dengiz ma'lumotlari muammosini hal qiladi.
Anomaliyalarni Aniqlash
Avtokodlovchilar va variatsion avtokodlovchilar normal tebranishning siqilgan tasvirini o'rganadi. Yangi o'lchov o'rgangan taqsimotdan tashqariga chiqsa, tizim uni anomal deb belgilaydi — barcha mumkin bo'lgan nosozlik turlarining oldingi namunalariga muhtoj bo'lmasdan. Bu, ayniqsa, kam uchraydigan ishdan chiqish rejimlari uchun juda qimmatlidir.
Digital Twins
A digital twin is a physics-based or hybrid model of a machine that runs in parallel with the real one, continuously updated with sensor data. Deviations between model predictions and real measurements indicate changing internal conditions. Digital twins enable scenario simulation ("what if we increase speed by 5 %?") and more reliable prognosis because they incorporate physics rather than relying solely on statistical extrapolation.
9.2 Wireless Sensors and Edge Computing
Simsiz tebranish sensorlari batareya muddati besh yildan oshadigan, aloqa ishonchliligi xavfsizlik bilan bog'liq bo'lmagan monitoring uchun yetarli bo'lgan va o'rnatilgan protsessor sensorga statistik parametrlarni mahalliy hisoblash, xom to'lqin shakllari o'rniga faqat xulosalar va signallarni uzatish imkonini beruvchi darajaga yetdi. Bu o'rnatish xarajatlarini sezilarli darajada kamaytiradi — kabel yo'q, kanal yo'q, tarmoq qutilar yo'q — va avval kuzatilmagan yuzlab yordamchi mashinalarni monitoring qilishni iqtisodiy jihatdan maqsadga muvofiq qiladi.
Chekka hisoblash ishlov berish quvvatini sensorda yoki unga yaqin joyda joylashtiradi va qirg'oqdagi bulut ulanishiga tayanmasdan real vaqt rejimida signal berish, mahalliy FFT va hatto neyron tarmoq inferensiyasini amalga oshirish imkonini beradi. Bu, sun'iy yo'ldosh kanalining kengligi cheklangan kunlar yoki haftalar davomida suv ustida sayohat qiladigan kemalar uchun muhimdir.
9.3 Autonomous Diagnostics and Integration
Uzoq muddatli tendentsiya minimal inson aralashuvi bilan aniqlash, tashxislash va harakat qiluvchi tizimlarga qarab yo'nalmoqda:
- O'z-o'zini kalibrlash sensörlari o'z holatini tekshiradigan va siljishni kompensatsiya qiladigan.
- Avtomatik nosozlik diagnostikasi kemaning rejalashtirilgan texnik xizmat ko'rsatish tizimi bilan integratsiyalashgan — podshipnikdagi nuqson aniqlanishi avtomatik ravishda ish buyrug'ini yaratadi, ehtiyot qismlar ombori mavjudligini tekshiradi va texnik xizmat ko'rsatish oynasini taklif qiladi.
- Butun flot bo'yicha tahlil — butun flot bo'ylab bir xil turdagi uskunalarni taqqoslash, bitta kema monitoringi aniqlay olmaydigan tizimli muammolarni (podshipniklarning yomon partiyasi, konstruktsiyaviy rezonans) aniqlaydi.
- Ko'p parametrli birlashma — tebranish, yog' tahlili, termografiya va ishlash ma'lumotlarini bitta holat indeksida birlashtirish, har qanday alohida usulga qaraganda yanada ishonchli holat baholashini ta'minlaydi.
Classification societies (DNV, Lloyd's Register, Bureau Veritas, ABS) maintain rules and class notations that recognise condition-based maintenance as an alternative to fixed-interval surveys. Robust, auditable vibration monitoring programmes are becoming a regulatory enabler, not just a cost-saving tool.
Qo'llashga Tayyorgarlik
Texnologiyaning o'zi yetarli emas. Muvaffaqiyatli qo'llash uchun kadrlarni rivojlantirish (algoritmlar emas, kalit bilan ishlashga o'rganib qolgan muhandislar uchun ma'lumot savodxonligi bo'yicha treninglar), kiberxavfsizlikni rejalashtirish (ulangan monitoring tizimlari hujum yuzasidir) va bosqichma-bosqich yondashuv talab etiladi — bir necha kemada pilot loyiha, qiymatni isbotlash, so'ngra kengaytirish.
10. Tez-tez so'raladigan savollar
Short answers to the questions marine engineers ask most often about vibration diagnostics.
Which ISO standards apply to vibration of marine machinery?
The general framework is the ISO 20816 series (formerly ISO 10816) for vibration measured on non-rotating parts. Ship-specific measurement is covered by the ISO 20283 series: Part 2 for structural vibration, Part 3 for pre-installation testing of shipboard equipment, Part 4 for propulsion machinery, and Part 5 for habitability. Reciprocating machines above 100 kW — including marine diesel engines — fall under ISO 10816-6, and generating sets under ISO 8528-9. Rotor balance quality is specified in ISO 21940-11 (formerly ISO 1940-1).
What vibration level is acceptable for a shipboard pump or motor?
It depends on the machine's power rating and mounting. As one example, for a medium machine (15–300 kW) on rigid supports under ISO 10816-3 / ISO 20816-3, up to 1.4 mm/s RMS is zone A (good), 1.4–2.8 mm/s is zone B (acceptable for unrestricted long-term operation), 2.8–4.5 mm/s is zone C (plan remedial work), and above 4.5 mm/s is zone D (risk of damage). Larger machines and flexibly mounted machines have higher limits — always check the group and support class that actually apply.
How is the blade-passing frequency of a propeller calculated?
Multiply the number of blades by the shaft speed in revolutions per second: BPF = Z × n / 60, with n in r/min. A four-blade propeller at 120 r/min gives 4 × 2 = 8 Hz, with harmonics at 16 and 24 Hz. These low frequencies can excite hull and deckhouse resonances, so elevated blade-rate vibration on aft-ship machinery does not necessarily indicate a fault in that machine.
Can a rotor be balanced on board without dismantling it?
Yes — this is field balancing. Using a portable instrument with vibration sensors and a tachometer, the influence-coefficient method needs only a reference run and one trial run per correction plane to compute the correction mass and angle. It corrects the rotor in its own bearings under real operating conditions, which is usually preferable to shop balancing when unbalance is caused by in-service fouling, erosion, or blade damage.
How often should vibration measurements be taken on ship machinery?
Critical propulsion and power-generation machinery is typically monitored continuously or on a weekly route; auxiliary pumps, fans, compressors, and separators monthly to quarterly. The interval should shorten as soon as a parameter starts trending upward — a machine in "early fault" state deserves weekly or even continuous attention until the fault is understood.
ISO 10816 va ISO 20816 o'rtasidagi farq nima?
ISO 20816 is the successor series that progressively replaces both ISO 10816 (vibration on non-rotating parts) and ISO 7919 (shaft vibration), combining them in one framework. ISO 20816-1:2016 replaced ISO 10816-1 and ISO 7919-1; ISO 20816-3:2022 replaced ISO 10816-3. The four-zone evaluation concept (A–D) is unchanged; references in older documentation to ISO 10816 zone values generally remain usable, but new specifications should cite ISO 20816.
Do sea state and vessel motion affect vibration readings?
Yes. Wave-induced hull vibration, slamming, and load changes raise background levels, particularly at low frequencies. Good practice is to log sea state, speed, and load with every measurement, take routine readings under repeatable conditions (calm water, steady load) where possible, and flag or exclude data collected in heavy weather from trend analysis.
Which sensor should be used for engine-room measurements?
An IEPE piezoelectric accelerometer is the default choice: robust, broadband (typically 1 Hz–10 kHz), and tolerant of long cable runs in electrically noisy environments. Use stud or adhesive mounting for bearing diagnostics above 2–3 kHz; magnetic mounts are acceptable for broadband velocity readings. Proximity probes are reserved for journal-bearing turbomachinery where shaft-relative motion matters.
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