How do I select the right vibration mount?

Select vibration mounts based on the machine mass, operating frequency, and desired isolation percentage. The mount must have a natural frequency well below the disturbing frequency — typically fn ≤ fd/√2 for any isolation, and fn ≤ fd/3 for 90% isolation.

What isolation percentage should I target?

For general machinery, 80-90% isolation is typical. For sensitive equipment near precision instruments, 95%+ is desired. The higher the isolation percentage, the softer (lower stiffness) the mounts must be, which increases static deflection.

靜態撓度與自然頻率之間有何關係？

Natural frequency fn = (1/2π)√(g/δst), where δst is static deflection and g is gravitational acceleration. A static deflection of ~25 mm gives fn ≈ 3.1 Hz. Softer mounts (more deflection) give lower natural frequency and better isolation.

How many mounts should I use?

Typically 4 mounts for rectangular machines (one per corner). Use 3 for triangular arrangements, 6 for large machines or when load distribution is uneven. Each mount carries a fraction of the total load.

What happens if mounts are too soft or too stiff?

Too stiff: insufficient isolation, vibration transmitted to the foundation. Too soft: excessive static deflection, potential instability, and amplification at resonance during startup/shutdown. The mount must be stiff enough to support the load with acceptable deflection.

免費工程工具 #063

振動安裝座選型計算器

根據機器質量、運轉頻率及目標隔振率選取振動隔振座。計算所需隔振座剛性、隔振座數量及靜態撓度。

隔振設計傳遞率自動計算

結果

總需求剛性

—

單個隔振座剛性

—

自然頻率

—

靜態撓度

—

傳遞率

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傳遞率

傳遞率 T 定義了透過隔振座傳遞的振動力比例：

其中 r = f/f_n 為頻率比。對於隔振 (T < 1)，需滿足 r > √2。

所需自然頻率

根據目標隔振率，所需的自然頻率為：

需求剛性

靜態撓度

範例 — 泵使用 4 個隔振座

已知： 機器質量 = 500 kg，運轉頻率 = 25 Hz，目標隔振率 = 90%，4 個隔振座

T = 1 − 0.90 = 0.10

r = √(1/T + 1) = √(11) = 3.317

f_n = 25 / 3.317 = 7.54 Hz

k_總 = m × (2πf_n)² = 500 × (2π × 7.54)² = 1,122 kN/m

k_{單個隔振座} = 1122 / 4 = 280.5 kN/m ≈ 280.5 N/mm

靜態撓度 = mg/k = 500 × 9.81 / 1,122,000 = 4.37 mm

⚠️ 注意： 此計算器假設為無阻尼單自由度隔振。實際隔振座具有阻尼，可降低共振放大效應，但會略微降低高頻隔振效果。

振動隔振座選型計算器 | 免費線上工具 #063

結果

傳遞率

所需自然頻率

需求剛性

靜態撓度

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