{"id":100223,"date":"2026-02-15T20:28:12","date_gmt":"2026-02-15T20:28:12","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100223"},"modified":"2026-03-05T15:43:12","modified_gmt":"2026-03-05T15:43:12","slug":"shaft-diameter-torsion","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/nb\/calculators\/shaft-diameter-torsion\/","title":{"rendered":"Kalkulator for akseldiameter for torsjon | Gratis verkt\u00f8y"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Shaft Diameter for Torsion Calculator\",\"alternateName\":[\"Torsion Shaft Calculator\",\"Shaft Sizing Calculator\"],\"description\":\"Calculate minimum shaft diameter for pure torsion loading. Enter torque and allowable shear stress.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/shaft-diameter-torsion\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2024-01-01\",\"dateModified\":\"2025-06-01\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"Solid and hollow shaft\",\"Multiple material presets\",\"Safety factor display\",\"Auto-calculation\"],\"keywords\":\"shaft diameter, torsion, shear stress, torque, shaft design\"}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What is the formula for minimum shaft diameter under torsion?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"For a solid circular shaft: d = \u221b(16T\/(\u03c0\u03c4_all)), where T is the applied torque and \u03c4_all is the allowable shear stress. This comes from the torsion formula \u03c4 = Tc\/J = 16T\/(\u03c0d\u00b3) for a solid shaft.\"}},\n{\"@type\":\"Question\",\"name\":\"How do I choose the allowable shear stress?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The allowable shear stress is typically 50-60% of the tensile yield strength: \u03c4_all = 0.577 \u00d7 \u03c3_y (von Mises criterion). For steel AISI 1045: \u03c4_all \u2248 180 MPa. Apply a safety factor of 1.5-3.0 depending on application criticality and loading type.\"}},\n{\"@type\":\"Question\",\"name\":\"How does a hollow shaft compare to a solid shaft?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"A hollow shaft with the same outer diameter has slightly less torsional strength but much less weight. The strength ratio is (1-k\u2074) where k = d_i\/d_o. For k = 0.5 (ID = half OD), you retain 93.75% of strength at about 75% of the weight.\"}},\n{\"@type\":\"Question\",\"name\":\"Should I account for keyways and stress concentrations?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. Keyways reduce shaft strength by 25-50% depending on type. Apply a stress concentration factor Kt (typically 1.6-3.0 for keyways). The effective stress becomes \u03c4_eff = Kt \u00d7 \u03c4. Size the shaft for the concentrated stress or reduce the allowable stress accordingly.\"}},\n{\"@type\":\"Question\",\"name\":\"What about combined bending and torsion?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"When both bending moment M and torque T act, use the equivalent torque: T_eq = \u221a(M\u00b2 + T\u00b2) for maximum shear stress theory, or T_eq = \u221a(M\u00b2 + 0.75T\u00b2) for von Mises criterion. Then size the shaft using T_eq in place of T.\"}}\n]}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[\n{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},\n{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},\n{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Shaft Diameter for Torsion\",\"item\":\"https:\/\/vibromera.eu\/calculators\/shaft-diameter-torsion\/\"}\n]}\n<\/script>\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n\n<link 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strong{color:var(--vc-ink)}.vc-promo-link{padding:8px 20px;font-size:13px;font-weight:700;color:#fff;background:var(--vc-accent);border-radius:var(--vc-radius);text-decoration:none;white-space:nowrap;transition:background .15s}.vc-promo-link:hover{background:var(--vc-accent-hover)}\n.vc-footer{text-align:center;padding:32px 16px;font-size:13px;color:var(--vc-ink-muted)}.vc-footer a{color:var(--vc-accent);text-decoration:none}.vc-footer a:hover{text-decoration:underline}.vc-footer-links{margin-top:8px;font-size:12px}.vc-footer-links a{margin:0 8px}\n@media print{.vc-section-body{max-height:none!important}.vc-faq-a{max-height:none!important}.vc-results{max-height:none!important;padding:24px!important}.vc-copy-btn,.vc-section-chevron,.vc-faq-chevron,.vc-presets,.vc-promo{display:none!important}}\n<\/style>\n\n<div class=\"vc-calculator\" id=\"vc-shaft-torsion\">\n\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool #071<\/p>\n    <h1 class=\"vc-header-title\">Shaft Diameter for Torsion Calculator<\/h1>\n    <p class=\"vc-header-subtitle\">Calculate the minimum shaft diameter required to transmit a given torque. Enter torque, allowable shear stress, and material to get the required diameter with safety factor.<\/p>\n    <div class=\"vc-badges\"><span class=\"vc-badge\">Shafts &amp; Rotors<\/span><span class=\"vc-badge\">Solid &amp; Hollow<\/span><span class=\"vc-badge\">Auto-Calc<\/span><\/div>\n<\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-T\">Torque T <span class=\"vc-label-hint\">(N\u00b7m)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-T\" inputmode=\"decimal\" step=\"any\" min=\"0.1\" placeholder=\"e.g. 500\" value=\"500\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-tau\">Allowable Shear Stress \u03c4<sub>all<\/sub> <span class=\"vc-label-hint\">(MPa)<\/span><\/label>\n                <select class=\"vc-select\" id=\"vc-tau\">\n                    <option value=\"40\">Mild Steel (AISI 1020) \u2014 40 MPa<\/option>\n                    <option value=\"80\" selected>Med Carbon (AISI 1045) \u2014 80 MPa<\/option>\n                    <option value=\"110\">Alloy Steel (4140) \u2014 110 MPa<\/option>\n                    <option value=\"140\">High-Strength (4340) \u2014 140 MPa<\/option>\n                    <option value=\"25\">Stainless 304 \u2014 25 MPa<\/option>\n                    <option value=\"custom\">Custom value&#8230;<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\" id=\"vc-custom-tau-field\" style=\"display:none\">\n                <label class=\"vc-label\" for=\"vc-tau-custom\">Custom \u03c4<sub>all<\/sub> <span class=\"vc-label-hint\">(MPa)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-tau-custom\" inputmode=\"decimal\" step=\"any\" min=\"1\" placeholder=\"e.g. 60\" value=\"60\">\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-sf\">Safety Factor<\/label>\n                <select class=\"vc-select\" id=\"vc-sf\">\n                    <option value=\"1.5\">1.5 \u2014 Steady load, known conditions<\/option>\n                    <option value=\"2.0\" selected>2.0 \u2014 Normal service<\/option>\n                    <option value=\"2.5\">2.5 \u2014 Shock\/impact possible<\/option>\n                    <option value=\"3.0\">3.0 \u2014 Heavy shock, uncertain loads<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-hollow\">Shaft Type<\/label>\n                <select class=\"vc-select\" id=\"vc-hollow\">\n                    <option value=\"0\" selected>Solid shaft<\/option>\n                    <option value=\"0.3\">Hollow \u2014 k = 0.3 (d_i\/d_o)<\/option>\n                    <option value=\"0.5\">Hollow \u2014 k = 0.5<\/option>\n                    <option value=\"0.7\">Hollow \u2014 k = 0.7<\/option>\n                <\/select>\n            <\/div>\n        <\/div>\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-T=\"100\" data-tau=\"80\" data-sf=\"2.0\" data-k=\"0\">Small motor 100 N\u00b7m<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-T=\"500\" data-tau=\"80\" data-sf=\"2.0\" data-k=\"0\">Pump drive 500 N\u00b7m<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-T=\"5000\" data-tau=\"110\" data-sf=\"2.5\" data-k=\"0\">Industrial 5 kN\u00b7m<\/button>\n        <\/div>\n    <\/form>\n\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\">\n            <h2 class=\"vc-results-title\">Results<\/h2>\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\"><svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy<\/button>\n        <\/div>\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\">\n                <div class=\"vc-rcard-label\">Minimum Shaft Diameter<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-d\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Actual Shear Stress<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-tau\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Safety Factor Applied<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-sf\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Polar Moment J<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-J\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Angle of Twist (per m)<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-theta\">\u2014<\/div>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Theory &amp; Formulas<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner vc-theory\">\n            <h3>Minimum Diameter (Solid Shaft)<\/h3>\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n            <h3>Hollow Shaft<\/h3>\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n            <h3>Angle of Twist<\/h3>\n            <div class=\"vc-formula-box\" id=\"vc-katex-3\"><\/div>\n            <table class=\"vc-table\">\n                <thead><tr><th>Material<\/th><th>\u03c3_y (MPa)<\/th><th>\u03c4_all (MPa)<\/th><th>G (GPa)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>AISI 1020 (mild)<\/td><td>210<\/td><td>40<\/td><td>79<\/td><\/tr>\n                    <tr><td>AISI 1045 (medium)<\/td><td>310<\/td><td>80<\/td><td>79<\/td><\/tr>\n                    <tr><td>AISI 4140 (alloy)<\/td><td>415<\/td><td>110<\/td><td>80<\/td><\/tr>\n                    <tr><td>AISI 4340 (high-str)<\/td><td>470<\/td><td>140<\/td><td>80<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n            <div class=\"vc-warning-box\"><p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary);\"><strong>\u26a0\ufe0f Note:<\/strong> This calculator sizes for pure torsion only. For combined bending + torsion, use the equivalent torque method. Always account for keyways and stress concentrations.<\/p><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section\" id=\"vc-sec-related\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udd17<\/span><span class=\"vc-section-title\">Related Calculators<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-related\">\n        <a class=\"vc-related-link\" href=\"\/calculators\/shaft-deflection-calculator\/\">Shaft Deflection<\/a>\n        <a class=\"vc-related-link\" href=\"\/calculators\/keyway-calculator\/\">Keyway Calculator<\/a>\n        <a class=\"vc-related-link\" href=\"\/calculators\/press-fit-calculator\/\">Press-Fit Calculator<\/a>\n        <a class=\"vc-related-link\" href=\"\/calculators\/rotor-moment-of-inertia\/\">Rotor Moment of Inertia<\/a>\n    <\/div><\/div><\/div>\n<\/div>\n\n<div class=\"vc-section\" id=\"vc-sec-faq\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\u2753<\/span><span class=\"vc-section-title\">Frequently Asked Questions<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button>\n    <div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div><\/div><\/div>\n<\/div>\n\n<div class=\"vc-promo\"><div class=\"vc-promo-text\"><strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>Professional field balancing instruments and software.<\/div><a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a><\/div>\n\n<footer class=\"vc-footer\"><p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p><p style=\"font-size:12px;margin-top:4px;\">Shaft diameter for torsion. Last updated: June 2025<\/p><div class=\"vc-footer-links\"><a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a><a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a><\/div><\/footer>\n<\/div>\n\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\n<script>\n(function(){\n    'use strict';\n    var SLUG='shaft-diameter-torsion';\n    function $(id){return document.getElementById(id)}\n    function fmt(n,d){if(isNaN(n)||!isFinite(n))return '\u2014';var f=n.toFixed(d===undefined?2:d);return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'')}\n\n    \/\/ G values in GPa by tau\n    var Gmap={'40':79,'80':79,'110':80,'140':80,'25':77,'custom':79};\n\n    $('vc-tau').addEventListener('change',function(){\n        $('vc-custom-tau-field').style.display=this.value==='custom'?'flex':'none';\n    });\n\n    function calculate(){\n        var T=parseFloat($('vc-T').value); \/\/ N\u00b7m\n        var tauSel=$('vc-tau').value;\n        var tauAll=tauSel==='custom'?parseFloat($('vc-tau-custom').value):parseFloat(tauSel);\n        var sf=parseFloat($('vc-sf').value);\n        var k=parseFloat($('vc-hollow').value);\n        if(!T||T<=0||!tauAll||tauAll<=0){$('vc-results').classList.remove('vc-visible');return}\n\n        var tauDesign=tauAll\/sf; \/\/ MPa\n        var Tmm=T*1000; \/\/ N\u00b7mm\n\n        var dMin;\n        if(k===0){\n            dMin=Math.pow(16*Tmm\/(Math.PI*tauDesign),1\/3);\n        } else {\n            dMin=Math.pow(16*Tmm\/(Math.PI*tauDesign*(1-Math.pow(k,4))),1\/3);\n        }\n\n        \/\/ Round up to nearest mm\n        var dRound=Math.ceil(dMin);\n\n        \/\/ Actual stress with rounded diameter\n        var J;\n        if(k===0){\n            J=Math.PI*Math.pow(dRound,4)\/32;\n        } else {\n            var di=k*dRound;\n            J=Math.PI*(Math.pow(dRound,4)-Math.pow(di,4))\/32;\n        }\n        var tauActual=Tmm*dRound\/2\/J; \/\/ MPa\n\n        \/\/ Angle of twist per meter\n        var G=(Gmap[tauSel]||79)*1000; \/\/ MPa\n        var thetaRad=Tmm*1000\/(G*J); \/\/ rad\/m (T in N\u00b7mm, L=1000mm)\n        var thetaDeg=thetaRad*180\/Math.PI;\n\n        $('vc-r-d').innerHTML=fmt(dMin,1)+' <span class=\"vc-rcard-unit\">mm<\/span> <span class=\"vc-rcard-unit\">(round up: '+dRound+' mm)<\/span>';\n        $('vc-r-tau').innerHTML=fmt(tauActual,1)+' <span class=\"vc-rcard-unit\">MPa<\/span> <span class=\"vc-rcard-unit\">(allow: '+fmt(tauAll,0)+' MPa)<\/span>';\n        $('vc-r-sf').innerHTML=fmt(sf,1)+' <span class=\"vc-rcard-unit\">(design \u03c4 = '+fmt(tauDesign,1)+' MPa)<\/span>';\n        $('vc-r-J').innerHTML=fmt(J,0)+' <span class=\"vc-rcard-unit\">mm\u2074<\/span>';\n        $('vc-r-theta').innerHTML=fmt(thetaDeg,3)+' <span class=\"vc-rcard-unit\">\u00b0\/m<\/span>';\n        $('vc-results').classList.add('vc-visible');\n\n        saveHistory({T:T,tau:tauAll,sf:sf,d:fmt(dMin,1),_summary:'T='+T+' N\u00b7m \u2192 d='+fmt(dMin,1)+' mm'});\n    }\n\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn){btn.addEventListener('click',function(e){e.preventDefault();$('vc-T').value=this.getAttribute('data-T');$('vc-tau').value=this.getAttribute('data-tau');$('vc-sf').value=this.getAttribute('data-sf');$('vc-hollow').value=this.getAttribute('data-k');$('vc-custom-tau-field').style.display='none';calculate()})});\n\n    $('vc-form').addEventListener('input',calculate);\n    $('vc-form').addEventListener('change',calculate);\n\n    $('vc-copy-btn').addEventListener('click',function(){\n        var text='Shaft Diameter (Torsion)\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nTorque: '+$('vc-T').value+' N\u00b7m\\nMin Diameter: '+$('vc-r-d').textContent+'\\nShear Stress: '+$('vc-r-tau').textContent+'\\nSafety Factor: '+$('vc-r-sf').textContent+'\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nvibromera.eu';\n        if(navigator.clipboard){navigator.clipboard.writeText(text).then(function(){var b=$('vc-copy-btn');b.classList.add('vc-copied');b.innerHTML='<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><polyline points=\"20 6 9 17 4 12\"\/><\/svg> Copied!';setTimeout(function(){b.classList.remove('vc-copied');b.innerHTML='<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy'},2000)})}\n    });\n\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn){btn.addEventListener('click',function(){var s=this.closest('.vc-section');s.classList.toggle('vc-open');this.setAttribute('aria-expanded',s.classList.contains('vc-open'))})});\n\n    var faqData=[\n        {q:'What is the formula for minimum shaft diameter under torsion?',a:'<p>For a solid shaft: d = \u221b(16T\/(\u03c0\u03c4_all)). This comes from the torsion formula \u03c4 = 16T\/(\u03c0d\u00b3). Apply a safety factor by using \u03c4_design = \u03c4_all \/ SF.<\/p>'},\n        {q:'How do I choose the allowable shear stress?',a:'<p>Allowable shear stress is typically 50\u201360% of tensile yield: \u03c4_all \u2248 0.577 \u00d7 \u03c3_y (von Mises). Apply safety factor 1.5\u20133.0 depending on application.<\/p>'},\n        {q:'How does a hollow shaft compare to solid?',a:'<p>A hollow shaft with k = d_i\/d_o = 0.5 retains 93.75% of torsional strength at about 75% of the weight. The diameter increases by factor 1\/(1\u2212k\u2074)^(1\/3).<\/p>'},\n        {q:'Should I account for keyways?',a:'<p>Yes. Keyways reduce shaft strength by 25\u201350%. Apply stress concentration factor Kt (typically 1.6\u20133.0). Size the shaft accordingly or reduce allowable stress.<\/p>'},\n        {q:'What about combined bending and torsion?',a:'<p>Use equivalent torque: T_eq = \u221a(M\u00b2 + T\u00b2) for max shear stress theory, or T_eq = \u221a(M\u00b2 + 0.75T\u00b2) for von Mises. Then size using T_eq.<\/p>'}\n    ];\n    var fl=$('vc-faq-list');faqData.forEach(function(f){fl.innerHTML+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>'+f.q+'<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">'+f.a+'<\/div><\/div><\/div>'});\n    fl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(!b)return;b.closest('.vc-faq-item').classList.toggle('vc-open')});\n\n    function saveHistory(entry){var key='vc_history_'+SLUG;var arr=[];try{arr=JSON.parse(localStorage.getItem(key))||[]}catch(e){}entry._ts=new Date().toISOString();arr.unshift(entry);if(arr.length>10)arr=arr.slice(0,10);try{localStorage.setItem(key,JSON.stringify(arr))}catch(e){}}\n\n    function renderFormulas(){\n        try{\n            katex.render('d = \\\\sqrt[3]{\\\\frac{16T}{\\\\pi \\\\tau_{all}\/SF}}',$('vc-katex-1'),{displayMode:true,throwOnError:false});\n            katex.render('d_o = \\\\sqrt[3]{\\\\frac{16T}{\\\\pi \\\\tau_{design}(1-k^4)}}, \\\\quad k = \\\\frac{d_i}{d_o}',$('vc-katex-2'),{displayMode:true,throwOnError:false});\n            katex.render('\\\\theta = \\\\frac{TL}{GJ} \\\\quad [\\\\text{rad}]',$('vc-katex-3'),{displayMode:true,throwOnError:false});\n        }catch(e){}\n    }\n\n    function init(){renderFormulas();calculate()}\n    if(document.readyState==='loading'){document.addEventListener('DOMContentLoaded',init)}else{init()}\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Gratis online kalkulator for minimum akseldiameter under torsjon. 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