{"id":100248,"date":"2026-02-15T20:29:37","date_gmt":"2026-02-15T20:29:37","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100248"},"modified":"2026-03-05T15:40:46","modified_gmt":"2026-03-05T15:40:46","slug":"stress-concentration-factor","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/nb\/calculators\/stress-concentration-factor\/","title":{"rendered":"Kalkulator for stresskonsentrasjonsfaktor i Kt | Vibromera"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Stress Concentration Factor Calculator\",\"description\":\"Kt calculator for common geometries: hole in plate, shoulder fillet, U-notch, V-notch.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/stress-concentration-factor\/\",\"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\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What is stress concentration factor Kt?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Kt is the ratio of maximum local stress to nominal stress at a geometric discontinuity. Kt = \u03c3_max \/ \u03c3_nom. It depends only on geometry, not material. A circular hole in a wide plate under tension has Kt \u2248 3.0.\"}},\n{\"@type\":\"Question\",\"name\":\"What causes stress concentrations?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Any abrupt change in geometry: holes, notches, fillets, keyways, threads, grooves, changes in cross-section. The stress flow lines crowd together at these features, increasing local stress.\"}},\n{\"@type\":\"Question\",\"name\":\"How does Kt affect fatigue life?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Stress concentrations dramatically reduce fatigue life because fatigue cracks initiate at the point of highest stress. The fatigue notch factor Kf \u2264 Kt accounts for material sensitivity: Kf = 1 + q(Kt-1), where q is the notch sensitivity factor.\"}},\n{\"@type\":\"Question\",\"name\":\"How can stress concentrations be reduced?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Use generous fillet radii, avoid sharp corners, use gradual transitions, add relief grooves near shoulders, polish surfaces at critical points, and use shot peening to introduce beneficial compressive residual stress.\"}},\n{\"@type\":\"Question\",\"name\":\"What is Peterson's Stress Concentration Factors?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Peterson's is the definitive reference book containing charts and equations for Kt values for hundreds of geometric configurations. It provides Kt as a function of geometric ratios (r\/d, D\/d, etc.) for tension, bending, and torsion loading.\"}}\n]}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Stress Concentration Factor\",\"item\":\"https:\/\/vibromera.eu\/calculators\/stress-concentration-factor\/\"}]}\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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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}@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-scf\">\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool<\/p>\n    <h1 class=\"vc-header-title\">Stress Concentration Factor Calculator<\/h1>\n    <p class=\"vc-header-subtitle\">Look up Kt for common geometries \u2014 hole in plate, shoulder fillet, U-notch \u2014 using simplified Peterson&#8217;s chart data.<\/p>\n    <div class=\"vc-badges\"><span class=\"vc-badge\">Peterson&#8217;s Charts<\/span><span class=\"vc-badge\">Kt Lookup<\/span><span class=\"vc-badge\">#173<\/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 vc-field-full\">\n                <label class=\"vc-label\" for=\"vc-geom\">Geometry<\/label>\n                <select class=\"vc-select\" id=\"vc-geom\">\n                    <option value=\"hole\" selected>Central Hole in Flat Plate (tension)<\/option>\n                    <option value=\"shoulder\">Shoulder Fillet \u2014 Stepped Round Bar (tension)<\/option>\n                    <option value=\"notch\">U-Notch in Flat Plate (tension)<\/option>\n                    <option value=\"groove\">Circumferential Groove in Round Bar (tension)<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-W\">Width W or D_major <span class=\"vc-label-hint\">(mm)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-W\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 100\" value=\"100\"><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-d\" id=\"vc-d-label\">Hole dia d or d_minor <span class=\"vc-label-hint\">(mm)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-d\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 20\" value=\"20\"><\/div>\n            <div class=\"vc-field\" id=\"vc-field-r\"><label class=\"vc-label\" for=\"vc-r\">Fillet\/Notch Radius r <span class=\"vc-label-hint\">(mm)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-r\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 5\" value=\"5\"><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-snom\">Nominal Stress \u03c3_nom <span class=\"vc-label-hint\">(MPa, optional)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-snom\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 100\" value=\"100\"><\/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-geom=\"hole\" data-W=\"100\" data-d=\"10\" data-r=\"5\">Plate W=100, hole d=10<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-geom=\"shoulder\" data-W=\"50\" data-d=\"30\" data-r=\"3\">Shaft D=50\u2192d=30, r=3<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-geom=\"notch\" data-W=\"80\" data-d=\"60\" data-r=\"5\">Notch plate W=80, d=60, r=5<\/button>\n        <\/div>\n    <\/form>\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Results<\/h2><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><\/div>\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Stress Concentration Factor Kt<\/div><div class=\"vc-rcard-value\" id=\"vc-r-Kt\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Max Local Stress \u03c3_max<\/div><div class=\"vc-rcard-value\" id=\"vc-r-smax\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Geometry Ratio<\/div><div class=\"vc-rcard-value\" id=\"vc-r-ratio\">\u2014<\/div><\/div>\n        <\/div>\n        <div class=\"vc-viz\" id=\"vc-viz\" style=\"text-align:center;margin:16px 0 8px\"><\/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\"><div class=\"vc-section-inner vc-theory\">\n        <h3>Stress Concentration Factor<\/h3>\n        <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n        <h3>Typical Kt Values<\/h3>\n        <table class=\"vc-table\">\n            <thead><tr><th>Geometry<\/th><th>Kt Range<\/th><\/tr><\/thead>\n            <tbody>\n                <tr><td>Central hole in wide plate<\/td><td>~3.0 (small d\/W)<\/td><\/tr>\n                <tr><td>Shoulder fillet (D\/d=2, r\/d=0.1)<\/td><td>~1.8\u20132.5<\/td><\/tr>\n                <tr><td>U-notch<\/td><td>~1.5\u20133.5<\/td><\/tr>\n                <tr><td>Circumferential groove<\/td><td>~1.5\u20133.0<\/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> These are approximate values from simplified curve-fit equations. For precise values, consult Peterson&#8217;s Stress Concentration Factors or perform FEA. Kt is for elastic analysis only.<\/p><\/div>\n    <\/div><\/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\/stress-calculator\/\">Stress Calculator<\/a><a class=\"vc-related-link\" href=\"\/calculators\/fatigue-life-calculator\/\">Fatigue Life<\/a><a class=\"vc-related-link\" href=\"\/calculators\/safety-factor-calculator\/\">Safety Factor<\/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. Used in 50+ countries.<\/div><a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a><\/div>\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;\">Peterson&#8217;s SCF simplified data. Last updated: February 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';var SLUG='stress-concentration-factor';\nfunction $(id){return document.getElementById(id)}\nfunction fmt(n,d){if(isNaN(n)||!isFinite(n))return'\u2014';var f=n.toFixed(d===undefined?2:d);return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'')}\n\nfunction updateUI(){\n    var g=$('vc-geom').value;\n    $('vc-field-r').style.display=(g==='hole')?'none':'';\n    $('vc-d-label').innerHTML=g==='hole'?'Hole Diameter d <span class=\"vc-label-hint\">(mm)<\/span>':g==='shoulder'?'Minor Diameter d <span class=\"vc-label-hint\">(mm)<\/span>':'Net Width d <span class=\"vc-label-hint\">(mm)<\/span>';\n}\n\nfunction calculate(){\n    updateUI();\n    var g=$('vc-geom').value;\n    var W=parseFloat($('vc-W').value),d=parseFloat($('vc-d').value),r=parseFloat($('vc-r').value),snom=parseFloat($('vc-snom').value);\n    if(!W||W<=0||!d||d<=0||d>=W){$('vc-results').classList.remove('vc-visible');return}\n    var Kt,ratioLabel;\n    switch(g){\n        case'hole':\n            \/\/ Howland: Kt = 3.0 - 3.13(d\/W) + 3.66(d\/W)^2 - 1.53(d\/W)^3  (for \u03c3_nom on net section)\n            var dW=d\/W;\n            Kt=3.0-3.13*dW+3.66*dW*dW-1.53*dW*dW*dW;\n            \/\/ Correct for gross section nominal \u2192 net: Kt_net = Kt_gross * W\/(W-d)\n            \/\/ The above formula gives Kt on net section already for small d\/W\n            ratioLabel='d\/W = '+fmt(dW,3);\n            break;\n        case'shoulder':\n            if(!r||r<=0){$('vc-results').classList.remove('vc-visible');return}\n            var Dd=W\/d,rd=r\/d;\n            \/\/ Simplified: Kt \u2248 C1 + C2*(r\/d) + C3*(r\/d)^2 based on D\/d\n            \/\/ Neuber approx: Kt \u2248 1 + 1\/sqrt(A*r\/d) \u2014 simplified\n            Kt=1+2*Math.sqrt((W\/2-d\/2)\/(2*r));\/\/ Neuber simplified\n            if(Kt<1)Kt=1;\n            ratioLabel='D\/d = '+fmt(Dd,2)+', r\/d = '+fmt(rd,3);\n            break;\n        case'notch':\n            if(!r||r<=0){$('vc-results').classList.remove('vc-visible');return}\n            var t=(W-d)\/2;\/\/ notch depth\n            Kt=1+2*Math.sqrt(t\/r);\/\/ Neuber for U-notch\n            ratioLabel='t\/r = '+fmt(t\/r,2)+', depth t = '+fmt(t,1)+'mm';\n            break;\n        case'groove':\n            if(!r||r<=0){$('vc-results').classList.remove('vc-visible');return}\n            var tg=(W-d)\/2;\n            Kt=1+2*Math.sqrt(tg\/r);\n            ratioLabel='t\/r = '+fmt(tg\/r,2)+', depth = '+fmt(tg,1)+'mm';\n            break;\n    }\n\n    var smax=snom&&snom>0?Kt*snom:NaN;\n\n    $('vc-r-Kt').innerHTML=fmt(Kt,3);\n    $('vc-r-smax').innerHTML=isNaN(smax)?'\u2014':fmt(smax,1)+' <span class=\"vc-rcard-unit\">MPa<\/span>';\n    $('vc-r-ratio').innerHTML='<span style=\"font-size:14px\">'+ratioLabel+'<\/span>';\n    $('vc-results').classList.add('vc-visible');\n    drawViz(g,W,d,r,Kt);\n\n    saveHistory({geom:g,Kt:Kt,_summary:'Kt='+fmt(Kt,2)+', '+g});\n}\n\ndocument.querySelectorAll('.vc-preset-btn').forEach(function(btn){btn.addEventListener('click',function(e){e.preventDefault();\n    $('vc-geom').value=this.getAttribute('data-geom');$('vc-W').value=this.getAttribute('data-W');$('vc-d').value=this.getAttribute('data-d');\n    if(this.getAttribute('data-r'))$('vc-r').value=this.getAttribute('data-r');\n    calculate();\n})});\n\n$('vc-form').addEventListener('input',calculate);$('vc-form').addEventListener('change',calculate);\n\n$('vc-copy-btn').addEventListener('click',function(){var text='Stress Concentration\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nKt: '+$('vc-r-Kt').textContent+'\\n\u03c3_max: '+$('vc-r-smax').textContent+'\\n\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\nvibromera.eu';if(navigator.clipboard){navigator.clipboard.writeText(text).then(function(){var b=$('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\ndocument.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\nvar faqData=[\n    {q:'What is Kt?',a:'<p>Kt = \u03c3_max \/ \u03c3_nom. Ratio of max local stress to nominal stress at a geometric discontinuity. Depends only on geometry, not material.<\/p>'},\n    {q:'What causes stress concentrations?',a:'<p>Any abrupt geometry change: holes, notches, fillets, keyways, threads, grooves. Stress flow lines crowd together, increasing local stress.<\/p>'},\n    {q:'How does Kt affect fatigue?',a:'<p>Dramatically reduces fatigue life. Fatigue notch factor Kf = 1 + q(Kt\u22121), where q is notch sensitivity (0 to 1, material-dependent).<\/p>'},\n    {q:'How to reduce Kt?',a:'<p>Generous fillet radii, avoid sharp corners, gradual transitions, relief grooves, polished surfaces, shot peening for compressive residual stress.<\/p>'},\n    {q:'What is Peterson\\'s reference?',a:'<p>The definitive reference with Kt charts for hundreds of geometries. This calculator uses simplified curve-fit approximations.<\/p>'}\n];\nvar fl=$('vc-faq-list');faqData.forEach(function(f){fl.innerHTML+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>'+f.q+'<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">'+f.a+'<\/div><\/div><\/div>'});\nfl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(!b)return;b.closest('.vc-faq-item').classList.toggle('vc-open')});\n\nfunction drawViz(geom,W,d,r,Kt){\n  var c=$('vc-viz'),SVW=380,SVH=200;\n  var svg='<svg width=\"'+SVW+'\" height=\"'+SVH+'\" viewBox=\"0 0 '+SVW+' '+SVH+'\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">';\n  svg+='<defs><marker id=\"sa\" markerWidth=\"6\" markerHeight=\"4\" refX=\"0\" refY=\"2\" orient=\"auto\"><path d=\"M0,0 L6,2 L0,4\" fill=\"#2a5c8c\"\/><\/marker>';\n  svg+='<marker id=\"sb\" markerWidth=\"6\" markerHeight=\"4\" refX=\"6\" refY=\"2\" orient=\"auto\"><path d=\"M6,0 L0,2 L6,4\" fill=\"#2a5c8c\"\/><\/marker><\/defs>';\n  var cx=SVW\/2,cy=SVH\/2;\n  var barH=60,barW=280,notchR=Math.max(6,Math.min(25,(r||5)*1.2));\n  var x0=cx-barW\/2,y0=cy-barH\/2;\n  \/\/ Main bar body\n  if(geom==='hole'){\n    var holeR=Math.max(8,Math.min(35,d*0.8));\n    svg+='<rect x=\"'+x0+'\" y=\"'+y0+'\" width=\"'+barW+'\" height=\"'+barH+'\" rx=\"2\" fill=\"#e0e7ef\" stroke=\"#7b8fa3\" stroke-width=\"1.5\"\/>';\n    svg+='<circle cx=\"'+cx+'\" cy=\"'+cy+'\" r=\"'+holeR+'\" fill=\"#f4f1ec\" stroke=\"#3578b2\" stroke-width=\"1.5\"\/>';\n    \/\/ stress lines curving around hole\n    for(var i=-2;i<=2;i++){\n      var ly=cy+i*12;\n      if(Math.abs(i)<=1){\n        var dx=holeR+4;\n        svg+='<path d=\"M'+x0+' '+ly+' L'+(cx-dx-15)+' '+ly+' Q'+(cx-dx)+' '+ly+' '+(cx-dx)+' '+(ly+i*3)+' Q'+(cx-dx)+' '+(ly+i*6)+' '+(cx-dx+10)+' '+(cy+i*(holeR+5))+'\" fill=\"none\" stroke=\"rgba(231,76,60,0.4)\" stroke-width=\"1\"\/>';\n        svg+='<path d=\"M'+(x0+barW)+' '+ly+' L'+(cx+dx+15)+' '+ly+' Q'+(cx+dx)+' '+ly+' '+(cx+dx)+' '+(ly+i*3)+' Q'+(cx+dx)+' '+(ly+i*6)+' '+(cx+dx-10)+' '+(cy+i*(holeR+5))+'\" fill=\"none\" stroke=\"rgba(231,76,60,0.4)\" stroke-width=\"1\"\/>';\n      } else {\n        svg+='<line x1=\"'+x0+'\" y1=\"'+ly+'\" x2=\"'+(x0+barW)+'\" y2=\"'+ly+'\" stroke=\"rgba(231,76,60,0.25)\" stroke-width=\"0.7\"\/>';\n      }\n    }\n    \/\/ Kt label at top of hole\n    svg+='<text x=\"'+cx+'\" y=\"'+(y0-6)+'\" text-anchor=\"middle\" fill=\"#e74c3c\" font-size=\"12\" font-weight=\"bold\">Kt = '+Kt.toFixed(2)+'<\/text>';\n  } else {\n    \/\/ Notched \/ shoulder \/ groove bar\n    var notchD=(W-d)\/2;var nVis=Math.max(8,Math.min(20,notchD*0.7));\n    svg+='<rect x=\"'+x0+'\" y=\"'+y0+'\" width=\"'+barW+'\" height=\"'+barH+'\" rx=\"2\" fill=\"#e0e7ef\" stroke=\"#7b8fa3\" stroke-width=\"1.5\"\/>';\n    \/\/ Top notch\n    svg+='<path d=\"M'+(cx-notchR)+' '+y0+' Q'+cx+' '+(y0+nVis)+' '+(cx+notchR)+' '+y0+'\" fill=\"#f4f1ec\" stroke=\"#3578b2\" stroke-width=\"1.5\"\/>';\n    \/\/ Bottom notch\n    svg+='<path d=\"M'+(cx-notchR)+' '+(y0+barH)+' Q'+cx+' '+(y0+barH-nVis)+' '+(cx+notchR)+' '+(y0+barH)+'\" fill=\"#f4f1ec\" stroke=\"#3578b2\" stroke-width=\"1.5\"\/>';\n    \/\/ Converging stress lines\n    var nLines=7;\n    for(var j=0;j<nLines;j++){\n      var frac=(j\/(nLines-1));\n      var ly1=y0+4+frac*(barH-8);\n      var ly2=y0+nVis+2+frac*(barH-2*nVis-4);\n      svg+='<line x1=\"'+x0+'\" y1=\"'+ly1+'\" x2=\"'+(cx-notchR-5)+'\" y2=\"'+ly2+'\" stroke=\"rgba(231,76,60,'+(0.25+frac*0.3)+')\" stroke-width=\"0.8\"\/>';\n      svg+='<line x1=\"'+(cx+notchR+5)+'\" y1=\"'+ly2+'\" x2=\"'+(x0+barW)+'\" y2=\"'+ly1+'\" stroke=\"rgba(231,76,60,'+(0.25+frac*0.3)+')\" stroke-width=\"0.8\"\/>';\n    }\n    svg+='<text x=\"'+cx+'\" y=\"'+(y0-6)+'\" text-anchor=\"middle\" fill=\"#e74c3c\" font-size=\"12\" font-weight=\"bold\">Kt = '+Kt.toFixed(2)+'<\/text>';\n    \/\/ radius label\n    svg+='<text x=\"'+(cx+notchR+8)+'\" y=\"'+(y0+12)+'\" fill=\"#3578b2\" font-size=\"10\">r<\/text>';\n  }\n  \/\/ Force arrows\n  svg+='<line x1=\"'+(x0-30)+'\" y1=\"'+cy+'\" x2=\"'+(x0-4)+'\" y2=\"'+cy+'\" stroke=\"#2a5c8c\" stroke-width=\"2\" marker-end=\"url(#sa)\"\/>';\n  svg+='<line x1=\"'+(x0+barW+30)+'\" y1=\"'+cy+'\" x2=\"'+(x0+barW+4)+'\" y2=\"'+cy+'\" stroke=\"#2a5c8c\" stroke-width=\"2\" marker-start=\"url(#sb)\"\/>';\n  svg+='<text x=\"'+(x0-32)+'\" y=\"'+(cy-6)+'\" fill=\"#2a5c8c\" font-size=\"11\" text-anchor=\"end\">\u03c3<\/text>';\n  svg+='<text x=\"'+(x0+barW+32)+'\" y=\"'+(cy-6)+'\" fill=\"#2a5c8c\" font-size=\"11\">\u03c3<\/text>';\n  svg+='<text x=\"'+cx+'\" y=\"'+(SVH-4)+'\" text-anchor=\"middle\" fill=\"#5a5650\" font-size=\"10\">'+geom.replace(\/-\/g,' ')+' \u2014 stress lines converge at notch<\/text>';\n  svg+='<\/svg>';\n  c.innerHTML=svg;\n}\n\nfunction 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\nfunction renderFormulas(){try{katex.render('K_t = \\\\frac{\\\\sigma_{max}}{\\\\sigma_{nom}}',$('vc-katex-1'),{displayMode:true,throwOnError:false})}catch(e){}}\n\nfunction init(){renderFormulas();calculate()}\nif(document.readyState==='loading'){document.addEventListener('DOMContentLoaded',init)}else{init()}\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Gratis kalkulator for spenningskonsentrasjonsfaktor i Kt. Forenklede Peterson-diagramdata for hakk-, hull-, avrundings- og skuldergeometrier. Skriv inn dimensjoner for \u00e5 f\u00e5 Kt.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100248","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100248","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":2,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100248\/revisions"}],"predecessor-version":[{"id":100764,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/calculator\/100248\/revisions\/100764"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/media?parent=100248"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/categories?post=100248"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/nb\/wp-json\/wp\/v2\/tags?post=100248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}