{"id":6874,"date":"2021-02-10T12:48:19","date_gmt":"2021-02-10T10:48:19","guid":{"rendered":"https:\/\/blog.federnshop.com\/types-of-stress-extension-springs\/"},"modified":"2021-02-10T14:33:40","modified_gmt":"2021-02-10T12:33:40","slug":"types-of-stress-extension-springs","status":"publish","type":"post","link":"https:\/\/blog.federnshop.com\/en\/types-of-stress-extension-springs\/","title":{"rendered":"Types of stress extension springs"},"content":{"rendered":"<p><a href=\"https:\/\/blog.federnshop.com\/wp-content\/uploads\/Formelzeichen_Zugfedern_komplett.pdf\" target=\"_blank\" rel=\"noopener noreferrer\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-6876\" src=\"https:\/\/blog.federnshop.com\/wp-content\/uploads\/Hubspannung_Zugfeder.jpg\" alt=\"Stroke tension extension spring\" width=\"600\" height=\"345\" data-wp-pid=\"1930\" srcset=\"https:\/\/blog.federnshop.com\/wp-content\/uploads\/Hubspannung_Zugfeder.jpg 800w, https:\/\/blog.federnshop.com\/wp-content\/uploads\/Hubspannung_Zugfeder-300x173.jpg 300w, https:\/\/blog.federnshop.com\/wp-content\/uploads\/Hubspannung_Zugfeder-600x345.jpg 600w, https:\/\/blog.federnshop.com\/wp-content\/uploads\/Hubspannung_Zugfeder-400x230.jpg 400w, https:\/\/blog.federnshop.com\/wp-content\/uploads\/Hubspannung_Zugfeder-200x115.jpg 200w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/a><\/p>\n<p style=\"text-align: right;\"><a href=\"https:\/\/blog.federnshop.com\/wp-content\/uploads\/Formelzeichen_Zugfedern_komplett.pdf\" target=\"_blank\" rel=\"noopener noreferrer\">Description Formula symbol tension springs<\/a><\/p>\n<p>Before interpreting the<a href=\"https:\/\/blog.federnshop.com\/en\/information-extension-springs\/\"> extension spring<\/a> it must be clarified whether the intended type of stress is a<strong> static<\/strong> or a<strong> dynamic stress<\/strong> acts.<\/p>\n<p>No general fatigue strength values can be given for dynamic loads on tension springs, as the<a href=\"https:\/\/blog.federnshop.com\/en\/information-extension-springs\/\"> Bending points of the eyelets<\/a> additional stresses can occur, some of which exceed the permissible stresses. Tension springs should therefore only be subjected to static loads if possible. If dynamic stress cannot be avoided, one should go for angled<a href=\"https:\/\/blog.federnshop.com\/en\/eyelet-shapes-extension-springs\/\"> Eyelets<\/a> renounce and<a href=\"https:\/\/blog.federnshop.com\/en\/eyelet-shapes-extension-springs\/\"> rolled or screwed in end pieces<\/a> deploy. When tension springs are subjected to dynamic loads, a life test under later operating conditions is important. A surface strengthening by shot peening cannot be carried out or only with great effort because of the closely spaced turns.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/blog.federnshop.com\/en\/types-of-stress-extension-springs\/#Static_stress_on_extension_spring\" >Static stress on extension spring<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/blog.federnshop.com\/en\/types-of-stress-extension-springs\/#Dynamic_stress_on_extension_spring\" >Dynamic stress on extension spring<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Static_stress_on_extension_spring\"><\/span>Static stress on extension spring<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Time-constant (static) load or time-variable load with less than 10,000 strokes in total or small stroke stresses (\u03c4h = \u03c42 &#8211; \u03c41) up to 0.1 x fatigue strength (\u03c4kh = \u03c4k2 &#8211; \u03c4k1).<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Dynamic_stress_on_extension_spring\"><\/span>Dynamic stress on extension spring<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Dynamic stress on springs is defined as stresses that change over time with more than 10,000 load changes or stroke stresses (\u03c4h) over 0.1 x fatigue strength (\u03c4kh) with constant and variable stroke stress.<\/p>\n<p>The existing shear stress is determined as follows.<\/p>\n<p>Shear stress from force: <img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Ctau%3D%5Cfrac%7B8DF%7D%7B%5Cpi%20d%5E%7B3%7D%7D\" alt=\"\\tau=\\frac&lt;wpml_curved wpml_value='8DF'&gt;&lt;\/wpml_curved&gt;{\\pi d^&lt;wpml_curved wpml_value='3'&gt;&lt;\/wpml_curved&gt;}\" align=\"absmiddle\" \/><\/p>\n<p>Shear stress from path: <img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Ctau%3D%5Cfrac%7BGds%7D%7B%5Cpi%20nD%5E%7B2%7D%7D\" alt=\"\\tau=\\frac&lt;wpml_curved wpml_value='Gds'&gt;&lt;\/wpml_curved&gt;{\\pi nD^&lt;wpml_curved wpml_value='2'&gt;&lt;\/wpml_curved&gt;}\" align=\"absmiddle\" \/><\/p>\n<p>For the dynamic load, the corrected stroke tension must be calculated because of the increase in tension.<\/p>\n<p>Corrected shear stress : <img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Ctau_%7B%7Bk%7D%7D%3Dk%5Ctau\" alt=\"\\dew_{ } = k \\ tau\" align=\"absmiddle\" \/><\/p>\n<p>Corrected stroke voltage: \u03c4kh = \u03c4k2 &#8211; \u03c4k1<\/p>\n<p>Where for k applies (according to Bergstr\u00e4sser):<\/p>\n<p><img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=k%3D%5Cfrac%7B%5Cfrac%7BD%7D%7Bd%7D%2B0%2C5%7D%7B%5Cfrac%7BD%7D%7Bd%7D-0%2C75%7D\" alt=\"k=\\frac{\\frac&lt;wpml_curved wpml_value='D'&gt;&lt;\/wpml_curved&gt;&lt;wpml_curved wpml_value='d'&gt;&lt;\/wpml_curved&gt;+0,5}{\\frac&lt;wpml_curved wpml_value='D'&gt;&lt;\/wpml_curved&gt;&lt;wpml_curved wpml_value='d'&gt;&lt;\/wpml_curved&gt;-0,75}\" align=\"absmiddle\" \/><\/p>\n<p>With the tension correction factor k, which depends on the winding ratio (ratio of mean diameter to wire thickness) of the spring, the highest tension can be approximately determined.<\/p>\n<p>Allowable voltage: <img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=%5Ctau_%7B%7Bzul%7D%7D%3D0%2C45%20%5Ccdot%20R_%7B%7Bm%7D%7D\" alt=\"\\dew_{ } = 0.45 \\ cdot R_ { }\" align=\"absmiddle\" \/><\/p>\n<p><a href=\"https:\/\/blog.federnshop.com\/zugfestigkeit-federwerkstoffe\/\" target=\"_blank\" rel=\"noopener noreferrer\">Minimum tensile strength values of spring materials <img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=R_%7B%7Bm%7D%7D\" alt=\"R_ { }\" align=\"absmiddle\" \/> <\/a><\/p>\n<p>The existing maximum stress \u03c4n at the greatest spring deflection sn is equated with the permissible stress. To however<a href=\"https:\/\/blog.federnshop.com\/en\/relaxation-for-springs\/\" target=\"_blank\" rel=\"noopener noreferrer\"> relaxation<\/a> To avoid this, only 80% of this spring travel should be used in practice.<\/p>\n<p><img decoding=\"async\" class=\"mathtex-equation-editor\" src=\"https:\/\/chart.apis.google.com\/chart?cht=tx&amp;chl=s_%7B%7B2%7D%7D%3D0%2C8%5Ccdot%20s_%7B%7Bn%7D%7D\" alt=\"s_ { } = 0.8 \\ cdot s_ { }\" align=\"absmiddle\" \/><\/p>\n<p>&nbsp;<\/p>\n<p><iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/cqsZmGz7Tng\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>Interesting links:<\/p>\n<ul>\n<li><a href=\"https:\/\/blog.federnshop.com\/en\/types-of-stress-compression-springs\/\">Types of stress compression springs<\/a><\/li>\n<\/ul>\n<ul>\n<li><a href=\"https:\/\/www.federnshop.com\/de\/federberechnung-auswahl.html\" target=\"_blank\" rel=\"noopener noreferrer\">Gutekunst spring calculation WinFSB<\/a><\/li>\n<\/ul>\n<ul>\n<li><a href=\"https:\/\/www.federnshop.com\/de\/service_informationen\/federnauslegung.html\" target=\"_blank\" rel=\"noopener noreferrer\">Spring design<\/a><\/li>\n<\/ul>\n<ul>\n<li><a href=\"https:\/\/www.federnshop.com\/de\/service-und-informationen\/technische-beratung.html\" target=\"_blank\" rel=\"noopener noreferrer\">Technical advice from Gutekunst Federn<\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>Description Formula symbol tension springs Before interpreting the extension spring it must be clarified whether the intended type of stress is a static or a dynamic stress acts. No general fatigue strength values can be given for dynamic loads on<\/p>\n","protected":false},"author":4,"featured_media":6876,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[861,860,457,857],"tags":[1466,1599,1198,552,1467,438],"class_list":["post-6874","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-endless-extension-springs","category-extension-springs","category-knowledge","category-wire-springs","tag-dynamische-beanspruchung-en","tag-lifting-tension","tag-loop-shapes","tag-schubspannung-en","tag-statische-beanspruchung-en","tag-tension-springs"],"_links":{"self":[{"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/posts\/6874","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/comments?post=6874"}],"version-history":[{"count":2,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/posts\/6874\/revisions"}],"predecessor-version":[{"id":6886,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/posts\/6874\/revisions\/6886"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/media\/6876"}],"wp:attachment":[{"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/media?parent=6874"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/categories?post=6874"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.federnshop.com\/en\/wp-json\/wp\/v2\/tags?post=6874"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}