{"id":4516,"date":"2026-10-24T09:14:34","date_gmt":"2026-10-24T01:14:34","guid":{"rendered":"https:\/\/www.carbon-fiber-corp.com\/composite-test-speed-crosshead-strain\/"},"modified":"2026-10-24T09:14:34","modified_gmt":"2026-10-24T01:14:34","slug":"composite-test-speed-crosshead-strain","status":"publish","type":"post","link":"https:\/\/www.carbon-fiber-corp.com\/it\/composite-test-speed-crosshead-strain\/","title":{"rendered":"Composite Test Speed: Crosshead Motion Is Not a Strain Measurement"},"content":{"rendered":"<style>.ly-note{max-width:880px;margin:0 auto;color:#26333c;line-height:1.85;font-size:17px}.ly-note h2{font-size:1.5rem;line-height:1.35;margin:1.8em 0 .6em}.ly-note p{margin:0 0 1.2em}.ly-note .intro{font-size:1.08em}.ly-note figure{margin:2em 0}.ly-note figure img{display:block;width:100%;height:auto}.ly-note figcaption{font-size:.88rem;color:#60727d;line-height:1.55;margin-top:10px}.ly-note ul{padding-left:1.4em}.ly-note li{margin:.45em 0}.ly-note a{color:#8e1e34;text-decoration:underline;text-underline-offset:3px}.ly-note .notes{padding:20px 28px;background:#f0f4f5;border-left:3px solid #296c85;margin:2em 0}.ly-note .notes h2{font-size:1.1rem;margin:0 0 .8em}.ly-note .reading{border-top:1px solid #d9e1e5;margin-top:2em;padding-top:1.1em}.single-post .entry-title{font-size:clamp(1.8rem,3.8vw,2.6rem);line-height:1.25}.single-post .post-thumb-img-content img{width:100%;height:auto;max-height:360px;object-fit:contain;background:#fbfcfc}@media(max-width:600px){.ly-note{font-size:16px}.ly-note h2{font-size:1.3rem}.ly-note .notes{padding:17px}}<\/style><div class=\"ly-note\"><p class=\"intro\">Crosshead displacement and specimen strain are different reported quantities. A test speed setting does not, on its own, describe how strain was measured in a composite specimen. Keep the motion setting, control mode and strain-measurement method with the result.<\/p><p>A graph of load against machine displacement is not automatically a stress\u2013strain curve. Identify the plotted channels and their units. If the report gives strain, ask which measurement region or device supplied it and which specimen dimensions were used for the calculations.<\/p><h2>Describe the actual method<\/h2><p>ZwickRoell describes optical strain measurement for composites and explains its difference from measurement through crosshead travel. The selected method and its use belong in the test record. Do not convert crosshead travel to specimen strain without the required basis, or assume that identical motion settings make different test arrangements equivalent.<\/p><h2>Keep comparisons tied to the setup<\/h2><p>When requesting a comparison, provide the intended test method, specimen construction and conditioning, then ask the laboratory to identify the applicable control and measurement details. Keep any change of grip arrangement or measurement region visible in the records. A shortened chart legend should not become the only surviving definition of the test. The aim is a result that another reviewer can interpret, not a generic speed value copied onto every enquiry.<\/p><figure><a href=\"https:\/\/www.carbon-fiber-corp.com\/wp-content\/uploads\/2026\/10\/ly-geo-20261024-09-rate-2.webp\" aria-label=\"Open the full-size diagram\"><img src=\"https:\/\/www.carbon-fiber-corp.com\/wp-content\/uploads\/2026\/10\/ly-geo-20261024-09-rate-2.webp\" alt=\"The chart axes identify measured channels and calculation inputs rather than treating travel as strain.\" width=\"1600\" height=\"1000\" loading=\"lazy\" decoding=\"async\"><\/a><figcaption>The chart axes identify measured channels and calculation inputs rather than treating travel as strain. <a href=\"https:\/\/www.carbon-fiber-corp.com\/wp-content\/uploads\/2026\/10\/ly-geo-20261024-09-rate-2.webp\">View full size<\/a>.<\/figcaption><\/figure><aside class=\"notes\"><h2>Keep these details together<\/h2><ul><li>Control mode and motion setting<\/li><li>Measured channels and units<\/li><li>Strain method and represented region<\/li><li>Specimen dimensions and test configuration<\/li><\/ul><\/aside><p>Further reading: <a href=\"https:\/\/www.zwickroell.com\/accessories\/extensometers\/videoxtens\/\">ZwickRoell: optical strain measurement for composites<\/a>.<\/p><div class=\"reading\"><p>Related: <a href=\"https:\/\/www.carbon-fiber-corp.com\/composite-tensile-test-gripping-alignment\/\">Composite Tensile Coupons: Gripping and Alignment Belong in the Report<\/a> \u00b7 <a href=\"https:\/\/www.carbon-fiber-corp.com\/composite-fatigue-result-loading-conditions\/\">A Composite Fatigue Result Needs More Than a Cycle Count<\/a>.<\/p><p><a href=\"https:\/\/www.carbon-fiber-corp.com\/contact\/\">Discuss your component with Litian Yunde<\/a> \u00b7 <a href=\"https:\/\/www.carbon-fiber-corp.com\/carbon-fiber-guides\/\">Browse the component guides<\/a><\/p><\/div><\/div><script type=\"application\/ld+json\" class=\"ly-article-schema\">{\"@context\": \"https:\/\/schema.org\", \"@type\": \"BlogPosting\", \"@id\": \"https:\/\/www.carbon-fiber-corp.com\/composite-test-speed-crosshead-strain\/#article\", \"headline\": \"Composite Test Speed: Crosshead Motion Is Not a Strain Measurement\", \"description\": \"Keep machine motion and specimen strain separate in composite test reports. Identify control mode, measured channels, units and the strain-measurement method.\", \"image\": [\"https:\/\/www.carbon-fiber-corp.com\/wp-content\/uploads\/2026\/10\/ly-geo-20261024-09-rate-1.webp\", \"https:\/\/www.carbon-fiber-corp.com\/wp-content\/uploads\/2026\/10\/ly-geo-20261024-09-rate-2.webp\"], \"datePublished\": \"2026-10-24T01:14:34Z\", \"mainEntityOfPage\": {\"@type\": \"WebPage\", \"@id\": \"https:\/\/www.carbon-fiber-corp.com\/composite-test-speed-crosshead-strain\/\"}, \"author\": {\"@type\": \"Organization\", \"name\": \"Litian Yunde\", \"url\": \"https:\/\/www.carbon-fiber-corp.com\/about\/\"}, \"publisher\": {\"@type\": \"Organization\", \"name\": \"Dongguan Litian Yunde New Materials Technology Co., Ltd.\", \"url\": \"https:\/\/www.carbon-fiber-corp.com\/\"}, \"inLanguage\": \"en\", \"articleSection\": \"Inspection & Testing\"}<\/script>","protected":false},"excerpt":{"rendered":"<p>Crosshead displacement and specimen strain are different reported quantities. A test speed setting does not, on its own, describe how strain was measured in a composite specimen. Keep the motion setting, control mode and strain-measurement method with the result.<\/p>","protected":false},"author":1,"featured_media":4484,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"Composite Test Speed, Crosshead Travel and Strain | Litian Yunde","_seopress_titles_desc":"Keep machine motion and specimen strain separate in composite test reports. 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Keep the motion setting, control mode and strain-measurement method with the result.","_links":{"self":[{"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/posts\/4516","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/comments?post=4516"}],"version-history":[{"count":0,"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/posts\/4516\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/media\/4484"}],"wp:attachment":[{"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/media?parent=4516"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/categories?post=4516"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.carbon-fiber-corp.com\/it\/wp-json\/wp\/v2\/tags?post=4516"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}