{"id":63201,"date":"2022-07-18T12:59:10","date_gmt":"2022-07-18T17:59:10","guid":{"rendered":"https:\/\/www.bjultrasonic.com\/what-is-the-distance-a-sheet-can-stretch-before-it-completely-breaks\/"},"modified":"2025-01-27T06:17:33","modified_gmt":"2025-01-27T11:17:33","slug":"what-is-the-distance-a-sheet-can-stretch-before-it-completely-breaks","status":"publish","type":"post","link":"https:\/\/www.bjultrasonic.com\/cs\/what-is-the-distance-a-sheet-can-stretch-before-it-completely-breaks\/","title":{"rendered":"Maxim\u00e1ln\u00ed prodlou\u017een\u00ed listu p\u0159ed roztr\u017een\u00edm"},"content":{"rendered":"<p>P\u0159edstavte si tenk\u00fd list pap\u00edru, tenk\u00e9 pl\u00e1tko kovu, nebo dokonce tenkou f\u00f3lii z plastu.  Kolik se d\u00e1 takov\u00fd materi\u00e1l nat\u00e1hnout, ne\u017e se definitivn\u011b utrhne?  Odpov\u011b\u010f na tuto ot\u00e1zku nen\u00ed jednoduch\u00e1 a z\u00e1vis\u00ed na mnoha faktorech.  Zat\u00edmco n\u011bkter\u00e9 materi\u00e1ly se prodlou\u017e\u00ed jen o nepatrn\u00e9 procento sv\u00e9 p\u016fvodn\u00ed d\u00e9lky p\u0159edt\u00edm, ne\u017e se zlom\u00ed, jin\u00e9 vykazuj\u00ed mnohem v\u011bt\u0161\u00ed ta\u017enost.  Tento \u010dl\u00e1nek se pokus\u00ed prozkoumat faktory ovliv\u0148uj\u00edc\u00ed maxim\u00e1ln\u00ed prodlou\u017een\u00ed materi\u00e1lu p\u0159ed jeho zlomov\u00e1n\u00edm a p\u0159edstav\u00ed n\u011bkter\u00e9 p\u0159\u00edklady.<\/p>\n<h3>Vliv materi\u00e1lu<\/h3>\n<p>Typ materi\u00e1lu je nejd\u016fle\u017eit\u011bj\u0161\u00edm faktorem ur\u010duj\u00edc\u00edm jeho ta\u017enost.  Kovy se obecn\u011b chovaj\u00ed odli\u0161n\u011b od polymer\u016f nebo kompozitn\u00edch materi\u00e1l\u016f.  Ocel je nap\u0159\u00edklad pom\u011brn\u011b k\u0159ehk\u00e1 a m\u00e1 malou ta\u017enost, zat\u00edmco m\u011b\u010f je podstatn\u011b ta\u017en\u011bj\u0161\u00ed.  Polymery, jako je polyetyl\u00e9n nebo silikon, mohou vykazovat velmi vysokou ta\u017enost p\u0159ed zlomen\u00edm.  N\u00e1sleduj\u00edc\u00ed tabulka ukazuje orienta\u010dn\u00ed hodnoty prodlou\u017een\u00ed p\u0159i poru\u0161e pro n\u011bkter\u00e9 b\u011b\u017en\u00e9 materi\u00e1ly:<\/p>\n<table class=\"table table-striped table-bordered\">\n<thead>\n<tr>\n<th>Materi\u00e1l<\/th>\n<th>Prodlou\u017een\u00ed p\u0159i poru\u0161e (%)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Ocel<\/td>\n<td>10-20<\/td>\n<\/tr>\n<tr>\n<td>M\u011b\u010f<\/td>\n<td>30-50<\/td>\n<\/tr>\n<tr>\n<td>Polyetyl\u00e9n<\/td>\n<td>200-500<\/td>\n<\/tr>\n<tr>\n<td>Silikon<\/td>\n<td>500-1000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>Vliv tlou\u0161\u0165ky a povrchov\u00e9 \u00fapravy<\/h3>\n<p>Tlou\u0161\u0165ka materi\u00e1lu tak\u00e9 hraje v\u00fdznamnou roli. Ten\u010d\u00ed listy se obvykle trhaj\u00ed p\u0159i men\u0161\u00edm prodlou\u017een\u00ed ne\u017e tlust\u0161\u00ed listy stejn\u00e9ho materi\u00e1lu.  Povrchov\u00e1 \u00faprava materi\u00e1lu m\u016f\u017ee rovn\u011b\u017e ovlivnit jeho ta\u017enost.  P\u0159\u00edtomnost trhlin, \u0161kr\u00e1banc\u016f nebo jin\u00fdch defekt\u016f m\u016f\u017ee v\u00e9st k p\u0159ed\u010dasn\u00e9mu zlomen\u00ed.<\/p>\n<h3>Vliv teploty a vlhkosti<\/h3>\n<p>Teplota a vlhkost prost\u0159ed\u00ed rovn\u011b\u017e ovliv\u0148uj\u00ed mechanick\u00e9 vlastnosti materi\u00e1l\u016f, a tedy i jejich ta\u017enost.  V\u011bt\u0161ina materi\u00e1l\u016f vykazuje sn\u00ed\u017eenou ta\u017enost p\u0159i n\u00edzk\u00fdch teplot\u00e1ch a zv\u00fd\u0161enou ta\u017enost p\u0159i vy\u0161\u0161\u00edch teplot\u00e1ch (do ur\u010dit\u00e9 mezn\u00ed hodnoty, kdy doch\u00e1z\u00ed k degradaci materi\u00e1lu). Vlhkost m\u016f\u017ee ovlivnit n\u011bkter\u00e9 materi\u00e1ly, zejm\u00e9na polymery, zp\u016fsobuj\u00edc\u00ed jejich bobtn\u00e1n\u00ed a zm\u011bnu mechanick\u00fdch vlastnost\u00ed.<\/p>\n<h3>M\u011b\u0159en\u00ed ta\u017enosti<\/h3>\n<p>Ta\u017enost materi\u00e1lu se m\u011b\u0159\u00ed pomoc\u00ed tahov\u00e9ho testu.  B\u011bhem tohoto testu se vzorek materi\u00e1lu natahuje konstantn\u00ed rychlost\u00ed, dokud se nezlom\u00ed.  Nam\u011b\u0159en\u00e1 data se pak pou\u017e\u00edvaj\u00ed k ur\u010den\u00ed pevnosti v tahu, prodlou\u017een\u00ed p\u0159i poru\u0161e a dal\u0161\u00edch mechanick\u00fdch vlastnost\u00ed.  P\u0159esnost m\u011b\u0159en\u00ed z\u00e1vis\u00ed na kvalit\u011b pou\u017eit\u00e9ho za\u0159\u00edzen\u00ed a na pe\u010dlivosti proveden\u00ed testu.<\/p>\n<h3>Z\u00e1v\u011br<\/h3>\n<p>Maxim\u00e1ln\u00ed prodlou\u017een\u00ed materi\u00e1lu p\u0159ed jeho zlomen\u00edm je slo\u017eit\u00fd parametr z\u00e1visl\u00fd na mnoha faktorech, v\u010detn\u011b typu materi\u00e1lu, jeho tlou\u0161\u0165ky, povrchov\u00e9 \u00fapravy, teploty a vlhkosti.  P\u0159esn\u00e9 ur\u010den\u00ed t\u00e9to hodnoty vy\u017eaduje pe\u010dliv\u00e9 experiment\u00e1ln\u00ed m\u011b\u0159en\u00ed pomoc\u00ed tahov\u00e9ho testu.  Znalost t\u011bchto faktor\u016f je kl\u00ed\u010dov\u00e1 pro v\u00fdb\u011br vhodn\u00e9ho materi\u00e1lu pro danou aplikaci a pro p\u0159edpov\u011b\u010f jeho chov\u00e1n\u00ed v re\u00e1ln\u00fdch podm\u00ednk\u00e1ch.  A\u010dkoliv se v tomto \u010dl\u00e1nku zmi\u0148ujeme o materi\u00e1lech obecn\u011b, principy z\u016fst\u00e1vaj\u00ed stejn\u00e9 bez ohledu na to, zda se jedn\u00e1 o pap\u00edr, kov nebo plast.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>P\u0159edstavte si tenk\u00fd list pap\u00edru, tenk\u00e9 pl\u00e1tko kovu, nebo dokonce tenkou f\u00f3lii z plastu. Kolik se d\u00e1 takov\u00fd materi\u00e1l nat\u00e1hnout, ne\u017e se definitivn\u011b utrhne? Odpov\u011b\u010f na tuto ot\u00e1zku nen\u00ed jednoduch\u00e1 a z\u00e1vis\u00ed na mnoha faktorech. Zat\u00edmco n\u011bkter\u00e9 materi\u00e1ly se prodlou\u017e\u00ed jen o nepatrn\u00e9 procento sv\u00e9 p\u016fvodn\u00ed d\u00e9lky p\u0159edt\u00edm, ne\u017e se zlom\u00ed, jin\u00e9 vykazuj\u00ed mnohem v\u011bt\u0161\u00ed<\/p>\n","protected":false},"author":1,"featured_media":5014,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6415],"tags":[],"class_list":["post-63201","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","prodpage-classic"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/posts\/63201","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/comments?post=63201"}],"version-history":[{"count":0,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/posts\/63201\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/media\/5014"}],"wp:attachment":[{"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/media?parent=63201"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/categories?post=63201"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bjultrasonic.com\/cs\/wp-json\/wp\/v2\/tags?post=63201"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}