In\u017einieri sa spoliehaj\u00fa na youngov modul, aby vyhodnotili, ak\u00e9 nam\u00e1hanie materi\u00e1l znesie, k\u00fdm sa trvalo nedeformuje alebo nezlyh\u00e1, a aby navrhli kon\u0161trukcie, ktor\u00e9 odol\u00e1vaj\u00fa vonkaj\u0161\u00edm sil\u00e1m bez toho, aby sa ohrozili alebo rozpadli.<\/p>\n
Nede\u0161trukt\u00edvne sk\u00fa\u0161ky, ako napr\u00edklad akustick\u00e1 a nanoindent\u00e1cia, poskytuj\u00fa \u00fa\u010dinn\u00e9 n\u00e1stroje na hodnotenie mechanick\u00fdch vlastnost\u00ed materi\u00e1lov; ich po\u017eiadavky na vzorky v\u0161ak m\u00f4\u017eu by\u0165 obmedzen\u00e9, \u010do vedie k menej rovnomern\u00fdm distribu\u010dn\u00fdm krivk\u00e1m v porovnan\u00ed s tradi\u010dn\u00fdmi met\u00f3dami \u0165ahov\u00fdch sk\u00fa\u0161ok.<\/p>\n
Youngov modul, ozna\u010dovan\u00fd aj ako modul pru\u017enosti, meria schopnos\u0165 materi\u00e1lov odol\u00e1va\u0165 deform\u00e1cii. In\u017einieri potrebuj\u00fa pozna\u0165 Youngov modul, preto\u017ee kvantifikuje odolnos\u0165 vo\u010di vonkaj\u0161\u00edm sil\u00e1m a umo\u017e\u0148uje im navrhova\u0165 efekt\u00edvnej\u0161ie syst\u00e9my.<\/p>\n
Na stanovenie Youngovho modulu sa vzorka materi\u00e1lu mus\u00ed najprv vystavi\u0165 rast\u00facemu \u0165ahov\u00e9mu nam\u00e1haniu, a\u017e k\u00fdm sa nedosiahne jeho hranica pru\u017enosti, a potom sa nech\u00e1 vr\u00e1ti\u0165 na p\u00f4vodn\u00e9 rozmery, ne\u017e sa aplikuje nov\u00e9 nam\u00e1hanie. Merania deform\u00e1cie vykonan\u00e9 po\u010das tohto procesu umo\u017e\u0148uj\u00fa vypo\u010d\u00edta\u0165 Youngov modul vykreslen\u00edm jeho sklonu na krivke nap\u00e4tie\/deform\u00e1cia.<\/p>\n
Hoci sk\u00fa\u0161ka \u0165ahom zost\u00e1va z\u00e1kladnou met\u00f3dou na meranie Youngovho modulu, jej presnos\u0165 pri meran\u00ed deform\u00e1cie v mikroskopickej mierke m\u00f4\u017ee by\u0165 problematick\u00e1. Nanoindent\u00e1cia pon\u00faka \u010fal\u0161\u00ed pr\u00edstup, ktor\u00fd dok\u00e1\u017ee presne zachyti\u0165 hodnoty Youngovho modulu v nanorozmeroch - vy\u017eaduje si v\u0161ak testovacie zariadenie s vysok\u00fdm rozl\u00ed\u0161en\u00edm a \u0161pecializovan\u00e9 n\u00e1stroje na pr\u00edpravu vzoriek na anal\u00fdzu.<\/p>\n
Youngov modul oxidu hlinit\u00e9ho sa sk\u00famal dynamicky po\u010das procesu spekania a uk\u00e1zal exponenci\u00e1lny vz\u0165ah s p\u00f3rovitos\u0165ou, ktor\u00fd je vo v\u00fdbornej zhode so statick\u00fdmi meraniami pri izbovej teplote. Dynamick\u00fd Youngov modul navy\u0161e exponenci\u00e1lne narast\u00e1 pri vy\u0161\u0161\u00edch teplot\u00e1ch, preto\u017ee procesy zhut\u0148ovania prevl\u00e1daj\u00fa nad procesmi spekania.<\/p>\n
Vzh\u013eadom na ni\u017e\u0161\u00ed modul pru\u017enosti oxidu hlinit\u00e9ho si jeho roztiahnutie vy\u017eaduje v\u00e4\u010d\u0161iu silu ako roztiahnutie podobn\u00fdch \u00fasekov oce\u013eov\u00e9ho materi\u00e1lu, v\u010faka \u010domu je testovanie pomocou Vernierovej stupnice z\u00e1kladn\u00fdm sp\u00f4sobom zberu presn\u00fdch \u00fadajov po\u010das \u0165ahov\u00fdch sk\u00fa\u0161ok. In\u017einieri bud\u00fa ma\u0165 prospech z presnej\u0161\u00edch v\u00fdpo\u010dtov Youngovho modulu, aby mohli tieto d\u00f4le\u017eit\u00e9 inform\u00e1cie vyu\u017ei\u0165 pri navrhovan\u00ed efekt\u00edvnej\u0161\u00edch kon\u0161trukci\u00ed. Pr\u00edklad: Pou\u017eitie oxidu hlinit\u00e9ho s ni\u017e\u0161\u00edm Youngov\u00fdm modulom ako oce\u013e m\u00f4\u017ee zabezpe\u010di\u0165 v\u00e4\u010d\u0161iu tuhos\u0165 zubn\u00fdch n\u00e1hrad a zn\u00ed\u017ei\u0165 praskanie pri p\u00f4soben\u00ed sily, \u010d\u00edm sa zlep\u0161\u00ed pohodlie pacienta a z\u00e1rove\u0148 sa zn\u00ed\u017ei riziko zlyhania implant\u00e1tu v d\u00f4sledku nadmern\u00e9ho za\u0165a\u017eenia.<\/p>\n
Oxid hlinit\u00fd sa vyzna\u010duje extr\u00e9mne vysok\u00fdm Youngov\u00fdm modulom, v\u010faka \u010domu je odoln\u00fd vo\u010di deform\u00e1cii. Nane\u0161\u0165astie, jeho krehk\u00e1 povaha br\u00e1ni jeho pou\u017eitiu v aplik\u00e1ci\u00e1ch vy\u017eaduj\u00facich plasticitu, ako s\u00fa kon\u0161truk\u010dn\u00e9 komponenty alebo rezn\u00e9 n\u00e1stroje, preto\u017ee nem\u00e1 body klzu - preto je tak d\u00f4le\u017eit\u00e9 pochopi\u0165 jeho spr\u00e1vanie pri nam\u00e1han\u00ed.<\/p>\n
Vibra\u010dn\u00e9 testovanie poskytuje rie\u0161enie prostredn\u00edctvom merania rezonan\u010dnej frekvencie objektu na pos\u00fadenie jeho elastick\u00fdch vlastnost\u00ed. Na vibra\u010dn\u00e9 testovanie sa pou\u017e\u00edvaj\u00fa mal\u00e9 projektily, ktor\u00fdmi sa poklep\u00e1va na vzorky, pri\u010dom sa zaznamen\u00e1vaj\u00fa vibra\u010dn\u00e9 sign\u00e1ly pomocou sn\u00edma\u010dov; potom sa konvertuj\u00fa sp\u00e4\u0165 na \u00fadaje vo frekven\u010dnej oblasti prostredn\u00edctvom r\u00fdchlej Fourierovej transform\u00e1cie a nakoniec sa vyu\u017e\u00edvaj\u00fa v softv\u00e9ri navrhnutom \u0161peci\u00e1lne na ich anal\u00fdzu s cie\u013eom vypo\u010d\u00edta\u0165 rezonan\u010dn\u00fa frekvenciu s vysokou presnos\u0165ou a ur\u010di\u0165 elastick\u00e9 vlastnosti vzoriek.<\/p>\n
Poissonov pomer v hlin\u00edku z\u00e1vis\u00ed od hustoty a bunkovej \u0161trukt\u00fary jeho zlo\u017eenia, preto presn\u00e9 meranie Poissonovho pomeru v hlin\u00edku m\u00f4\u017ee by\u0165 kv\u00f4li t\u00fdmto premenn\u00fdm zlo\u017eit\u00e9. Napriek tomu ho nieko\u013eko \u0161t\u00fadi\u00ed sk\u00famalo prostredn\u00edctvom vibra\u010dn\u00fdch testov alebo in\u00fdch prostriedkov.<\/p>\n
Jednou z tak\u00fdchto met\u00f3d je syst\u00e9m Sonelastic na meranie \u0161myku, Poissonovho pomeru a tlmenia. Zariadenie meria rezonan\u010dn\u00e9 frekvencie vzoriek pomocou presnej dr\u00f4tenej podpory na ur\u010denie modulov pru\u017enosti materi\u00e1lov s hrubou mikro\u0161trukt\u00farou, ako s\u00fa bet\u00f3ny alebo \u017eiaruvzdorn\u00e9 materi\u00e1ly - merania sa vykon\u00e1vaj\u00fa pri n\u00edzkych aj vysok\u00fdch teplot\u00e1ch.<\/p>\n
Normalizovan\u00fd Poissonov pomer v hlin\u00edkov\u00fdch pen\u00e1ch sa men\u00ed v z\u00e1vislosti od ich relat\u00edvnej hustoty a najlep\u0161ie sa modeluje pomocou mocninov\u00e9ho z\u00e1kona s exponentom 1,72 +- 0,10. T\u00e1to hodnota sa dokonale zhoduje s in\u00fdmi formami hlin\u00edkov\u00fdch pien, \u010d\u00edm sa potvrdzuj\u00fa ich merania. Alternat\u00edvne by modely zmesi alebo perkol\u00e1cie mohli vysvetli\u0165, pre\u010do Poissonov pomer kles\u00e1 so zvy\u0161uj\u00facou sa p\u00f3rovitos\u0165ou.<\/p>\n
Dynamicky po\u010das spekania sa Youngov modul line\u00e1rne zni\u017eoval s teplotou a potom sa pri vy\u0161\u0161\u00edch teplot\u00e1ch r\u00fdchlo zvy\u0161oval, ke\u010f pokra\u010dovali procesy zhut\u0148ovania. Dynamick\u00e9 merania Youngovho modulu mali pre t\u00fato vzorku podobn\u00e9 trendy ako statick\u00e9 merania pri izbovej teplote.<\/p>\n
Oxid hlinit\u00fd je jedn\u00fdm z najpevnej\u0161\u00edch materi\u00e1lov v\u010faka svojej vynikaj\u00facej pevnosti v \u0165ahu. Dok\u00e1\u017ee odola\u0165 ve\u013ekej z\u00e1\u0165a\u017ei a nam\u00e1haniu bez toho, aby praskol, v\u010faka \u010domu je vhodn\u00fd pre stavebn\u00e9 projekty vy\u017eaduj\u00face vysokopevnostn\u00e9 materi\u00e1ly, a m\u00f4\u017ee sa pochv\u00e1li\u0165 aj p\u00f4sobivou odolnos\u0165ou proti oderu, tak\u017ee je vhodn\u00fd pre komponenty, ktor\u00e9 bud\u00fa vystaven\u00e9 opotrebovaniu a oderu.<\/p>\n
Hlin\u00edkov\u00e1 keramika je zn\u00e1ma svojou odolnos\u0165ou vo\u010di tepeln\u00fdm \u0161okom, \u010do znamen\u00e1, \u017ee dok\u00e1\u017ee odol\u00e1va\u0165 vysok\u00fdm teplot\u00e1m bez toho, aby ju n\u00e1hle zv\u00fd\u0161enie teploty po\u0161kodilo. V\u010faka tomu je oxid hlinit\u00fd ide\u00e1lny pre aplik\u00e1cie, ktor\u00e9 zah\u0155\u0148aj\u00fa vysok\u00e9 teploty, ako je leteck\u00e1 technika alebo v\u00fdroba energie. Okrem toho jeho vynikaj\u00faca elektrick\u00e1 vodivos\u0165 umo\u017e\u0148uje jeho pou\u017eitie v aplik\u00e1ci\u00e1ch elektroin\u0161tal\u00e1cie alebo zapojenia in\u00fdch predmetov.<\/p>\n
Sk\u00fa\u0161ka \u0165ahom je jedn\u00fdm z najlep\u0161\u00edch sp\u00f4sobov presn\u00e9ho merania Youngovho modulu v materi\u00e1loch, pri ktorom sa postupne zvy\u0161uje sila p\u00f4sobiaca na vzorku a\u017e do jej hranice pru\u017enosti. V ka\u017edom bode tohto procesu sa meria sila a deform\u00e1cia v r\u00f4znych bodoch na jej trase a\u017e do dosiahnutia tejto oblasti pru\u017enosti - a jej sklon sa vykresl\u00ed ako s\u00fa\u010das\u0165 krivky nap\u00e4tia a deform\u00e1cie. Hoci sa t\u00e1to met\u00f3da v\u00fdborne osved\u010duje pri meran\u00ed mechanick\u00fdch vlastnost\u00ed na \u00farovni mikrorozmerov a nanorozmerov, na jej efekt\u00edvne vykon\u00e1vanie m\u00f4\u017ee by\u0165 potrebn\u00e9 \u0161pecializovan\u00e9 vybavenie a odborn\u00e9 znalosti.<\/p>\n
Existuj\u00fa v\u0161ak aj in\u00e9 met\u00f3dy merania Youngovho modulu, ktor\u00e9 poskytuj\u00fa presnej\u0161ie v\u00fdsledky ako \u0165ahov\u00e9 sk\u00fa\u0161ky. Jednou z tak\u00fdchto met\u00f3d je nanoindent\u00e1cia AFM, ktor\u00e1 umo\u017e\u0148uje presn\u00e9 meranie vlastn\u00e9ho Youngovho modulu materi\u00e1lov; pri tejto technike sa konzola vybaven\u00e1 hrotom AFM oh\u00fdba proti povrchu vzorky a z tohto procesu sa zaznamen\u00e1vaj\u00fa krivky z\u00e1vislosti sily od deform\u00e1cie.<\/p>\n
Vedci m\u00f4\u017eu t\u00fato met\u00f3du pou\u017ei\u0165 na porovnanie hodn\u00f4t Youngov\u00fdch modulov r\u00f4znych materi\u00e1lov a ur\u010di\u0165, ktor\u00fd z nich m\u00e1 najvy\u0161\u0161iu vlastn\u00fa hodnotu. Okrem toho sa tento pr\u00edstup d\u00e1 vyu\u017ei\u0165 aj na anal\u00fdzu toho, ako po\u0161kodenie ovplyv\u0148uje hodnoty Youngovho modulu materi\u00e1lov.<\/p>\n
Vedci tie\u017e zistili, \u017ee p\u00f3rovitos\u0165 oxidu hlinit\u00e9ho ovplyv\u0148uje jeho Youngov modul a Poissonov pomer. Zatia\u013e \u010do predch\u00e1dzaj\u00face \u0161t\u00fadie zoh\u013ead\u0148ovali len gu\u013eov\u00fd tvar p\u00f3rov po\u010das zhut\u0148ovania, t\u00e1to nov\u00e1 \u0161t\u00fadia zoh\u013ead\u0148uje aj v\u0161etky modifik\u00e1cie po\u010das zhut\u0148ovania, ktor\u00e9 menia tvar p\u00f3rov.<\/p>\n
In\u017einieri pou\u017e\u00edvaj\u00fa Youngov modul na ur\u010denie toho, ak\u00e9 ve\u013ek\u00e9 nam\u00e1hanie m\u00f4\u017ee materi\u00e1l vydr\u017ea\u0165 pred trvalou deform\u00e1ciou alebo zlyhan\u00edm, \u010do umo\u017e\u0148uje in\u017einierom vytv\u00e1ra\u0165 kon\u0161trukcie schopn\u00e9 odol\u00e1va\u0165 vonkaj\u0161\u00edm sil\u00e1m bez toho, aby sa rozpadli alebo zr\u00fatili. V\u00fdskumn\u00edci \u010dasto vyu\u017e\u00edvaj\u00fa met\u00f3dy nede\u0161trukt\u00edvneho testovania, ako s\u00fa ultrazvukov\u00e9 vlny, na presn\u00e9 v\u00fdpo\u010dty Youngovho modulu; merania r\u00fdchlosti ultrazvukov\u00fdch v\u013an umo\u017e\u0148uj\u00fa korel\u00e1ciu Youngovho modulu s mikro\u0161trukt\u00farou materi\u00e1lu, ve\u013ekos\u0165ou z\u0155n a charakteristikami p\u00f3rovitosti \u017eiaruvzdorn\u00fdch materi\u00e1lov.<\/p>\n
Pru\u017en\u00e9 vlastnosti oxidu hlinit\u00e9ho z\u00e1visia od jeho teploty a procesu spekania, ako aj od zlo\u017eenia sklovit\u00fdch f\u00e1z pr\u00edtomn\u00fdch na hraniciach z\u0155n. T\u00e1to druh\u00e1 f\u00e1za m\u00f4\u017ee ma\u0165 dramatick\u00fd vplyv na mieru odolnosti proti te\u010deniu; pri vystaven\u00ed vysok\u00fdm teplot\u00e1m spekania sa viskoelastick\u00e1 deform\u00e1cia v\u00fdrazne zvy\u0161uje, zatia\u013e \u010do pri ni\u017e\u0161\u00edch teplot\u00e1ch tento parameter line\u00e1rne kles\u00e1.<\/p>\n
Hlin\u00edk mo\u017eno spevni\u0165 pridan\u00edm prvkov, ktor\u00e9 zvy\u0161uj\u00fa koncentr\u00e1ciu sklovitej f\u00e1zy a pevnos\u0165, ako aj zlep\u0161en\u00edm kry\u0161t\u00e1lovej \u0161trukt\u00fary na zv\u00fd\u0161enie Youngovho modulu a odolnosti proti te\u010deniu. Dopovanie La, Mg alebo Y m\u00f4\u017ee zn\u00ed\u017ei\u0165 teplotu spekania a z\u00e1rove\u0148 zn\u00ed\u017ei\u0165 r\u00fdchlos\u0165 te\u010denia pri s\u00fa\u010dasnom zv\u00fd\u0161en\u00ed pevnosti v \u0165ahu.<\/p>\n
Na obr\u00e1zku 11 s\u00fa zobrazen\u00e9 \u0165ahov\u00e9 fraktografy kompozitov ABOw\/Al-12Si vystu\u017een\u00fdch whiskermi pri 350 a 400 stup\u0148och C, ktor\u00e9 vykazovali makroskopicky krehk\u00fd lom ako celok, ale mikroskopicky tv\u00e1rny lom v lok\u00e1lnych oblastiach, ktor\u00e9 vykazovali rozpojenie medzi matricou a whiskrami, ako aj zn\u00e1mky f\u00e1z krem\u00edka alebo intermetalick\u00fdch zl\u00fa\u010den\u00edn na hlin\u00edkov\u00fdch povrchoch, \u010do nazna\u010duje, \u017ee medzif\u00e1zov\u00e9 rozpojenie na povrchu pri te\u010den\u00ed bolo zrejm\u00e9 na povrchu pri te\u010den\u00ed, pri\u010dom na hlin\u00edkovom povrchu boli vidite\u013en\u00e9 f\u00e1zy krem\u00edka alebo intermetalick\u00fdch zl\u00fa\u010den\u00edn, ako je vidie\u0165 zo sn\u00edmok povrchu pri te\u010den\u00ed (obr. 11).<\/p>","protected":false},"excerpt":{"rendered":"
Engineers rely on young’s modulus to evaluate how much stress a material can bear before deforming permanently or failing, and […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"categories":[3],"tags":[],"class_list":["post-742","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts\/742","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/comments?post=742"}],"version-history":[{"count":1,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts\/742\/revisions"}],"predecessor-version":[{"id":743,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/posts\/742\/revisions\/743"}],"wp:attachment":[{"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/media?parent=742"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/categories?post=742"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/artehistoria.net\/sk\/wp-json\/wp\/v2\/tags?post=742"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}