"Stiffness" yog hais txog lub zog uas yuav tsum tau ua rau chav deformation ntawm ib yam khoom; "Flexibility" yog hais txog deformation ntawm ib yam khoom nyob rau hauv ib chav tsev quab yuam. Nws tuaj yeem pom tias qhov loj dua qhov "tuaj" yog, qhov tsawg dua qhov khoom yog deform (pom los ntawm qhov me me elongation); Cov khoom uas muaj "kev yoog raws" ntau dua yuav deform (qhia los ntawm ntau dua elongation). Nyob rau hauv ib lub xeev zoo tagnrho, qhov tawv ntawm cov khoom nyhav mus rau infinity (los yog deformation ntawm cov khoom nyob rau hauv lub quab yuam yog me me uas nws yuav tsis quav ntsej), yog li peb hu cov khoom ib tug nruj lub cev. Hauv kev tshuaj xyuas txhua yam, nws tus kheej deformation yuav tsis raug txiav txim siab. Yog li ntawd, rigidity yog tus cwj pwm cuam tshuam txog qhov nyuaj ntawm cov khoom deformation. Cov khoom siv ductile yog qhov muag muag, thiab lub tensile elongation ntawm kev tawg thiab cuam tshuam lub zog ntawm daim ntawv ntawm lub cev yog qhov loj; Hardness, tensile zog thiab tensile modulus ntawm elasticity yog me me. Lub hardness thiab tensile lub zog ntawm cov ntaub ntawv nruj yog kuj siab; elongation ntawm so thiab cuam tshuam lub zog yuav qis dua; Lub tensile modulus ntawm elasticity yog loj. Lub zog khoov qhia qhov rigidity ntawm cov khoom. Qhov ntau dua qhov khoov lub zog yog, qhov ntau dua qhov rigidity ntawm cov khoom yog. Ntawm qhov tsis sib xws, qhov ntau dua qhov toughness yog. Raws li ASTM D790 Standard Test Methods for Flexural Properties, cov kev xeem no tsim nyog rau ob qho tib si nruj thiab ib nrab-rigid cov ntaub ntawv. Nws tsis tau hais tias nws tsim nyog rau cov ntaub ntawv ductile, yog li elastomers nrog zoo toughness yuav tsis raug kuaj rau lub zog dabtsi yog khoov.
Cov lus hais saum toj no toughness thiab rigidity yog txheeb ze rau cov khoom siv kho tshuab. Tej zaum yuav muaj xwm txheej. Piv txwv li, tom qab siv cov iav fiber reinforced yas, nws rigidity yuav loj dua, tab sis lub zog tensile thiab cuam tshuam lub zog kuj yuav nce. Raws li kev cuam tshuam thiab kev vibration loads, cov ntaub ntawv tuaj yeem nqus lub zog loj los tsim qee yam deformation yam tsis muaj kev puas tsuaj, uas yog hu ua toughness lossis cuam tshuam toughness. Lub tsev steel (me me steel), ntoo, yas, thiab lwm yam yog cov khoom siv ductile. Lub toughness ntawm cov ntaub ntawv yuav tsum tau txiav txim siab rau pavement, choj, crane nqaj thiab cov qauv nrog seismic yuav tsum tau. Rigidity thiab brittleness feem ntau txuas nrog. Brittleness yog hais txog cov cuab yeej uas thaum lub zog sab nraud mus txog ib qho kev txwv, cov khoom raug puas tsuaj tam sim ntawd yam tsis muaj kev ceeb toom, thiab tsis muaj qhov pom tseeb ntawm cov yas deformation thaum nws raug puas tsuaj. Cov yam ntxwv ntawm cov khoom siv ntawm cov khoom siv tawv tawv yog tias lub zog compressive ntau dua li lub zog tensile, thiab qhov txwv tsis pub muaj tus nqi ntawm qhov tsis ua haujlwm yog tsawg heev. Cib, pob zeb, ceramics, iav, pob zeb, cam khwb cia hlau, thiab lwm yam yog cov khoom siv nkig. Piv nrog rau cov ntaub ntawv ductile, lawv yog qhov tsis zoo rau kev tiv thaiv kev cuam tshuam thiab kev vibration.
Raws li engineering plastics, peb cia siab tias nws muaj qhov zoo toughness thiab rigidity tib lub sijhawm. Txhawm rau txhim kho qhov toughness ntawm cov ntaub ntawv, kev siv zog kuj yuav tsum tau ua los txhim kho lub rigidity. Feem ntau, ntxiv elastomer tuaj yeem ua kom tawv nqaij, thiab ntxiv cov khoom siv tsis muaj zog tuaj yeem ua rau kom muaj zog. Txoj kev ua tau zoo tshaj plaws yog muab cov tawv tawv ntawm elastomer nrog kev ntxiv dag zog ntawm cov muab tub lim. Kev cuam tshuam tsis zoo yog qhov ua haujlwm tsis zoo ntawm qee cov yas tseem ceeb hauv kev lag luam. Piv txwv li, PVC, PS, PP, thiab lwm yam, lawv daim ntawv thov raug txwv tshwj xeeb tshaj yog nyob rau ntawm qhov kub thiab txias vim lawv tsis tshua muaj kev cuam tshuam. Txawm li cas los xij, qhov cuam tshuam tsis zoo ntawm cov thermoplastics tuaj yeem txhim kho tau zoo los ntawm kev ntxiv "kev cuam tshuam kev hloov pauv". Muaj ntau ntau yam kev hloov pauv, xws li ACR acrylate resin, MBS methyl methacrylate butadiene styrene copolymer, CPE chlorinated polyethylene, ABS, EVA, thiab EPDM. Los ntawm qhov kev xav ntawm kev hloov pauv ntawm cov khoom siv yas, ACR muaj qhov ua tau zoo tshaj plaws. MBS yog qhov kev hloov pauv tseem ceeb rau cov khoom lag luam pob tshab thiab ua lub luag haujlwm tseem ceeb hauv kev lag luam cuam tshuam thoob ntiaj teb.