Vpliv temperature na strižno napetostno mejo linearne teorije viskoelastičnosti polieterimida (PEI)

Jan, Petra (author), Emri, Igor (mentor)

Polimerne materiale se vedno pogosteje uporablja v zahtevnejših inženirskih aplikacijah, zato je pomembno pravilno napovedovanje življenjske dobe takih izdelkov znotraj obratovalnih pogojev, ki pa je možno zgolj dokler se material vede linearno (odziv polimera je sorazmeren obremenitvi oz. v danem obremenitvenem območju so mehanske lastnosti konstantne). Cilj zaključne naloge je določiti vpliv temperature na spreminjanje strižne napetostne meje linearne teorije viskoelastičnosti materiala PEI, kar predstavlja mejo med linearnim in nelinearnim območjem vedenja materiala. Vpliv temperature na strižno napetostno mejo smo določili preko meritev mehanskih lastnosti, t.j. strižne voljnosti, v napetostnem območju od 0,1 do 10 MPa, ter temperaturnem območju od 90 do 210°C. Iz rezultatov smo ugotovili, da je strižna napetostna meja konstantna, t.j. 5MPa, do 160°C ter nato močno pade. Poleg določitve območja uporabnosti materiala, kar je pomembno za konstrukcijske namene, izvedeno eksperimentalno delo prispeva tudi k širšemu razumevanju vedenja polimernih materialov in podaja eno izmed možnih metodologij za določitev napetostno-deformacijske meje linearne teorije viskoelastičnosti.

• Language: Slovenian
• Keywords: polimeri časovno odvisni materiali polieterimid (PEI) linearno vedenje nelinearno vedenje strižno lezenje napetostno deformacijska meja linearne teorije viskoelastičnosti vpliv temperature
• Work type: Bachelor thesis/paper
• Organization: FS - Faculty of Mechanical Engineering
• Year: 2017
• PID: 20.500.12556/RUL-92390
• Publication date in RUL: 31.05.2017

Secondary language

• Language: English
• Title: Effect of Temperature on Shear Stress Limit of Linear Theory of Viscoelasticity of Polyetherimide (PEI)

Abstract

Polymeric materials are increasingly used in engineering applications, which requires a correct lifetime prediction of products within their operating conditions. That is only possible if the material behaves linearly (response of polymer is proportional to the external load or its mechanical properties are constant within the given loading conditions). The aim of this thesis is to determine the influence of temperature on the shear stress limit of linear theory of viscoelasticity of material PEI, which represents the boundary between linear and non-linear behaviour of the material. The influence of temperature on shear stress limit of linear theory of viscoelasticity was determined through measurements of mechanical properties, i.e. shear creep compliance in stress range from 0,1 to 10 MPa and temperature range from 90 to 210°C. From the results it can be concluded, that the shear stress limit is constant and around the value of 5 MPa up to 160°C and falls drastically afterwards. The experimental work of this thesis not only serves to establish the range of usefulness for the material, but also broadens the general understanding of polymer behaviour and presents one of the possible methodologies for determining the stress-strain limit of linear theory of viscoelasticity.

• Keywords: polymers time-dependent materials polyetherimide (PEI) linear behaviour non-linear behaviour shear creep stress strain limit of linear theory of viscoelasticity effect of temperature