Brezdotična metoda za identifikacijo materialnih parametrov polimernih materialov

Korbar, Jure (author), Čepon, Gregor (mentor)

Polimerni materiali v sodobnem svetu pogosto predstavljajo alternativo kovinam za izdelavo številnih izdelkov in komponent. Za ustrezno dimenzioniranje je poznavanje materialnih parametrov polimernih materialov, posebej modula elastičnosti, bistvenega pomena. Slednji se, v primeru polimernih materialov, spreminja v odvisnosti od temperature. Običajen pristop določanja modula, kjer preizkušance vpenjamo, se izkaže kot težaven, saj polimeri pri povišanih temperaturah lezejo. V nalogi je predstavljena brezdotična metoda, ki zaradi alternativnega načina vpetja polimernega preizkušanca, ki mu vsilimo proste robne pogoje, ni občutljiva na lezenje in omogoča identifikacijo modula elastičnosti na podlagi eksperimentalno določenih lastnih frekvenc. Lastne frekvence smo identificirali v temperaturnem območju od 30 °C do 120 °C, kar nam kasneje služi kot osnova za izračun modula elastičnosti pri teh temperaturah. V istem temperaturnem območju smo identificirali tudi razmernik viskoznega dušenja.

• Language: Slovenian
• Keywords: brezdotična metoda, polimerni materiali, frekvenčna prenosna funkcija, vzbujanje z zrakom, laserski vibrometer, lastne frekvence, viskozno dušenje, modul elastičnosti
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [J. Korbar]
• Year: 2020
• Number of pages: 31 str.
• PID: 20.500.12556/RUL-118831
• UDC: 678.7:539.32.620.174.22(043.2)
• COBISS.SI-ID: 27060995
• Publication date in RUL: 01.09.2020

Secondary language

• Language: English
• Title: Non-contact method for material parameter identification of polymers

Abstract

Polymers are nowadays often used in the process of manufacturing of numerous products and components. The knowledge of material parameters is essential for proper sizing of products. This is especially the case with regards to modulus of elasticity. In the case of polymers, the latter is well known to vary with temperature. The standard approach, which is based on clamping test samples, appears to cause creep-related issues at elevated temperatures. The paper presents a non-contact method, which is not sensitive to creep and enables the identification of the elasticity modulus based on experimentally obtained natural frequencies. This is done by utilizing an alternative clamping method of the test sample which imposes free boundary conditions. The natural frequencies were identified in the temperature range from 30 °C to 120 °C, which are used for calculating the modulus of elasticity at these temperatures. Viscous damping ratio was also identified in the same temperature range.

• Keywords: non-contact method, polymers, frequency response function, air excitation, laser vibrometer, natural frequencies, viscous damping, modulus of elasticity