IDENTIFICATION OF MATERIAL PROPERTIES OF COMPOSITE MATERIALS

Abstract

Present paper describes the facilities of composite material properties identification technique using specimen vibration tests, genetic algorithms, finite elements analysis and specimen shape optimization. In identification process the elastic constants in a numerical model is updated so that the output from the numerical code fits the results from vibration testing. Main problem analysed in this paper is that Poisson's ratio is the worst determined elastic characteristic due to its low influence on specimen eigenfrequencies. It is shown that it is possible to increase its influence by choosing specific test specimen characteristics (side aspect ratio, orthotropy angle, etc.) via optimization routine. In this paper are presented test results of some experiments wherein glass‐epoxy and carbon‐epoxy material properties were identified. Santrauka Straipsnyje aprašomas kompozitiniu medžiagu tamprumo charakteristiku identifikavimo metodas naudojant bandiniu vibracinius bandymus, genetinius algoritmus, baigtiniu elementu metoda ir bandiniu formos optimizavima. Identifikavimo metu tamprumo charakteristikos skaitmeniniame modelyje yra atnaujinamos tol, kol skaitinio eksperimento rezultatai nustatytu tikslumu sutampa su vibracinio bandymo rezultatais. Šio straipsnio pagrindinis uždavinys yra padidinti Puasono koeficiento identifikavimo tiksluma, kadangi šis, palyginti su kitu tamprumo charakteristiku identifikavimo tikslumais, yra menkas del ypač mažos koeficiento itakos bandinio tikriniams dažniams. Darbe parodyta, kad imanoma padidinti Puasono koeficiento itaka optimizavimo procedūromis, pasirenkant konkrečias bandinio savybes (kraštiniu proporcijas, ortotropijos kampa ir t.t.). Pateikiami keleto stiklo ir anglies pluoštais armuotu kompozitiniu medžiagu tamprumo charakteristiku identifikavimo rezultatai.