Viscoelastic behavior of polymeric composite materials under mechanical loads

The importance of material damping in the design process has increased in recentyears as the control of noise and vibration in high precision, high performancestructures and machines has become more of a concern. The main objective of thepresent work is to investigate the influence of some materials and test variables onthe viscoelastic behavior (Dynamic Mechanical Properties) of glass fiber reinforced(GFR)/plastics composites. Material variables include: matrix type, off-axis angleand fiber configuration. Variation of matrix (epoxy, vinylester and polyester) andfiber configuration (unidirectional, woven and chopped) result in five differentcomposite materials. These composite laminates are unidirectional GFR/polyester(UD-GFRP), unidirectional GFR/vinylester (UD-GFRV), unidirectionalGFR/epoxy (UD-GFRE), woven GFRP and chopped GFRP.These composites are locally manufactured using hand lay-up technique. Toinvestigate the influence of fiber orientation on dynamic mechanical properties, theunidirectional composite laminates with different matrices are cut at different offaxisangles ( = 0°, 15°, 30°, 45°, 60° and 75°). Test variables include: temperatureand the frequency of the dynamic load. Longitudinal sinusoidal dynamic loads withdifferent loading frequencies (3.5, 11, 35 and 110 Hz) were implemented on thecomposite materials under wide temperature range (25°C up to 130°C) usingRheovibron DDV-III-C instrument. from experimental results the creepcompliances and relaxation moduli behaviors were predicted theoretically using anInverse Fourier Transform and numerical integration.