الفهرس | Only 14 pages are availabe for public view |
Abstract The importance of material damping in the design process has increased in recent years as the control of noise and vibration in high precision, high performance structures and machines has become more of a concern. The main objective of the present work is to investigate the influence of some materials and test variables on the viscoelastic behavior (Dynamic Mechanical Properties) of glass fiber reinforced (GFR)/plastics composites. Material variables include: matrix type, off-axis angle and fiber configuration. Variation of matrix (epoxy, vinylester and polyester) and fiber configuration (unidirectional, woven and chopped) result in five different composite materials. These composite laminates are unidirectional GFR/polyester (UD-GFRP), unidirectional GFR/vinylester (UD-GFRV), unidirectional GFR/epoxy (UD-GFRE), woven GFRP and chopped GFRP. These composites are locally manufactured using hand lay-up technique. To investigate the influence of fiber orientation on dynamic mechanical properties, the unidirectional composite laminates with different matrices are cut at different offaxis angles ( = 0°, 15°, 30°, 45°, 60° and 75°). Test variables include: temperature and the frequency of the dynamic load. Longitudinal sinusoidal dynamic loads with different loading frequencies (3.5, 11, 35 and 110 Hz) were implemented on the composite materials under wide temperature range (25°C up to 130°C) using Rheovibron DDV-III-C instrument. from experimental results the creep compliances and relaxation moduli behaviors were predicted theoretically using an Inverse Fourier Transform and numerical integration. |