Environmental Effects on Tensile Strength and Other Mechanical Properties of Hand Lay-Up GRP Panels
The use of fiber reinforced composites as structural mechanical components is on the increase. Glass reinforced plastics (GRP) are the least-priced and most commonly used on account of their several advantages over the more expensive composites. Production related defects in these composites frequently promote degradations in mechanical properties when exposed to hostile media. Coupon test specimens cut from a GRA automobile panel, produced by hand lay-up technique, were investigated for responses to specific environmental conditions. Results indicate up to about 30% reductions in tensile strengths and tensile moduli due to exposure to wetness or diurnal cycling of wetting, drying and temperature variations. These effects tend to be reversible upon thorough drying. However continuous soaking in mud appears to have more permanent effects on the tensile modulus, with a 20% reduction even after washing and drying. Exposure to wet conditions also resulted in less brittle failure, with about 23% increases in the maximum strains.