EFFECT OF FIBER WAVINESS ON STIFFNESS AND STRENGTH REDUCTION OF UNIDIRECTIONAL COMPOSITES UNDER COMPRESSIVE LOADING

An investigation has been conducted of the effect of fiber waviness on stiffness and strength reduction of unidirectional composites under c ompressive loading Analytical models have been developed for determini ng the elastic properties and compressive strength as a function of fi ber waviness for three types of wavy patterns: uniform, graded and loc alized waviness. Compression tests were conducted to verify the predic tions. Experimental results were in good agreement with predictions ba sed on the analytical models. It is shown that in unidirectional compo sites both major Young's modulus and compressive strength ave degraded seriously with increasing fiber waviness. Material anisotropy is also shown to influence the degree of stiffness and strength reduction. In terlaminar shear failure was found to be the dominant failure mechanis m for unidirectional wavy composites under compressive loading. (C) 19 96 Published by Elsevier Science Limited