Control Volume Analysis of Elastic Wave Front in Composite Materials

Abstract

A theory is proposed for the analysis of an elastic wave front in unidirectionally laminated as well as fiber reinforced composite mate rials. According to this theory, which is based on the concept of control volume, elastic wave front due to abrupt loadings propagates at a velocity which is bounded by the wave velocities of the fiber material and of the matrix material. The theory includes a nonlinear effect of area change; the wave front velocity is a function of the impact intensity. But for linearly elastic materials, this non-linear effect is small; if it is neglected, then wave front speed in the com posite becomes independent of the impact intensity. Consideration has also been given to the determination of the shear force along the interface between the reinforcing fiber and the matrix. It is found that for certain combination of fiber and matrix, the shear stress attains an extremum value which may cause debond ing of the composite under moderate impact loading.