An electromechanical study of the transverse behavior of carbon fiber polymer-matrix composite

The transverse behavior of continuous carbon fiber epoxy-matrix composite was studied by measuring the 0° electrical resistance of a [90]32 composite during 0° tension and compression. The number of fiber-fiber contacts was found to decrease by 0.7% upon tension to 0.5% strain (resistance increasing) and increase by 1.1% upon compression to -0.5% strain (resistance decreasing), such that this number decreased with increasing strain and the resistance varied linearly with strain (fractional resistance change per unit strain = 2), until damage (probably matrix cracking) occurred and caused the resistance to increase with compressive strain beyond 1% (84 MPa stress) and increase abruptly with tensile strain beyond 0.5% (43 MPa stress). Prior to damage, the resistance varied with strain reversibly; slight reversibility was due to plastic deformation of the matrix.