Three-dimensional boundary element analysis of residual stresses in a cross-ply fiber composite model

The residual stress distribution in cross-ply laminates is investigated at the microstress level within the scope of linear viscoelasticity. A three-dimensional model is presented and analyzed to estimate the residual stresses induced during the polymerization and the cool-down phases. Matrix and fibers are treated as subzones coupled with displacement continuity and traction equilibrium conditions along the interface. This problem is preceded by a unidirectional laminate problem which is a preliminary step to analyzing the three-dimensional model.;In this research, a three-dimensional boundary element method appropriate to estimate residual stresses in a cross-ply laminate model is presented, in which the time domain method for viscoelastic analysis of matrix zone is used. In order to achieve an accurate and efficient integration scheme, a modified Simpon's rule with respect to time is employed.;New two-dimensional BEM computer programs (BEM2DV) and three-dimensional BEM programs (BEM3DV) have been developed. Analysis capabilities of these new computer codes include stress analysis of two-dimensional and three-dimensional elastic, viscoelastic, and thermoviscoelastic objects with subregions of different materials. PATRAN is used as a pre and post processor for the BEM2DV and BEM3DV codes.;Final results are presented in colored contour maps to illustrate the residual stress distribution in the matrix zone. The resulting residual stresses are the same order of magnitude as that of the matrix strength.