Interfacial stress estimation using least-square extrapolation and local stress smoothing in laminated composites

This paper applies the finite element least-square extrapolation and smoothing technique to demonstrate its advantages in the evaluation of interfacial stress distributions in composite laminates. The analysis uses the quasi-three-dimensional finite element modeling technique and complete three-dimensional analysis using ABAQUS to investigate the stress distributions in graphite/epoxy laminates. Linear (two points integration) and quadratic (three point integration) least square fits in eight-node quadrilateral and 20-node solid isoparametric elements are demonstrated. The evaluation of transformation matrix from Gaussian stresses to nodal stresses was performed using symbolic mathematics on ''Mathematica''. The results show that use of extrapolation and smoothing offer better estimates of stress distributions and the interfacial stresses in composite laminates.