Title: A SIMPLIFIED METHOD FOR SIMULATING RESIDUAL STRESSES IN ASYMMETRIC TEXTILE COMPOSITES
Abstract: Residual stresses can form within composite structures composed of asymmetric laminates during the elevated temperature curing processes common to composite materials. These residual stresses are primarily the result of unbalanced thermal strains that develop throughout the structure due to the composite’s orthotropic coefficients of thermal expansion. Furthermore, structures composed of textile, or woven, composite fabrics lend themselves to the formation of these residual stresses, as extreme care must be taken during the lay-up of such parts to ensure that adjacent plies are placed front-to-front or back-to-back, as opposed to front-to-back, to eliminate the potential for any unbalanced thermal strains. Depending upon the specific geometric details of the composite structure of interest, it is possible that these residual stresses could result in fracture within the composite. Therefore, the consideration of potential residual stresses formed throughout the manufacturing process is important. However, the experimental determination of residual stresses in prototype parts can be time and cost prohibitive. As an alternative to physical measurement, it is possible for computational tools to be used to quantify potential residual stresses in composite prototype parts. Therefore, the objectives of this study are two-fold. First, a simplistic method for simulating the residual stresses formed in polymer matrix composite structures is developed within the Sandia National Laboratories’ SIERRA/SolidMechanics code Adagio. Subsequently, the required level of model fidelity necessary to provide realistic predictions of a textile composite’s residual stress state is determined. Concurrent with the computational activities, asymmetric plates of a woven carbon fiber/epoxy composite are manufactured with varying thicknesses and the residual stresses exhibited by the plates are quantified through the measurement of deformation. The developed computational approach is used to simulate the manufacturing process of these asymmetric plates and final comparisons of the predicted and experimental results show reasonable agreement.
Authors: Stacy Nelson, Brian Werner, Kevin Nelson, Alexander Hanson, Timothy Briggs
Conference: CAMX 2017 –Orlando