Multiphysics simulations of cure residual stresses and springback in a thermoset resin using a viscoelastic model with cure‐temperature‐time superposition

Abstract

Simulations of evolution of cure‐induced stresses in a viscoelastic thermoset resin are presented. The phenomenology involves evolution of resin modulus with degree of cure and temperature, the development of stresses due to crosslink induced shrinkage, and the viscoelastic relaxation of these stresses. For the simulations, the detailed kinetic and chemo‐thermo‐rheological models for an epoxy‐amine thermoset resin system, described in Eom et al. (Polym. Eng. Sci. 2000, 40, 1281) are employed. The implementation of this model into the simulation is facilitated by multiphysics simulation strategies. The trends in simulated cure‐induced stresses obtained using the full‐fledged viscoelastic model are compared with those obtained from two other equivalent material models, one involving a constant elastic modulus, and the other involving a cure‐dependent (but time‐invariant) elastic modulus. It is observed that the viscoelastic model not only results in lower estimates of cure‐induced stresses, but also provides subtle details of the springback behavior. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Numerical Analysis of Curing Residual Stress and Deformation in Thermosetting Composite Laminates with Comparison between Different Constitutive Models

“…Currently, the viscoelastic model, even if there are some disadvantages (such as running time consumption and complex formulas) [26,27,28,31,33], remains the most accurate method to forecast the viscoelastic behavior of resins and thermosetting materials. This model factors in the time, temperature, and the change of DOC, a Boltzmann superposition principle.…”

“…Accordingly, composite models with n Maxwell elements, related to viscoelasticity on the basis of a generalized Maxwell model, are prioritized by other scholars to indicate the features related to viscoelasticity taken on by the composites during the course of the cure period [17,26,27]. Through incorporating FEA and this model, the internal stress and deformation taken on by the composite laminates in the entire course of the curing period can be forecast accurately and effectively [28]. This model fails to be extensively adopted, arising from difficulty in numerical implementation, tedious runtimes, and the lacked experiment evidence, even though the current simplified integration approaches are adopted, or models related to viscoelasticity takes on evident strengths for making the composite more accurate [29].…”

Multiscale Modeling of Residual Stress Development in Continuous Fiber-Reinforced Unidirectional Thick Thermoset Composites

“…The implementation of the methodology is facilitated by multiphysics modeling strategies which have enabled detailed and comprehensive accounting of cure phenomenology (see, e.g., [24]). The multiscale framework demonstrated here may be broadly divided into three steps: (1) the first step involves thermomechanical characterization of reinforcing fibers, measurement of cure-kinetics and curedependent properties of the matrix, and development of correlations for cure-dependent property-evolution of the composite as a whole.…”

“…In such rendition, the instantaneous properties of the matrix are governed only by the instantaneous degree of cure, and are not affected by the processing history. On the other hand, it was observed by Patham [24] that, by employing a more comprehensive cure-and temperature-dependent viscoelastic model for the thermoset resin, subtle details of the interplay between the processing history and springback behavior may be brought forth, which are not available from elastic models. Therefore it would be interesting to investigate the effect of viscoelasticity of the matrix resin in governing the residual stress development both at the part-level and at the mesolevels.…”

Fabrication induced spring-back in thermosetting woven composite parts with variable thickness

“…Hygroscopic loads contributing to stress formation were also included in model [19]. Simulation of stresses and their corresponding change in the geometry was predicted using different FE models for different shapes to avoid the huge cost of hit and trail tool correction [20–26]. Modeling of shape distortions while considering the fabric drape and fibers reorientation was done [27,28].…”