Novel Test Cell for Overall and Spatial Mechanical Analysis of Sheet Molding Compound Composite Part in view of Heterogeneity

Abstract

Sheet molding compound (SMC) is widely used due to multiple advantages, e.g., low material cost, short production cycle, and ability to adjust the formulation. However, the manufactured SMC parts exhibit spatial property variations in heterogeneity and anisotropy, induced during raw material manufacturing and compression molding. To overall and spatially characterize the SMC part performance with consideration of the local morphology, a test cell was developed, consisting of a mechanical test bench and an optical measurement system. Displacement and force control modes were customizable realized on the test bench with adjustable test parameters. Different load cases and tests were integrated, like a cantilever, three-and four-point bending, creep, and endurance. The overall part geometry, deformation, and full field surface strain could be provided. Furthermore, one unique platform for the real-time finite element analysis of the SMC part performance was developed and integrated. In the exemplary case studies, the functionalities of this test bench were demonstrated based on bending, creep, and endurance test on threedimensional SMC parts. The parts showed varied bending stiffness with spatially significant heterogeneity. Different creep stages were identified, and local stiffer areas under high stress were prone to creep.