A thick-walled sheet moulding compound automotive component: Manufacturing and performance

Abstract

Carbon Fibre Sheet Moulding Compounds (CF-SMCs) are lightweight materials very suitable for automotive parts. So far, their use was limited to thin components. This work presents a feasibility study on the compression moulding of a thick-walled SMC component, with a compound of randomly oriented chopped carbon fibre tapes.Bending tests were used to evaluate the effects of the manufacturing conditions on the mechanical performance. The choice of the charge pattern configuration played the paramount role in the final part performance, especially via the creation of weld surfaces, leading to a maximum strength difference of over 400%. The moulding temperature, pressure and cooling method showed no statistically significant influence on both strength and stiffness of the part. The results of this work can be used as a starting point in the design of manufacturing processes for thick SMC components.

Morphology-induced fatigue crack arresting in carbon fibre sheet moulding compounds

“…In addition, considering complex parts, features like corners, section variations or thick-walled designs can result in larger manufacturing defects. In [43], µCT scans revealed the presence of significantly larger manufacturing defects (up to 30 mm) on a thick-walled part. Considering such defect size, it is reasonable to assume that they might impact the part fatigue life.…”

Weld lines in tow-based sheet moulding compounds tensile properties: Morphological detrimental factors

“…The investigation, however, was part of a broader work on a component, and the causes for such strength reduction were thus not analysed. Martulli et al [32] compression moulded a CF-SMC component with different charge patterns. The authors showed that a variation of the number, location and extension of the weld surfaces (given the thick geometries involved) resulted in a strength increase of more than 300%.…”

“…However, no studies have linked the weld lines to the microstructure, highlighting what the detrimental factors are, and whether they are the same 5 as for SFRP. Since those defects are often unavoidable for complex parts [27,32], it is important to understand how these defects reduce the strength compared to the pristine material.…”

Direct Fiber Simulation of a Compression Molded Ribbed Structure Made of a Sheet Molding Compound with Randomly Oriented Carbon/Epoxy Prepreg Strands—A Comparison of Predicted Fiber Orientations with Computed Tomography Analyses

“…SMCs with those randomly oriented strands (ROS) show a high degree of heterogeneity (variability in intra-and inter-part structure on the meso-and macro-scale) yet seek to reach quasiisotropic mechanical properties [13][14][15]. This material class is also called prepreg platelet molding compound (PPMC) [4,[16][17][18][19][20][21][22][23][24][25][26][27] or tow-based discontinuous composite (TBDC) [28][29][30][31][32][33]. The material system is characterized by a high fiber volume fraction with good impregnation, comparable to continuous fiber layups, and therefore higher mechanical properties are reachable than with traditional SMCs [18].…”