Effects of defects in hybrid sheet moulding compound – Evaluation of defects and the impact on mechanical properties

Abstract Sheet moulding compound is a widely used fibre‐reinforced material. Generally, it consists of discontinuous glass fibres in a thermoset matrix system. Due to the finite fibre length, mechanical properties of structural components are limited. To overcome this drawback, sheet moulding compound is locally reinforced with a unidirectional carbon fibre sheet moulding compound material in the approach presented in this contribution. The manufacturing of this hybrid material consisting of discontinuous glass fibre sheet moulding compound and continuous carbon fibre sheet moulding compound can result in different defects, such as folds or fibre misalignments. These defects may affect mechanical properties of the hybrid material. Consequently, this article deals with the investigation and analysis of defective hybrid sheet moulding compound components, which were examined by means of tensile tests. Results point out that investigated defects have different effects on mechanical properties. However, independent from the type of defect, mechanical properties were reduced. With a reduction of 68.86 %, folds have one of the greatest influences on tensile strength. In addition, depending on the angle deviation, even greater reductions can occur. Furthermore, the reduction of the mechanical properties can be identified clearly with increasing angle deviation.