Investigation of the damage evolution of metal inserts embedded in carbon fiber reinforced plastic by means of computed tomography and acoustic emission

Carbon fiber reinforced plastics are promising materials for lightweight structures, for instance in automotive applications due to their outstanding specific mechanical properties. However, the load transfer in structural carbon fiber reinforced plastics parts via a detachable connection poses a challenge for the composite. Conventionally, the parts have to be drilled for this purpose whereby the fiber continuity is interrupted and hence the associated local stress accumulation decreases the load bearing capacity of the composite. This can be prevented by using embedded metal elements, so-called inserts, for joining parts in structures. The damage behavior under tensile loading of inserts turned out to be extremely complex and is based on different mechanisms. In order to understand the damage evolution under tensile loading detailed knowledge about the deformation of the insert, crack growth in the laminate and debonding between metal insert and carbon fiber reinforced plastics is necessary. This paper aims for an investigation of the insitu failure behavior during tensile loading of composite sheets equipped with two different types of inserts by means of acoustic emission and computed tomography analysis. An inductive strain gauge was additionally installed underneath the laminate when performing the tensile tests monitored by acoustic emission analysis.