Numerical Modelling of Bond Strength in Overmoulded Thermoplastic Composites

Abstract

Overmoulding of thermoplastic composites combines the steps of thermoforming and injection moulding in an integrated manufacturing process. The combination of continuous fibre-reinforced thermoplastics with overmoulded polymer enables the manufacturing of highly functionally integrated structures with excellent mechanical properties. When performed as a one-shot process, an economically efficient manufacturing of geometrical complex lightweight parts within short cycle times is possible. However, a major challenge in the part and process design of overmoulded thermoplastic composites (OTC) is the assurance of sufficient bond strength between the composite and the overmoulded polymers. Within the framework of a simulation-based approach, this study aims to develop a methodology for predicting the bond strength in OTC using simulation data and a numerical model formulation of the bonding mechanisms. Therefore, a modelling approach for the determination of the bond strength depending on different process parameters is presented. In order to validate the bond strength model, specimens are manufactured with different process settings and mechanical tests are carried out. Overall, the results of the numerical computation are in good agreement with the experimentally determined bond strength. The proposed modelling approach enables the prediction of the local bond strength in OTC, considering the interface conditions and the processing history.

Improving bonding strength of injection Overmolded composites

“…[1,7,8] The main advantages of HTPCs are their higher mechanical properties, lower cost, ease of processability, and higher corrosion resistance. [4,5,[7][8][9] At this point, due to having a relatively lower processing temperature and affordable price, polypropylene (PP) is one of the most widely utilized thermoplastics in the automotive industry for HTPC applications. [10,11] On the other hand, interfacial bonding between the two components is a crucial parameter in achieving lightweight molded products with outstanding mechanical properties.…”

“…They stated that numerical computation results are well‐correlated with the bond strength determined experimentally. [ 9 ] Mechanical bonding is another factor for improving adhesion strength. Lucchetta et al formed different types of cracks at the aluminum surfaces, and they injected the polymer onto the metal surfaces.…”