Metal composite joints

Apart from monolithic composite – composite joints, multi material joints are commonplace in modern light-weight structures. As an example, metal inserts can be used in thermoplastic composite structures for load transfer purposes to other parts of the structure. A predictable and robust insert behavior requires a proper understanding of the factors that affect its performance.

Contact: Yibo Su

M2i / TPRC
PhD student

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Objective

To provide processing guidelines for manufacturing metal – thermoplastic composites joints employing a co-consolidation process. The guidelines focus on metal pre-treatment methods as well as on processing conditions, both of which need to be optimized on order to achieve the desired joint performance.

Keywords: co-consolidation, metal surface treatment, metal-thermoplastic bonding, mechanical interlocking

Background/Introduction

Apart from monolithic composite – composite joints, multi material joints are commonplace in modern light-weight structures. Metal inserts can be used in thermoplastic composite structures for load transfer purposes and to ease multi material assembly. The inserts can be co-consolidated or co-molded with thermoplastic composite material. The thermoplastic matrix material, already present in the prepreg, is thus used for bonding and no additional adhesives are employed and no composite pre-treatment is required.

The strength of the metal-composite interface, which is a crucial factor that affects the performance of the entire hybrid joint, can be tailored by choosing the appropriate metal pre-treatment methods and processing conditions. A predictable and robust joint behavior requires a proper understanding of physical mechanisms underlying the interface strength development. Within this project, these mechanisms are investigated for titanium – C/PEEK hybrid joints using a combination of experimental and analytical work.

Approach

The physical mechanisms governing the performance of co-consolidated titanium – C/PEEK joints are investigated experimentally. For this purpose, a fracture mechanics based test methodology was developed. The test method involves peeling of a thermoplastic composite tape from a metal substrate with help of a mandrel to prevent tape breakage. The specimens comprise a unidirectional fiber reinforced tape which was co-consolidated on a metal substrate using an autoclave process. Elaborate experiments are performed to study the effect of metal pre-treatment and molding cycle on the measured interfacial toughness. Extensive analytical surface analysis before molding and after testing helps to identify, isolate and analyse the governing mechanisms. Supported by micro-scale finite element models to study the effect of surface topography, these experiments results are finally translated to processing guidelines for hybrid titanium – C/PEEK joints.

Related projects

Contact

  • Interested in application of the developed knowledge? Please contact Sebastiaan Wijskamp .
  • Interested in the underlying scientific background? Please contact Yibo Su.

Research overview