Numerical simulation for thermoplastic composites overmoulding process

About the Project

This project aims to develop a numerical simulation model for thermoplastic composites overmoulding process and validate the model using experimental manufacturing data.

Thermoplastic overmoulding is an advanced composites manufacturing process combining stamp forming of aligned, continuous fibre composites (CFCs) and injection moulding of randomly orientated, short fibre composites (SFCs). Such process offers great design flexibility as it combines the superior mechanical properties of CFCs and the high formability of SFCs and therefore has attracted particularly strong interests in aerospace and automotive industries for high-volume structural applications.

Process simulation uses numerical models to investigate the manufacturing process, significantly reduces the physical resources required compared to experimental trial-and-error approach. There’s no dedicated process simulation model available for overmoulding due to several technical challenges. Firstly such process is of a multi-physics nature and requires coupling of different numerical methods: the deformation in SFCs is dominated by shear flows, and typically solved using fluid mechanics models through finite volume methods, while the deformation in CFCs is dominated by compaction and in-plane shear, and typically solved using solid mechanics models through finite element methods. In addition, the constitutive models for SFCs and CFCs are both complicated, involving high level of non-linearities, and temperature and rate dependency. Incorporating suitable modelling techniques to address these fundamental physics in a single process simulation model represents a significant numerical challenge.

The complicated interaction behaviour between the SFC and the CFC poses another challenge in overmoulding process simulation. One important behaviour is the distortion in CFC caused by the flow of high-viscosity SFC, as the pressures required to form CFCs is much lower than the pressures required for forming SFCs, and consequently CFCs are not designed to withstand the high processing pressures in injection moulding processes. As a result, existing experimental and numerical studies on CFC forming processes were only conducted at low pressures, and new experimental procedures and numerical models need to be developed to capture the material’s behaviour under typical overmoulding conditions.

This PhD project aims to establish an overmoulding process simulation model by addressing the challenges mentioned above, through a combination of experimental material characterisation studies and numerical simulation model developments. The model will then be validated against experimental manufacturing data. This project will be supervised by academics who are internationally renowned experts in their field, and with strong links to the composites industry. Through this project, the candidate will acquire essentials and knowledges in high-volume composites manufacturing, advanced experimental material characterisation and process simulation, through a well-designed research programme. These are sough-after skills in many high-value manufacturing sectors, notably aerospace and automotive, offering excellent career choices following graduation.

Essential and desirable criteria:

We require an enthusiastic graduate with a 2:1 class master degree or 1st class bachelor degree in a relevant discipline, such as mechanical engineering, material engineering or applied physics.

The successful candidate will have:

• Strong background in solid mechanics and engineering mathematics
• Strong interests in computational work and laboratory work
• Some hands-on experience in numerical simulation techniques such as FEA and CFD
• Experience related to composite manufacturing and process simulation would be a distinct advantage but not essential.