CFD-informed finite element analysis for thermal control in wire-arc directed energy deposition PhD

We are looking for a highly motivated candidate to pursue a PhD programme titled "CFD-informed finite element analysis for thermal control in wire-arc directed energy deposition." This research opportunity focuses on advancing the field of large-scale additive manufacturing, utilising metal wire as the feedstock and electric arc as the heat source. The project aims to enhance our understanding of the complex physics governing the interaction between the heat source and the material, and to develop an efficient modelling approach to accurately predict and control the temperature field, ultimately optimising the deposition process.

Additive manufacturing (AM) is a rapidly advancing technology, driving numerous innovations and finding diverse applications across industries such as aerospace, energy, and automotive. Among its variants, wire-arc directed energy deposition (WA-DED) is emerging as an increasingly compelling approach for building large-scale structural components. This process involves feeding a metal filler wire, either coaxially or off-axis, into an electric arc to create a molten pool that solidifies on a substrate, enabling the layer-by-layer construction of 3D objects. The temperature field generated by the interaction between the arc and the material plays a critical role in determining the microstructure, residual stress, and distortion of the built parts—all of which profoundly affect their mechanical properties and overall performance.

Finite element analysis (FEA) is widely used to predict the temperature field during the WA-DED process. Traditional FEA models rely heavily on empirical heat source definitions, such as the double ellipsoidal model, to represent energy input. While effective in reproducing the temperature field for analysing residual stresses and distortions after experimental calibration, these models lack a direct correlation with process parameters, limiting their ability to predict temperature fields under varying process conditions. In contrast, computational fluid dynamics (CFD) models can capture the arc physics and molten pool dynamics, including arc energy transfer and liquid metal convection within the molten pool. However, these models are computationally intensive and impractical for widespread simulations of large-scale part deposition.

This project aims to develop a novel FEA-based approach that incorporates realistic energy input linked to arc physics and equivalently accounts for the effects of liquid metal convection on temperature predictions, informed by small-scale, high-fidelity CFD simulations.

Key research objectives and activities include:
• Developing a CFD model to analyse arc physics and establish correlations between transferred energy distribution and deposition conditions (including WA-DED process parameters, underlying material geometry and process environment).
• Integrating process-dependent transferred arc energy distributions into an improved heat source model for FEA simulations.
• Creating an FEA-based method to approximate the CFD-revealed effects of liquid metal convection on molten pool temperature predictions.
• Designing and conducting instrumented WA-DED experiments to validate the developed models.
• Applying the CFD-informed FEA model to predict and control temperature fields for building parts with representative geometries in industrial applications.

The student will be based at the Welding and Additive Manufacturing Centre (WAMC), a renowned hub for impactful research into advanced fusion-based processing and manufacturing methods. This project will be closely aligned with the ATI research program (I-Break: Wire-based DED Technology Maturation and Landing Gear Application) and other industrial research projects within WAMC. There will be opportunities to work with WAMC's industrial partners, such as WAAM3D and members of WAAMMat.

The student is expected to acquire the following knowledge and skills:
• Techniques, requirements, and applications of metal additive manufacturing
• Analysis of the temperature evolution, distribution and control in wire-based additive manufacturing
• Calibration and validation experiments for modelling
• Computational fluid dynamics techniques
• Finite element analysis method
• Reviewing literature, planning and managing research, writing technical reports/papers, presenting in meetings/conferences, and teamwork

Entry Requirements: Applicants should hold the equivalent of a first or second-class UK honours degree in a related discipline, such as mechanical, manufacturing, or materials engineering. International candidates must also meet Cranfield University's English language requirements. A strong interest in modelling and manufacturing, along with a foundational understanding of arc physics, fluid flow, and heat transfer is expected. Previous experience with thermal processes or additive manufacturing would be highly advantageous. The successful candidate should demonstrate self-motivation, proactivity, and good communication and teamwork skills.

Funding: Self-funded. The cost for running experiments and accessing research facilities will be supported by the Welding and Additive Manufacturing Centre.

Supervisors: 1st Supervisor: Dr Yongle Sun; 2nd Supervisor: Dr Xin Chen.