CFD-FEA Combined Thermal-Fluid-Mechanical Modelling for Defect Control in Additive Manufacturing PhD

We are seeking a highly motivated candidate to embark on a research journey leading to either a PhD or MSc by Research. This opportunity is centred around the disruptive technology of additive manufacturing, specifically focused on directed energy deposition process utilising metal wire as the primary feedstock. Within this exciting realm, through CFD-FEA combined thermal-fluid-mechanical modelling, we aim to advance our understanding of the mechanisms underlying defect formation and enhance the process control to prevent or mitigate the defects. This research endeavour holds great promise in ensuring the highest standards of quality assurance for directed energy deposition additive manufacturing.

Additive manufacturing (AM) stands at the forefront of a rapidly evolving technological landscape, driving innovation across various industries, including aerospace, energy, automotive and many other sectors. Wire-based directed energy deposition (w-DED) is an emerging AM variant that is usually implemented through the coaxial or side feeding of a metal wire into an intense energy source, such as electric arc and laser beam, to melt and fuse the material and thereby build a 3D object layer by layer. This intricate process involves complicated interaction of different physical factors, and the possible defects formed during the process have significant implications on the quality of the w-DED process. Therefore, an in-depth exploration of the mechanisms governing defect formation becomes paramount. The scientific understanding of the defect formation lays the cornerstone for developing effective techniques to control the defects.  

Defects, such as solidification / liquation cracks and deposit geometry irregularity, often manifest in w-DED processes, and they are closely linked to the fluid flow in melt pool and the thermal-induced stress in fusion zone. However, on one hand, experimental measurement of the transient temperature and stress near the fusion line presents formidable challenges, potentially limiting our grasp of how these defects take shape and, consequently, how to effectively address them. On the other hand, although computational fluid dynamics (CFD) modelling can provide high-fidelity temperature and fluid flow information, it falls short in providing stress-related data, while the finite element analysis (FEA) is widely used for determining residual stress and distortion, but it has great uncertainty in predicting high-resolution temperature and stress near the fusion line. This project aims to bridge these knowledge gaps through developing a thermal-fluid-mechanical model using a CFD-FEA combined approach, enabling more accurate predictions of thermal and mechanical variables at high temperatures. Thereby, we aim to unlock a deeper understanding of the intricate mechanisms underpinning defect formation and develop practical solutions to the defect problems. The key facets of the investigation encompass: 

• Developing a thermal-fluid-mechanical model for w-DED using a CFD-FEA combined approach.  
• Numerical analyses of the temperature, fluid flow, and stress and deformation during the w-DED process.  
• Uncovering the mechanisms underlying the formation of defects, such as solidification / liquation cracks and deposit geometry irregularity. 
• Exploring effective methods for preventing or mitigating defects. 
• Formulating and performing meticulously designed experiments to validate the proposed modelling approach and defect control method.

The student will be based at the Welding and Additive Manufacturing Centre (WAMC). The Centre is recognised for the impact of its research into advanced fusion-based manufacturing on industry, through extensive MSc and PhD research, and its rolling technology development programme on large-scale additive manufacturing. This project will have close links to EPSRC research programme of Sustainable Additive Manufacturing (SAM - EP/W01906X/1) and Innovate UK research programme (Wire based DED technology maturation and landing gear application). The student will be integrated in a diverse and vibrant researcher community at WAMC and benefit from direct access to a wide range of research expertise, facility and network. In addition, opportunity for working with WAMC’s industrial partners (e.g., WAAM3D, https://waam3d.com/; WAAMMat, https://waammat.com/) would be also provided.  

The student is expected to gain a comprehensive set of knowledge and skills through his/her research activities in this project, encompassing, though not limited to, the following areas 

• Techniques, requirements, and applications of metal additive manufacturing 
• Defect control for wire-based additive manufacturing 
• Computational fluid dynamics modelling of additive manufacturing process 
• Finite element analysis of additive manufacturing process 
• Experiments for validating process models and defect control method 
• Reviewing literature, planning and managing research, writing technical report / paper, presenting in meetings / conferences, teamwork, etc.     

At a glance

• Application deadline20 Mar 2024
• Award type(s)PhD
• Start date20 May 2024
• Duration of award3 years
• EligibilityUK, Rest of world
• Reference numberSATM419

Entry requirements
Applicants should have an equivalent of first or second class UK honours degree in a related discipline or subject area (e.g., mechanical, manufacturing, and materials engineering). For international students, the English Language requirement set by Cranfield University should also be satisfied. This project would suit a candidate with interest in modelling and manufacturing, as well as some understanding of heat transfer, fluid flow, and stress and deformation. Previous experience with thermal process or additive manufacturing is also desirable. The candidate should be self-motivated, proactive, and good at communication and teamwork.
Funding
Self-funded. The cost for running experiments and accessing to research facilities will be supported by the Welding and Additive Manufacturing Centre.
Cranfield Doctoral Network

Research students at Cranfield benefit from being part of a dynamic, focused and professional study environment and all become valued members of the Cranfield Doctoral Network.  This network brings together both research students and staff, providing a platform for our researchers to share ideas and collaborate in a multi-disciplinary environment. It aims to encourage an effective and vibrant research culture, founded upon the diversity of activities and knowledge. A tailored programme of seminars and events, alongside our Doctoral Researchers Core Development programme (transferable skills training), provide those studying a research degree with a wealth of social and networking opportunities.

How to apply

For further information please contact: 

If you are eligible to apply for this studentship, please complete the online application form.