Speaker Interviews: Residual Stress 2017

Could you briefly explain your role and involvement with residual stress?

Residual stresses often exist in components due to their fabricating process (e.g. welding, additive manufacturing). These residual stresses must be accounted for in structural integrity analysis in order to accurately life components. Thus residual stresses need to be accurately predicted (through verified models) to safely predict the failure of components. 

What is the number one challenge facing engineers working in residual stress in today’s current market?

The ‘number one challenge’ will be different for different industries. A novel issue is dealing with residual stresses through additive manufacturing. e.g. in selective laser melting as residual stresses cause part distortion during build which can cause the build to fail. 

What is the most exciting development in this field at the moment, either within your organisation or in the industry in general? 

Within our organisation, recent developments are building and validating models to simulate the selective laser melting process to predict the residual stress and distortion during the build process

Where do you see the future of residual stress and structural integrity going over the next 5 – 10 years?

Residual stress and structural integrity research is well established in some industries (e.g. Nuclear). However,  other industries such as manufacturing industries could also benefit from the understanding gained from simulations to predict residual stresses and distortions to alleviate their issues. 

What topics are you most looking forward to discussing at this year’s seminar?

Residual Stresses in High Value Manufacturing

Why is it important for engineers to join events like this?

To learn from and network with others

Could you briefly explain your role and involvement with residual stress?

I am an engineering specialist in nickel base superalloys for aero engine applications except turbine blades.

What is the number one challenge facing engineers working in residual stress in today’s current market?

Effect of residual stress on fatigue is not clear. 

What is the most exciting development in this field at the moment, either within your organisation or in the industry in general? 

More measurement methods have become mature and readily accessible, e.g., contour, FIB-DIC etc.

Where do you see the future of residual stress and structural integrity going over the next 5 – 10 years?

Additive manufacturing

What topics are you most looking forward to discussing at this year’s seminar?

There are several topics: 

• Micro-residual stress measurement
• Residual stress and crack propagation
• How to differentiate between the effect of residual stress and work hardening at the shot-peened surface?

Why is it important for engineers to join events like this?

To learn if there is a limit in what we do – what can be realistically measured and what can be modeled. 

Could you briefly explain your role and involvement with residual stress?

I am a Senior Fellow in Mechanical Engineering and work on Lightweight Materials and Net-Shape Manufacturing at WMG, University of Warwick. My research interests are Stress Analysis and Finite Element simulation with a focus on Additive Manufacturing (AM). Currently, a main barrier in implementing AM technology for industrial applications is geometrical accuracy, how comparable the product is to the original CAD model, and mechanical and material properties. One of the main drivers for shape and size distortion is the evolution of residual stresses during the manufacturing process, and this is of utmost importance for metal AM techniques due to the thermo-mechanical phenomena involved in the process. Also, evolution of residual stresses could affect the final mechanical performance and material properties. I have been investigating residual stress in AM parts by using a wide range of techniques, including non-destructive diffraction techniques as well as destructive mechanical methods.

What is the number one challenge facing engineers working in residual stress in today’s current market?

There are a number of drivers for the significance of residual stresses in different industrial sectors. Depending on the type of manufacturing, joining, post-processing and even repairing and maintenance in different sectors for different applications, the origin of residual stress could be a wide range of phenomena and in most cases a complex combination of them. Hence, considering these phenomena it would be critical to choose and implement the most appropriate residual stress measurement technique. The whole process could become costly and time-consuming depending on the scale of the part, the level of residual stress and the importance of accuracy. For some industries such as aerospace, it is vital to have a detailed understanding of residual stresses while in some others less costly procedures could be employed. Also, material, geometry and manufacturing process play a role in residual stress measurement procedure. Considering all of these, it is always a good approach to have a simulation-based solution to evaluate the level and effects of residual stresses. There is typically a need to establish a complex multi-physics simulated models to take the residual stress phenomena into consideration in full details. And the developed model is often required to be validated via a rigorous experimental procedure. Therefore, a combination of computing and simulation capability are of utmost importune for residual stress analysis in almost all sectors.

What is the most exciting development in this field at the moment, either within your organisation or in the industry in general? 

I would say, the developments in central facilities for residual strain/stress measurement has been very useful and helpful in developing new methodologies and solutions for residual stress measurement for different industrial applications. Use of central facilities such as Diamonds Light Source and ISIS in the UK, ESRF and ILL in France and other similar centres and facilities around the globe have been providing non-destructive procedure to determine residual stresses in different materials, products and in some cases during manufacturing process. Also, availability and development of high-power computing equipment have brought opportunities to develop cost-effective solution to determine residual stress in different manufacturing and industrial sectors.

Where do you see the future of residual stress and structural integrity going over the next 5 – 10 years?

Well, considering all advancement in strain/stress measurement techniques and computer capabilities to simulate processes and interpret data in real-time, I’d expect to see real time residual stress management solution for high value manufacturing sector in mid-term (maybe up to 5 years). Hopefully, such advancements and developments will lead to developing more comprehensive analysis towards tailoring mechanical and material behaviour for different applications and delivering accurate geometrical features for manufactured parts and components. That would bring the high value manufacturing sector a more cost-effective solution while providing safer and more reliable structural integrity, probably providing lightweight and optimised design and structures.

What topics are you most looking forward to discussing at this year’s seminar?

Considering all advancements in residual stress determination, I would like to see more realistic approaches to predict and manage the level and distribution of residual stress and their significance for high value manufacturing sector. A main challenge for today’s industries is developing more cost-effective and less risky technologies as sustainable manufacturing solutions for the future. Understanding and managing residual stresses play a considerable role in this way as stress analysis would be an inevitable part of any design, manufacturing, optimisation and development process. I believe we need to develop more solution to deliver residual stress management tools to be integrated within almost every manufacturing sector.

Why is it important for engineers to join events like this?

The IMechE residual stress seminar is based on the industry trends and provide insight into cutting-edge solutions and developments in technical / engineering / manufacturing areas. Events like this specialise in finding compelling subject matter and usually relevant speakers to present their latest issues as well as hints on their latest projects and advancements. So, on top of networking and meeting friends and colleagues from different sectors, benefitting from other people’s experience and confronting different case studies, the attendees always take advantage of being exposed to new problems and ideas to develop new projects, finding new partners and basically renew their excitement about their areas of work.