Improving the durability of truck chassis components
01 Jun 2026 - Rohini Gupta
Industry partners SSAB and Scania, together with researchers from KTH Royal Institute of Technology (Sweden), came to ISIS to investigate how manufacturing processes influence steel fatigue in real-world truck chassis components.
SSAB is a world-leading producer of high-strength steels for advanced automotive applications, while Scania is a global leader in heavy-duty trucks and sustainable transport solutions.
Challenges
Heavy-duty truck chassis (the main frame that supports the vehicle and carries the load) are commonly manufactured using punching operations to create holes in high-strength steel plates. Punching is widely used in industry because it is fast, cost-effective, and suitable for large-scale production, especially for making holes needed to assemble and join different truck components such as brackets, suspension parts, and structural assemblies.
These structures are typically made from high-strength low-alloy (HSLA) steels, which provide high strength while remaining relatively lightweight and formable. However, punching affects the material around the hole. It introduces microstructural changes, surface roughness, defects, and, critically, tensile residual stresses, all of which can influence fatigue performance, particularly under long-term service conditions where cracks may initiate in regions of high residual stress.
For industry, a key challenge is understanding how different punching methods influence fatigue performance and how residual stresses develop within the material. Another challenge is accurately measuring these stresses, since many conventional techniques are limited to near-surface measurements and often require the samples to be damaged or destroyed during analysis. This creates a need for non-destructive methods capable of measuring residual stresses deep within thick steel components to better understand and improve fatigue performance.
Solutions
SSAB and Scania, together with researchers from KTH Royal Institute of Technology (Sweden), used neutron diffraction measurements on the Engin-X beamline at the ISIS Neutron and Muon Source. This allowed them to measure residual stresses in HSLA steel without damaging the samples, and to map how these stresses vary through the full thickness of the material. Steel plates were punched using four different tool designs and then subjected to repeated loading cycles to represent the conditions that truck components experience during service.
The results revealed that tensile residual stresses build up through the full thickness of the punched steel, peaking at mid-thickness — a region inaccessible to conventional surface-based techniques.
At high loads, where failure occurred after hundreds of thousands of cycles, fatigue performance was largely comparable across different punching conditions, indicating that the material response is less sensitive to punching-induced changes in this regime.
However, at lower loads, where failure occurred after millions of cycles, the punching method has a stronger influence. The researchers found that fatigue cracks initiated near mid-thickness, which corresponds to the region of highest tensile residual stress through the thickness, confirming that residual stress is the dominant driver of crack initiation, with surface roughness and microstructural changes playing secondary roles.
“This study shows that residual stresses through the thickness of the punched hole, which are difficult to access using conventional surface-based techniques, play a key role in where fatigue cracks initiate and how long the component survives in service,” says Nader Heshmati, first author from KTH Royal Institute of Technology (Sweden). “Neutron diffraction allowed us to reveal these stresses and better understand how manufacturing processes affect the durability of structural components.”
Neutron diffraction allowed us to reveal these stresses and better understand how manufacturing processes affect the durability of structural components.
First author Nader Heshmati from KTH Royal Institute of Technology (Sweden)
Benefits
This research provides new insights into how fatigue cracks develop in HSLA steel components used in heavy-duty vehicle structures, helping manufacturers better understand the factors affecting durability. These findings support the design of more reliable chassis components.
Understanding how punching creates residual stresses, surface conditions, and local microstructural damage helps manufacturers optimise the punching process. This could reduce fatigue damage by selecting punching conditions that limit harmful defects and tensile stresses while preserving the benefits of fast, cost-effective production.
The study also demonstrates the value of neutron diffraction at Engin-X for industrial applications. By enabling non-destructive measurement of residual stresses deep within engineering components, this approach can be extended to other materials, thicknesses, and manufacturing processes, supporting the development of more general design and manufacturing guidelines for industry.
“Our measurements at ENGIN-X gave us access to residual stresses deep within the material that no other technique could provide non-destructively. This kind of insight is essential for understanding how manufacturing affects component life and for making better-informed decisions in industrial design.” — Nader Heshmati , first author from KTH Royal Institute of Technology (Sweden).
This research has supported industrial innovation, manufacturing optimisation, and the development of more durable lightweight structures for the advanced manufacturing sector.
Our measurements at ENGIN-X gave us access to residual stresses deep within the material that no other technique could provide non-destructively. This kind of insight is essential for understanding how manufacturing affects component life and for making better-informed decisions in industrial design.
First author Nader Heshmati from KTH Royal Institute of Technology (Sweden)
