Manufacturing processes like forging, rolling, extrusion, quenching, and welding lock spatially varying stress fields into structural materials. Known as residual stress, this locked-in stress can cause distortion, where parts deform (or even crack) during fabrication. Residual stress also affects structural integrity, particularly the ability to resist corrosion and fatigue damage. Our approach to residual stress engineering uses a range of aligned technologies to address challenges faced in industry.
A clear customer goal is the most useful starting point for a residual stress engineering program. Customer goals often arise out of difficulties caused by residual stress, like problems in manufacturing, constraints on design, or unexpected performance shortfalls in prototypes or operational fleets. Other customer goals are driven by a desire to derive performance benefits from processes that produce compressive residual stress, like cold expansion of holes, conventional shot peening, laser shock peening, or other advanced processes. Initial engineering therefore must make a quantitative connection between customer goals and residual stress. Further engineering steps apply technology to measure residual stress, model manufacturing processes, and perform tests to quantify the effects of residual stress in manufacturing or on performance. These steps establish, with increasing precision, benefits to be gained by changes in manufacturing or use of performance-improving processes that control residual stress.
Our past work in residual stress engineering has supported a variety of goals, with representative programs focused on extending fatigue life, quality control, and distortion engineering. We have developed a set of technologies that enable effective execution of residual stress engineering programs. The technologies allow simulation of manufacturing processes, prediction of fatigue behavior, measurement of residual stress fields, and capture and reuse of historical residual stress engineering data.
We are actively working with manufacturers, operators, and government agencies to further develop and deploy these capabilities to provide improvements to both new and existing components and systems.