Category
Basic
Description
Metal structures in engineering are limited by mechanical fatigue. When a material is repeatedly stressed, even beneath its ultimate strength, it slowly develops nano-fractures that propagate and eventually cause the material to suddenly fracture or fail. When this occurs in high-precision, cyclically stressed applications, such as commercial airliners, unchecked material fatigue is catastrophic. This study has shown promising increases in weld-site material fatigue life through a newly developed processing method. Researchers at Liberty University’s Center for Engineering Research and Education (CERE) custom-built a machine to perform position and energy controlled surface mechanical attrition treatment (PECSMAT), which harnesses the advantages of classic surface mechanical attrition treatment (SMAT) while circumventing its haphazard nature. Surface mechanical attrition treatment has been shown to improve mechanical properties of metallic structures near the site of impact, but current methods create impacts randomly and without precise control of impact force. The PECSMAT machine can precisely control impact force and position, leading to precision SMAT processing that can be quantitatively tested for its ability to increase material properties. CERE researchers processed and tested several identical weld samples and found approximately a 40% increase in fatigue life. Although bent samples led to some error, the increases were significant enough to show that PECSMAT has significant benefits for fatigue life. Because PECSMAT is scalable to an industrial level where it can increase fatigue lives of industrial components with a minimal increase in costs, more research is warranted to quantify property increases for different impact patterns, impact energies, and sample geometries.
Increasing Fatigue Life: Position and Energy Controlled Surface Mechanical Attrition Treatment
Basic
Metal structures in engineering are limited by mechanical fatigue. When a material is repeatedly stressed, even beneath its ultimate strength, it slowly develops nano-fractures that propagate and eventually cause the material to suddenly fracture or fail. When this occurs in high-precision, cyclically stressed applications, such as commercial airliners, unchecked material fatigue is catastrophic. This study has shown promising increases in weld-site material fatigue life through a newly developed processing method. Researchers at Liberty University’s Center for Engineering Research and Education (CERE) custom-built a machine to perform position and energy controlled surface mechanical attrition treatment (PECSMAT), which harnesses the advantages of classic surface mechanical attrition treatment (SMAT) while circumventing its haphazard nature. Surface mechanical attrition treatment has been shown to improve mechanical properties of metallic structures near the site of impact, but current methods create impacts randomly and without precise control of impact force. The PECSMAT machine can precisely control impact force and position, leading to precision SMAT processing that can be quantitatively tested for its ability to increase material properties. CERE researchers processed and tested several identical weld samples and found approximately a 40% increase in fatigue life. Although bent samples led to some error, the increases were significant enough to show that PECSMAT has significant benefits for fatigue life. Because PECSMAT is scalable to an industrial level where it can increase fatigue lives of industrial components with a minimal increase in costs, more research is warranted to quantify property increases for different impact patterns, impact energies, and sample geometries.
