Research on Fatigue and Fracture Practical Aspects of Basic Research on Fatigue and Fracture by Professor Pedro D. Peralta F racture can be one of most dangerous and expensive ways in which machine components can fail. If anything, this percentage is increasing due to the country's growing infrastructure. One of the most dangerous types of fracture is due to metal fatigue. This type of failure usually occurs over long periods of time due to loads that oscillate between two values, the highest of which is often lower than what is required to produce a permanent deformation in a material or component.
Fatigue cracks can take a long time to grow and final failure is usually fast and unexpected.
This type of failure is then responsible for a good fraction of the overall cost attributed to fracture and is quite important in some strategic areas. One pressing fatigue issue is the aging of our civil and military aircraft fleets. The design life of an aircraft is 20 years, the limitations to durability being corrosion and fatigue, with the latter being the most significant because it threatens the safety of the aircraft. The average age of our civil fleet is in the late teens. Although new aircraft are being introduced, the average age will reach the 20's early in the new millennium.