The recently developed nanobainitic steels show high strength as well as high ductility. Although this combination seems to be promising for fatigue design, fatigue properties of nanostructured bainitic steels are often surprisingly low. To improve the fatigue behavior, an understanding of the correlation between the nanobainitic microstructure and the fatigue limit is fundamental. Therefore, o...

The objective of the study was to evaluate the ability of a nonlinear ultrasound technique, the so-called nonlinear resonant ultrasound spectroscopy (NRUS) technique, for detecting early microdamage accumulation in cortical bone induced by four-point bending fatigue. Small parallelepiped beam-shaped human cortical bone specimens were subjected to cyclic four-point bending fatigue in several ste...

A system for ultrasonic fatigue testing at temperatures as high as 700 C and at positive mean stresses has been developed. Its use is demonstrated by examining the fatigue behavior in the lifetime range of 10 to 10 cycles for the nickel-base superalloy Rene' 88 DT at 20 and 593 C for a load-ratio of 0.05. Crack initiation occurred from large grains and from inclusions, consistent with crack ini...

Many factors are known to influence the mechanical fatigue life of rubber components. Four major categories of factors are reviewed here: the effects of mechanical loading history, environmental effects, effects of rubber formulation, and effects due to dissipative aspects of the constitutive response of rubber. For each category, primary factors are described, and existing literature is presen...

This study aims to validate, using finite element analysis (FEA), the design concept by comparing the fatigue behavior of hip implant stems coated with composite (carbon/PEEK) and polymeric (PEEK) coating materials corresponding to different human activities: standing up, normal walking and climbing stairs under dynamic loadings to find out which of all these models have a better performance in...

The conventional French fatigue test has yielded significantly different results for two asphalt materials with the same grade of pure asphalt. A research program was begun to study the influence of the asphalt nature on the fatigue behavior of asphalt materials. The program included full-scale experimentation on the circular test track of the Laboratoire Central des Ponts et Chaussees, laborat...

Jet Propulsion Laboratory California Institute of Technology Pasadena, CA 91109 Differential expansion induced fatigue resulting from temperature cycling is a leading cause of solder joint failures in spacecraft. Achieving high reliability flight hardware requires that each element of the fatigue issue be addressed carefully. This includes defining the complete thermal-cycle environment to be e...