Fatigue limit

About: Fatigue limit is a research topic. Over the lifetime, 20489 publications have been published within this topic receiving 305744 citations. The topic is also known as: endurance limit & fatigue strength.

Comparison of Ultrasonic Impact Treatment (UIT) and Other Fatigue Life Improvement Methods

Abstract: Considerable recent attention has been paid to investigating the efficiency of ultrasonic impact treatment (UIT) as one of the post-weld methods for improving the reliability and fatigue lives of welded joints. Investigations were carried out at different times in Russia, Ukraine, France, Japan, Norway, Sweden and the USA. The work under review is intended to determine and study the benefits of UIT according to the IIW Collaborative Test Program on Improvement Methods, by comparison with well-known methods for increasing the fatigue strengths of welded joints. The paper presents comparative fatigue test results for welded specimens in the as-welded condition and specimens treated by hammer peening, shot peening, TIG dressing, ultrasonic impact treatment and a combination of TIG dressing and ultrasonic impact treatment. The specimens were fabricated from structural steel (SSAB Weldox 420). It is shown that, by correctly choosing the conditions, UIT can produce the highest improvement in fatigue life.

Thermomechanical properties of P/M β titanium metal matrix composite

Abstract: A high performance β titanium metal matrix composite (TMC) reinforced with in situ TiB particles has been developed via a low-cost blended elemental (BE) powder metallurgy process. The TMC shows anomalous mechanical properties as a titanium based material in tensile and fatigue strength, Young's modulus and wear resistance. Besides the high performance, the TMC has the potential to be fabricated at a lower cost far below that of the practical titanium alloys made by the conventional ingot metallurgy process. The as-sintered density of the TMC reached to 99% of theoretical with a unique activation sintering mechanism and has an excellent hot-workability superior to that of the conventional unreinforced Ti–6Al–4V alloy.

Cyclic loadings and crystallization of natural rubber: An explanation of fatigue crack propagation reinforcement under a positive loading ratio

Abstract: Natural rubber is known to have excellent fatigue properties. Fatigue crack propagation studies show that, under uniaxial tension loading, fatigue crack growth resistance increases with the loading ratio, even if the peak stress increases. Studies dealing with crack initiation confirm this trend. If strain induced crystallization is believed to play a major role in this reinforcement process, it is not clear yet by which mechanism this reinforcement takes place. Using SEM investigation, it is shown here that the reinforcement process is associated with strong crack branching in the crack tip region. From experimental results it is shown that under particular reinforcing loading condition a cyclic strain hardening process can be observed on the natural rubber which is able to overcome classically observed softening effects. A cumulative strain induced crystallization process is proposed to explain the stress ratio effect on fatigue crack initiation and propagation properties of natural rubber.