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.

The validation of some methods of notch fatigue analysis

Abstract: This paper is concerned with the testing and validation of certain methods of notch analysis which the authors have developed theoretically in earlier publications. These methods were developed for use with finite element (FE) analysis in order to predict the fatigue limits of components containing stress concentrations. In the present work we tested and compared these methods using data from standard notches taken from the literature, covering a range of notch geometries, loading types, R-ratios and materials: a total of 47 different data sets were analysed. The greatest predictive success was achieved with critical-distance methods known as the point, line and area methods: 94% of these predictions fell within 20% of the experimental fatigue limits. This was a significant improvement on previous methods of this kind, e.g. that of Klesnil and Lucas [(1980) Fatigue of Metallic Materials, Elsevier Science]. Methods based on the Smith and Miller [(1978) Int. J. Mech. Sci. 20, 201–206] concept of crack-like notches were successful in 42% of cases; they experienced difficulties dealing with very small notches, and could be improved by using an ElHaddad-type correction factor, giving 87% success. An approach known as ‘crack modelling’ allowed the Smith and Miller method to be used with non-standard stress concentrations, where notch geometry is ill defined; this modification, with the same short-crack correction, had 68% success. It was concluded that the critical-distance approach is more accurate and can be more easily used to analyse components of complex shape, however, the crack modelling approach is sometimes preferable because it can be used with less mesh refinement.

Fatigue Behavior of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Plastic Laminates

Abstract: Although there has been growing interest and field applications of poststrengthening concrete structures using carbon fiber reinforced plastic (CFRP) laminates, very little information exists regarding the flexural fatigue behavior of reinforced concrete beams strengthened with CFRP. This paper presents the results of an investigation into the fatigue behavior of reinforced concrete beams poststrengthened with CFRP laminates. The results of twenty 3 m and six 5 m beams loaded monotonically and cyclically to failure are discussed. Comparisons are made between beams without and with CFRP strengthening. The effect on fatigue life of increasing the amount of CFRP used to strengthen the beams is also examined.

Measured mechanical properties of LIGA Ni structures

Abstract: Room and elevated temperature tensile, creep and high-cycle fatigue properties of electrodeposited LIGA Ni microsamples have been measured and are being used to predict the reliability of LIGA Ni MEMS structures Tensile specimens with dimensions of hundreds of microns have been LIGA fabricated and characterized in terms of their underlying microstructure, elevated temperature tensile and creep strength and their high-cycle fatigue performance The stiffness of these LIGA Ni structures was found to be reduced by the introduction of porosity during the plating process The strength of these structures was observed to decrease dramatically at temperatures above 200 °C At stresses significantly below the yield strength, substantial creep deformation was observed at moderately elevated temperatures The fatigue life of the LIGA Ni microsamples increased with decreasing stress amplitude in a manner comparable to what has been reported for wrought Ni An apparent fatigue limit was observed for the LIGA Ni microsamples, but the importance of underlying microstructure and component geometry on the fatigue life was also highlighted