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.

Stress Analyses and Parametric Study on Full-Scale Fatigue Tests of Rib-to-Deck Welded Joints in Steel Orthotropic Decks

Abstract: Fatigue tests of full-scale orthotropic steel decks were recently conducted to evaluate the fatigue performance of rib-to-deck partial-joint-penetration (PJP) groove welded joints. The test results indicated that rib-to-deck joints are more prone to fatigue cracks in the deck plate than in the rib wall. A shallower weld penetration (for example, an 80% PJP) also appeared to have a slightly higher fatigue resistance than a deeper one (for example, a 100% weld penetration). These PJP welds were also more vulnerable to cracking initiated from the weld toe than from the weld root. Finite-element analyses of the test specimens, using the effective notch stress method, were performed to supplement the laboratory testing and provide additional information on the behavior of these welded joints. The analysis results showed a good correlation with the observed crack patterns. A parametric study also showed that the fatigue resistance of the PJP joint can be significantly influenced by the transverse loading location, deck plate thickness, and the weld penetration ratio. Increasing the deck plate thickness was effective in reducing the stresses, while the rib wall thickness had a little effect. A shallower weld penetration at the PJP joint appeared to have a positive effect in enhancing the fatigue resistance.

Dynamic stabilization device for spine

Abstract: A dynamic stabilization device is disclosed. The device includes a dual spring member comprising an outer spring and an inner spring that have approximately equal working lengths. The dynamic stabilization device is also configured so that the dual spring member does not undergo stresses greater than an effective fatigue limit that is related to a fatigue limit of the spring.

On Stress Interaction in Fatigue and a Cumulative Damage Rule

Abstract: The paper presents the underlining physical concepts as well as the results of an investigation of the interaction of repeated stress cycles of variable amplitude in producing progressive (fatigue) damage. The materials investigated were 2024 aluminum alloy and 4340 aircraft steel; and the applied load spectra were based on simplified exponential distributions of gust loads and maneuver loads, as suggested by Lundberg. The fatigue tests were performed on rotating bending fatigue machines of special design, in which randomized sequences of load amplitudes, derived from the given spectra, were applied. The results of the investigation support the proposition of a quasi-linear cumulative damage rule, deviating significantly from the simple linear (so-called Miner) rule, but equally easy to apply in design. They also demonstrate the lack of design significance of the conventional endurance limit in ferrous metals.