Papers by Keyword: Flexural Fatigue

Abstract: This paper studies the flexural fatigue performance for hose reinforcement layer fiber bundles including polyester fibers, para-aramid fiber and liquid crystal polyester fiber. Bending fatigue life and changes of three fiber bundles strength during the course of fatigue development were measured. Morphology of three fiber bundles was observed by scanning electron microscopy. From the analysis of the molecular structure of the three fibers, the Molecular chain flexibility is one of the main factors of impacting resistance to bending fatigue performance. Liquid crystal polyester fiber bundles have excellent mechanical properties and the high strength retention in bending fatigue test, which is an ideal material for the production of high-strength hose.

Abstract: Based on a large number of experiments, two-parameter and three-parameter Weibull distribution probability models have been established to study the flexural fatigue with different kinds of glass fiber contents (0%,0.6%,0.8%,1%) and different stress levels(0.7,0.75,0.8)in this paper. It is the S-N Curve and P-S-N Curve that we have obtained. According to the comparison of two probability models, We can see that the fatigue life of glass fiber concrete beam can preferably obey two-parameter and three-parameter Weibull distribution, but the three-parameter Weibull distribution is so much the better. The fatigue life will augment with the increase of the volume fraction of glass fiber.

Abstract: The aim of this work is to investigate the fatigue behaviors of the steel honeycomb sandwich beams at 400°C through three point bending experiments. A stiffness reduction approach was adopted which was further based on the interpolation by the empirical functions of experimental results. For load control fatigue experiments, the evolution relations between number of cycles and displacement were obtained through real-time deformation monitoring of the specimens. A method based on exponential function fit was adopted in the further analysis, whose coefficients depended on the material properties, loading levels and high temperature conditions. This approach allowed us to predict the high temperature fatigue life of specimens while avoiding a large number of experiments. The results showed that experimental and prediction results were in a good agreement.

Abstract: This paper presents an experimental study on the flexural fatigue characteristics of Ultra-High Toughness Cementitious Composites (UHTCC), in contrast with plain concrete and Steel Fiber Reinforced Concrete (SFRC) which have similar compressive strength. The results show that UHTCC improves fatigue life and exhibits a bi-linear fatigue stress-life relationship. The deflection ability, failure characteristics of UHTCC were investigated in the tests. It was observed that, similar to static loading situation, multiple cracks were formed under fatigue loading, while the number of cracks decreased with the degradation of stress levels. For this reason, the deformability is much weaker at lower fatigue stress levels than that at higher stress levels. Moreover, the failure section is divided into three different districts, and the proportion of fiber rupture to fiber pullout is different under different stress levels.

Abstract: In order to study the damage evolution law for layered fiber reinforced concrete subjected to flexural fatigue, the flexural fatigue tests were carried out on both layered steel fiber reinforced concrete(LSFRC) and layered hybrid fiber reinforced concrete(LHFRC) beams of which the type of steel fiber was uniform on the same concrete mix. At the same time the flexural fatigue tests with original concrete(OC) were carried out. Based on the experiments, both flexural fatigue life and damage characteristic of LSFRC LHFRC and OC were compared and analyzed. The results indicated that the fatigue life of LHFRC was a little larger than that of LSFRC under the stress level, which was more than an order of magnitude of OC. And the fatigue distortion of LSFRC, LHFRC and OC were similar. They all followed three-phase law. However, the proportion of every phase was different, which proved that layered steel fibers and polypropylene fibers could effectively restrain the degradation of concrete.