Papers by Keyword: Fatigue Property

Abstract: This paper has studied the mechanical properties (freeze-thaw splitting strength, and dynamic modulus) and road performance (dynamic creep and fatigue life) of the asphalt mixture under the freeze-thaw circle test, and made the quantitative analysis of the influence on the material performance under freeze-thaw circle test.

Abstract: The microstructure of metal material would change with temperature, the roughness of the metal fracture would also vary. The mechanical properties of materials closely related to roughness of fracture. In this paper, after high temperature the crack strain fatigue fracture roughness and fatigue mechanical properties were analyzed for 16MnR steel. Further, relationships between roughness of fatigue fracture and temperature were also discussed.

Abstract: In order to explore the durability of high bending strength pavement concrete, adding silica flour, fibrous reticulum, SD emulsion and HG emulsion separately in concrete mixture, the shrinkage characteristic, wear resistance and fatigue property of different high bending strength pavement concrete are tested, and contrastive analysis with the plain concrete material is researched. The test results show that the early contraction of HBSPC is bigger, but the total drying shrinkage strain is smaller than plain concrete, and the drying shrinkage stable stage of HBSPC is shorter than plain concrete. The temperature shrinkage of HBSPC and plain concrete is uniform basically, the temperature shrinkage coefficient of HBSPC is lower than the plain concrete in the negative warm area and warm area, but it is higher in 0 °C neighbor. The mixtures of the material enhance the wear resistance and fatigue property of concrete.

Abstract: In order to signify the thermal damage and the influence it has on the fatigue property, a 3D finite element method, as well as experiment investigation, was employed for this research. By the study, it suggests that laser surface scanning can bring about some tensile residual stress and a heat affected zone in the workpiece, so as to lead a fall in fatigue life cycles. Since the fatigue character is affected by the residual stress and the microstructure change, which relate to the laser process parameters, it is expected to draw a scalar variable from stress feature and microstructure parameter to stand the level of thermal damage influence.

Abstract: To detect the chemical composition and physic-mechanical properties of converter steel slag of Jigang Group Co., Ltd and evaluate its feasibility as aggregate of the bituminous mixture. Prepare three kinds of AC20 bituminous mixtures by all using the steel slag as aggregate, by partially using the steel slag as aggregate and by all using macadam as aggregate respectively, and analyze the physic-mechanical properties of such three kinds of bituminous mixtures. The test analysis results prove that the high-temperature stability, low-temperature crack resistance and fatigue property of the bituminous mixture with all steel slag as aggregate or partial steel slag as aggregate are superior to those of macadam mixture. Although its water stability is a little bad, it still can meet the specification requirements, and it is suggested to be used widely in the middle and lower surface layers of pavement structure layer.

Abstract: The fatigue property of rectangular section beam for semi-flexible cold recycling mixtures has been analyzed basing on damage-fracture mechanics principles. Fatigue models of rectangular section beam have been put forward respectively, which includes both macroscopic cracks appearance and propagation process. Then parameters for fatigue models have been determined by the standard test for determining fatigue failure of compacted asphalt concrete subjected to repeated flexural bending. Finally, a fatigue life estimate formula of rectangular section beam is proposed by using mathematical decoupling method. Results indicate that the fatigue damage process play an important role in the whole fatigue process. Also, damage-fracture mechanics principles and methods are suitable for estimating the fatigue property of modified asphalt emulsion-cement cold recycling mixtures, which has a definite guiding purpose for projects.

Abstract: Surface treatment was carried out on the cruciform joint of 16MnR steel by using the HJ-II-type ultrasonic impact machine. The impact current is 1.2A, impact amplitude is 30 microns. Fatigue experiments were carried out for impact treated specimen, impact treated and heattreated specimen and un-heattreated specimen. The effect of ultrasonic impact on the hardness of the weldment and weld toe was researched. The experimental results show that the fatigue life of the cruciform joint of 16MnR steel can be significantly improved through the ultrasonic impact treatment and the hardness of weld toe can also be promoted. Compared to the sample without impact treatment, its fatigue life was increased 692.52%. The hardness of weld toe was increased 31%. Compared to the sample with heat treatment, the fatigue life of impact specimen was increased 316.67%. Compared to the sample without impact treatment, the fatigue life of impact and heat treated specimen was increased 218.69%.

Abstract: The fatigue property of welded specimen of different form of Ti6Al4V Titanium Alloy plate was researched in the environmental condition of atmosphere and salt fog,The test results indicate the holes along weld seam in welding specimen have great influence on fatigue property, The fatigue life of Ti6Al4V Titanium Alloy doesn’t low under the salt fog condition in high stress range. The salt fog brings about the influence on fatigue life obviously at the same corrosion condition with fatigue stress lowering.

Abstract: A type of small-scale fibers with dumbbells on two ends and notches in the middle was first designed to improve the workability and crack resistance of fresh high performance steel fiber reinforced concrete (HPSFRC). By using the fiber, the HPSFRC was continuously pumped to 306 meter high Sutong bridge tower. To ensure crack resistance of HPSFRC, tests concerning both non-loaded crack and structural crack were systematically performed, respectively. Then, the mechanisms behind the macro-behaviors were explored. Finally, life assessment method of HPSFRC that focused on the fatigue loading coupled with chloride and carbonation environment was presented by considering the effects of different fatigue degree on concrete durability. The results demonstrate that the steel fiber has the remarkable ability to restrain shrinkage and resist structural crack. It was also shown that the small-scale steel fiber can greatly improve the fracture toughness and fatigue property. In addition, the increased degree of damage due to fatigue loading would shorten the service life of concrete and the service life of HPSFRC under the multi-damage of fatigue loading and environmental loading would be longer than that of plain concrete.

Abstract: Automobile body sheets mainly resist impact and pressure. However, the fatigue property is one of the main factors with regard to properties of sheet steels. Continuous vibration happens all over the sheet steels (especially chassis) while the vehicle is in motion. And the fatigue property becomes particularly important in the condition above. Fatigue tests are conducted to four kinds of thin sheet steels for automobile in this paper. The fatigue lives of samples from sheet steels are obtained according to the various stresses. The inferior limits of fatigue life and the inferior limits of fatigue strength under the higher stresses are acquired by the computation of fatigue data. Furthermore, the test results show that there is a certain relationship among the tensile strength, yielding strength and inferior limit of fatigue strength for these sheet steels. This paper is of certain reference significance for other similar test.