Papers by Keyword: Fatigue Property

Abstract: Various types of welded joints are of wide application in industrial and productional regions, including T-shaped, butt, and fillet joints of steel, stainless steel, and cast steel. Under cyclic fatigue load, the fatigue performance of welded joints is significant for the engineering design and it’s of interest to investigate the fatigue property of the welded joints using the recommended prediction methods. In this paper, the fatigue performance of welded T-shaped joints is investigated. The mesh-insensitive property of the structural stress method is validated with the comparison of various prediction methods. The fatigue cyclic life of welded T-shaped joints under tensile loads is analyzed. The structural stress curve of T-shaped joints with various base metal thicknesses is determined for the engineering design.

Abstract: The rotating bending fatigue properties of Ti65 titanium alloy blisk forging was studied in the present investigation. The smooth and notched specimens were prepared to test the fatigue properties at room temperature and 650°C. Meanwhile, the influences on rotating bending fatigue of temperature and type were analyzed. Furthermore, the fractural morphology was observed through scanning electron microscopy. The results showed that the medium fatigue strength of Ti65 titanium alloy decreased at 650°C compared with that at room temperature, and the fatigue strength of notched specimens indicated the same significant declination at different temperatures compared with smooth specimens. At room temperature the medium fatigue strength of smooth and notched are 473MPa and 173MPa, respectively, and the fatigue notch sensitive coefficient was 0.87. At 650°C the medium fatigue strength of smooth and notched specimens are 427MPa and 168MPa, where the fatigue notch sensitive coefficient was 0.78.

Abstract: A series of fatigue tests is performed for polymethyl methacrylate (PMMA) specimens without scratches and with scratches. The scratch depth is set to be 0.2mm, 0.3mm and 0.4mm, respectively. Based on the experimental results, it can be deduced that contained fatigue limit of specimens with scratches significantly decreases compared to specimens without scratches. Besides, contained fatigue limit decreases gradually with scratch depth increasing from 0.0mm to 0.4mm. Consequently, it can be concluded that fatigue properties of PMMA will decrease when there exists scratch and for scratch depth from 0.0mm to 0.4mm, fatigue property decreases remarkably with deeper scratch.

Abstract: The fatigue property of the butt welded joint has significant influence to hoisting equipment’s design, manufacture and using safety for its extensive application. This paper conducted a study on the fatigue properties of a series of the most commonly used thickness steel Q345 butt welded joints. Through fatigue tests and fracture analysis, the fatigue pattern and fracture law of the joints were revealed. Combining with the finite element modeling, the all field stress distribution situation was obtained. This has profound reference significance to hoisting machinery research.

Abstract: The fatigue cracks are inevitably existed in steel bridges after they are working for a fairly short time because of the environmental pollution, overloading vehicles and larger numbers of automobiles. Due to the fact that the scholars have put few emphases on the influence of corrosive environment which inevitably affects the fatigue property of steel bridge, an experiment design of corrosive and fatigue property of steel box girder with the specific environment controlling equipment is taken into account. Through the data from the experiment design, the important residual strain can be gained, which can be used for the analysis of the damage developing regularity.

Abstract: The research of fatigue properties of the butt welded joint, though a large number of fatigue tests are need to be carried out, has significant influence to hoisting equipment’s design, development and using safety. This paper conducted a study on simulating the fatigue properties of widely used steel Q345 butt welded joint’s by finite element method based on the improved linear equivalent structural stress theory. The originally massive amount of fatigue tests and data processing could be saved. In order to ensure the accuracy of the fatigue modeling, a batch of Q345 butt welded joints were prepared for the fatigue tests which is used to contrast with the modeling result. The stress distribution under different load situation and the fatigue life of the joints, which have profound reference significance to hoisting machinery industry, can be acquired through modeling.

Abstract: TIG dressing combined with ultrasonic peening was conducted on low-strength steel Q235B in this paper, the fatigue strength of which was compared with original welding state, TIG dressing and ultrasonic peening respectively. The results indicate that fatigue strength of welded joints treated by TIG dressing is increased by 36%, composite processing method 57% and ultrasonic peening 56%, with little difference between composite processing method and ultrasonic peening in loading condition R=0.1. Stress concentration factor at weld toe treated by composite processing method is less than that by ultrasonic peening and with less residual compressive stress relief, the former is more effective in improving fatigue life at high stress level. Residual compressive stress at weld toe treated by composite processing is close to ultrasonic peening method and the effect of stress concentration is weakened, the two methods don’t appear to be much different.

Abstract: Steel slag reserves of our country has reached 200 million tons and each year it will increase 100 million tons. Slag accumulation occupied a large number of enterprises space and made pollution to the environment. Since steel slag based asphalt pavements have been utilized for a certain history, their fatigue life necessitates comprehensive investigation imperatively. In this paper, the fatigue life of steel-slag asphalt mixture was tested through the four-point bending test. The results showed that steel slag prepared mixture was superior to limestone mixture after several freeze-thaws, with respect to moisture sensitivity, and was suitable for asphalt treated base (ATB). The fatigue life of slag asphalt mixture with low content limestone was longer.

Abstract: To save energy, the heavy machinery industries are encountering the challenge of reducing the equipment weight. The paper introduced a 550 MPa grade steel plate to replace the traditional 345 MPa grade steel for heavy machinery manufacturing. The niobium and vanadium micro-alloyed steel plate is characterized as bainite microstructure with high toughness, improved welding performance, and good fatigue resistance. A comparison between the present 550 MPa grade steel plate and a Ni, Mo, Cu bainite steel was studied. The developed steel plate shows competitiveness for a high performance and low cost. The 15% of weight reduction is achieved in a 50 ton digger at a typical engineering machinery plant.

Abstract: To investigate the fatigue property of A356 cast aluminum alloy, the pore size distribution in two kinds of A356 alloy were statistically tested, and the S-N curves were plotted by conducting four-point bend fatigue test, then the fractography of the fatigue specimens were examined under scan electron microscope (SEM). It was indicated that the fatigue strength of the A356.2 alloy contenting more large pores and rougher crystalline grain was lower than that of A356.1 alloy, though the yield strength of A356.2 alloy was higher. Most of the fatigue cracks initiated from the pores that located on or close to the surface of the specimens, and the fracture of the specimens were induced from the growth of multi-sites initiated fatigue crack.