Papers by Keyword: Failure Mechanism

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Authors: Yue Ting Niu, Xi Hui Mu, Xin Yong Qiao
Abstract: Transmission casing fatigue fracture is one of the most serious failure of the transmission system in the form of tracked vehicles. This article through the analysis of materials and structural stress analysis of a typical fracture failure mechanism of the tracked vehicle transmission cabinet. And in obtaining the stress on the basis of load spectrum its fatigue life was calculated. The results show that in the structure of the stress concentration and cabinet material number ZL101 cast aluminum defects such as inclusions, porosity are the main cause of fatigue crack initiation and propagation.
Authors: Xiao Hu, Xiao Bing Ma
Abstract: Traditional Weibull distribution is unable to model the complete lifetime of systems with a bathtub failure rate function. As a consequence, a new model is quoted in this paper, in which the conditions of models with bathtub failure rate function failure mechanism and the method to determine acceleration factor are discussed in detail. Furthermore, I make an example by using the best overall unbiased estimation to illustrate the method. In addition, parameter range of the acceleration factor is given at last.
Authors: Kai Wu, Jian Yang Xue, Ping Zhou Cao, Hong Tie Zhao, Jian Guang Yue
Abstract: Bond stress between concrete and shape steel makes both materials cooperate as a whole, but diminished at final stage of loading period. A shear model is established to throw illumination on mechanism of bond failure. Tensile stress in concrete leaded to bond cracks and eventually the bond failure, which is due to the shear passing from concrete to shape steel. A new approach for bearing capacity of SRC columns with bond failure is put forward which based on the equivalent law of shear stress and shear stress distribution of rectangular section for formula derivation, the calculated results are consistent with those of the test.
Authors: Cheng Jiang Deng, Xiao Cong He, Bao Ying Xing
Abstract: This paper studied the performance of self-piercing riveting (SPR) of aluminum and copper alloy sheet. The SPR process of two copper alloy sheets was analyzed by experimental tests and finite elements stimulation, and good agreements between the simulations and test results of SPR process were obtained. Two different specimen geometries were adopted in experiment: a lap-shear type specimen and a T type specimen. The influence of combination of different materials on the static strength of SPR joints were studied through the tensile-shear and peeling experiments, and the strength of the SPR joints were evaluated by the force-displacement curves of two type specimens. The failure mechanisms corresponding to the static strength were also discussed. On the other hand, the engineering stress - strain curves of two materials have also been studied roughly. These results could provide designer engineers with some application messages of SPR.
Authors: Jian Li Dong, Yan Wang
Abstract: By the method of ANSYS finite element analysis, this paper in depth studies the affection of widened width and length of the widened beam flange joints on seismic behavior of the ultimate load and ductility performance. According to the test and failure results of finite element simulation specimen the cracking possibility of the weak link easily leading to fracture of joints is evaluated. By introducing the equivalent plastic strain index, the fracture mechanism of widened beam flange joints is analyzed theoretically. The research can provide valuable data and reference for the seismic design of steel frame joints.
Authors: Shu Cheng Jin, Yong Tao Zhang, Qi He Wu
Abstract: As a new type of deep water offshore foundation, suction caisson is widely used to offshore structures. However, the current methods of evaluation and design cannot meet the increasing requirement of engineering practice. In this dissertation, the studies are emphasized on finite element method for analyzing the suction caisson bearing capacity behavior and the failure mechanism under the vertical load. Based on studying the vertical bearing behavior of caissons with different ratio of length to diameter L / D, it shown that as L / D increases, the vertical bearing capacity growth slowed.
Authors: Lee Hsiu Eik, Mohd Shahir Liew
Abstract: This paper addresses the structural response and characteristics of a Tarpon platform, presented as an in depth sensitivity study of its structural system from the perspective of its reserve strength ratio and mode of failure. The Tarpon platform is one of many marginal field minimal platform concepts in use worldwide. PETRONAS currently owns and operates several Tarpons in Malaysian waters. A single platform of which its data is most complete and available is chosen to represent the fleet of Tarpon Monopods in Malaysian waters. The platform, heretofore named Platform A, situated offshore Terengganu, is modeled and simulated in SACS v5.3 to reflect it’s as built condition. The SACS Collapse module was utilized to simulate the Tarpon’s ultimate strength which serves as a benchmark for the comparison of the static in place analysis to obtain the Reserve Strength Ratio (RSR). The initiating mode of failure was determined to be at the anchor piles. The results point out that the Tarpon Monopod has a low structural redundancy, especially where there is a loss of wire rope.
Authors: Hyun Gyu Shin, Yong Nam Kim, Jun Kwang Song, Hee Soo Lee
Abstract: Thermal degradation of indium tin oxide (ITO) thin film has been investigated. ITO thin film was fabricated on glass substrate using RF magnetron sputtering and was characterized. The resistivity of the film which was thermally degraded at high temperatures in air atmosphere was increased highly. Thermally-degraded specimen was analyzed using XPS and Hall measurement to reveal failure mechanism. Result showed that failure mechanism was the decrease in charge carrier concentration and mobility due to oxygen diffusion and chemisorption. Accelerated degradation test (ADT) was performed to predict the lifetime of ITO thin film. The lifetime under normal operating condition could be predicted via statistical analysis and modeling of data acquired from ADT of a short period.
Authors: A. Movaghghar, G. I. Lvov
Abstract: In this paper an energy-based model for predicting fatigue life and evaluation of progressive damage using plane-stress assumption is proposed. This model allows us to predict fatigue durability taking into account principal directions of the stress tensor relative to planes of elastic symmetry of material. First, the unknown parameters of this model will be calculated for three different composites with various lays-up. Method for determining these parameters is based on the minimum necessary set of experimental data. Afterwards the model was used to predict fatigue life and estimate accumulated fatigue damage in a unidirectional composite under different angles of loading. The analysis of conclusions of the theory for various loading conditions was carried out and performed comparison between the experimental data and predicted results. The predicted fatigue lives obtained by the proposed energy model were in good agreement with the experimental data.
Authors: Kuk Tae Youn, Young Mok Rhyim, Jong Hoon Lee, Chan Gyu Lee, Yun Chul Jung
Abstract: It is well known that the main failure mechanisms in die-casting mould are heat checking due to thermal fatigue and melt-out caused by chemical reaction between die and molten alloys. Thermal fatigue tests were carried out using the thermal cycle simulator to establish the proper method to estimate the thermal fatigue resistance of hot die steel. In this study, the thermal shock tester consisted of induction heating and water spray cooling unit was constructed to evaluate thermal crack propagation resistance and the sum of crack length per unit specimen length, Lm is proposed as the index representing the susceptibility to crack initiation and propagation. Also, new concept of measurement for the melt-out behavior was suggested. AISI H13 hot work tool steel was solution treated and tempered at various temperatures, to control the hardness and toughness that have effect on the behavior of thermal crack propagation. The result of thermal fatigue test showed that there is optimum value of hardness and impact energy to maximize the thermal crack propagation resistance. The influence of nitriding on melt-out resistance was also investigated. The dissolution rate due to melt-out phenomenon tended to be smaller for thicker compound layer. Furthermore, the resistance to melt-out was affected by the compound layer thickness rather than that of diffusion layer. The results of the both tests properly reflect the effect of materials properties on failure modes of die-casting mould and it means those test methods are suitable to evaluate the durability of hot work tool steel for die-casting.
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