Papers by Keyword: Crack

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Authors: Guang Can Jin, Shu Ying Chen, Mei Zhao, Qing Chun Li, Xu Dong Yue, Guo Wei Chang
Abstract: The tensile process of 800MPa grade dual-phase steel was observed in-situ by SEM. The initiation and propagation of crack in dual-phase steel, the initiation of micro-pores, the deformation behavior of ferrite and martensite were analyzed in this paper. The results show that the main crack goes across the soft ferrite and around the hard martensite during its propagation in the beginning. When the applied stress is small, the micro-pores are easy to form inside the ferrite grain or on the interface of ferrite and martensite. The micro-pores can also form in the fracture site of martensite with the increase of applied stress. The fracture morphology of the dual-phase steel is dimple and the formation of fracture belongs to plastic fracture.
Authors: S. Mohammadi, S. Forouzan-Sepehr
Authors: Kahina Chabane, Salaheddine Harzallah, Mohamed Chabaat
Abstract: In this paper, we present a nondestructive Testing by sensor Eddy current is used as a tool to control cracks and micro-cracks in materials. A new method for computing by measuring and testing related 3D Eddy currents is considered. In the process, a Potential Magnetic Vector is provided on the basis of formulations taken from the theoretical set up. Thus, results of relevant applications are obtained to check the theory consistency. A simulation by a numerical approach using Finite element discretization of 3-D Eddy Current governing equations is employed to detect cracks and damaged zones in materials and eventually to study their propagation.
Authors: Cristian Sorin Nes, Nicolae Faur, Liviu Marsavina
Abstract: Objectives: Numerical determinations of Stress Intensity Factors (SIFs) for a shaft under mixed-mode load with a crack of different sizes in the connection zone between square and circular cross-sections. Methods: Linear-elastic Fracture Mechanics principles are used. The numerical analysis program used was ABAQUS CAE version 6.9-3. The shaft consists in a circular section and a square section, with a fillet connecting zone. Cracks of different lengths and different depths are modeled. The shaft is subjected to torsion and bending. The SIFs were determined using the contour integral method. Results: The stress distribution was determined and plotted, and the stress concentration effect of the notches was highlighted. Crack propagation was also performed, using the XFEM module of ABAQUS code. The computed SIFs were plotted along the crack front. Conclusions: Crack initiation and propagation matched the pattern obtained in experimental tests, thus validating the model. The results confirmed that the fillet zone between the two sections acts as a stress concentrator. The fillet radius determines the magnitude of stress concentration. Crack geometry has a significant influence on SIFs, as well as on the global stress distribution.
Authors: Jiu Jun Wang
Abstract: people usually think that the cracks of cast-in-place floor slab is the inevitable phenomenon in theory, but by finding reason in some ways, it is completely possible that people determine the preventive measures to reduce and control the crack. When appearing cracks, people reduce the impact of crack in the lowest by correctly understanding and dealing with crack.
Authors: Manuel Marya
Abstract: In both Oil & Gas (OG) and automotive industries, welding is an essential part of fabrication routes and the challenges in welding metallic materials are frequently similar. Processes that are fast, robust, and therefore tolerate variations in process parameters (including operators for manual processes) and materials (i.e. compositions and properties) are important to reproduce high weld quality and facilitate non-destructive examinations (NDE). New grades of high-strength alloys, required to be weldable by common processes and preferably without post-weld heat treatments, are not only needed by both industries, but dissimilar-metal welding is also becoming unavoidable, thereby demanding for novel processes with either low heat inputs or high-energy densities. In this paper, technologies for dissimilar-metal welding are examined in reference with both OG and automotive applications.
Authors: Shi Lun Feng, Qing Qing Guo, Yong Hong Wu
Abstract: Temporary bracing is often viewed as an unnecessary step in the process of constructing a structural facility. Unfortunately, many times this often-neglected step becomes the subject of avoidable litigation and lawsuits. This paper presents a remedy case of a deep foundation pit during the construction of the bracing system located at the business center in HePing district, TianJin. Through frequent inspection and suitable countermeasures, the potential disaster was mitigated in time. There were some lessons learned from this case history.
Authors: Wei Jiu Huang, Rong Chang Zeng, An Hua Chen
Abstract: The paper studied the fretting properties and the fretting mechanism of AZ91D and AM60B magnesium alloy. The results showed that the AZ91D alloy displayed lower friction coefficient and smaller wear volume than those of AM60B alloy, and also showed superior ability than those of AM60B in resisting crack nucleation and propagation. The fretting wear mechanisms of AZ91D and AM60B alloy were similar, including adhesion wear, surface fatigue wears and abrasive wear.
Authors: A.J. Morris, R.F. Robey, P.D. Couch, E. De los Rios
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