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Study on tensile fracture failure of a steel plate with a surface crack

Chong Zhewen, Tao Jing, Xie Yuehui, Wu Dongrong, Li Tao

Journal of Theoretical and Applied Mechanics

2023

Vol. 61 nr 2

343--354

In order to study the effect of different surface crack parameters on the fracture failure of steel plate, the model was established by FEM. The results showed that the edge surface crack has the greatest influence on the fracture failure of the steel plate, and for non-edge surface cracks, the central surface crack has the greatest influence on the fracture failure of the steel plate. The larger the a/t and the smaller the a/c, the easier the steel plate fracture failure occurs. The a/c has a certain influence on the variation law of K and the position where Kmax appears.

Sensitivity analysis in life prediction of extrusion dies

Qamar S. Z., Pervez T., Siddiqui R. A., Sheikh A. K., Arif A. F. M.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 25, nr 1

49-54

Purpose: Building up on the fracture mechanics (Paris law for crack propagation) based fatigue life prediction model developed earlier by the authors, Monte Carlo simulation has been performed to evaluate sensitivity of die life related to important geometrical and material parameters. Stochastic nature of various fatigue-related die parameters is used to reflect their variability. Design/methodology/approach: Life of the die is one of the most important factors affecting productivity and profitability in hot extrusion of metals. It has been reported in earlier works by the authors that extrusion dies most often fail by fatigue fracture. Experimental studies have shown that cracks preexist in dies due to various factors including heat treatment, machining, and surface hardening. High levels of repeated mechanical and thermal loads result in crack propagation leading to ultimate fracture failure. Findings: Findings of the sensitivity analysis are that fracture life of an extrusion die is very sensitive to initial crack size, section thickness, profile outer diameter and billet length; moderately sensitive to Paris constant and extrusion ratio; and only slightly sensitive to fracture toughness and ram speed. Practical implications: The study can be of direct utility in extrusion die design improvement, formulation of an optimum die replacement strategy, etc. Originality/value: The paper provides basis for a deeper understanding of the factors responsible for fracture failure of an extrusion die exposed to thermo-mechanical fatigue environment.

Cyclic tests on improved beam-column connections

Shi Y. J., Chen Z. F., Wang Y. Q.

International Journal of Applied Mechanics and Engineering

2004

Vol. 9, no 1

81-89

After the Northridge earthquake in 1994, some researches in USA have identified three critical issues that significantly affect the strength and ductility of beam-column connections: (i) fracture toughness of weld metal, (ii) geometry and size of weld access hole, and (iii) control of panel zone deformation. This paper reports the experimental results from the second phase of a major research program on ductility of welded beam column connections under cyclic loadings which is supported by the Natural Science Foundation of China. The experiments focus on the geometry and size of weld access hole. Three new types of connection details are proposed and eight full size specimens are tested under cyclic loading. The ductility, the stress concentration behaviour, and the hysteretic behavior of these connections are investigated. Moreover, the influence of connection details on both the ultimate strength and the premature fracture behaviour of these connections are also analyzed, formulating advices on improvement of connection details. The experimental results provide valuable information for updating the seismic design code of high-rise steel buildings in China.