•Journal•ISSN: 0387-5008
Transactions of the Japan Society of Mechanical Engineers. A
Japan Society Mechanical Engineers
About: Transactions of the Japan Society of Mechanical Engineers. A is an academic journal. The journal publishes majorly in the area(s): Crack closure & Finite element method. It has an ISSN identifier of 0387-5008. It is also open access. Over the lifetime, 5869 publications have been published receiving 18016 citations.
Topics: Crack closure, Finite element method, Stress intensity factor, Fracture mechanics, Fatigue limit
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TL;DR: In this paper, the effects of nonmetallic inclusions on the fatique strength of metals are reviewed and the influential factors are revealed, and the equation for the prediction of the threshold stress intensity factor range ΔKth and fatigue limit σw for defects and small cracks was applied to predict those for inclusions contained in high strength steels.
Abstract: First, the effects of nonmetallic inclusions on the fatique strength of metals are reviewed and the influential factors are revealed. Next, it is emphasized that the effects of nonmetallic inclusions must be analyzed from the viewpoint of small defects or small cracks, because the threshold condition at the fatigue limit is not the condition for crack initiation but the condition for the non-propagation of a crack emanating from defects or inclusions. Finally. from this point of view, the equation for the prediction of the threshold stress intensity factor range ΔKth and fatigue limit σw for defects and small cracks was applied to predict those for inclusions contained in high strength steels. It is demonstrated that the square root of the projected area of inclusions and the Hv of the matrix are the crucial parameters to predict the fatigue limit of metals containing inclusions. The predictions by the proposed equations were in very good agreement with the experimental results obtained from the fracture surface showing fish-eye patterns. The reasons why the fatigue limit σw of high strength steels does not increase linearly with increasing hardness, and why the scatters of fatigue limit are so large are made clear.
195 citations
141 citations
TL;DR: In this paper, a weight function method has been developed to analyze the stress intensity factors for surface cracks which are subject to arbitrarily distributed surface stresses, which can be easily incorporated with the ordinary three dimensional finite element code which utilyzes the 20-noded isoparametric elements with quadratic shape functions.
Abstract: A weight function method has been developed to analyze the stress intensity factors for surface cracks which are subject to arbitrarily distributed surface stresses. The method is based upon the superpositon of the unit distributed load at each nodal point on the cracked surface. It can be easily incorporated with the ordinary three dimensional finite element code which utilyzes the 20-noded isoparametric elements with quadratic shape functions. Some examples in the paper show that the method guarantees the reasonable accuracy and that it is effective especially for the analysis of unsteady thermal stress problems.
87 citations
TL;DR: In this paper, an electromechanical coupling constant is defined on the basis of group velocities of the acoustic waves in a functionally gradient piezoelectric material (FGPM) plate.
Abstract: The numerical methods which have been proposed by the present authors for investigating the characteristics of waves in a functionally gradient piezoelectric material (FGPM) plate and its transient responses are used to investigate SH waves in FGPM plates. The material properties of the plate change gradually with the thickness of the plate. To evaluate the properties of the energy transfer between the electrical and mechanical energies during acoustic wave propagation in dispersive media, an electromechanical coupling constant is defined on the basis of group velocities of the acoustic waves. Numerical examples are given for a hypothetical FGPM plate and a homogeneous plate. It is found that there are SH surface waves propagating on the softer surface of the FGPM plate. Furthermore, for waves in dispersive media, the electromechanical coupling constant based on group velocities is found to be much better than that based on phase velocities.
69 citations
TL;DR: In this article, the numerical methods which have been proposed by the present authors for Lamb waves in an anisotropic laminated plate and its transient responses are expanded for wave propagation analysis of functionally gradient material (FGM) plates.
Abstract: The numerical methods which have been proposed by the present authors for Lamb waves in an anisotropic laminated plate and its transient responses are expanded for the wave propagation analysis of functionally gradient material (FGM) plates. The material properties of the plate change gradually in the thickness direction, and are anisotropic in the plane of the plate. The plate is divided into N plate elements. In the element, we assume that the material properties change linearly in the thickness direction, and that the displacement field is expressed by second-order polynomials. The principle of virtual work is used to develop approximate dynamic equilibrium equations. The dispersion relation and the mode shape of the Lamb waves are obtained by using the free boundary conditions. The energy velocities of the Lamb waves are formulated with the aid of the Rayleigh quotient. The method of Fourier transforms in conjunction with the modal analysis is used to determine the response of displacements. The formulation of the theory is described in this paper.
68 citations