Papers by Keyword: Circular Hole

Abstract: The main objective of the present work is the study the experimental and numerical study of multi hole extrusion process for making circular rods. The pure lead is used as extrude material for extrusion. The die consists of 5 holes with 5mm diameter. For prediction work, process has simulated using a Finite Element Method (FEM) code metal forming software DEFORM-3D®. All the experimental work and simulation are done at ambient conditions. The maximum load and maximum ram displacement are calculated for circular rods during the experimental work. From the results, it is noted that the behavior of load vs displacement is almost same for both experimental and numerical study of multi hole extrusion process. This study becomes illustration the behavior of the other tough materials by which one can understand the extrusion behavior of nonferrous materials.

Abstract: Based on the two distinct solutions, as classical solution for an elastic half space containing a circular hole at nanoscale, the complex variable and superposition method was proposed and employed to investigate the state of stress and displacement in an half space with surface tension for nanoelastic material.The results indicate some characteristics in half space which are different from those in classical elasticity theory .

Abstract: This paper presents an analytical method to reduce the stress concentration in a functionally graded material (FGM) plate, having a circular cutout, under axial loading. An exponential radial variation and the variation by the power law, of the Young’s modulus is assumed here. This is achieved by decomposing the plate into a number of rings. Muskhelishivili’s method of the complex variable function is used for this piece of work study of stress distribution in the plate. It is observed that the stress concentration decreases as the Young’s modulus increases radially away from the hole.

Abstract: One of the needs of modern sheet metal forming is reliable knowledge about the formability of a given material. In sheet metal forming formability is usually related to the ability to have high values of the strain until failure, where this failure can be local necking and/or fracture. This high values of strain is called limiting strain which is not only influenced by material but also by the geometric features of sheet material. In this work, influence of hole shape and the patterns in which holes are arranged on limiting strain, are studied using experimental and numerical techniques. Both experimental and numerical analysis reveals the same.

Abstract: The stress concentration around a hole in an infinite plate is discussed in elasticity. However, the problem that how large of a plate can be considered as an infinite plate does not be solved still in engineering. Based on the analysis of prerequisite of Kirch’s solution in the rectangular coordinates, two indicators defined as dimensionless stresses are proposed to determine the application range of Kirch’s stress solution. In relation to the diameter of the central hole, several minimum coefficients of the dimension of the plate are obtained and discussed. These coefficients are useful to engineers.

Abstract: This paper focuses on the thermo-mechanical behaviors of a shape memory alloy (SMA) plate with a circular hole under biaxial uneven tension. The phase transformation behaviors of SMA under complex stress state are formulated based on the one-dimensional phase transformation model developed by Zhou and Yoon. The stress field equation of the SMA plate with a circular hole is derived according to linear elastic mechanics. The phase transformation behaviors near the region around the circular hole are numerically simulated under different conditions of applied stress.

Abstract: In the present work, the Cosserat micro-polar continuum theory is introduced into the FEM numerical model, which is used to simulate the stress concentration problems. The stress concentration phenomena around circular hole, elliptic hole and rhombic hole in plane strain condition, are numerically simulated by two types of Cosserat continuum finite elements of the standard displacement and rotation u4ω4 and u8ω8 based on Dirichlet principle. It is indicated that, compared with the classical continuum finite element, these two Cosserat continuum finite elements can reflect the steep strain gradient and scale effects occurring in the stress concentration problems, and they can weaken the stress concentration and may get consistent solution with actual situation.

Abstract: Coating craft process is often used on the hole surface, thus it must affect the degree of the stress concentration near the hole edge. Airy stress function methodology is used to obtain the analytical stress solution for a plate with a small coating circular hole in the center and subjected to the uniaxial uniform tension in this paper. With the help of the finite element software MSC.Patran & Nastran, the K3alloy plate is numerically analyzed, and its coating material is a ZrO₂, and with the comparison of the acquired analytical solutions, it can be found that the numerical results coincide with the analytical ones very well. The results show that coating affects greatly the stress distribution near the hole edge, and the stress concentration factor in the coating increases with the coating thickness but decreases in the plate, and it increases with the shear modular ratio of the coating to the plate but decreases in the plate. The effect of the coating on the stress distribution near the hole and the stress concentration cannot be neglected.

Abstract: In mechanical engineering, circular hole is used widely in structure design. When the structure is overloaded or the load is changed regularly, cracks emerge and spread. Based on the former study of dynamic stress concentration problem of SH wave by a crack originating at a circular hole edge, in this paper, the method of Green’s function is used to investigate the problem of dynamic stress intensity problem of double linear cracks near a circular hole impacted by incident SH-wave. The train of thought for this problem is that: Firstly, a Green’s function is constructed for the problem, which is a fundamental solution of displacement field for an elastic space possessing a circular hole and a linear crack while bearing out-of-plane harmonic line source force at any point; Secondly, in terms of the solution of SH-wave’s scattering by an elastic space with a circular hole and a linear crack, anti-plane stresses which are the same in quantity but opposite in direction to those mentioned before, are loaded at the region where the second crack is in existent actually, we called this process “crack-division”; Finally, the expressions of the dynamic stress intensity factor(DSIF) of the cracks are given when the circular hole and double linear crack exist at the same time. Then, by using the expressions, an example was provided to show the effect of circular hole and cracks on the dynamic stress intensity factor of the cracks.

Abstract: To analyze the stress distribution and the crack initiation due to the location of the defects, artificial defects were made on the different locations of the high strength monolithic Al and GLAss fiber REinforced laminate (GLARE). Experimental study shows that the defect location in the vicinity of the circular hole was changed from ° = 90 4 θ to ° = 0 1 θ , the stress concentration was increased. The stress concentration of GLARE was about 15% higher than that of the monolithic Al. When the defect was at ° = 30 2 θ , Multi Site Damage (MSD) crack was found in the monolithic Al but not in GLARE. Instead of MSD crack, a delamination was made in GLARE and that it resulted in the prevention against the second crack initiation.