Papers by Keyword: Cutout

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Authors: Jalil Rezaeepazhand, H. Sabori
Abstract: The performance of perforated metallic plates repaired with laminated composite patches is presented in this study. A square aluminum plate with a central circular cutout is considered as a damaged structural element. Numerical studies using commercial finite element code were conducted to investigate the effects of variation in laminate parameters such as number of plies, fiber orientation, and stacking sequences on free vibration responses of the repaired plates. Particular emphasis is placed on the effect of imperfect bonding (patch debonding). A quantitative measure for the effectiveness of the composite patches parameters is taken to be the relative change in natural frequencies of the deboned patches compare to the patches with perfect bonding. The results presented herein indicated that, vibration response of a repaired perforated metallic plate is affected by the number of plies, stacking sequences of the patch and the quality of bonding between the patch and the base plate.
Authors: Qian Li, Deng Feng Wang
Abstract: Not only the geometrical imperfection induced by welding but also cutouts will influence the buckling of large-scale thin-walled steel cylindrical shell under wind loading. Based on the practical cylindrical shells of a desulphurizing absorption tower, in consideration of the correlation between welding induced imperfection and circular cutouts, the influence of cutout position on buckling of cylinder under wind loading is investigated by nonlinear finite element method. The results indicate that the buckling capacity varies slightly when the cutout position moves along meridional direction in the neighboring region of welding imperfection. The buckling capacity varies significantly when the cutout position moves circumferentially as the cutout is located in the welding imperfection. The buckling capacity reaches the minimum value as the cutout is located in the buckle center of cylindrical shells without cutout.
Authors: Miftahul Iman, Bambang Suhendro, Henricus Priyosulistyo, Muslikh
Abstract: Pitting corrosion often leads to the creation of small holes in steel tubular member of platform structures when a protective coating is damaged. A single pit on slender compression element can cause a significant reduction in the buckling capacity of the member. Euler formula is no longer applicable for determining the critical buckling load when cutout presence on the member. This research was conducted to numerically study the effect of a circular hole on the buckling capacity of slender steel tubular member. A variation on hole positions was at 0.125 L, 0.25 L, 0.375 L, and 0.5 L, where L is the length of the member. The hole was taken to be 0.5 pipe diameter. Two nonlinear geometric 3D Finite Element models were developed to analyzed the member critical buckling load: (a) buckling analysis, where the problem was formulated as eigenvalue problem based on the nonlinear incremental equilibrium equations, and (b) nonlinear analysis, where the nonlinear equilibrium equations were developed and solved by several schemes to get the load – deflection curve. For the both models, the tubular member was discretized into: (a) shell elements, and (b) solid elements. The numerical results were verified by experimental investigation. The results showed that: (a) the presence of cutout reduced the buckling load significantly, (b) the reduction ranging from 3% to 10% depending on the hole positions, (c) the maximum reduction occurs when the hole position was in the middle of the member length, (d) compared to experimental results, the critical buckling load obtained from buckling analysis deviated 1~4% while those of nonlinear analysis deviated 1~5%, (e) the buckling mode corresponded with member bent away to opposite side of the cutout position.
Authors: Zhong Lei Sun, Mei Ying Zhao, Li Long Luo
Abstract: A dual-zone reinforcement ply stacking sequence optimization method used for comosite laminate with large cutout is present. The optimization method utilized a new Genetic Algorithm. The new Genetic Algorithm introduced a new strategy which can improve the efficiency of the traditional Genetic Algorithm and overcome the shortages of the worse convergency and prematurity of the Simple Genetic Algorithm. In the new Genetic Algorithm, the selection probability and the mutation probability are self-adaptive. Compared with the Simple Genetic Algorithm, the new Genetic Algorithm method shows good consistency, fast convergency and practical feasibility. By using the new Genetic Algorithm, the reinforcement ply stacking sequence optimization method got reasonable symmetric and balance stacking sequence which could meet the design requirements.
Authors: Ahmad Akbari Rahimabadi, Sundararajan Natarajan, Stephane Pa Bordas
Abstract: In this paper, the effect of a centrally located cutout (circular and elliptical) and cracksemanating from the cutout on the free flexural vibration behaviour of functionally graded materialplates in thermal environment is studied. The discontinuity surface is represented independent of themesh by exploiting the partition of unity method framework. A Heaviside function is used to capturethe jump in the displacement across the discontinuity surface and asymptotic branch functions areused to capture the singularity around the crack tip. An enriched shear flexible 4-noded quadrilateralelement is used for the spatial discretization. The properties are assumed to vary only in the thicknessdirection. The effective properties of the functionally graded material are estimated using the Mori-Tanaka homogenization scheme and the plate kinematics is based on the first order shear deformationtheory. The influence of the plate geometry, the geometry of the cutout, the crack length, the thermalgradient and the boundary conditions on the free flexural vibration is numerically studied.
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