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RISS 인기검색어
- 검색키워드
- 저자 : Ahmad Zeshan (검색결과 3 건)
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Fixture layout optimization for multi point respot welding of sheet metals
Zeshan Ahmad,Tipu Sultan,Muhammad Asad,Matteo Zoppi,Rezia Molfino 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
The high quality of welding in the automotive industry is achieved by proper positioning of the fixture elements. A new method, N-3-2-1 (N ≥ 1), is proposed for fixture layout optimization of sheet metals. The flexible nature of the sheet metals requires N+3 fixture elements to constrain it normal to the surface (primary plane), but 2-1 fixture elements for other two directions (secondary and tertiary). The objective function is to achieve high stiffness of the workpiece and is calculated in terms of strain energy. Finite element analysis (FEA) was combined with genetic algorithm. A method was also proposed to find the optimum fixturing position of the workpiece in multipoint respot welding operation. Two different kinds of case studies were solved and the performance of the proposed method was also tested in the industrial scenario by fixturing the workpiece and completing the respot welding operation with satisfactory results.
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Naseer Ahmad,Shahid Kamal,Zulfiqar Ali Raza,Sharjeel Abid,Muhammad Zeshan 한국섬유공학회 2020 Fibers and polymers Vol.21 No.5
Present work investigates multi-response optimization in development of super-oleohydrophobic cotton fabricunder pad-dry-cure method. A bleached cotton fabric was treated with ZnO nanoparticles (NPs) incorporated oil and waterrepellent finish (Oleophobol CP-C®) to impart in it antibacterial activity, UV protection and super oleo/hydrophobicity. Taguchi based fuzzy logics and grey relational analytical techniques were employed to obtain simultaneous optimum settingsof input parameters including concentrations of ZnO NPs, O-CPC® finish and Knittex FEL®, and curing temperature formultiple responses. The fuzzy logics and grey relational analysis were employed on the experimental data to determinesignificant process parameters for optimization of multiple responses. The present set of techniques was effectively used todevelop super-hydrophobic (WCA: 162 o) and oleophobic (OCA: 140 o) cotton fabric along with appropriate textileproperties as reported in the text. The developed fabric has potential uses in various domestic and house-hold applicationsdue to its antibacterial, self-cleaning, non-staining and UV-protection properties.
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등가하중을 이용한 비선형 정적 응답 위상최적설계의 기초연구
이현아(Hyun-Ah Lee),Ahmad Zeshan,박경진(Gyung-Jin Park) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.12
실제 대부분의 공학 문제들은 크고 작은 비선형성을 내포한다. 구조물의 최적설계 과정에서는 다수의 구조물 사이에 발생하는 접촉이나 비선형 물성치를 가지는 재료, 또는 대변형을 고려해야만 한다. 그러나 민감도 계산이 고가이기 때문에 비선형성을 최적화에 고려하는 것은 매우 어렵다. 따라서 비선형 정적 반응 위상최적설계를 위하여 등가하중법을 사용한다. 등가하중이란 비선형 해석에서 유발되는 반응장과 동일한 반응장을 유발하는 선형 정적하중이다. 등가하중법은 치수/형상최적설계를 위하여 연구되어 왔다. 위상최적설계는 치수/형상최적설계에 비하여 설계변수가 많기 때문에 기존의 등가하중법을 그대로 적용할 수 없기 때문에 위상최적설계를 위하여 등가하중법을 확장하고 수정한다. 간단한 예제를 통하여 등가하중법을 이용한 위상최적설계 결과가 수치적으로 도출한 결과와 유사함을 보이고 실제 공학 예제의 위상최적설계를 통하여 기존의 선형 정적 위상최적설계와 결과를 비교한다. Most components in the real world show nonlinear response. The nonlinearity may arise because of contact between the parts, nonlinear material, or large deformation of the components. Structural optimization considering nonlinearities is fairly expensive because sensitivity information is difficult to calculate. To overcome this difficulty, the equivalent load method was proposed for nonlinear response optimization. This method was originally developed for size and shape optimization. In this study, the equivalent load method is modified to perform topology optimization considering all kinds of nonlinearities. Equivalent load is defined as the load for linear analysis that generates the same response field as that for nonlinear analysis. A simple example demonstrates that results of the topology optimization using equivalent load are very similar to the numerical results. Nonlinear response topology optimization is performed with a practical example and the results are compared with those of conventional linear response topology optimization.
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