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扼要地论述了滚压成形的相关理论、变形机理和工艺设计步骤。通过近几年来笔者为工矿企业设计用不锈钢板料滚压成窗框的实例 ,介绍其设计原理、成形工艺、成形辊轮和滚压成形的特点 ,以使此特种工艺的加工方法得到推广、应用和发展 相似文献
994.
P.-P. Jeunechamps K.C. Ho J. Lin J.-P. Ponthot T.A. Dean 《International Journal of Mechanical Sciences》2006,48(6):621-629
An efficient numerical method has been developed and programmed to predict springback in creep age-forming (CAF) of aluminium shell components. Physically based unified creep-ageing constitutive equations determined for AA7010 at 150 °C are used to evaluate age-hardening and creep deformation in CAF processes. The studies are mainly concentrated on the pure bending of aluminium plates. Effects of plate thickness, single and double curvature bending, ageing time and stress relaxation features on springback are investigated. It is shown that the proposed algorithm can predict springback accurately and gives a relationship between geometrical data and springback. 相似文献
995.
M. Elchalakani X. L. Zhao R. H. Grzebieta 《International Journal of Mechanical Sciences》2002,44(6):1117-1143
There are a number of solutions available to predict the response of a circular steel tube under pure bending. However, most of these solutions are based on an elasto-plastic treatment, which is complex and difficult to use in any routine design. This paper describes a theoretical treatment to predict the moment-rotation response of circular hollow steel tubes of varying D/t ratios under pure bending. The Mamalis et al. (J. Mech. Sci. 1989;203:411–7) kinematics model for a circular tube under a controlled moment gradient was modified to include the effect of ovalisation along the length of the tube. Inextensional deformation and rigid plastic material behaviour were assumed in the derivation of the deformation energy. The plasticity observed in the tests was assumed to spread linearly along the length of the tube. Two local plastic mechanisms (Star and Diamond shapes) were studied to model the behaviour observed in the tests especially during the unloading stage. The theoretical predictions are compared with the experimental results recently obtained by Elchalakani et al. (Quartral. J. Struct. Eng. 2000;3(3):1–16). Good agreement was found between the theoretical predictions and experimental moment-rotation responses, particularly for the Star shape mechanism. A closed-form solution is presented suitable for spreadsheet programming commonly used in routine design. 相似文献
996.
提出了一种大型密封法兰成形新工艺,包括分段弯曲、现场组焊、现场精加工。新工艺免去了大型立车的粗加工,取而代之的是分段弯曲成形工艺,最后在施工现场进行组焊并采用多功能机床进行精加工。通过小型模拟件的实验与数值模拟研究,分析了L形非对称截面法兰弯曲成形过程中工件的变形规律,以及弯曲成形后工件的截面形状变化和侧弯情况,并采用L形非对称截面法兰成对弯曲的方法,使其截面形式成为对称结构,从而有效地解决了非对称截面法兰单件弯曲存在的侧弯缺陷。采用新工艺制造了某风洞工程上直径为8.5m的大型密封法兰,实践表明,采用新工艺成形大型法兰是完全可行的,其加工制造精度完全满足设计要求。由于新工艺不需立车,为特大直径法兰的制造开辟了新途径。 相似文献
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999.
谢灵 《广东工业大学学报》1998,(4)
介绍材料力学中纯弯曲实验的简易加载设备,它具有结构简易,操作方便,地方小,节省经费等优点.从实验结果可以看出简易加载设备完全能满足材料力学的实验教学要求. 相似文献
1000.
P. Aurojyoti P. Raghu A. Rajagopal J. N. Reddy 《International journal for numerical methods in engineering》2019,120(9):1071-1107
In this study, a locking-free n-sided C1 polygonal finite element is presented for nonlinear analysis of laminated plates. The plate kinematics is based on Reddy's third-order shear deformation theory (TSDT). The in-plane displacements are approximated using barycentric form of Lagrange shape functions. The weak-form Galerkin formulation based on the kinematics of TSDT requires the C1 approximation of the transverse displacement over the polygonal element. This is achieved by embedding the C0 Lagrange interpolants over a cubic Bernstein-Bezier patch defined over the n-sided polygonal element. Such an approach ensures the continuity of the derivative field at the inter-element edges. In addition, Eringen's stress-gradient nonlocal constitutive equations are used in the present formulation to account for nonlocality. The effect of geometric nonlinearity is taken by considering the von Kármán geometric nonlinearity. Examples are presented to show the effect of nonlocality, geometric nonlinearity, and the lamination scheme on the bending behavior of laminated composite plates. The results are compared with analytical solutions, conventional FEM results, and with those available in the literature. Shear locking is addressed considering reduced integration and consistent interpolation techniques. The patch test is used to check the convergence of the element developed. 相似文献