共查询到18条相似文献,搜索用时 171 毫秒
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摩擦过程中真实接触面积的灰色分析 总被引:1,自引:1,他引:1
灰色系统理论是近几年以随机过程为研究对象而形成和发展起来的,在农业和自动控制等方面的研究与应用发展较快.为了使这种理论应用于摩擦学研究领域,从光全反射测量和计算机数值计算两方面,考察了粗糙表面接触时真实接触面积的随机特性,指出摩擦过程中的真实接触面积是一种含有随机成分的变化量,研究目标应当侧重于真实接触面积的变化趋势和范围,而不是它的精确解.在此基础上,首次利用灰色系统理论,分别对静态和动态接触条件下真实接触面积的变化规律进行了灰色分析,建立了精度比较高的预测真实接触面积的灰色模型CM(1,1).这种模型对动、静接触面积的计算值与实测值具有良好的一致性,可以用于动态跟踪描述摩擦过程中真实接触面积的变化规律 相似文献
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板材成形有限元数值模拟的研究进展 总被引:11,自引:0,他引:11
本文以不同时期引起人们广泛注意的标准考题1)为主要线索,对板材成形有限元数值模拟的发展作了简要的综述.并讨论了研究中仍存在的问题和研究的发展方向. 相似文献
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干摩擦振动系统响应计算方法研究综述 总被引:34,自引:2,他引:32
首先讨论了两固体接触表面间的干摩擦力模型,重点介绍了滞迟摩擦模型方面的研究工作;然后,论述了含有各种干摩擦环节的振动系统简谐、随机和冲击激励下的响应计算方法,着重讨论了基于滞迟恢复力模型的响应计算方法,并对各种计算方法的特点进行了评述.最后,指出了干摩擦振动系统响应计算方法亟待解决的一些重大问题. 相似文献
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高强度钢板热成形技术及力学问题研究进展 总被引:2,自引:0,他引:2
高强度钢板热成形技术是将传统的热处理技术(淬火)与冷冲压技术相结合的最新制造工艺,可以成形强度超过1 600 MPa的超高强度钢板.本文首先介绍了热成形技术的原理、一次及多次成形工艺和热成形过程中的核心制造技术;随后分析了热成形过程中材料的微观组织及力学性能变化,包括成形前、成形中及成形后材料性能的演变,介绍了与温度、马氏体转变速率相关的高温奥氏体材料模型,指出了其在热成形过程中的应用方法;研究了高强度钢板热成形材料的成形性能:分析了硬化指数n值对材料高温成形性的影响,并给出了最佳n$值温度区间;介绍了材料初始轧制各向异性对材料性能的影响,实验结果说明在热成形温度下晶格的各向异性将消失.对热成形过程中材料的本构关系进行了介绍:重点介绍了热、力及相变耦合本构模型;对热成形过程中的多相材料热力学参数和力学性能进行等效分析的混合定律进行了说明;介绍了相变体积应力及相变塑性应力等新概念;随后对热成形数值模拟技术进行了介绍:重点介绍了自主开发的KMAS(King-Meshanalysis sytem)热成形软件的动力显示、静力显示算法及温度场模拟技术;说明了将材料的高温性能引入接触与摩擦模型的接触控制参数的概念;随后基于车身碰撞力学的分析,介绍了热成形钢板在车身中应用的设计方法.最后对热成形技术今后的研究作出了展望. 相似文献
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钛合金板材是一种高模量弹塑性材料,在冷成形加工的过程中,回弹控制难度较大.金属板材的冷成形加工过程,实际涵盖了多种冷成形加工工况.就板材冷成形加工过程中遇到的各种工况进行梳理分析,归纳为若干典型的工况,针对不同的冷成形加工工艺所含盖的典型工况,对高模量弹塑性板材在冷成形加工脱模后的初始回弹问题,进行了精细的分析,并提出了高精度的解析解.从而,在理论上为诸如钛合金之类的高模量弹塑性板材的冷成形加工,冷成形模具设计,及其冷成形加工工艺的工序优化,提供参考依据. 相似文献
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板材多点成形过程的有限元分析 总被引:8,自引:0,他引:8
多点成形过程采用静力隐式格式进行数值模拟是比较合适的。本文建立了用于多点成形过程分析的静力隐式弹塑性大变形有限元方法 ,给出了对稳定迭代收敛过程效果较好的板壳有限单元模型、处理多点不连续接触边界的接触单元方法以及增量变形过程中应力及塑性应变计算的多步回映计算方法。基于这些方法编制了计算软件 ,应用该软件进行了矩形板的液压胀形过程及球形模具拉伸成形过程的有限元分析 ,数值计算结果与典型的实验结果及计算结果吻合很好。最后给出了球形、圆柱形目标形状的实际多点成形过程的数值模拟结果。 相似文献
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《International Journal of Plasticity》2001,17(2):237-271
Successful numerical simulations of forming operations require robust and accurate tool-workpiece interface friction models. In this paper we extend the rate-independent, isotropic, isothermal interface friction model proposed by Anand (Anand, L., 1993. A constitutive model for interface friction. Computational Mechanics 12, 197–213) to a rate-dependent formulation. Material parameters in the friction model are determined for lubricated interfaces between Al6111-T4 sheet and D2 tool steel. The lubricants used are MP404 and boric acid; the MP404 lubricant is currently used in industry, whereas boric acid has recently been proposed as a solid-film lubricant for sheet forming by Erdemir (Erdemir, A., 1991. Tribological properties of boric acid and boric acid-forming surfaces. Part i: crystal chemistry and mechanisms of self-lubrication of boric acid. Lubrication Engineering 47, 168–173). The interface friction model is implemented in the finite element code ABAQUS/Explicit (ABAQUS Reference Manual., 1999. Providence, RI), and the finite element program is used to simulate two sheet forming operations: axisymmetric cup-drawing and square pan-drawing. The predictions from the finite element simulation are shown to be in very good agreement with experimental results. 相似文献
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双金属板拉延成形的有限元分析 总被引:2,自引:1,他引:2
双金属板拉延成形同时包含几何非线性、塑性、接触、摩擦以及双金属板中组元金属力学性能差异等多种复杂因素。组元金属之间不均匀的塑性变形是导致组元金属在拉延过程中产生缺陷的主要根源。本文基于刚塑性有限元方法,对双金属板的拉延成形过程进行了有限元分析,揭示了组元金属的等效应变分布规律和厚向应变分布规律。本文的研究方法和结论可以为工艺参数的合理选择和优化提供参考和依据。 相似文献
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Zhongjin Wang Jianguang Liu 《Acta Mechanica Solida Sinica》2011,24(2):153-165
The present paper is devoted to developing a new numerical simulation method for the analysis of viscous pressure forming (VPF), which is a sheet flexible-die forming (FDF) process. The pressure-carrying medium used in VPF is one kind of semisolid, flowable and viscous material and its deformation behavior can be described by the visco-elastoplastic constitutive model. A sectional finite element model for the coupled deformation analysis between the visco- elastoplastic pressure-carrying medium and the elastoplastic sheet metal is proposed. The resolution of the Updated Lagrangian (UL) formulation is based on a static explicit approach. The frictional contact between sheet metal and visco-elastoplastic pressure-carrying medium is treated by the penalty function method. Coupled deformation between sheet metal and visco-elastoplastic pressure-carrying medium with large slip is analyzed to validate the developed algorithm. Finally, the viscous pressure bulging (VPB) process of DC06 sheet metal is simulated. Good agreement between numerical simulation results and experimental measurements shows the validity of the developed algorithm. 相似文献
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本文采用基于随动坐标系的假定应变域壳单元及显式有限元格式求解三维板料成形问题。板材料服从Hil各向异性弹塑性准则,板料与模具之间的接触界面由主仆面接触搜寻法处理,接触力由罚参数法计算。文中给出了几个三维成形过程的计算实例。数值算例表明,本文方法具有较高的计算精度和计算效率,可在微机上分析中等复杂程度的成形过程 相似文献
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A. Salahouelhadj F. Abed-Meraim H. Chalal T. Balan 《Archive of Applied Mechanics (Ingenieur Archiv)》2012,82(9):1269-1290
This paper proposes an extension of the SHB8PS solid–shell finite element to large strain anisotropic elasto-plasticity, with application to several non-linear benchmark tests including sheet metal forming simulations. This hexahedral linear element has an arbitrary number of integration points distributed along a single line, defining the “thickness” direction; and to control the hourglass modes inherent to this reduced integration, a physical stabilization technique is used. In addition, the assumed strain method is adopted for the elimination of locking. The implementation of the element in Abaqus/Standard via the UEL user subroutine has been assessed through a variety of benchmark problems involving geometric non-linearities, anisotropic plasticity, large deformation and contact. Initially designed for the efficient simulation of elastic–plastic thin structures, the SHB8PS exhibits interesting potentialities for sheet metal forming applications—both in terms of efficiency and accuracy. The element shows good performance on the selected tests, including springback and earing predictions for Numisheet benchmark problems. 相似文献