球面形状零件含拉深筋拉延的计算机模拟

运用有限元数值分析方法,对球面形状零件含拉深筋的拉延成形过程进行了分析和模拟,开发了相应的分析软件,给出了分析实例。本文的研究方法和结果为实际工艺的设计和生产提供了一定的参考和依据     

基于JSTAMP/NV的AA5042薄壁筒形件变薄拉深仿真

针对罐用铝材拉深成型后通常产生不均匀制耳的问题,采用变薄拉深工艺减少制耳缺陷.简介变薄拉深的变形特点,以2011年国际板材成型数值模拟会议(Numisheet’2011)上提出的某标准考题为例,概述应用JSTAMP/NV进行AA5042薄壁筒形件变薄拉深仿真分析的过程.仿真结果与试验结果吻合良好,表明该方法能精确预测该件成型过程中的制耳缺陷.     

球面形状零件拉深的计算机模拟

球面形状零件的拉深是一个材料非线性, 几何非线性和摩擦等因素相耦合的力学过程。本文基于有限元数值分析方法,对球面形状零件的拉深进行了计算机模拟,为实际工艺的设计和生产提供了一定的参考和依据。     

基于JSTAMP/NV和HEEDS的汽车前纵梁冲压工艺优化分析

为优化高强度钢汽车构件的冲压工艺并精确预测其回弹情况,以2011年国际板材成形数值模拟会议（Numisheet’ 2011）上提出的基于CAE的汽车前纵梁冲压工艺优化考题为例,介绍用JSTAMP/NV和HEEDS对汽车前纵梁进行拉深成形和回弹仿真及其工艺参数优化的应用过程,并将采用最优化工艺参数进行仿真获取的回弹结果与实验结果进行比较,结果表明仿真结果与实验结果吻合良好.     

一种大行程高精度微执行器的研究

为了解决宏/微驱动系统中大行程和高精度之间的矛盾,研制了一种基于摩擦工作原理的压电陶瓷驱动的新型大行程、高分辨率步进式微执行器,该微执行器的行程为300mm、位移分辨率为0.02μm.提出了一种新型的基于压电陶瓷的柔性四杆型可调预压装置,并进行有限元分析.建立了微执行器系统的动力学模型,基于Karnopp“粘滞-滑移“摩擦模型分析微执行器力学特性.对微执行器的运动特性进行实验测试.     

轮轨式扒渣机防滑夹轨装置研究

轮轨式扒渣机在驻机作业的过程中,工作装置受到渣石阻力的影响,使整机产生水平方向的作用力,导致设备产生滑动,影响工作稳定性及安全性.针对此类情况,通过对机器作业过程中整体受力情况进行分析,提出了通过安装一套水平缸式夹轨装置提高机器与轨道间摩擦阻力的方案来解决此类问题.通过对夹轨装置的运动轨迹分析以及整机的虚拟样机仿真分析,验证了安装该类型夹轨装置防滑方案的可行性.     

应用逆向数值模拟分析覆盖件成形性能

研究了逆向数值模拟技术原理,针对覆盖件模型不规则而导致传统成形分析求解困难的问题,提出采用改进膜单元构造板料网格,以准确地描述毛坯变形行为;为提高边界条件定义的可信度,根据摩擦性质差异对非平面压料圈分类处理,凹凸模作用由冲压力和摩擦力的合力求解,开放式拉延筋则建立包含弯曲和摩擦效应的等效阻力模型;分析计算数据,并结合成形缺陷形成机理,完成产品成形性能评估．实验结果表明,经改进的算法能快速求解展开料参数、预测复杂产品破坏特征分布,适合用于覆盖件冲压设计。     

聚变实验装置数据库设计

聚变实验装置是开展聚变堆设计及实验研究的重要平台.但目前聚变领域缺乏集成的聚变实验装置数据库及有效的装置性能分析工具,限制了科研人员聚变设计研究效率的提升.本文设计并研发了一套聚变实验装置数据库,解决了多源数据规整与异构数据存储等问题,实现了典型聚变实验装置的相关参数与资料的统一入库管理,以及多字段智能检索与多维可视化比对分析,为聚变研究人员提供可靠,便利的聚变实验装置数据服务.     

高精度鲁棒运动控制器设计及实验研究

针对影响运动控制性能的因素,设计了一种新型的高精度鲁棒运动控制器.该控制器建立在一种新型摩擦模型基础上,对摩擦状态进行估计和补偿.提出了时间延迟控制估计扰动的补偿方案,并对此方案进行了分析和实验研究.实验结果表明,所提出的控制方案鲁棒性强,具有很大的工业应用价值.     

介绍两种英国使用的防跑车装置

<正> 1.安装在轨道上的吸能阻车器这类装置具有代表性的有以下三种: 1)摩擦制动器。该制动器一般在运输轨道内侧设立制动轨。通过它与成对的钢质摩擦闸瓦之间产生的摩擦阻力来实现制动。这种类型的阻车器由顶住矿车的撞头、产生阻力的滑块及固定的滑道三部分组成。滑块在轨道(制动轨)上运行,滑道的长度足以吸收全部能量。图1表示矿车沿斜坡自由下滑进     

A theoretical optimization method for drawbead restraining forces in automotive panel forming based on plastic flow principles

Aiming at improving the optimization efficiency, a theoretical optimization method for drawbead is proposed based on plastic flow principles. Essentially different from the existing common optimization methods which are on the basis of mathematics or statistics, this method, which can accurately reflect the relationship between the forming quality and the drawbead restraining force from the perspective of plastic flow theory, is a professional optimization method with higher efficiency. Plastic flow principles are first established to determine the influence degree of the drawbead restraining force to the forming quality. Then an evaluation model of the forming quality near a drawbead segment can be established based on the plastic flow principles to qualify the forming quality near the drawbead segment. Finally, a theoretical optimization method for drawbead is proposed based on the evaluation model, according to which the restraining force of each drawbead segment can be directly adjusted. By using the method, the optimal drawbead scheme in automotive panel forming can be obtained with only 3–5 iterations. The efficiency and accuracy of the optimization method are verified by a numerical example of a fender panel.     

A robust and accurate geometric model for automated design of drawbeads in sheet metal forming

A robust and accurate geometric model of real drawbeads that can be used for the automated design of drawbeads is presented in the paper. A three-dimensional geometric drawbead is a lofted surface, of which the section curves are constructed parallel to the stamping direction on the control points. Adaptive control point interpolation is introduced to simplify the management of the drawbead geometry and avoid unexpected shapes. Given primitive control points on a drawbead curve, dominant control points are adaptively obtained with the shapes of both the drawbead curve and the binder considered. An a priori heuristic parameter adjustment strategy is proposed to correct the parameter errors of section curves, which improves the accuracy and consistency of the drawbead geometry. By incorporating the proposed geometric drawbead with a previously developed intelligent drawbead optimization algorithm, a fully automated design process for drawbeads is realized that includes geometric modeling, finite element analysis, intelligent optimization of the drawbead geometry, and die manufacturing. Finally, a fender example is presented to verify the feasibility and validity of the fully automated drawbead design process. The simulation results with the optimized geometric drawbeads and equivalent drawbeads are compared with the experimental results. The proposed geometric drawbead shows remarkable practicability and accuracy in the automated design of drawbeads in sheet metal forming and demonstrates good consistency with the experimental results while the equivalent drawbead model introduces unneglectable deviations.     

有限元法在板料二次成形中的应用

本文建立了板料成形动力显式有限元模拟，采用四节点退化壳单元对板料进行离散化，利用中心差分法离散时间域，建立显式计算格式，采用罚函数法和修正库仑定理计算接触力和摩擦力。对二次成形过程，建立了有限元分析计算模型。通过Dynaform对板料成形进行仿真得出最后结论。     

Parallel boundary and best neighbor searching sampling algorithm for drawbead design optimization in sheet metal forming

In the present paper, a Kriging-based metamodeling technique is used to minimize the risk of failure in a sheet metal forming process. The Kriging-based models are fitted to data that are obtained for larger experimental areas than the areas used in low-order polynomial regression metamodels. Therefore, computational time and memory requirement can be an obstacle for Kriging for data sets with many observations. To improve the usability of the Kriging-based metamodeling techniques, a parallel intelligent sampling approach: boundary and best neighbor searching (BBNS) (Wang et al., J Mater Process Technol 197(1–3):77–88, 2008a) is suggested. Compared with the serial BBNS version, the sampling procedure is performed synchronously. Thus, larger sample size should be considered for real-life problems when multiple processors are available. Furthermore, the parallel strategy is prone to converge based on more samples. The performance of the parallel approached is verified by means of nonlinear test functions. Moreover, the drawbead design in sheet metal forming is successfully optimized by the parallel BBNS approach and Kriging metamodeling technique. The optimization results demonstrate that the parallel BBNS approach improves the applicability of the Kriging metamodeling technique substantially.     

Reliability assessment for sheet metal forming operations

Methodology developed for reliability calculations of structures is applied to estimate reliability of sheet metal forming operations. Sheet forming operations are one of the most common technological processes but still the tool and process design is a difficult engineering problem. Product defects are often encountered in the industrial practice. Material breakage, wrinkling, shape defects due to springback are most frequent defects in sheet metal forming operations. Numerical simulation allows us to evaluate product manufacturability and predict the defects at early stages of the design process. In the paper the so-called forming limit diagrams (FLD) are used as a criterion of material breakage in the manufacturing process. A zone of a FLD where good results are guaranteed with sufficient probability is considered as safe zone. Sheet forming operations are characterized with a significant scatter of the results. This can be caused by differences that can occur in forming of each part. Small differences in the contact conditions, for instance, can lead to significant changes in the deformation state of the sheet. In reliability-like approach we try to quantify intuitive terms of probability of failure/success of forming operations given some uncertainty of parameters characterizing a forming process like friction parameters or blankholding force. Since the employment of the gradient-based reliability techniques is very much limited due to the some degree of numerical noise introduced by the explicit dynamic algorithm used to perform sheet stamping simulation the method of adaptive Monte Carlo simulations were chosen for reliability assessment.     

基于有限元逆算法的压边力优化

依据理想形变理论，研究开发了冲压成形过程模拟的有限元逆算法，实现了计算机程序，并利用有限元逆算法，以变形后工件中厚度分布误差为目标函数，对冲压过程中的压边力进行优化。通过实例证明了逆算法及基于逆算法的冲压工艺参数优化方法的有效性。     

不等截面拉延筋结构优化设计

关于不等截面拉延筋取决于控制冲压件成形质量优化问题,薄板件拉伸件拉延成型过程中,由于受力不均,形成缺陷。为解决上述问题,研究了一种快速优化设置不等截面拉延筋结构参数的方法。通过构建拉裂和起皱缺陷的目标评价函数,构建相应的响应曲面,采用遗传算法优化响应曲面获取等效拉延阻力,再结合等效阻力模型反求出不同截面处拉延筋的几何参数,从而获得更加合理的拉延阻力,提高成形质量。以某车型内板冲压成形为例进行住仿真,验证了方法对设计不等截面拉延筋结构参数的有效性,为工程实际设计提供了依据。     

径向基函数网络在变压边力反演中的应用

变压边力策略是在冲压件成型中控制回弹的一种有效措施。综合运用径向基函数（RBF）神经网络和三维回弹模拟技术开展了由冲压件成形质量反求变压边力的研究, 同时研究了径向基函数神经网络的动态结构设计问题,提出一种基于泛化的径向基函数神经网络的动态结构设计方法DYNSDRBF,编制了相应的计算程序。DYNSDRBF方法在变压边力反演神经网络设计中的应用结果表明,运用该方法设计的神经网络具有较好的计算精度,可有效地提高冲压件的成形质量。     

板材多点成形过程的非参数模型及自适应控制

研究了三维板类件的多点成形复杂的非线性过程。将影响成形精度的诸多因素看作系统扰动，成形过程简化为离散的单输入单输出系统，得到其非参数模型。在满足一定假设务件的前提下，多点成形过程可线性化为一个带有单参数的线性时变系统：通过对系统的分析，得到了多点成形过程的闭环递推自适应控制算法。仿真结果表明，在自适应算法的逐次控制下，工件形状以较快的速度收敛到设计的目标形状，实现了对板类件多点成形这一复杂过程的有效控制。