基于MARC的混模法冲压回弹分析

针对有模法在成形后需再次计算接触、无模法添加的弹性地基约束无法限制工件纵向刚性位移的问题,提出在MARC中利用混模法对厚板回弹进行分析。首先分析了薄厚板成形的差异性,总结出厚板数值模拟的控制要点,梳理出基于MARC的厚板回弹模拟分析的一般流程;并依据相应分析流程和控制要点设置厚板成形过程。获得成形结果后,以有模法释放凸模与工件之间接触,降低凹模与工件之间的接触反力;其次,再以无模法并附加定位约束释放凹模。最后以某纵梁为例,对混模法进行验证,结果表明,混模法在降低计算成本的同时能够最大限度地降低人为分离拉应力的产生,且回弹值模拟结果与实测结果最为接近。

Simultaneous Identification of Thermophysical Properties of Semitransparent Media Using a Hybrid Model Based on Artificial Neural Network and Evolutionary Algorithm

A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductivity and effective absorption coefficient of semitransparent materials.For the direct model,the spherical harmonic method and the finite volume method are used to solve the coupled conduction-radiation heat transfer problem in an absorbing,emitting,and non-scattering 2D axisymmetric gray medium in the background of laser flash method.For the identification part,firstly,the temperature field and the incident radiation field in different positions are chosen as observables.Then,a traditional identification model based on PSO algorithm is established.Finally,multilayer ANNs are built to fit and replace the direct model in the traditional identification model to speed up the identification process.The results show that compared with the traditional identification model,the time cost of the hybrid identification model is reduced by about 1 000 times.Besides,the hybrid identification model remains a high level of accuracy even with measurement errors.

MARC在厚板回弹分析中的应用

由于高强板的应用使厚板回弹更加难以精确控制,而传统冲压分析软件的壳单元对厚板回弹基本失效,为此,利用具有强大非线性分析功能的MARC软件对厚板回弹进行分析。通过分析厚板相对于薄板的成形性特点,归纳出厚板回弹分析的控制要点,并依据相应的控制要点梳理出MARC回弹分析的一般流程。为最大限度降低有模法人为拉应力的形成以及计算成本,提出有模法与无模法相结合的混模回弹分析方法。最后以某车架纵梁为例,对该算法进行验证,结果表明所提及的算法在减少计算成本的同时有效降低人为拉应力的产生,且实体单元的回弹更加逼近实测值。