LYl2半球形件拉深成形过程的动力显式有限元模拟

基于连续介质力学及有限变形理论 ,建立了用于三维板料成形过程模拟的有限元模型 ,开发了动力显式算法的板料成形过程模拟的有限元分析程序DESSFORMM3D。最后 ,用笔者新开发的动力显式弹粘塑性有限元程序对不同压边情况下半球形件的拉深过程进行分析 ,并把数值结果与实验进行对比 ,验证了软件的计算结果。     

某导弹振动夹具设计及测试分析

目的 设计符合某导弹振动试验要求的夹具.方法 采用SolidWorks和Workbench两种软件协同分析的方法,对振动夹具进行设计.首先使用SolidWorks建立导弹振动夹具的实体模型,之后在Workbench中采用有限元方法对夹具进行模态分析.根据模态分析结果,在对夹具进行多次的结构修改和分析计算后,得到满足设计要求的夹具.将设计合格的夹具加工制作后,在振动台进行传递特性分析,以验证设计和分析结果.结果 根据振动夹具模态振型的变化趋势,可以通过增加夹具的底板和立板的厚度来提高夹具的固有频率.通过计算,将夹具底板和立板的厚度均增加到30.0 mm时,夹具的固有频率达到了311.68 Hz.将加工好的夹具按照实际试验方式固定在振动台,并进行动态响应测试,得到夹具一阶频率为410.0 Hz.结论 设计方法达到了振动夹具的基频大于被试品3～4倍的目标,满足了导弹振动夹具的动力学特性要求.     

钨合金棒材无模流变成形有限元分析

采用刚塑性有限元法分析钨合金棒材无模流变成形变形区速度场、应力场及变形力。收敛条件采用总能量泛函收敛准则、速度收敛准则、节点力不平衡量收敛准则的 3个条件同时满足的收敛判定。给出钨合金棒材无模流变成形力能参数的数值解。变形力理论计算值与实验结果相吻合 ,相对误差小于 10 %。     

九寨黄龙机场填方高边坡静力稳定性分析

某机场工程位于青藏高原东缘高山峡谷区,飞行区横跨5条大的冲沟,最大填方高度102 m。本文利用三维有限元法对地基沉降、填方边坡稳定性等问题进行了分析,对工程施工提出了相应的建议。     

斜拉桥动力特性的有限单元分析

斜拉桥动力特性在工程设计中是要重点考虑的内容，本文基于有限单元法理论，确定了斜拉桥合乎构造的空间计算模型，建立了其三维空间自振方法，并对其动力特性进行了求解和分析。通过算例，验证了该分析方法的正确性。     

焊接残余应力数值模拟的研究与发展

分析了用有限元法计算焊接残余应力的基本理论,其中包括温度场和应力场的数值模拟,介绍了焊接残余应力数值模拟方法的近期研究成果,并探讨了焊接残余应力数值模拟技术的发展趋势。     

浅水流动有限体积法/Osher格式的二维水流-水质模拟

应用无结构网格有限体积法 /Osher格式的二维水流 -水质耦合数值模型 ,采用黎曼近似解计算模拟区域水量、动量及污染物输送通量。通过对长江南京八卦洲江段浓度场的模拟计算 ,其结果与遥感卫星图片确定的污染带分布相吻合 ,证实了模型的合理性和模拟能力     

薄板深拉延成形有限元仿真

板材成形有限元仿真采用虚拟制造技术反映模具与板材之间的相互作用以及板材实际变形的全过程,有助于推动生产的快速化和设计的智能化。汽车企业通过对板材成形过程的有限元仿真可确定钢板性能参数范围和冲压工艺参数范围,以保证生产的稳定性。采用动力显式有限元软件LS-DYNA,对上海宝钢St14-T冷轧薄板的深拉延成形过程进行了仿真计算,分析了变形过程的金属流动规律。     

MODELING PERCOLATION LOSSES FROM A PONDED FIELD UNDER VARIABLE WATER-TABLE CONDITIONS1

ABSTRACT: A numerical simulation model was developed to predict the vertical and lateral percolation losses from a ponded agricultural field. The two-dimensional steady-state unsaturated/ saturated flow equation was solved using the finite-difference technique. A constant ponding depth was maintained at the soil surface with different water table conditions in an application of the model for rice fields bordered by bunds. Field experiments were conducted for two different water table depths to collect data on the spatial distribution of volumetric soil-moisture content for model verification. The measured soil-moisture content values were found to be in close agreement with those predicted by the model. The sensitivity analysis of the model with selected hydrologic conditions shows that the model is most sensitive to the values of saturated hydraulic conductivity, but relatively less sensitive to water table depth, ponding depth, and evaporation rate from the soil surface. It implies that, in a ponded rice field condition, the lateral and vertical percolation losses are mostly governed by the hydraulic conductivity of the soil. The vertical percolation losses were almost equal to the saturated hydraulic conductivity values and, in most cases, these losses increased with deeper water table depths. The lateral percolation losses also increased with deeper water table depths; however, these losses were relatively small in comparison to the vertical percolation losses. The vertical and lateral percolation losses increased with the increase in ponding depths. The lateral percolation losses through the bund decreased when the evaporation losses increased from the soil surface. The results of this study indicate that the percolation losses from a ponded field may be predicted accurately for a wide range of soil and hydrological conditions when the values of hydraulic conductivity, evaporation rate, depth of ponding, and water table depth are accurately known.     

基于ANSYS的高速机夹式铣刀强度设计与安全性分析

当把离心力作为主要载荷进行高速铣刀的强度计算时,经典力学计算方法存在一定误差,不能满足安全性设计要求。笔者分析高速铣刀的离心力效应;建立高速机夹式端面铣刀强度设计有限元模型;模拟不同转速下刀具各组成部分的应力与变形的大小和分布;并结合分析结果,对高速铣刀安全性设计提出了改进意见。分析表明,对于100mm机夹式端面铣刀,当转速达到15000r/min时,螺钉的等效应力已达到材料的临界应力状态,出现明显的弯曲变形,刀片产生的位移达0.04mm。