钝圆头质量块对简支梁的多次弹塑性撞击

考虑多次局部弹塑性接触变形行为、多次撞击和多次分离过程,提出了1种采用有限差分方法研究柔性结构多次弹塑性撞击问题的MCIS方法,研究了钝圆柱头刚性质量块水平撞击简支梁的过程。研究结果表明,该撞击过程实际上是1个复杂的多次弹塑性撞击过程,一般存在2个以上的明显撞击区,每个撞击区包含了形式多样的复杂的次生撞击过程。其他撞击区的冲量值与第1个撞击区的冲量值相当,其他撞击过程中损失的撞击动能的总和与首次撞击过程中损失的撞击动能相当,因此,多个撞击区和多次撞击过程将对梁的撞击物理行为产生重要影响。研究还发现,小质量块刚性体撞击时,首次撞击过程的撞击动能损失明显。在大质量刚性体撞击时,后续的多次撞击过程的撞击动能损失明显。 更多还原     

Elastic-plastic analysis of antiplane crack near crack surface region

The elastic-plastic stress distribution and the elastic-plastic boundary con- figuration near a crack surface region are significant but hard to obtain by means of the conventional analysis. A crack line analysis method is developed in this paper by consid- ering the crack surface as an extension of the crack line. The stresses in the plastic zone, the length, and the unit normal vector of the elastic-plastic boundary near a crack surface region are obtained for an antiplane crack in an elastic-perfectly plastic solid. The usual small scale yielding assumptions are not needed in the analysis.     

基于CE/SE方法的二维Euler型多物质流体弹塑性问题计算

将CE/SE方法推广到二维固体流体弹塑性问题的数值计算,同时结合杂交粒子水平集方法追踪物质界面和合适的边界条件,提出一套完整的二维Euler型流体弹塑性计算方案.通过长钨杆侵彻装甲钢实验的数值模拟,对方法的精度和有效性进行验证.     

水下爆炸气泡与复杂弹塑性结构的相互作用研究

计及结构的弹塑性,将边界元法(BEM)与有限元法(FEM)耦合提出了气泡与弹塑性结构耦合动力学计算方法,并开发了全套的三维水下气泡分析程序（UBA）,计算值与实验值之间误差在10%以内．以水面舰船为例,将三维计算程序工程化．并分析了水下爆炸气泡载荷作用下船体的弹塑性响应,从船体结构典型单元上的应力时历曲线可以看出,在气泡坍塌时出现应力峰值,证实了气泡坍塌压力及射流引起的压力对舰船等结构造成严重毁伤．从气泡与舰船的相互作用中可以看出,舰船低阶垂向振型被激起,在气泡作用下呈鞭状运动,同时舰船随着气泡的膨胀和收缩作升沉运动,通过本文的分析得到了适合于工程应用的规律及结论．     

Study on the generalized prandtl-reuss constitutive equation and the corotational rates of stress tensor

I.IntroductionTilepl'ogl'ess11as.toifcertainextent,beenmadeintheelastic-plasticconstitutivetheoryatII[litedefbrlllations.Coil'paredwitllotherconstitutiverelations,thegeneralizedPrandtlReuss(P-R)equatiollsareextensivelystudiedandwidelyapplied.IndevelopingthegeneralizedP-Requation.itisusuallyassumedthatthedeformationrate(thesymmetricpartorvelocitygradiellt)isdecolllposedintotheelasticpartandplasticpart.TheplasticLIcf\'l.llliltlollrittcobeystilenormalfi(,xvrilleasillthecaseofinfinitcsilllnld…     

一、二维弹塑性流体动力学数值计算的高精度新自由面格式

提出了适用于X射线或电子束辐照、爆炸和高速碰撞等问题的一、二维弹塑性流体动力学数值模拟计算的一种新自由面格式。对于X射线及电子束辐照材料与结构的热-力学效应的数值计算结果表明,该新自由面格式明显优于目前一直沿用的Richtmyer格式。从理论上证明了该新自由面格式具有三阶精度,而Richtmyer格式为一阶精度。     

PATH-INDEPENDENT J-INTEGRAL AND ITS DUAL FORM IN ELASTIC-PLASTIC SOLIDS WITH FINITE DISPLACEMENTS

IntroductionJ-integralwasfirstProposedbyXiceLI]in1968andfacePOintedoutthatthephysicalmdringofJ-integralisequivalenttotheenergyreleaseratedefinedasthenegativeofchangeinthepotentialenergywithrespeCttounitadvanceofthecrackinitsplane(perunitthickness).KhowiesandSterberg,basingontwodimension(2D)J-integral,definedsevencurvesquareindependentintegralsinIM2.OUyangChang['],LuMeiziI3]andChenTIdaL4)etal.havedevelopedandextendedthoseworkbasedondynamicsandthreedimension(3D).TheproPOsalofJ-integra…     

Converging spherical and cylindrical elastic–plastic waves of small amplitude

Converging spherical and cylindrical elastic–plastic waves in an isotropic work-hardening medium is investigated on the basis of a finite difference method. The small amplitude pressure is applied instantaneously and maintained on the outer surface of a spherical or a cylindrical medium. It is found that for undercritical loading, the induced wave structure is an elastic front followed in turn by an expanding plastic region and an expanding elastic region. For supercritical loading, the elastic front is followed in turn by an expanding plastic region, a narrowing elastic region and an expanding plastic region.After yielding is initiated, the strength of the elastic front is constant and equal to the critical loading pressure. The motion of the continuous elastic–plastic interface is discussed in detail. Spatial distributions of pressure near the axis show the strength of the converging wave is nearly doubled in the reflecting stage.     

随机有限元方法在断裂分析中的应用

在幂律非线性随机有限元基础上,以单边裂纹板为例给出计算含量钢继裂参数,J（J积分）,δ（裂纹张开位移）,Δ（由裂纹引起的裂纹板上下底面相对位移）,θ（由裂纹引起的裂纹板上下底在相对转角）及其对基本随机变量变化率的方法和分析算例。     

弹塑性有限变形的广义Prandtl—Reuss本构方程和应力共旋率研究

本文通过一种新的途径研究弹塑性有限变形的广义Ｐｒａｎｄｔｌ＿Ｒｅｕｓ本构方程·研究表明对于广义Ｐｒａｎｄｔｌ＿Ｒｅｕｓ本构方程，变形率弹塑性和分解的假设并非必须·研究了采用物质共旋率的广义Ｐｒａｎｄｔｌ＿Ｒｅｕｓ本构方程，从理论上分析了简单剪切应力振荡的原因·提出一种用于构造广义Ｐｒａｎｄｔｌ＿Ｒｅｕｓ本构方程中应力和背应力共旋率的修正相对旋率·最后，对简单剪切变形进行应力计算·