首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 265 毫秒
1.
复合材料非线性本构关系的机算机模拟   总被引:1,自引:0,他引:1       下载免费PDF全文
本文对单向连续纤维增强复合材料的弹塑性本构关系进行了数值模拟。首先提出了基于统一弹粘塑性本构理论的有限无法,然后利用微观力学模型研究了弹性纤维增强弹粘塑性基体的复合材料应力——应变关系。  相似文献   

2.
本文对单向连续纤维增强复合材料的弹塑性本构关系进行了数值模拟。首先提出了基于统一弹粘塑性本构理论的有限无法,然后利用微观力学模型研究了弹性纤维增强弹粘塑性基体的复合材料应力——应变关系。  相似文献   

3.
非线性样条有限条法及其应用   总被引:1,自引:0,他引:1  
陈士林  方山峰 《工程力学》1993,10(1):119-128
本文基于完全的增量形式Lagrange描述法,根据虚功原理导出了大挠度弹塑性样条有限条法,用以分析板、壳和薄壁结构与构件的几何与材料非线性问题。本文方法适用于任意边界支承条件和加荷方式,可以计入任意形式的初始缺陷的影响以及沿厚度方向的塑性开展。所给算例表明,该方法具有计算量少.连续性强、精度高、应用广泛等优点.  相似文献   

4.
板料成形过程是涉及几何非线性、材料非线性和边界条件非线性等的多重非线性问题.介绍了板料冲压成形CAD数字化分析所涉及到的基本理论--非线性弹塑性材料的本构关系、板壳成形单元模型、接触问题、有限元方程及求解.  相似文献   

5.
通过橡胶材料在不同温度及应变率下的霍普金森杆冲击试验(SHPB),结合粘弹、超弹理论,建立了一种能反映橡胶材料温度、应变率效应的大应变非线性热粘超弹性本构模型,并开发了相应模型的ABAQUS(VUMAT)软件材料用户子程序。数值模拟很好地再现了橡胶片的SHPB试验,验证了本构模型及材料用户子程序的有效性。  相似文献   

6.
论文基于双剪统一强度准则应变软化模型对圆形隧道稳定性的分析,提出一种简单的数值计算方法来对围岩进行弹塑性分析。该文采用差分法,基于广义形式的双剪应力屈服准则,并采用相关联流动法则,建立本构方程。对于应变软化模型,该文选定塑性应变增量作为软化参数,并且假设强度参数随软化参数成线性函数关系。弹性区的解答引用拉梅解答,而求解塑性区的解答时,将塑性区分成很多微元圆环,并假设每个圆环的径向应力?r沿半径向内均匀递减;其次,建立每个微元圆环的平衡微分方程、本构方程、几何方程及相邻两微元之间的应力增量和应变增量的关系。从弹塑性交界面处的塑性区最外一个圆环开始,求解出每一个微元圆环的解答。并且利用MATLAB进行编程求解出最终的结果:应力场、应变场、径向位移场的数值解。此外还分析讨论了中间主应力影响系数b、软化参数临界值η*对解答的影响,并分析了影响塑性区半径的因素。  相似文献   

7.
建立材料的粘塑性本构模型,进行粘塑性裂纹扩展试验,是开展聚合物粘塑性裂纹扩展问题研究的基础.采用恒定应变速率的方法,对硬聚氯乙烯进行低应变速率下的拉伸试验,确定各应变速率下应力与应变的关系曲线.实验数据表明,该材料的力学性能对应变速率有依赖性,与时间相关,是典型的粘塑性材料.根据实验测得的不同应变速率下应力-应变关系的曲线族,对实验数据进行多元回归分析,确定有关的材料常数,建立了硬聚氯乙烯材料Bailey-Norton公式形式的粘塑性本构模型.进行硬聚氯乙烯的粘塑性裂纹扩展试验研究,得到了裂纹长度增量与时间的关系.  相似文献   

8.
在基于混合物理论的多孔介质模型的基础上,将固体相视为弹粘塑性体,建立了饱和多孔介质的弹粘塑性模型。模型的基本思想是在无粘弹塑性本构关系中引入-时间参数,使固体骨架具备了粘性效应。利用Galerkin加权残值法推导得到了罚有限元格式,并采用Newmark预估校正法求解率相关饱和多孔介质的非线性有限元动力方程,此算法可以很...  相似文献   

9.
聚氨酯泡沫材料是一种应用广泛、应变率敏感、静水压力相关的多孔介质材料。文中综述了近年来国内外聚氨酯泡沫材料本构关系的研究进展。通过对几种应变率相关的本构模型,如粘弹、粘弹塑性等类型本构进展的介绍,分析了这些本构的特点和适用范围。根据已有的实验和本构关系,指出建立聚氨酯泡沫材料动态本构关系过程中需要考虑的主要问题,最后展望了聚氨酯泡沫材料的本构关系发展趋势。  相似文献   

10.
在研究复合材料的多层、夹层和加筋板壳的非线性弹性和塑性失稳问题时,需要用到失稳前的应力与应变之间和失稳时的应力增量与应变增量之间的非线性关系。复合材料在纤维断裂和基体开裂以前的物理非线性,主要是由基体引起的。本文对非线性弹性和处于主动塑性变形阶段的各向同性基体,采用小弹塑性变形理论,导得了应力与应变之间的各向同性非线性关系和应力增量与应变增量之间的各向异性非线性关系。假定纤维是线性弹性的。用复合材料的复合定律,求得了单向增强纤维复合材料层片的应力与应变之间和应力增量与应变增量之间的非线性关系。  相似文献   

11.
秦荣 《工程力学》2001,18(1):14-22
本文提出一个分析复合材料板壳的样条有限点法,建立了静力分析、热效应分析、稳定性分析及动力分析的新计算格式。这个方法是以B样条函数、高阶剪切变形理论及变分原理为基础而建立的,由于采用样条离散化,不存在剖分协调问题。利用这个方法分析复合材料板壳,不仅计算简便,而且精度也高。  相似文献   

12.
Minimum principles in velocities, stress rates and plastic strain rates are extended in order to derive formulations for finite increments of displacement, stress and plastic strain fields defining complete numerical methods. Kinematical, statical and mixed principles are developed from a new variational formulation of the elastic-plastic work-hardening constitutive relation. The consequences of this time discretization are discussed independently of any discretization of the continuum. In particular, the incremental formulations derived from extended rate principles account for local elastic unloading and produce stress field approximations complying with equilibrium and plastic admissibility without any additional procedure, at least for piecewise linear yield functions. These properties are not fulfilled when the incremental analysis is based on direct discrete versions of classical rate principles. Finally, FEM approximations are formally introduced and the solution of the resulting finite dimensional quadratic optimization problem is considered.  相似文献   

13.
本文研究压电智能结构力电耦合性能分析的新理论新方法.以智能本构关系、瞬时变分原理及样条离散化为理论基础,利用智能样条有限点法建立了压电智能简支梁力电耦合性能方程.分析中考虑了不同荷载值、材料类型和材料参数等因素对压电智能梁性能的影响.与通用有限元软件ANSYS的结果进行比较说明了本文研究方法的正确性和有效性.  相似文献   

14.
An accuracy analysis of a new class of integration algorithms for finite deformation elastoplastic constitutive relations recently proposed by the authors, is carried out in this paper. For simplicity, attention is confined to infinitesimal deformations. The integration rules under consideration fall within the category of return mapping algorithms and follow in a straightforward manner from the theory of operator splitting applied to elastoplastic constitutive relations. General rate-independent and rate-dependent behaviour, with plastic hardening or softening, associated or non-associated flow rules and nonlinear elastic response can be efficiently treated within the present framework. Isoerror maps are presented which demonstrate the good accuracy properties of the algorithm even for strain increments much larger than the characteristic strains at yielding.  相似文献   

15.
刘理  刘土光  李天匀 《振动与冲击》2000,19(3):60-62,51
研究了轴向冲击载荷作用下材料应变率对圆柱壳弹塑性冲击屈曲的影响,采用Karman-Donnell运动方程,本构关系采用增量理论,联立Cowper-Symonds关系,求得相应的动屈服应力,借助增量数值计算方法注解运动方程,计算表明:材料的应变率敏感性显著地提高了结构的抗冲击屈曲能力;基于B-R准则的屈曲判断方法和采用Southwell方法可以获得一致的临界屈曲载荷。  相似文献   

16.
The viscoplastic deformation behavior of the shell is governed by any of the more recently proposed unified constitutive models with internal state variables and with the assumption that the total strain rate tensor can be decomposed additively into an elastic and an inelastic part. For the numerical analysis of viscoplastically deformed shells we use a hybrid strain finite element based on a geometrically linear theory of inelastic shells proposed by Kollmann and Mukherjee (1985). This theory gives the reduction of a two-field variational principle originally proposed by Oden and Reddy (1974) for elastic shells to the shell midsurface. It contains strain and displacement rates as variables to be independently varied. The shell formulation of this variational principle is the basis for the present work. First, a general hybrid finite element model is derived in which the shape functions for the strain and displacement rates can be polynomials of different order. Here we use the term hybrid in the sense of Pian (1988), i.e. in our two-field finite element the strain rates are condensed statically on the element level, leaving nodal displacements as the only unknowns in the final matrix equation. Then the finite element model is specialized for an axisymmetrically loaded conical shell with linear approximation of the strain rate field and quadratic interpolation of the displacement rates. Special emphasis is given to the derivation of the inelastic pseudo-forces and pseudo-moments. Numerical results for elastically and viscoplastically deformed shells are presented, where viscoplastic deformations are described by Hart's (1976) constitutive model.  相似文献   

17.
混凝土弹性-徐变的本构关系   总被引:1,自引:0,他引:1  
混凝土的变形不仅和加荷后的时间(t-τ)有关,而且和加荷时刻混凝土的龄期有关,应变和应力之间成复杂的积分式关系。由于本构关系的复杂性,对钢筋混凝土或预应力混凝土超静定结构未能圆满求解。在特定情况作者曾给出本构关系的Laplace变换形式并提供求解方法。本文就当前国际上所给出的弹性-徐变的普遍形式给出t→∞时应变、应力之间的代数关系(线性或非线性),以及在周期荷载下,例如长期温度变化,应变、应力的线性关系。为简单计,本文仅考虑一维的应变、应力问题,不难按照文[2]推广到三维情况。当本构关系确定后可按文献[1]、[2]方法求解预应力混凝土的框架和板、壳问题。  相似文献   

18.
A linear theory for facet-like thin elastic shells is derived where strain/displacement, curvature change/displacement and constitutive relations appear the same as for flat plates. Application of Koiter's arguments shows that the theory is a valid first approximation. The theory is of interest for limiting cases of faceted finite element analysis of smooth shells. Although the final equations of facet-like shell theory do not have quite as simple a form as more conventional equations it is possible that their derivation from equations for flat plates may appeal to engineers. A specialization of the equations is given to circular cylindrical shells where four simple illustrative examples show no essential differences with results from more conventional theory.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号