An integrated procedure for three‐dimensional structural analysis with the finite cover method

In this paper an integrated procedure for three‐dimensional (3D) structural analyses with the finite cover method (FCM) is introduced. In the pre‐process of this procedure, the geometry of a structure is modelled by 3D‐CAD, followed by digitization to have the corresponding voxel model, and then the structure is covered by a union of mathematical covers, namely a mathematical mesh independently generated for approximation purposes. Since the mesh topology in the FCM does not need to conform to the physical boundaries of the structure, the mesh can be regular and structured. Thus, the numerical analysis procedure is free from the difficulties mesh generation typically poses and, in this sense, enables us to realize the mesh‐free analysis. After formulating the FCM with interface elements for the static equilibrium state of a structure, we detail the procedure of the finite cover modelling, including the geometry modelling with 3D‐CAD and the identification of the geometry covered by a regular mesh for numerical integration. Prior to full 3D modelling and analysis, we present a simple numerical example to confirm the equivalence of the performance of the FCM and that of the standard finite element method (FEM). Finally, representative numerical examples are presented to demonstrate the capabilities of the proposed analysis procedure. Copyright © 2005 John Wiley & Sons, Ltd.     

Werkstoffkennwerte für die Lebensdauerberechnung von Strukturen aus Stahlfeinblechen für den Automobilbau

Materials Data for Fatigue Life Calculation of Steel Sheet Structures for Automotive Engineering Within a joint project of the steel and automotive industry 17 steel sheet materials for automotive engineering in various delivery and forming conditions at temperatures of –40 °C, 22 °C and 100 °C were investigated. In the course of 37 test series strain controlled fatigue curves to crack initiation and stress‐strain‐curves under monotonic and cyclic loading were determined. All experimental data, hysteresis loops and determined cyclic properties are available in a database. A correlation between the mechanical properties from tensile tests and the properties from strain controlled cyclic experiments seems to be possible.     

压力型锚杆锚固段长度确定方法研究

通过对压力型锚杆锚固段的受力分析,推导出了压力型锚杆锚固段的轴力分布和剪应力分布,以及锚固段长度的计算公式。并在此基础上进一步分析了压力型锚杆锚固段长度与岩土体弹性模量、泊松比、粘聚力以及内摩擦角等参数的关系。结果表明：锚固段长度随岩土体弹性模量、粘聚力和内摩擦角的增大而减小;随岩土体泊松比的增大几乎呈线性增加,但增幅极为有限;随拉拔荷载的增加而增加。     

不同围压下混凝土受压弹塑性损伤本构模型的研究

在ＭＴＳ公司８１５０２型电液伺服系统上，完成了围压由０～４０ＭＰａ范围内混凝土受压试验，发现随着围压的增大，应力应变全曲线的峰值应力与峰值应变均有所提高，但弹性模量基本不变在此基础上，根据等效应变假定和内变量理论，建立了考虑不可逆应变影响的弹塑性损伤本构模型只要计及峰值应力和峰值应变的变化，该模型可以统一地描述不同围压下混凝土的力学性能     

建筑结构在罕遇地震下弹塑性变形验算的讨论

本文对现行抗震设计规范中罕遇地震作用下结构抗震变形验算有关规定存在的问题进行了分析,并提出了改进建议。指出了目前钢筋混凝土结构弹塑性位移计算结果与实际地震反应存在较大差异的主要原因。在对大量数据统计分析的基础上,讨论了框架结构层间弹塑性位移角限值的合理性,提出了框架—抗震墙结构、抗震墙结构和框架—筒体结构的弹塑性层间位移角限值。     

温度作用下脆性岩石的损伤分析

从花岗岩弹性模量随温度的变化规律入手,提出了热损伤的概念,在此基础上导出了热２演化方程和一维耦合弹脆性损伤本构方程,并讨论了损伤释放度随温度的演化规律。     

硬化材料中的波传播与层裂效应研究

给出了简明有效的塑性本构关系及其在数值计算中的应用，并利用所建立的本构关系对高能炸药在钢板表面接触爆炸时钢板中应力波的传播及所产生的层裂现象进行了数值分析．对钢板材料采用理想塑性、各向同性硬化、随动硬化、联合的各向同性－随动硬化等模型进行了系统数值计算，从而得出了材料塑性硬化行为对波传播和层裂规律的影响，并进行了相应的分析．     

Simulation of strength difference in elasto‐plasticity for adhesive materials

Experimental evidence of certain adhesive materials reveals elastic strains, plastic strains and hardening. Furthermore, a pronounced strength difference effect between tension, torsion or combined loading is observed. For simulation of these phenomena, a yield function dependent on the first and second basic invariants of the related stress tensor in the framework of elasto‐plasticity is used in this work. A plastic potential with the same mathematical structure is introduced to formulate the evolution equation for the inelastic strains. Furthermore, thermodynamic consistency of the model equations is considered, thus rendering some restrictions on the material parameters. For evolution of the strain like internal variable, two cases are considered, and the consequences on the thermodynamic consistency and the numerical implementation are extensively discussed. The resulting evolution equations are integrated with an implicit Euler scheme. In particular, the reduction of the resulting local problem is performed, and for the finite‐element equilibrium iteration, the algorithmic tangent operator is derived. Two examples are presented. The first example demonstrates the capability of the model equations to simulate the yield strength difference between tension and torsion for the adhesive material Betamate 1496. A second example investigates the deformation evolution of a compact tension specimen with an adhesive zone. Copyright © 2005 John Wiley & Sons, Ltd.     

高拱坝的有限元分析方法和设计判据研究

本文研究了高拱坝的有限元分析方法和判断准则，将上游开裂状态，下游压剪屈服和点安全度，面安全度做为新的设计准则和方法，并介绍了工程应用情况。     

水压机活动横梁的弹塑性有限元分析

把水压机活动横梁假设成一交叉梁系,对其做了弹塑性有限元分析,导出了部分节点弯矩超过弹性极限时的梁单元刚度矩阵,讨论了计算方法的收敛性.