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1.
大变形扭转塑性硬化的实验和仿真研究   总被引:10,自引:0,他引:10  
赵慧娟  庄茁  郑泉水 《力学学报》2002,34(5):804-811
通过拉伸和扭转实验以及理论分析发现:在扭转实验中,当等效名义伸长率达到 286%时发生扭断,在此之前无明显局部化现象出现;相比较而言,单轴拉伸实验中的试件在颈缩失稳断裂时标距的最大伸长率仅为 29%.因此,用实心圆柱的扭转实验作为研究低碳钢这类弹塑性材料在大变形特征下的更为有效的基本实验,而以单轴拉伸实验作为补充是十分必要的.并通过数值模拟对在扭转过程中弹性核演变的历史进行了分析.  相似文献
2.
Nonlinear airship aeroelasticity   总被引:7,自引:0,他引:7  
The aeroelastic derivatives for today's aircraft are calculated in the concept phase using a standard procedure. This scheme has to be extended for large airships, due to various nonlinearities in structural and aerodynamic behaviour. In general, the structural model of an airship is physically as well as geometrically nonlinear. The main sources of nonlinearity are large deformations and the nonlinear material behaviour of membranes. The aerodynamic solution is also included in the nonlinear problem, because the deformed airship influences the surrounding flow. Due to these nonlinearities, the aeroelastic problem for airships can only be solved by an iterative procedure. As one possibility, the coupled aerodynamic and structural dynamic problem was handled using linked standard solvers. On the structural side, the Finite-Element program package ABAQUS was extended with an interface to the aerodynamic solver VSAERO. VSAERO is based on the aerodynamic panel method using potential flow theory. The equilibrium of the internal structural and the external aerodynamic forces leads to the structural response and a trimmed flight state for the specified flight conditions (e.g. speed, altitude). The application of small perturbations around a trimmed state produces reaction forces and moments. These constraint forces are then transferred into translational and rotational acceleration fields by performing an inertia relief analysis of the disturbed structural model. The change between the trimmed flight state and the disturbed one yields the respective aeroelastic derivatives. By including the calculated derivatives in the linearised equation of motion system, it is possible to judge the stability and controllability of the investigated airship.  相似文献
3.
用ABAQUS软件处理管土相互作用中的接触面问题   总被引:3,自引:0,他引:3  
采用ABAQUS软件处理管土相互作用中的接触面问题,利用ABAQUS软件中的主控-从属接触算法,使管道和海床形成一个接触对;并且建立了管土系统有限单元模型.海床土体分别采用非线性弹性模型、多孔弹性模型、Ramberg-Osgood塑性模型对管土系统进行计算通过分析计算,得到了管道沉降量与管重间的关系,以及由于管道沉陷而形成的土体楔形,土体楔形的存在,增加了管道的稳定性.计算结果和有关试验结果相符合,说明采用该软件进行管土相互作用问题分析是可行的.  相似文献
4.
分层递变梯度蜂窝材料的面内冲击性能   总被引:3,自引:0,他引:3       下载免费PDF全文
提出了一种分层递变梯度蜂窝材料模型,以期控制蜂窝材料的能量动态吸收性能。此模型通过改 变胞元的半径来改变蜂窝材料的面内特征参数,以实现蜂窝材料面内动力响应特性的多目标优化设计。计算 结果表明,此模型可以在减小初始峰值应力水平的前提下,同时实现材料能量吸收过程的控制,并可以有效控 制进入被保护结构的应力水平。此模型可为蜂窝材料冲击动力学性能的多目标优化设计提供理论指导和设 计思路。  相似文献
5.
Q235钢板对半球形头弹抗侵彻特性   总被引:1,自引:0,他引:1  
利用轻气炮进行了半球形头杆弹正撞击单层板和等厚接触式三层板的实验,得到了这两种结构靶体的初始-剩余速度曲线以及弹道极限.采用ABAQUS/EXPLICIT数值模拟软件对杆弹撞击金属板的过程进行了数值模拟研究,通过对比数值模拟和实验结果,验证了数值模拟材料模型和参数的有效性.研究了靶体结构对抗侵彻特性的影响,并分析了弹体对靶体的撞击过程.研究结果表明:多层板的弹道极限高于等厚单层板.单层板主要失效模式为剪切,而多层板的主要失效模式为整体的蝶形变形和局部的盘式隆起.对于多层板,靶板具体的失效模式与其在靶中位置相关.  相似文献
6.
整体加筋壁板裂纹扩展轨迹模拟及控制分析   总被引:1,自引:1,他引:0  
应用有限元方法并结合裂纹扩展方向判据分析模拟了飞机整体加筋壁板裂纹的扩展轨迹,与实验结果对比证明此方法的有效性;并通过壳单元模型和粘聚区渐进损伤模型详细讨论了影响整体加筋壁板裂纹扩展的筋条参数,研究了壁板筋条对裂纹止裂的控制,并对不同参数下裂纹的应力强度因子和扩展情况作对比分析.文章所述方法和结论对于飞机整体加筋壁板的损伤容限设计具有指导意义.  相似文献
7.
The purpose of this paper is to propose a method for the evaluation of plate elements in the finite element engineering software comparatively to the Kirchhoff and Reissner plate theories. The method is based on the study of transverse deflection near a crack tip. A numerical work has been conducted for the shell elements in Abaqus software with different crack lengths and various thicknesses. The deflection can be written as a function of the exponent of the distance between the crack tip and one point along the crack. This exponent is accepted to describe the behaviour of finite elements.  相似文献
8.
栗明  许金泉 《上海力学》2007,28(1):92-97
破前漏(简称LBB)是压力容器、核电站设备结构设计与评价中的一个重要准则.表面裂纹准静态扩展的几何形貌变化规律的预测是破前漏(LBB)评判十分重要的课题之一.本文对特定焊接残余应力场加载作用下,含三维表面裂纹的压力容器模型,用有限元软件(ABAQUS)进行了表面裂纹准静态扩展模拟计算,得到在此残余应力场作用下应力强度因子沿裂纹前缘的分布规律.结合外载引起的应力强度因子,就可以判别裂纹的扩展形貌,从而判断结构是否满足LBB要求.  相似文献
9.
The responses of metallic plates and sandwich panels to localized impulse are examined by using a dynamic plate test protocol supported by simulations. The fidelity of the simulation approach is assessed by comparing predictions of the deformations of a strong-honeycomb-core panel with measurements. The response is interpreted by comparing and contrasting the deformations with those experienced by the same sandwich panel (and an equivalent solid plate) subjected to a planar impulse. Comparisons based on the center point displacement reveal the following paradox. The honeycomb panel is superior to a solid plate when subjected to a planar impulse, but inferior when localized. The insights gained from an interpretation of these results are used to demonstrate that a new design with a doubly-corrugated soft core outperforms solid plates both for planar and localized impulses.  相似文献
10.
研究了厚薄板通用三角形广义协调单元TCGC-T9的固有振动特性.通过编制程序,采用子空间迭代法求得不同板厚的前5阶固有频率值,并将计算结果与理论解和有限元软件ABAQUS的结果进行比较.结果表明:TCGC-T9单元在固有振动分析方面收敛速度快,数值稳定性好、实用性强(无需区分厚板和薄板).  相似文献
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