共查询到20条相似文献,搜索用时 15 毫秒
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Z. Wang C. K. Chiang T.-J. Chuang 《Journal of research of the National Institute of Standards and Technology》1997,102(1):15-28
An optimization procedure for designing a ceramic tensile creep specimen to minimize stress concentration is carried out using a finite element method. The effect of pin loading and the specimen geometry are considered in the stress distribution calculations. A growing contact zone between the pin and the specimen has been incorporated into the problem solution scheme as the load is increased to its full value. The optimization procedures are performed for the specimen, and all design variables including pinhole location and pinhole diameter, head width, neck radius, and gauge length are determined based on a set of constraints imposed on the problem. In addition, for the purpose of assessing the possibility of delayed failure outside the gage section, power-law creep in the tensile specimen is considered in the analysis. Using a particular grade of advanced ceramics as an example, it is found that if the specimen is not designed properly, significant creep deformation and stress redistribution may occur in the head of the specimen resulting in undesirable (delayed) head failure of the specimen during the creep test. 相似文献
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某型发动机涡轮盘片叶冠有限元边界条件的计算对比分析 总被引:1,自引:0,他引:1
涡轮带冠叶片叶冠间留有间隙,叶冠在工作中相互间接触、摩擦和间隙几种情况并存,边界条件十分复杂.为分析涡轮盘片组合振动模态,采用循环对称结构法,计算分析了叶冠全接触(耦合)和全间隙(分离)两种极限状态下涡轮盘片耦合振动.计算结果表明冠间相互耦合有效地消除了因叶片扭转、弯曲产生的低频盘片耦合振动模态,叶冠的边界条件对节径振动影响较大,对节圆振动影响相对较小;叶冠间的相互作用具有提高或降低节径振动频率的两种可能. 相似文献
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高温下的金属基复合材料双剪切试样应力应变有限元分析 总被引:1,自引:0,他引:1
对金属基复合材料双剪切试样的应力应变分布进行蠕变有限元计算分析,得到受剪区的应力应变随时间的分布规律。通过典型取向试样分析,表明受剪区的应力应变与纤维随机分布平面和加载方向夹角θ之间存在很大的相关性:随角度θ的减小,其蠕变应力分布越均匀;当角度θ=45°时,其稳态蠕变率γ·最大。双剪切试样能得到较均匀的剪应力区域,适合研究材料纯剪应力状态下的蠕变行为。 相似文献
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A rectangular plate with inclined cracks of different crack lengths at different crack inclination angles under biaxial loading condition are being analyzed in mixed mode condition using finite element method (FEM) for the determination of stress intensity factors (SIFs). With increases of the width of the plate and the crack length ratio, SIF increases up to 45° of crack inclination angle and then decreases; maximum value is obtained at 45° of crack inclination angle. With the increasing value of size factor, the value of SIF starts decreasing. The accuracy of the results of the proposed method is validated by comparing with the previously obtained results by theoretical and experimental methods. The FEM results give significant result for the two-dimensional mixed mode loading conditions. 相似文献
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L. Duggen N. Lopes M. Willatzen H.-G. Rubahn 《International Journal of Thermophysics》2011,32(4):774-785
The finite-element method (FEM) is used to simulate the photoacoustic signal in a cylindrical resonant photoacoustic cell.
Simulations include loss effects near the cell walls that appear in the boundary conditions for the inhomogeneous Helmholtz
equation governing the acoustic pressure. Reasonably good agreement is obtained between theoretical results and experimental
data. However, it was anticipated that loss mechanisms other than viscous and thermal boundary losses occur and should be
included. Nevertheless, the feasibility to use FEM together with the derived boundary conditions to simulate the photoacoustic
signal was demonstrated and good agreement with experiments for the actual resonance frequency and the quality factor of the
cell was obtained despite its complicated geometry. 相似文献
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利用有限元与边界元耦合法对三维无界区域中直立圆柱所受的波浪力进行进行计算,把整个求解区域分成内域或外域两部分,在内域采用有限元法,对外域采用边界元法,数值计算的结果与理论解吻合良好,表明该方法有效。 相似文献
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Shvab’yuk V. I. Rotko S. V. Fedorus’ V. Yu. Shvab’yuk V. V. 《Strength of Materials》2021,53(3):440-448
Strength of Materials - On the basis of the equations of the nonclassical model of bending of transtructural plates of average thickness, which takes into account the influence of normal stress... 相似文献
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本文在重点考虑TiNi合金高弹性变形量的前提下,采用等向强化模型,对不锈钢和超弹TiNi合金在法向接触载荷作用下的六种模型进行了有限元(FEM)分析。结果表明:在相同载荷条件下,超弹TiNi合金产生的von Mises弹性应变要高于不锈钢,但其von Mises应力和塑性应变却恰恰相反,在同一载荷下该合金发生塑性变形的区域要小于不锈钢;此外,超弹TiNi合金发生塑性变形要比不锈钢困难,所需的临界载荷值随其最大弹性变形量(屈服点处的应变值)的增加而增加。最后,基于本文的有限元计算结果对超弹TiNi合金的蘑粒磨损和疲劳磨损机制进行了讨论。 相似文献
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Majid Azimi Seyed Sajad Mirjavadi Seyed Ali Asli A. M. S. Hamouda 《Journal of Failure Analysis and Prevention》2017,17(2):304-314
Some of the most important characteristics due to a fracture investigation of a special specimen are taken into account. Debonding considerations for a composite/steel cracked lap shear (CLS) specimen by utilization of finite element methods (FEM) as well as a virtual crack closure technique (VCCT) approach have been investigated. Strain energy release rate, delamination load case and direct cycle fatigue analysis have taken into consideration in this study, and the corresponding simulations have been done by ABAQUS/Standard. Linear elastic fracture criteria are used for validation of numerical results from the simulation. For comparison of three different categories of analysis, some special characteristics such as effective energy release rate ratio, bond state, time at bond failure and opening behind crack tip at bond failure have been illustrated. In this work, a detailed analysis of a special CLS specimen debonding by using VCCT and FEM is presented and varied results for validation of this kind of combination are obtained and have been discussed. 相似文献
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初始裂纹的形态影响着裂纹尖端的应力场和扩展方向,进而决定着橡胶材料的使用寿命。目前人们关于预制裂纹试样拉伸断裂的研究主要集中在直裂纹,很少涉及预制裂纹角度的改变对橡胶拉伸断裂的影响。文中应用ANSYS有限元分析软件计算拉伸状态下含不同裂纹角度橡胶试样裂纹尖端的等效应力值和撕裂能的大小,判断裂纹是否扩展及扩展方向,并对橡胶试样进行拉伸验证试验测试。结果表明,在拉伸断裂过程中,裂纹尖端的应力值和撕裂能随着初始预制裂纹角度的增大而增大,裂纹尖端形状均由初始的尖点变成圆弧状;含不同裂纹角度橡胶试样的拉伸断裂形貌与裂纹预测扩展方向基本一致,验证了有限元分析的正确性。 相似文献
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本文用有限元分析的方法,对受法向和切向联合载荷作用下的无裂纹类金刚石(DLC)薄膜系统内部应力进行了模拟计算,分析了不同摩擦系数和膜厚比对于内部应力的影响,数值模拟结果表明:较大的摩擦系数可以使得界面处剪切应力和Mises等效应力以及y轴Mises等效应力显著增大,而对于界面处的y向压应力影响不是很大。在一定的范围内(0相似文献
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通过单元正交展开的余项中添加若干待定的低次项,得到所需的超接近于有限元解的逼近函数,由此导出了一类非线性两点边值问题的强超收敛性。最后给出了一个数例验证了这一结论。 相似文献
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为了更好的实现对光学元件抗振性能的分析和评估。以直角垫板元件模型为例,开展一系列不同约束条件下的模态测试实验。首先结合ANSYS有限元模拟结果和模态测试结果,控制偏差在系统允许范围内,对模型模态属性的定义和模型建立的可靠性进行验证。其次,在基准有限元模型基础上,对不同约束条件下的该光学元件的模态参数进行计算,得到不同约束条件下不同的模态参数。最后,根据不同约束条件下元件所表现出来的不同的动力学特性,分析在不同装配状态下元件的工作稳定性,为进一步改善光学元件在不同振动噪声干扰下的工作性能和抗振性能奠定了基础。 相似文献
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在有限区间带边界条件的小波插值与分解 总被引:2,自引:0,他引:2
小波是近年国际研究的热点,被认为是在工具及方法上取得重大突破的分析学中一个完美的结晶,在众多领域中有广泛的用途。最初小波是在无穷区间中研究的,实际问题往往出现在有限区间,有时还带边界条件,用原来方法小波分解并不理想,f0(t)≠f-1(t)+g-1(t),f-1(t)与g-1(t)又不正交,∫a^bf-1(t)g-1(t)dt≠0。重建时出现失真。本文试图解决这个问题,联系到B样条与小波的关系,比 相似文献
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根据C/SiC复合材料的属性,建立单纤维顶出的二维轴对称模型,采用有限元法对C/SiC复合材料的界面剪切强度进行数值研究,分析中考虑材料制备过程中的残余应力对界面剪切强度的影响,在细观力学层面上系统分析纤维顶出过程的界面剪应力及其相关影响因素。分析得出,残余应力会对界面造成损伤,降低界面脱粘载荷。材料的界面承受能力与热膨胀系数呈正相关,与固化温度呈负相关。 相似文献
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