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To investigate the cracking reason in welding structure with transition changing faces at cylinder block on boom of medium excavator during fatigue test, the finite element model of boom was established by using ANSYS finite element software. The stress distribution of the boom was obtained under fatigue loading spectrum of medium excavator. In addition, the fine model of welding structure with solid element length 2 mm was set up with the help of sub-model technology in ANSYS software to get the accurate hot spot stresses around welding toes. Finally, the fatigue life of this welding structure was calculated according to IIW fatigue class. The results show that the stress gradient along with the thickness direction can be acquired by fine three-dimensional finite element sub-model of welding structure. Therefore, the weakest point in thick plate was located, which was in accordance with the experiment result. 相似文献
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This paper analyzes the causes of fracture of the double pipe aerial cannon stellate star-separator, which occurred during the fighting plane mission. The linear finite element method (FEM) is used to determine the stresses that the star-shaped star-separator is subjected to during the grenade belts withdrawal and introduction into the bearing tube during gun action and under finite load, which resulted in high strains concentration of the star-separator’s parts pulling the gun belt links.Therefore, in this paper we are particularly focusing on the static and dynamic behavior and the fatigue behavior of the star-separator which is an integral part of the cannon fire shutter mechanism used for the belt’s withdrawal. In this study, the techniques such as numerical analysis, hardness measurement and fractographic examination were used. The testing results showed that the peel and longitudinal cracks started from the low-cycle fatigue and wear of the surface material in the thinnest area of the star-separator tooth, but without influence of the stress load. 相似文献
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Static and Fatigue Behaviour of Hexagonal Honeycomb Cores under In-plane Shear Loads 总被引:1,自引:0,他引:1
Due to their high specific strength and high specific stiffness properties the use of honeycomb panels is particularly attractive
in spacecraft structures. However, the harsh environment produced during the launch of a satellite can subject the honeycomb
cores of these sandwich structures to severe quasi-static and dynamic loads, potentially leading to static or early fatigue
failures. Knowledge of the static and fatigue behavior of these honeycomb cores is thus a key requirement when considering
their use in spacecraft structural applications. This paper presents the findings of an experimental test campaign carried
out to investigate the static and fatigue behaviors of aluminum hexagonal honeycomb cores subject to in-plane shear loads.
The investigation involved carrying out both static and fatigue tests using the single block shear test method. These results
are also discussed in relation to the observed damage and failure modes which have been reported for the statically tested
specimens and for the fatigue tested specimens at various stages of fatigue life. As well as conducting tests for the more
conventional principal cell orientations (L and W), results are also presented for tests carried out at intermediate orientations
to investigate the variation of core shear strength with loading orientation. The results are further investigated using explicit
non-linear finite element analysis to model the buckling failure mechanisms of the tested cores. 相似文献
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Eugenio Oate Jerzy Rojek Robert L. Taylor Olgierd C. Zienkiewicz 《International journal for numerical methods in engineering》2004,59(11):1473-1500
Many finite elements exhibit the so‐called ‘volumetric locking’ in the analysis of incompressible or quasi‐incompressible problems.In this paper, a new approach is taken to overcome this undesirable effect. The starting point is a new setting of the governing differential equations using a finite calculus (FIC) formulation. The basis of the FIC method is the satisfaction of the standard equations for balance of momentum (equilibrium of forces) and mass conservation in a domain of finite size and retaining higher order terms in the Taylor expansions used to express the different terms of the differential equations over the balance domain. The modified differential equations contain additional terms which introduce the necessary stability in the equations to overcome the volumetric locking problem. The FIC approach has been successfully used for deriving stabilized finite element and meshless methods for a wide range of advective–diffusive and fluid flow problems. The same ideas are applied in this paper to derive a stabilized formulation for static and dynamic finite element analysis of incompressible solids using linear triangles and tetrahedra. Examples of application of the new stabilized formulation to linear static problems as well as to the semi‐implicit and explicit 2D and 3D non‐linear transient dynamic analysis of an impact problem and a bulk forming process are presented. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Centrifugal forces are generated by a spinning impeller, of magnitudes that create large stresses. Aerodynamic forces are also imparted on an impeller blade, which varies with time and position. These two forces play different roles during compressor events. Damage accumulated from these events results in the fatigue failure of impeller material and structure. Therefore, it is important to design an impeller against dynamic and fatigue failure. The finite element method has been used in the study of impeller fracture mechanics and is regarded as an important tool in the design and analysis of material and structures. 相似文献
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Edward L. Wilson Mehdi Khalvati 《International journal for numerical methods in engineering》1983,19(11):1657-1668
Several new finite elements are presented for the idealization of two- and three-dimensional coupled fluid-solid systems subjected to static and dynamic loading. The elements are based on a displacement formulation in terms of the displacement degrees-of-freedom at the nodes of the element. The formulation includes the effects of compressible wave propagation and surface sloshing motion. The use of reduced integration techniques and the introduction of rotational constraints in the formulation of the element stiffness eliminates all unnecessary zero-energy modes. A simple method is given which allows the stability of a finite element mesh of fluid elements to be investigated prior to analysis. Hence, the previously encountered problems of ‘element locking’ and ‘hour glass’ modes have been eliminated and a condition of optimum constraint is obtained. Numerical examples are presented which illustrate the accuracy of the element. It is shown that the element behaves very well for non-rectangular geometry. The optimum constraint condition is clearly illustrated by the static solution of a rigid block floating on a mesh of fluid elements. 相似文献
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汽车悬架稳定杆连杆支架的疲劳仿真分析及结构优化 总被引:1,自引:0,他引:1
针对某型车辆常规耐久性试验过程中稳定杆连杆支架出现断裂的问题,对稳定杆连杆支架进行疲劳寿命分析和结构优化.首先运用ANSYS软件建立稳定杆连杆支架的有限元模型;然后基于静态有限元疲劳分析方法对连杆支架进行强度分析计算,并依据强度分析结果对稳定杆连杆支架进行疲劳寿命预测分析;其次根据等强梁理论对稳定杆连杆支架进行结构优化,支架截面由原来的等截面改为变截面,并对优化后的结构进行疲劳寿命预测;最后通过疲劳台架试验和裂纹断口分析,验证仿真分析结果.通过台架试验和仿真结果的对比可以得出,稳定杆连杆支架优化前后其疲劳寿命预测准确,优化后结构疲劳寿命符合预期. 相似文献
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提出一种汽车驱动桥系统的模态综合动力学建模与分析方法,采用非线性轴承单元实现传动系模型与桥壳模型的耦合建模,采用模态综合法对驱动桥各部件的有限元模型进行缩维变换,能够在准确模拟驱动桥系统动力学特性的同时大大缩减系统模型规模,从而快速准确地实现驱动桥系统的静力学非线性求解和动力学分析。以准双曲面齿轮有限元接触分析求得的动态啮合力作为系统激励,计算驱动桥系统的动力学响应,并进行试验验证,数值计算结果能够准确体现准双曲面齿轮动态啮合力激励下的驱动桥系统动力学特性,有效指导驱动桥的减振降噪设计。 相似文献
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针对枪炮冲击型MR阻尼器的特点,以某单管25mm火炮为研究对象,基于Herschel-Bulkley本构模型,建立了该25mm火炮磁流变后坐阻尼器的轴对称一维层流模型。同时运用ANSYS软件,建立了该阻尼器MR阀的电磁有限元模型,求得了环状流口间MR流体的磁通密度。将MR流体流动模型和MR阀有限元结果相结合,求得了不同MR流体行为指数和不同磁场作用下阻尼力随活塞速度的变化规律。建立了火炮后坐运动方程,评价了MR流体行为指数对后坐阻尼器性能的影响。 相似文献
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传统的火炮设计和分析均基于“平面、对称和静平衡”三个基本假设,实际上是一种静态的分析方法,虚拟样机技术的出现为基于动力学的火炮动态分析提供了新的途径。在建立火炮动力学模型的基础上,利用虚拟样机技术系统地研究了高低机刚度和阻尼、大架刚度和阻尼、土壤介质刚度和阻尼、后坐质量偏心和耳轴位置偏心对火炮射击稳定性的影响。通过引入相对灵敏度分析公式,解决了具有不同量纲的影响因素的比较难题,进而获得影响火炮射击稳定性的重要结构参数。针对目前优化技术存在非线性优化问题的局限性,以火炮射击稳定性为目标,采用广义简约梯度算法对火炮射击稳定性进行了优化,得到一组使火炮稳定性最优的匹配结构参数,仿真及优化算例证明了利用虚拟样机技术对火炮系统动态特性仿真的可行性和灵活性。最后,展望了虚拟样机技术在武器装备领域应用的前景。 相似文献
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为研究大跨混凝土斜拉桥施工过程中结构的断索动力响应,以湖南赤石特大桥火灾后九根拉索断裂的事故为背景,采用有限元软件建立了赤石特大桥的非线性动力实体有限元分析模型,通过对比灾后检测得到的索力、主梁和索塔位移及裂缝开展情况与有限元模型中相应的计算结果,证明了模型的有效性。基于已验证的有限元模型,对斜拉桥结构在多根拉索断裂过程中的动力响应进行了分析。结果表明:(1)拉索静态断裂只会对断索区域附近的截面内力和索力造成影响,而拉索骤断引起的冲击作用则会导致全桥结构都产生较大内力变化;(2)单侧索面部分拉索断裂导致主梁顶板及腹板受到扭矩和双向弯矩的共同作用而产生大量裂缝,裂缝在第五根拉索断裂后出现;(3)主梁扭矩、竖向弯矩和横向弯矩最不利截面在断索过程中的动力放大系数分别在1.09~1.55、1.21~2.05及1.21~1.76,最大主压应力动力放大系数在1.02~1.58;(4)预应力筋及拉索最大拉应力的动力放大系数分别在1~1.9及1.05~1.4;(5)索塔塔顶位移动力放大系数在1.23~1.65。 相似文献
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H.W. Zhang H. Liu J.K. Wu 《International journal for numerical methods in engineering》2013,93(7):714-746
A uniform extended multiscale finite element method is developed for solving the static and dynamic problems of heterogeneous materials in elasticity. To describe the complex deformation, a multinode two‐dimensional coarse element is proposed, and a new approach is elaborated to construct the displacement base functions of the coarse element. In addition, to improve the computational accuracy, the mode base functions are introduced to consider the effect of the inertial forces of the structure for dynamic problems. Furthermore, the orthogonality between the displacement and mode base functions is proved theoretically, which indicates that the proposed multiscale method can be used for the static and dynamic analyses uniformly. Numerical experiments show that the mode base functions almost do not work for the static problems, while they can improve the computational accuracy of the dynamic problems significantly. On the other hand, it is also found that the number of the macro nodes of the multinode coarse element has a great influence on the accuracy of the numerical results for both the static and dynamic analyses. Numerical examples also indicate that the uniform extended multiscale finite element method can obtain sufficiently accurate results with less computational cost compared with the standard FEM. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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为了提高机床主轴箱的静、动、热态综合性能,主轴箱必须具备良好的结构特性。在CAE软件ANSYS中建立某机床主轴箱的有限元模型,然后分别进行热——力耦合分析和模态分析,以主轴箱的质量、最大耦合应力、最大耦合变形、一阶固有频率为目标函数,主体部分的长度、宽度、高度为设计变量进行了多目标正交优化设计。利用灰色关联分析法获得了优化设计的最佳解,使主轴箱在质量仅增加2.585%的情况下,最大热——力耦合应力降低9.817%,最大热——力耦合变形减小16.393%,并且一阶固有频率提高8.634%。研究表明,正交试验法和灰色关联分析法具有较高的工程实用性。 相似文献
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Interval Finite Element Analysis using Interval Factor Method 总被引:1,自引:0,他引:1
Wei Gao 《Computational Mechanics》2007,39(6):709-717
A new method called the interval factor method for the finite element analysis of truss structures with interval parameters
is presented in this paper. The structural parameters and applied forces can be considered as interval variables by using
the interval factor method, the structural stiffness matrix can then be divided into the product of two parts corresponding
to the interval factors and the deterministic value. From the static governing equations of interval finite element method
of structures, the structural displacement and stress responses are expressed as the functions of the interval factors. The
computational expressions for lower and upper bounds, mean value and interval change ratio of structural static responses
are derived by means of the interval operations. The effect of the uncertainty of the structural parameters and applied forces
on the structural displacement and stress responses is demonstrated by truss structures. 相似文献