Finite element analysis of dynamic stability of skeletal structures under periodic loading

INTRODUCTION Some structures fail geometrically before thestrength failure because of lack of stability and such afailure is known as instability failure or bucklingfailure. Determination of buckling load is importantin order to ensure the stability of a structure. If thestructure under consideration is subjected to a dy-namic load then this problem comes under the pur-view of dynamic stability problems. Examples areslender offshore structures subjected to periodic ex-citations and colum…     

Finite element model analysis of thermal failure in connector

Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was investigated. It was found that the contact resistance increased due to the Joule heating, and that increased contact resistance produced more Joule heating; this mutual action causes the connector to lose efficiency. The thermal distribution in the connector was analyzed using finite element method (FEM). The failure mechanism is discussed. It provides basis for improving the structure. The conclusion was verified by experimental results.     

考虑楼板作用的半刚性组合节点的有限元分析

文章通过SAP2000程序,建立了半刚性组合节点理论分析模型,采用转动弹簧单元来模拟实际中钢管柱与组合梁的半刚性连接。通过分析比较节点在低周反复荷载作用下的荷载(P)-位移(Δ)关系滞回曲得到,组合节点的承载力、刚度和耗能能力有所提高,耗能较好,但承载力相差不大,所以在正常的施工条件下,应优先选用方钢管。     

平板式半挂车车架有限元分析

应用Pro/E对平板式半挂车车架进行三维实体建模。对该模型进行简化处理、抽中面和修补后导入ANSYS。采用壳单元建立平板式半挂车车架的有限元模型,对车架进行静力分析和模态分析。结果表明,车架在弯曲和扭转工况下,刚度和强度满足要求;车架结构的低阶模态频率不在路面激励频带之内,不会产生共振现象。     

Finite element simulation of stress intensity factors in elastic-plastic crack growth

INTRODUCTION The finite element method (FEM) has been widely employed for solving linear elastic and elas-tic-plastic fracture problems. The evaluation of stress intensity factors in 2D geometries by FEM is a tech-nique widely used for non-standard crack configura-tions. Basically, there are two groups of estimation methods, those based on field extrapolation near the crack tip (Chan et al., 1970; Shih et al., 1976) and those using the energy release when the crack propagates. However…     

土钉支护边坡土工安全系数有限元分析法计算

采用弹塑性有限元方法对一土钉支护边坡工程实例进行详细分析 ,给出边坡侧向变形、土钉应力随边坡开挖过程的变形 ,并且在各个开挖阶段中都进行土工安全系数计算     

岩质边坡稳定分析三维与二维的比较

提出岩质边坡沿软弱结构面滑移-剪切的三维稳定分析方法。在分析模型中,下滑体沿滑动面下滑,在其他的面上则产生剪切破坏。在结构面上满足莫尔库伦破坏准则,把剪切面上的摩阻力向下滑方向投影,由下滑体的力学平衡条件求解出未知力,通过迭代可以求得稳定系数。同时推导了摩阻力倾向与倾角的计算式,编制了相应的程序,并利用这个程序,研究了边坡长度、岩层与坡面夹角等因素对边坡稳定系数的影响,比较了三维分析与二维分析的差别。     

Arc-length technique for nonlinear finite element analysis

Nonlinear solution of reinforced concrete structures, particularly complete load-deflection response, requires tracing of the equilibrium path and proper treatment of the limit and bifurcation points. In this regard, ordinary solution techniques lead to instability near the limit points and also have problems in case of snap-through and snap-back. Thus they fail to predict the complete load-displacement response. The arc-length method serves the purpose well in principle, Received wide acceptance in finite element analysis, and has been used extensively. However modifications to the basic idea are vital to meet the particular needs of the analysis. This paper reviews some of the recent developments of the method in the last two decades, with particular emphasis on nonlinear finite element analysis of reinforced concrete structures.     

Neural network method for solving elastoplastic finite element problems

INTRODUCTION An Artificial Neural Network (ANN) is an in-formation-processing paradigm that is inspired by the way biological nervous systems, such as the brain, process information. It is composed of a large number of highly interconnected processing elements (neu-rons) working in unison to solve specific problems. In recent years, neural network has been widely applied in the field of engineering construction as a large dimensional nonlinear dynamic system, because of its support for …     

一个新十二参矩形板元的构造及收敛性分析

采用双参数法构造了一个新的十二参矩形元,并对其收敛性进行了分析;同时把该元与著名的Adini元作了比较.     

Finite element analysis of dynamic response and structure borne noise of gearbox

A dynamic finite element method combined with finite element mixed formula for contact problem is used to analyze the dynamic characteristics of gear system. Considering the stiffness excitation, error excitation and meshing shock excitation, the dynamic finite element model is established for the entire gear system which includes gears, shafts, bearings and gearbox housing. By the software of I-DEAS, the natural frequency, normal mode, dynamic time-domain response, frequency-domain response and one-third octave velocity grade structure borne noise of gear system are studied by the method of theoretical modal analysis and dynamic response analysis. The maximum values of vibration and structure borne noise are occurred at the mesh frequency of output grade gearing.     

轻钢结构临建房屋骨架结构有限元计算分析

以轻钢结构临建房屋骨架结构试验为基础,采用有限元分析软件Ansys提出轻钢结构临建房屋的有限元计算模型建立方法,并对轻钢结构临建房屋骨架结构的水平侧移进行计算和分析。计算结果表明,所采用的有限元计算模型建立方法正确合理,且轻钢结构临建房屋骨架结构在设计荷载作用下的水平侧移不能满足规范要求。     

拱梁组合体系拱桥关键节点有限元分析

以某主跨85m钢管混凝土拱桥为研究对象,采用ANSYS建立局部精细化模型,对拱座进行受力分析。研究表明:拱梁组合体系拱桥拱座的结构刚度比较大,在拱脚最大弯矩工况下,最大变形出现在哑铃型拱肋加载截面下缘,变形值仅为4.3mm;拱座整体应力分析表明,结构受力以纵桥向受压为主,整体应力值不大,拱肋与拱座节点交界面因刚度突变出现了较大的应力变化,存在不大于1MPa的主拉应力;除了端横梁预应力锚固处压应力在10MPa左右,其他部位应力绝对值均在1MPa以下,满足要求;为了进一步优化结构受力,避免局部应力集中,应在结构中增加加腋、倒角等。     

中压反应釜人孔凸缘的有限元分析

采用有限元法对中压反应釜人孔凸缘结构进行了应力分析，揭示了其应力分布情况。应力评定结果表明，在压力较高的情况下，人孔接管与高颈法兰也可以用凸缘结构来代替，以降低设备成本，且人孔凸缘结构满足强度要求。     

Modeling of contact surface morphology and dust particles by using finite element method

The effect of dust particles on electric contacts and a hazardous size range of hard dust particles using a rigid model were discussed before. As further research, elastic-plastic model of finite element analysis was established in this work, which is closer to real condition. In this work, the behavior of large size and small size particles, and the influence of particles hardness were investigated. The calculating result of small-size particles presents a general hazardous size coefficient for different contact surface morphology; for large-size particles, it presents a hazardous size coefficient for complicated composition of the dust. And the effect of the dust shape is also discussed.     

Finite element analysis of internal gear in high-speed planetary gear units

The stress and the elastic deflection of internal ring gear in high-speed spur planetary gear units are investigated. A rim thickness parameter is defined as the flexibility of internal ring gear. Six evenly spaced linear springs are used to describe the fitting status between internal ring gear and the gearcase, The finite element model of the whole internal ring gear is established by means of Pro/E and ANSYS. The loads on meshing teeth of internal ring gear are applied according to the contact ratio and the load-sharing coefficient. With the finite element analysis （FEA）, the influences of flexibility and fitting status on the stress and elastic deflection of internal ring gear are predicted. The simulation reveals that the principal stress and deflection increase with the decrease of rim thickness of internal ring gear. Moreover, larger spring stiffness helps to reduce the stress and deflection of internal ring gear. Therefore, the flexibility of internal ring gear must be considered during the design of high-speed planetary gear transmissions.     

预应力混凝土连续箱梁有限元损伤分析(英文)

为了确定预应力混凝土箱粱的极限承载能力,进行了预应力混凝土连续箱梁的破坏性试验,提出一种有限元损伤分析方法模拟箱梁结构行为.基于实体退化壳单元对箱梁进行模拟,并考虑了结构材料的非线性效应.由于预应力混凝土箱梁中通常存在大量曲线预应力钢筋,提出一种组合单元,并用该单元模拟箱梁中的预应力钢筋,该方法可使结构分析时单元数量大大降低.试验结果和理论分析对比表明:提出的方法能够有效地用于预应力混凝土连续箱梁的破坏性试验计算分析中;研究的旧桥依然存在较大的极限承载能力.     

超长混凝土结构硬化阶段温度作用有限元分析

超长混凝土结构硬化阶段的裂缝,由于影响因素的复杂性和结构的空间效应,很难采用手算法进行定量运算.利用ANSYS有限元程序建立瞬态温度场的分析模型,并对北京某实验用房在混凝土硬化阶段温度场和应力场进行了数值计算分析.计算结果表明混凝土经历了先压后拉的受力过程,温度应力由结构的两端向中心逐步增大,并与结构长度相关.在施工中采取必要的保温和散热措施、合理控制结构内的温度梯度,就可增加设缝间距,并避免裂缝产生.     

3D finite element analysis of the residual stresses in butt-welded plates with modeling of the electrode-movement

In this paper the residual stresses in a butt-welded plate of2.25Cr 1Mo has been analyzed using a 3D and transient finite element （FE） model. Also the effect of the welding-electrode speed has been studied using death and birth of FEs. For this purpose, a coupled thermo-mechanical FE solution has been used to obtain the temperature distribution and the resulting residual stresses. Also, the variations of the physical properties of the material with temperature have been taken into account. Results show that the residual stresses in the heat affected zone （HAZ） are maximum and change along the weld and also in the plate-thickness. It has been shown that use of the 3D and transient model will lead to more accurate and realistic results which are well compared with the experimental test data.     

壳梁组合结构自由阻尼处理有限元分析

构造了壳梁组合结构自由阻尼处理薄板结构的有限元模型, 将板单元的节点作为主节点, 梁单元的节点作为从属节点, 推导出相应的刚度矩阵和质量矩阵. 在用有限元法进行结构动态特性分析的基础上, 用模态变形能法估算了结构的模态损耗因子. 最后以一计算实例将本文方法所得结果与用ANSYS软件计算所得结果进行了比较, 结果表明本文方法计算效率高、简单可行, 且具有较高的精度和工程实用性.