多层波纹管接触分析及稳定性屈曲分析

通过建立三层四波多层波纹管平面轴对称模型和三维实体模型,探讨了波纹管在内压载荷下所涉及到的层间接触问题和稳定性屈曲问题.针对多层结构接触问题所涉及到的摩擦系数、接触刚度和层间间隙等参数的取值进行了模拟试验对比,最后对非线性屈曲分析的初始缺陷和弹塑性极限分析所需施加的载荷值进行了描述,目的在于通过对多层波纹管有限元分析的...     

基于波纹管简化模型的排气系统模态分析

为了探究汽车排气系统波纹管简化模型的合理性,对简化模型进行数值分析和理论研究.首先,以某重型卡车排气系统为研究对象建立有限元模型,将波纹管简化为零长度的CBUSH单元,对系统自由模态进行分析;其次,用波纹管将排气系统分隔开简化为二自由度模型进行理论计算;最后,综合对比分析表明,第7阶和第8阶模态频率接近于零,主要原因是绕X,Z轴刚度较小,验证了波纹管在该方向的隔振效果良好.理论方法与数值计算具有普遍性和工程指导意义.     

高空真多层绝热低温管道中波纹管简化有限元模拟方法

基于有限元方法对高真空多层绝热(HV-MLI)低温管道进行多场耦合分析时,由于内管道波纹管几何及材料的非线性特性,使整个分析过程极为耗时,限制了有限元法在HV-MLI低温管道优化设计中的应用。为提高有限元分析效率,结合HV-MLI低温管道对所受载荷的响应特征,提出了用Combine14弹簧单元或等截面管等效替代波纹管的方法。通过对Combine14弹簧单元和等截面管相关参数的理论计算及定义,建立了两种HV-MLI低温管道内管的等效有限元计算模型,并对含波纹管、Combine14弹簧单元及等截面管内管道模型分别进行了有限元模拟计算,得到了各模型内管的应力及变形结果。结果表明:建立的两种等效模型合理、有效;与含波纹管模型相比,两种等效模型均在保证分析精度的同时,将分析效率提高了300倍;相比含Combine14弹簧单元模型,含等截面管模型在结构不连续处的应力集中程度较轻,且与含波纹管模型相符,更适于HV-MLI低温管道的多场耦合分析。     

波纹管动力学分析研究进展

从理论模型、试验研究及有限元分析等方面回顾了波纹管固有频率、阻尼特性及机械阻抗等动力学参数的研究进展,总结了波纹管动力学响应的有限元分析方法及试验方法,分析了流体诱导振动的研究现状,展望了波纹管动力学研究亟待解决的问题.     

瓦楞纸板屁曲临界载荷的一种等效计算方法

为了方便确定屈曲临界载荷,对瓦楞纸板进行合理简化,建立了两种瓦楞纸板的简化模型,并使它们在计算屈曲临界载荷分析方面等效。在有限元分析中,各向同性板模型与正交各向异性板模型相比,减少了建模所需的参数,并可以达到用各向同性板取代瓦楞纸板进行屈曲分析的目的。通过理论计算和有限元分析,结果表明两种简化模型在屈曲临界载荷的分析方面基本等效,误差在5%以内。     

基于ADINA的轴向冲击载荷下薄壁方管屈曲分析

根据屈曲分析的有限元基本理论并基于有限元分析软件ADINA对轴向冲击载荷下薄壁方管进行动力屈曲分析。ADINA的动力屈曲有限元分析分为前处理、求解和后处理三个部分。前处理包括设置单元属性、创建模型、网格划分、定义接触、定义初始条件与约束和设定求解时间。利用ADINA软件进行前处理文件输出提交求解。使用ADINA-Processing对速度进行刷新、演示模拟动画过程并查看分析结果。分析结果表明:基于ADINA对轴向冲击载荷作用下薄壁方管动力屈曲特性分析结果与实验结论相符,该成果对研究冲击载荷作用下薄壁方管的动力屈曲特性具有一定的理论与指导意义。     

复合材料圆柱壳轴压屈曲性能分析

对完整复合材料圆柱壳轴向压缩性能进行了试验研究,得到了圆柱壳结构的破坏载荷和各测量点的载荷-应变曲线,通过分析得出结构的破坏形式为屈曲破坏。利用ANSYS有限元软件建立了模型,对复合材料圆柱壳进行屈曲分析,将有限元计算的结构变形和屈曲载荷与试验结果进行对比,计算结果与试验结果一致,验证了模型的有效性。利用建立的有限元模型,分析了开口尺寸和铺层角度对含矩形开口的复合材料圆柱壳屈曲载荷的影响。在开口处加装复合材料口盖对结构进行补强,补强后的柱壳结构满足强度设计要求。     

U形波纹管疲劳寿命有限元分析

运用ANSYS有限元软件对波纹管进行应力分析,得出波纹管应力集中位置,借助Fatigue tool模块,采用E—N方法进行疲劳寿命分析,得到波纹管的疲劳寿命分布。有限元分析结果与经验公式及试验结果的比较,得出有限元模拟结果比经验公式更加接近试验结果。最后指出了在进行波纹管疲劳寿命有限元分析过程中需要注意的问题。     

复合材料柱面壳压缩性能分析

对三分之一复合材料柱面壳进行压缩性能试验研究与理论分析, 试验得到柱面壳的破坏方式为屈曲破坏。利用有限元法对其建模分析和静强度分析, 得到的静强度远大于屈曲强度, 因此柱壳应该首先发生屈曲破坏, 这与试验结果相符; 且理论计算所得的屈曲强度与试验结果相符, 说明该模型可以用来分析整个复合材料柱壳的压缩破坏行为, 研究结果可为柱壳的结构设计提供参考。对比某一载荷下理论模型与实际模型上对应点的应变, 发现二者结果相符, 证明有限元建模有效。然后分别对理论模型进行屈曲分析。      

基于ANSYS Workbench 的瓦楞纸箱抗压性能仿真研究

建立了瓦楞纸箱的有限元模型并进行了结构修正,应用ANSYS Workbench有限元分析软件对纸箱结构模型进行了屈曲分析,从而求得了瓦楞纸箱的抗压强度,最后通过抗压试验进行了验证。有限元分析结果与试验结果比较接近,验证了模型的有效性。     

460MPa高强钢箱形截面轴压柱局部稳定有限元分析和设计方法研究

为研究460MPa高强度钢材等边箱形截面轴心受压柱的局部稳定受力性能和设计方法, 该文采用有限元软件ANSYS建立有限元模型, 考虑残余应力和局部初始几何缺陷的影响, 对3组共10个460MPa等边箱形截面轴心受压短柱的局部屈曲进行了有限元分析, 并将极限承载力计算值与试验实测值进行对比, 结果证明该模型能够准确分析计算460MPa高强度钢材等边箱形截面轴心受压柱的局部屈曲受力性能。利用该模型进行有限元参数分析, 与钢板的宽厚比相比, 钢板厚度、钢板长宽比、残余压应力值和局部初始几何缺陷幅值等因素对局部屈曲受力性能的影响都很小。将试验实测值和参数分析的结果与中国、美国和欧洲钢结构设计规范中箱形截面局部稳定设计曲线进行对比, 表明现行规范的设计方法不够安全。该文提出的建议设计公式适用于460MPa高强度钢材等边箱形截面轴心受压柱局部屈曲极限应力的设计计算。     

Nonlinear large deflection buckling analysis of compression rod with different moduli

Many novel materials exhibit a property of different elastic moduli in tension and compression. One such material is graphene, a wonder material, which has the highest strength yet measured. Investigations on buckling problems for structures with different moduli are scarce. To address this new problem, first, the nondimensional expression of the relation between offset of neutral axis and deflection curve is derived based on the phased integration method, and then using the energy method, load–deflection relation of the rod is determined; second, based on the improved constitutive model for different moduli, large deformation finite element formulations are developed, and combined with the arc-length method, finite element iterative program for rods with different moduli is established to obtain buckling critical loads; third, material mechanical properties testing of graphite, which is the raw material of graphene, is performed to measure the tensile and compressive elastic moduli; moreover, buckling tests are also conducted to investigate the buckling behavior of this kind of graphite rod. By comparing the calculation results of the energy method and finite element method with those of laboratory tests, the analytical model and finite element numerical model are demonstrated to be accurate and reliable. The results show that it may lead to unsafe results if the classic theory was still adopted to determine the buckling loads of those rods composed of a material having different moduli. The proposed models could provide a novel approach for further investigation of nonlinear mechanical behavior for other structures with different moduli.     

Buckling response of laminated composite stiffened plates subjected to partial in-plane edge loading

This article presents the buckling analysis of laminated composite stiffened plates subjected to partial in-plane edge loading. The finite element method is used to carry out the analysis. The eight-noded isoparametric degenerated shell element with C⁰ continuity and first-order shear deformation and a compatible three-noded curved beam element are used to model the plate skin and the stiffeners, respectively. The eigen value analysis is carried out to track the buckling load. The convergence study is performed for some specific problems and the results are compared with the available results in the literature. It is observed that the convergence of results is very fast for this finite element model. Effect of different parameters like orientation of fibers, number of layers, and loading types are considered in the present investigation. It is also observed that all these parameters have significant effect on the buckling response of the composite stiffened plate.     

Lateral buckling analysis of thin-walled laminated channel-section beams

The lateral buckling of a laminated composite beam with channel section is studied. A general analytical model applicable to the lateral buckling of a channel-section composite beam subjected to various types of loadings is derived. This model is based on the classical lamination theory, and accounts for the material coupling for arbitrary laminate stacking sequence configuration and various boundary conditions. The effects of the location of applied loading on the buckling capacity are also included in the analysis. A displacement-based one-dimensional finite element model is developed to predict critical loads and corresponding buckling modes for a thin-walled composite beam with arbitrary boundary conditions. Numerical results are obtained for thin-walled composites under central point load, uniformly distributed load, and pure bending with angle-ply and laminates. The effects of fiber orientation, location of applied load, and types of loads on the critical buckling loads are parametrically studied.     

Numerical analysis and experimental correlation of composite shell buckling and post-buckling

This paper deals with the buckling and post-buckling behaviour of carbon fibre reinforced plastic cylindrical shells under axial compression. The finite element analysis is used to investigate this problem and three different types of analysis are compared: eigenvalue analysis, non-linear Riks method and dynamic analysis. The effect of geometric imperfection shape and amplitude on critical loads is discussed. A numerical–experimental correlation is performed, using the results of experimental buckling tests. The geometric imperfections measured on the real specimens are accounted for in the finite element model. The results show the reliability of the method to follow the evolution of the cylinder shape from the buckling to the post-buckling field and good accuracy in reproducing the experimental post-buckling behaviour.     

A semi-analytical finite element model for the analysis of laminated 3D axisymmetric shells: Bending, free vibration and buckling

A general semi-analytical finite element model is developed for bending, free vibration and buckling analysis of shells of revolution made of laminated orthotropic elastic material. The 3D elasticity theory is used and the equations of motion are obtained by expanding the displacement field and load in the Fourier series in terms of the circumferential coordinate, θ. The coefficients of the expansion are functions of (r, z), and they are approximated using the finite element method. This leads to a semi-analytical finite element in the (r, z) plane. The element is validated by comparing the present results with the analytical and numerical solutions available in the literature.     

常温及火灾下蜂窝梁腹板屈曲承载力计算方法

采用斜压柱理论模型及有限元方法,研究了常温及火灾下圆角多边形孔蜂窝梁孔间腹板受剪屈曲性能和受剪屈曲承载力计算方法。孔间腹板S/d₀和d₀/t_w的取值范围分别为1.4~2.0和41.4~80.7。在参数分析的基础上,对斜压柱的有效宽度及压力进行修正,用于计算孔间腹板的屈曲承载力;并提出了等效矩形理论,用于计算孔洞截面的受剪屈服承载力。蜂窝梁受剪承载力为孔间腹板屈曲承载力和孔洞截面受剪屈服承载力的较小值。采用修正的斜压柱理论模型和等效矩形理论得到的圆角多边形孔蜂窝梁受剪承载力稍小于有限元结果,比值在0.856~0.978之间。采用修正的斜压柱模型,并按照规范BS5950计算斜压柱屈曲应力,反算火灾下蜂窝梁孔间腹板屈曲温度,得到的火灾下圆角多边形孔蜂窝梁的孔间腹板屈曲温度仅稍低于有限元结果,偏差为0.17%~6.28%。