校车车身模态分析

建立某校车有限元模型,用Abaqus对该校车车身骨架进行有限元动态分析,计算出车身骨架的振型和对应模态值,分析其动态特性,为骨架的设计和优化提供参考.     

基于MSC Nastran的轻卡车架结构强度分析

建立某轻卡车架及其简化悬架的有限元模型,计算车架在弯曲、扭转、制动和转向等4种典型工况下的强度,并对应力较大处进行结构优化.     

集成上层建筑开口群力学性能分析

针对船舶上层建筑的多种复杂开口群结构形式,用Abaqus进行数值模拟,得到各工况开口区域的振动频率以及在抨击载荷与惯性力载荷作用下的最大von Mises应力和最大位移.给出开口位置、开口尺寸和开口排列方式等情况对结构强度与刚度的影响规律.结果表明,最大von Mises应力和最大位移均出现在过渡面与舷侧的顶部交际处,最大von Mises应力大小在70~90 MPa,最大位移约为5 mm.     

某V型柴油机曲轴疲劳寿命仿真

为了对某V型柴油机将最大爆发压力由15.5 MPa提升至16.5 MPa后曲轴的强度及疲劳寿命进行预测,首先在ADAMS/Engine中根据发动机模型及参数建立了发动机动力学模型,获取曲柄销处的载荷时程数据,然后建立了最大爆发压力为15.5 MPa和16.5 MPa一缸点火及二缸点火共4个工况有限元模型,由各工况的应力结果结合材料的S-N曲线及载荷时程曲线,计算得到各工况曲轴的疲劳寿命。计算结果表明,曲轴在各工况下其最大应力小于材料弯曲疲劳极限,应力集中处主要出现在连杆轴颈过渡圆角处,各工况下曲轴寿命高于1 000小时。     

基于光纤智能夹层的车架有限元分析与试验研究

以某型轻卡车架为研究对象,建立了车架有限元模型,提出采用光纤智能夹层结构分析弯曲、扭转工况下车架的应力分布。采用波分复用形式构建了分布式光纤智能夹层传感器网络,对车架在弯曲、扭转工况下车架关键点的应力分布进行了试验研究,并用Patran软件进行了车架结构静强度的有限元分析。试验结果与有限元模拟结果吻合得较好。该研究结果为同型车型开发、改型及优化设计提供了技术手段和依据。     

微型面包车承载式白车身的扭转、弯曲刚度有限元分析

本文应用国际上先进的分析元件I-DEAS Master Series7.0 对一种微型面包车承载式车身进行了扭转刚度、弯曲刚度有限元分析。研究出了一种同类型车承载式车身的扭转刚度、弯曲刚度的解算方法,同时反求出一些对整车性能影响较大的关键部位在额定扭转和弯曲载荷下的允许变形标准,为我国对该车型作后续自主改型开发提供设计依据。一、概述对于承载式车身结构而言,白车身的抗扭刚性和抗弯刚性是必须满足的基本性能之一。如果刚性不足,在使用过程中车体变形大,特别是立柱、门框、窗框等关键部位的变形过大,就可能造成门锁变形,内饰脱落…     

某隧道盾构刀盘仿真与力学性能研究

针对以长沙某地铁施工的地质条件为依据设计的盾构刀盘,利用SOLIDWORKS建立刀盘三维精确模型,通过ANSYS软件对盾构刀盘在土压平衡和土压不平衡两种工况下的受力特性进行了具体分析,得到两种工况下的应力和变形分布;同时对刀盘进行模态分析,得到了刀盘的固有振动特性。结果表明：危险截面均位于牛腿与面板交界处,土压不平衡下刀盘最大应力为230 MPa,最大变形为2.1 mm;土压平衡下最大应力为143 MPa,最大变形为1.63 mm。刀盘的最大应力小于材料的屈服极限345 MPa,变形相对刀盘尺寸不大,满足强度和刚度要求。根据模态分析可知刀盘的激励频率小于刀盘固有频率,刀盘不会发生共振,刀盘满足动力学要求。     

船用柴油机连杆结构有限元分析

对一种新型连杆进行结构有限元及疲劳分析,计算连杆在不同载荷下的变形以及应力分布,进而得到连杆的疲劳安全因数.通过动力学计算求得连杆在上止点时小端的受力,并得出连杆相对于曲柄销中心的加速度和旋转角速度.基于Abaqus对连杆的1/4模型进行静力学计算,得到连杆的轴向变形量、应力以及接触面的接触压力.对所有节点在所有工况下的等效应力进行组合分析,求得每个节点的最大应力幅值,而后得到连杆的疲劳安全因数.连杆的最大压缩量小于1.14 mm,最大伸长量小于0.86 mm,最大主应力、接触压力小于材料的屈服极限,疲劳安全因数大于2.14,因此该连杆满足设计要求.     

两柱掩护式放顶煤液压支架力学性能分析

浅埋深煤层基岩比较薄、松散层较厚,工作面易出现台阶下沉等状况,矿压展现剧烈,应用于浅埋深煤层工作面的两柱掩护式放顶煤液压支架易出现工作阻力不足,对顶板的支护效果不好,从而造成生产安全问题。针对以上问题,采用空间力学分析及结构有限元分析,对适用于浅埋深煤层的ZFY12000/25/42D型两柱掩护式放顶煤液压支架在顶梁受偏心载荷且底座两端受载、顶梁受扭转载荷且底座两端受载、顶梁受偏心载荷且底座受扭转载荷3种最危险工况下的受力状态进行了分析。分析结果表明:在不同工况下,支架各结构件的应力大小均会有所不同,分布状况也不尽相同,从支架整体应力分布来看,受顶板、立柱和底板的相互作用,顶梁和底座将承受较大的应力,而前后连杆、掩护梁作为连接过渡部件,所承受的应力明显较小;顶梁受扭转载荷且底座两端受载工况下支架承受应力最大,为712.69MPa;支架位移变形趋势基本相同,均是从顶梁到底座变形量逐渐减小,整体变形状况良好。在保证结构可靠性的前提下,在应力集中部位选用高强度板材或者提高材料厚度,可改善支架应力分布状况,增强支架控顶能力,从而确保支架工作的可靠性和稳定性。     

柔性太阳翼叠层电池弯曲适应性仿真与设计

航天器在轨进、出地影时，基于复合结构柔性基板的柔性太阳翼叠层电池在高、低温交变作用下会产生热弯曲变形。针对这一问题，采用有限元建模仿真，分析由太阳电池、盖片胶和抗辐照玻璃盖片组成的叠层电池的弯曲适应性，计算不同结构尺寸、不同叠层材料参数的叠层电池在跨中弯曲载荷下的最大应力。借助响应面技术研究设计变量与复合结构性能之间的关系，采用目标驱动优化分析，获得理想的结构尺寸参数。结果表明：叠层电池的宏观力学性能取决于微观不同叠层材料的组合方式；等效弹性模量不是定值，而是与叠层材料的参数有关；弯曲工况的失效模式取决于电池单体的最大拉应力，而不是宏观表征的整体弯曲强度。     

钢管弯制过程有限元仿真及断裂原因分析

针对某金属结构公司在钢管弯制过程中出现的个别钢管断裂现象进行研究,根据现场钢管弯制工艺和工序的情况描述,采用非线性有限元软件Marc对钢管的多工位弯制过程进行模拟仿真.以最恶劣的情况即曲率最大的胎具进行多工位弯制,仿真结果显示6个工位的连续弯制过程最大应力为552 MPa,没有达到材料的抗拉极限626 MPa,该弯制过程不会引起钢管强度失效.模拟钢管多种曲率胎具弯制下的应力应变分布情况和回弹后残余应力应变情况.仿真结果表明,弯制此种钢管最大曲率的圆弧时,钢管上的最大应力为542 MPa,小于材料的抗拉强度626 MPa;最大塑性应变为0.031,小于材料允许的最大伸长应变0.2.经过模拟仿真分析,该公司采用的弯制工艺不会引起材料强度失效断裂.引起钢管弯制断裂的原因为个别材料夹杂或气孔造成的小概率事件.     

Hysteretic damping of structures vibrating at resonance: An iterative complex eigensolution method based on damping-stress relation

In this paper the damping is examined as an engineering property used in analysis and design of structures and machines. The design engineer needs to know not only the stresses of his structure or machine, under steady state conditions but also the stresses under resonance conditions. Then the material damping, as a function of the stress of the structure, has an important role to play and ignoring the damping the calculated stresses are far from reality. The nonlinearity here is due to the dependence of the hysteretic damping on the stress of the structure. Specifically here two problems are investigated in the following way:Firstly the direct problem is solved. The direct problem is to find the maximum bending stress at the resonance when the relation of the dissipating energy (or of the hysteretic damping) vs. the bending stress is known in advance. To perform this calculation, a useful tool for the design engineer, the structure is modelled using the continuum mechanics analytical approach or the finite elements (FE) method. Then the eigenvalues are calculated and using an iterative procedure the real stress. The procedure presented here is called iterative complex eigensolution method (ICEM). Secondly the inverse problem is solved. The inverse problem is to find the relation between the hysteretic damping and the bending stress. For this purpose the logarithmic decrement is experimentally measured, the eigenvalues and the maximum bending stress of the structure, excited at the eigenvalue, when the damping is the same as the measured one, are computed using the finite elements method. Once the bending stresses are found in each discrete element of the structure, then the mathematical expression of the relation of the dissipating energy and the stresses can be specified by minimizing a suitably formed objective function.     

Flexible SU-8 microstructures for neural implant design

This work investigates the use of SU-8 microstructures for applications within flexible neural implants. Six different microstructures are fabricated and tested in both tension and bending to determine their Young’s modulus and their failure stress when deformed about a small radius of curvature. A numerical model is presented that accurately predicts the performance of the structures under bending, and physical testing shows that stresses of up to 300 MPa are achievable.     

客车空气弹簧悬架边界条件模拟与试验验证

针对客车车架强度分析时空气弹簧悬架边界条件难以设置的问题,提出使用等效静态载荷法进行悬架模拟的思路。分析空气弹簧刚度的非线性和双横臂独立悬架的机构模型,建立整车多体动力学模型,计算多工况下车架与空气弹簧悬架连接位置处的受力,求解得到等效静态载荷并施加到有限元模型中,添加辅助约束完成边界条件设置;对车架进行多工况下的强度分析,比较不同工况下车架的应力分布和最大应力出现的位置。搭建试制样机的动态测试平台,对比仿真结果与试验结果,验证模拟方法的有效性。     

Curved box beam bridge analysis

A finite difference procedure is used to determine the response of a single and multi span curved single box beam bridge with any number of interior diaphragms. The bending and torsional distortions as well as cross-sectional distortions are determined throughout the box girder. The forces that are determined include bending moment and shear, pure torsion, warping torsion, and bimoment. These forces, in addition to distortional functions, yield resulting normal bending, normal warping, and normal distortional stresses.The entire analysis scheme has been programmed for use on an UNIVAC 1108 computer, FORTRAN IV language, as given herein.     

Numerical method for analysing open thin-walled structures under interaction of bending and torsion

A computer program is developed to analyse concrete beams of open thin-walled sections, at different stages of loading from zero load to failure. The program is divided into two parts; the first part deals with the beam from zero load to cracking. Of course, loading is combined bending, shear and torsion (warping torsion and St Venant's torsion). In this part of the program, Vlassov's theory has been used. The cracking load is defined as that load which causes principal tensile stresses equal to the tensile strength of concrete. The second part of the program deals with all post-cracking stages of loading from cracking point to failure. An iteration procedure is used until full convergence occurs at a particular cross-section. The geometrical properties are calculated; these include the contribution of steel in the cross-section and that of concrete in the compressive zones. The mathematical model is given. The computer results are compared with earlier experimental results, and the two sets of results show reasonable agreement. The program is written in FORTRAN.     

Optimal plastic design of a bar under combined torsion, bending and shear

Optimal plastic design of a bar or beam under torsion with superposed bending and shear is obtained via the boundary perturbation method. Effects of bending and shear are expressed by a small parameter α. The results of optimization of solid bars and of hollow bars are shown. Received May 15, 2000     

A high precision coupled bending–extension triangular finite element for laminated plates

It is well recognized that the estimation of interlaminar stresses and strain energy release rates is important in designing laminated composite panels. Generally coupled bending–extension finite elements are necessary to study laminates to include the effects of coupling and/or combined transverse and extensional loads. Such elements are normally formulated adapting the classical theory of bending and extension. While the classical laminated plate theory of bending has provision to obtain interlaminar stresses due to transverse loading, it is necessary to include certain higher order terms in the extensional theory in order to obtain the interlaminar stresses due to inplane loads. A high precision triangular element based on a theory which includes both the bending and extension with necessary higher order terms is presented in this paper. The performance of this element is validated with the aid of examples. Numerical results for displacements in symmetric and unsymmetric laminates under bending loads have been given. Numerical results for interlaminar stresses in symmetric and unsymmetric laminates have been given for the well-known benchmark problem of a coupon with free edges. Strain energy release rate components at the delamination tip in coupons with unsymmetric sublaminates have been given. The effects of delamination length and location on the components of the strain energy release rate have been studied. Results indicated that with the use of this element, the interlaminar stresses can be estimated reasonably accurately, over a major part of the laminate except in a small local region close to the free edge. Global–local analysis with three-dimensional elements in the local region, is suggested to obtain local stresses more accurately. Interlaminar stresses at the boundary of a hole in a perforated plate under extension have been obtained to illustrate the use of the present element in a global–local analysis strategy.