振动时效试验研究及有限元法在确定时效性态上的应用

主要是进行振动时效的试验设计并利用有限元法仿真计算来确定试验用等强度梁的振动时效性态参数-固有频率和固有振型,通过计算可以准确选择等强度梁的振动时效试验电机机型以及频率,避免了扫频等步骤,使试验得到简化,并为采用振动时效技术选择性态参数提供指导意义.     

大型矿用载重车轮辋强度计算的建模分析

以轮辋只受胎内气压并卸去车轮隔圈的工况为例这是一较危险的工况，对轮辋的受力作了分析研究，建立了强度计算的两种解析模型－梁模型和壳模型，使轮辋的强度计算大为简化。模型的建立提供了轮辋受力分析的原则，这一原则同样适应于其他工况。本文将所建立的模型用于某百吨矿用车强度计算分析中，并用有限元法作了分析对比，证明了所提出的计算模型及分析方法的可靠性。     

客车车骨架有限元建模技术及结果分析

对于客车身骨架类的框架结构，用梁单元建模不仅具有建模简单、计算量小的优点，而且通过一些建模技术，精度能很好地满足工程要求。以某集团的CJ6121GCHK型客车车身骨架为例来阐述框架结构的梁单元建模技术及结果分析技术，通过一些模型简化措施，建立并简化了梁单元模型；采用短梁单元对其连接区域进行模拟，提高了框架结构梁单元的建模精度；通过不同典型工况下结构的强度、刚度性能较核，进行了结果分析，提出了对该客车车身骨架进行结构粗略修改的依据。     

标准圆柱齿轮设计中齿数的一种确定方法

介绍了一种等强度设计下标准圆柱齿轮齿数的计算方法，使得齿轮设计中的齿数初选量化，进而达到简化设计步骤、优化设计结果、改善齿轮传动啮合质量的目的。     

超大直径土压平衡盾构前中盾结构强度计算研究

为确保盾构具备足够的结构强度和刚性,对盾构的主要支撑结构进行受力载荷分析与强度校核。采用SpaceClaim软件对前中盾进行中面抽取,建立壳单元有限元静力学分析模型,根据材料的厚度将前中盾划分成4组壳体,根据有限元计算结果分析了前中盾及其拼装梁的应力和变形情况。结果表明：前中盾的结构强度符合设计要求;最大变形位于拼装梁与后配套设备的连接处,变形较大,经过结构优化改进后变形量降低34.9%。     

全圆针梁台车结构设计与校核

主要针对水工隧道施工设计了一套全圆针梁台车,并对其整体结构进行校核。运用有限元软件ANSYS合理简化分块建模,分析不同工况、不同载荷情况下模板面板及其加劲肋、框架横纵梁、底模架及立柱等的强度及位移,其整体及局部稳定性和强度刚度均满足设计要求。     

新型市域快轨车辆转向架的研制

介绍了一种新型市域快轨车辆转向架的主要技术参数、各部件的基本结构特点,采用正向设计理念,对构架、枕梁、牵引梁等主要结构部件进行有限元仿真分析,完成了动力学仿真计算,并对转向架主要部件的结构强度及动力学性能进行了试验验证.经过理论计算和试验验证,该转向架的结构强度和动力学等各个方面的性能均满足要求.该转向架的研制以160...     

锅炉强度计算软件的开发与研究

基于锅炉强度分析计算模型，依据AutoCADR12版本开发了出了锅炉强度计算应用软件，并就锅炉强度计算流程、程序界面设计、锅筒筒体强度计算和数据存储等内容进行了深入研究。     

滑行类游艺机的强度校核计算

游乐设施设计文件必须经核准的技术机构进行鉴定，执行设计审查程序，文中就滑行类游艺机的强度校核计算分析问题，阐述了塑性材料一般采用的计算方法和原则。     

立体车库有限元分析

这里利用有限元方法计算分析了立体车库的结构应力，从而提供了保证立体车库安全可靠的理论依据，同时也简化了其设计过程。     

Ion beam capture and charge breeding in electron cyclotron resonance ion source plasmas

Beam capture of injected ions and charge breeding in electron cyclotron resonance (ECR) charge breeder ion source plasmas has been investigated utilizing an ECR plasma modeling code, the generalized ECR ion source model, and a Monte Carlo beam capture code. Beam capturing dynamics, charge breeding in the plasma, and the extracted charged ion states are described. Optimization of ion beam energy is performed for (1) high beam capture efficiency and (2) high charge state ion beam extractions. A sample case study for ANL-ECR has been performed. Ions entering ECR ion source plasma are slowed down mostly by the background ions. Assuming Maxwellian plasma ions, maximum beam energy loss occurs when the beam velocity is around the background thermal velocity in magnitude. It is also found that beam capture location affects charge state distribution. For instance, with a majority of beam ions captured near the middle of the device higher currents for higher charge states are obtained. The beam ions captured near the entry have a higher probability of backstreaming after they are captured. For this reason, the optimum beam energy of the injected Ar(+) beam ions for charge breeding is generally higher than the optimum input beam energy for maximum beam energy loss.     

半导体激光阵列合束技术的研究

综述了几种典型的半导体激光阵列合束方法,介绍了近年来半导体激光光束合成的最新进展,分析了各种合成方法的技术特点,总结了半导体激光阵列合束技术的发展趋势.研究发现光谱合束技术的输出光束光强分布不随阵列单元数而变化,且在远场和近场均能保持较好的叠加,大大提高了远场光束的亮度,有望成为未来半导体激光光束合成的重要发展方向.     

基于ZEMAX的激光光束整形技术试验研究

由于半导体激光器的发散角较大且输出的光束光斑是椭圆形,因此需要对其输出的光束进行空间整形,形成一个近似圆形的激光光斑。激光扩束镜就是一种比较简单且非常方便的激光光束整形器件,本文将激光扩束镜作为一个激光整形系统与半导体激光器耦合,形成一个完整的激光光束整形系统。利用ZEMAX光学仿真,并进行室外试验验证,最后对试验结果进行了分析。     

Free vibration analysis of Euler-Bernoulli beam with double cracks

In this paper, the influence of two open cracks on the dynamic behavior of a double cracked simply supported beam is investigated both analytically and experimentally. The equation of motion is derived by using the Hamilton’s principle and analyzed by numerical method. The simply supported beam is modeled by the Euler-Bemoulli beam theory. The crack sections are represented by a local flexibility matrix connecting three undamaged beam segments. The influences of the crack depth and the position of each crack on the vibration mode and the natural frequencies of a simply supported beam are analytically clarified for the single and double cracked simply supported beam. The theoretical results are also validated by a comparison with experimental measurements.     

Ultrasonic beam propagation in highly anisotropic materials simulated by multi-Gaussian beams

The necessity of nondestructively inspecting fiber-reinforced composites, austenitic steels, and other inherently anisotropic materials has stimulated considerable interest in developing beam models for anisotropic media. The properties of slowness surface play a key role in the beam models based on the paraxial approximation. In this paper, we apply a modular muiti-Gaussian beam (MMGB) model to study the effects of material anisotropy on ultrasonic beam profile. It is shown that the anisotropic effects of beam skew and excess beam divergence enter into the MMGB model through parameters defining the slope and curvature of the slowness surface. The overall beam profile is found when the quasilongitudinal (qL) beam propagates in the symmetry plane of a transversely isotropic gr/ep composite. Simulation results are presented to illustrate the effects of these parameters on ultrasonic beam diffraction and beam skew. The MMGB calculations are also checked by comparing the anisotropy factor and beam skew angle with other analytical solutions.     

梁的破损对频率振型及振型曲率的影响

本文用欧拉梁振动理论，改变简支梁中某一小段的高度以模拟破损。仿真结果表明，破损对某些阶频率、振型的影响不大，对振型曲率的影响较大．用振型曲率监测简支梁的破损优于用频率或振型的监测方法。     

Dynamic plastic behavior of a free–free beam striking the mid-span of a clamped beam with shear and membrane effects considered

Recently Yu et al. (Int. J. Solids Struct. 38 (2001) 261) made a study on the dynamic behavior of a flying free–free beam striking the tip of a cantilever beam using the rigid, perfectly plastic (r-p-p) material model. Later, also based on the r-p-p material model Yang and Yu (Mech. Struct. Mach. 29 (2001) 391) analyzed another impact problem of a free rotating hinge beam striking a cantilever beam. Both of these studies ignored the finite deflection effects on the plastic behavior of the colliding beams. However if the free–free beam strikes a clamped beam, the influence of finite-deflections, or, geometric changes, must be retained in the governing equation if the maximum permanent transverse displacement of the clamped beam exceeds the corresponding beam thickness. The problem becomes more interesting since the deformation mechanisms of the beam system and the partitioning of energy dissipation in the beams are significantly different from those predicted by ignoring the influence of membrane forces. Accordingly the failure modes of the structure are different.In the present paper, a theoretical model based on the r-p-p material idealization is proposed to simulate the dynamic behavior when the mid-point of a translating free–free beam impinging on the mid-span of a clamped beam with the beam axes perpendicular to each other. The plastic behavior of the beam system is explored with shear sliding and finite deflection effects taken into account. The final deflection, the dissipation of energy within the two beams after impact and the influence of the structural and material parameters are discussed. It is shown that membrane force plays an important role during the response process, especially when the deflection is of the same order as the thickness of the clamped beam.     

Techniques trend analysis of propagating laser beam quality measurement

Different methods of measuring a propagating laser beam quality are summarized.The disadvantages in traditional way in measuring a laser beam quality is analyzed and the insufficiencies of the Shack-Hartmannin method which is commonly using wave front technique at present is pointed out.Finally,the transmission intensity equation based(TIE-based)measuring way in a laser beam quality evaluation and the corresponding advantages are discussed,which is believed to be a deve-l oping trend in laser beam evaluation.     

大变形曲梁多体系统动力学建模

为了提高大变形曲梁多体系统数值仿真的计算精度和计算效率,引入弧线坐标,采用曲梁单元,从非线性应变关系式出发,用绝对节点坐标法建立了大变形曲梁多体系统的动力学模型,该方法的特点是不需要引入单元转换矩阵,收敛性好。用曲梁单元模型对曲梁单摆进行数值仿真计算,将计算结果与将曲梁细化为若干个直梁单元的动力学模型的计算结果进行对比,验证了曲梁单元动力学模型的准确性和有效性。在此基础上用曲梁单元模型实现了四连杆曲梁多体系统的动力学仿真。     

Vacuum electron acceleration and bunch compression by a flat-top laser beam

The field intensity distribution and phase velocity characteristics of a flat-top laser beam are analyzed and discussed. The dynamics of electron acceleration in this kind of beam are investigated using three-dimensional test particle simulations. Compared with the standard (i.e., TEM(00) mode) Gaussian beam, a flat-top laser beam has a stronger longitudinal electric field and a larger diffraction angle. These characteristics make it easier for electrons to be trapped and accelerated by the beam. With a flat-top shape, the laser beam is also applicable to the acceleration of low energy electron and bunch compression.