直列六拐曲轴轴承负荷的分析

通过发动机动力学仿真分析软件GT-SUITE／Crank模块对曲柄连杆机构进行动力学仿真分析。并计算了轴心轨迹和轴承负荷，为了减少轴承的负荷，分别采用了对曲柄臂施加四平衡块和八平衡块两种平衡方案，并给出了两种方案的对比。     

有限元方法数值模拟往复压缩机管路的振动

建立了往复压缩机管道振动的数学模型,提出了恰当的边界条件。利用有限元分析软件CAE—SAR对往复压缩机级间管道的振动模型进行求解,获得了管道系统的振动模态和振幅的计算结果。应用这种方法对7M50—305／314型氮氢气压缩机陕西管道振动进行了计算分析,并对其各个弯头位置的振幅进行了实际的测量。测量结果证实了理论分析中所建模型及其边界条件的合理性。     

Variable heat flux in numerical simulation of grinding temperatures

In this paper, temperature results obtained by numerical simulations based on three different methods of defining the heat flux load distribution are compared to directly measured temperatures acquired using infrared camera measurement techniques. The heat flux calculations are based on recorded instantaneous grinding power, average grinding power, and power calculated by multiplying the measured tangential forces and the cutting velocity (referred to as calculated power). The results show that the method applied to characterize the input flux load in the numerical model has a significant effect on the estimated grinding temperatures and that the calculated power data produce the best temperature results.     

喷水推进器斜流泵级的性能预测研究

使用商用CFD软件NUMECA研究了喷水推进器斜流泵级的性能和内部三维紊流流场。采用结构网格对全流道区域进行剖分，选用k-ε双方程紊流模型，使用时间推进法计算流场中的各流动参数。并根据流场计算结果对泵级的流量-扬程特性和流量-效率特性进行了预测，试验测试和计算结果相一致，说明该计算方法具有较好的可信度及较高的计算精度。     

层合板多钉机械连接载荷分配三维有限元分析

用三维有限元方法对层合板单排四钉机械连接钉载分配进行了分析。计算了复材板与钢板、铝板双搭接时的载荷分布。结果表明,在最大承载孔上理论值与试验值误差不大于１６％。各孔的载荷分配主要取决于连接板的刚度,与孔径关系不大。     

高速高性能电主轴热态性能分析

基于高速电主轴的能量流模型,应用摩擦学和电磁学理论分别计算轴承的生热率和内置电机的电磁损耗;应用传热学理论,确定电主轴的热边界条件.在此基础上建立电主轴有限元分析模型,并对其仿真分析和求解.结果表明,前端轴承、主轴前端和定子是电主轴温升最严重的部位,且在主轴运行初始阶段,温升最快.因此要改善电主轴的热态性能,不仅要在温...     

细直梁弯曲振动中的局域共振带隙

通过将声子晶体中的局域共振思想引入到细直梁的结构设计中,构造了一种具有低频局域共振带隙的周期结构细直梁。采用传递矩阵法计算了周期边界条件下该细直梁弯曲振动中的弹性波能带结构,计算结果表明该结构中存在低频弯曲振动带隙。采用有限元法计算了有限周期该细直梁的振动传输特性。以有机玻璃、橡胶/铜块振子构成的该局域共振细直梁为例,采用振动试验方法对其振动传输特性进行了测试。试验结果同理论及仿真结果相吻合。结果表明,局域共振结构可大大降低带隙频率,并增大带隙衰减。梁类结构是噪声及振动控制领域研究的主要对象之一,局域共振结构的应用为其提供了一种新的思路。     

轴向缝切向进气径向气体轴承的稳定性研究

本文利用小扰动法分析了轴向缝切向进气径的气体轴承的稳定性问题,在理论分析中考虑了气流的惯性项对该类轴承稳定的影响,得出了轴承的设计参数怀轴承失稳转速及失稳涡动比的关系曲线,实验结果与计算结果吻合较好。     

齿轮参数对内啮合斜齿轮传动振动特性的影响

本文运用三维有限元较全面地研究了齿数、模数、齿宽、螺旋角和变位系数等参数对内啮合齿轮副载荷分布、齿间载荷分配、刚度及计算振幅的影响。计算结果表明，随着螺旋角的增加，齿轮副的刚度值有所增加，而其计算振幅显著下降；变位系数对齿轮副刚度及计算振幅都将产生很大影响。文中还讨论了其他齿轮参数的影响并与ＩＳＯ标准进行了对比分析，得出一些规律性结论，从而指导内啮合斜齿轮副的参数设计。     

基于美学、人体工学及性能的多因素融合设计

传统设计方法主要考虑产品功能及性能,较少考虑美学等其他因素,难以满足综合要求的提升。为解决这一问题,提出多因素的融合设计方法,实现基于美学、人体工学及性能的智能化融合设计。首先确定多个因素的评价方法,包括依据美学计算原理的多个美学维度的计算公式,以及人体工学和性能的评价公式。结合粗糙层次分析法确定的各因素权重系数,得到多因素的综合评价,建立寻优模型。采用自适应边界的遗传算法求解模型,实现优化设计和创新设计两种模式的设计,最后由 NX10.0 的参数接口生成设计模型,实现智能化的融合设计。通过自行车整体结构的设计案例对所提方法进行检验,得到了明显优化的和具有创新性的设计方案。结果表明,该方法可快速生成满足多因素综合要求的优化方案或若干优质的创新方案,有效解决设计因素单一的问题。     

等离子熔射涂层导热性能的数值模拟

等离子熔射快速制模中 ,由于熔射工艺本身的特点 ,熔射涂层具有一定的孔隙。本文中 ,作者采用基于元胞(U nit Cell)的有限元数值方法 ,直接计算涂层宏观等效热传导系数与细观球形多孔结构的联系 ,计算了不同孔隙率下材料等效热传导系数的变化。并与基于匀质化理论 (Homogenization Theory)和多孔材料理论计算公式得到的等效热传导系数作了对比 ,分析了计算结果。这对于找到影响熔射层质量的基本规律 ,为熔射快速制模工艺参数的合理设计和熔射质量的诊断分析提供了科学依据     

Flow past airfoil moving reciprocally in a channel by vortex method

The velocity and pressure fields of a ship’s propulsion mechanism of the Weis-Fogh type, in which a airfoil moves reciprocally in a channel, are studied in this paper using the advanced vortex method. The airfoil and the channel are approximated by a finite number of source and vortex panels, and the free vortices are introduced from the body surfaces. The viscous diffusion of fluid is represented using the core-spreading model to the discrete vortices. The velocity is calculated on the basis of the generalized Biot-Savart law and the pressure field is calculated from integrating the equation given by the instantaneous velocity and vorticity fields. Two-dimensional unsteady viscose flows of this propulsion mechanism are numerically clarified, and the calculated results agree well with the experimental ones.     

新型速冻机内流场的理论与试验研究

对一种新型食品速冻机风道内的流场进行了数值计算和试验研究。分析了不同进口风速下风道出口风速的均匀性。同时通过试验测定了实际系统中出口风速分布，发现模拟结果和试验结果有一定的差距，并对其原因进行了分析，提出了改进方法。     

轮对参数自动化测量中的误差分析

介绍了一套轮对参数非接触自动检测系统,针对该系统中由多传感器及系统标定值融合处理而产生的多误差源,进行了详细的分析估算。检测结果表明：分析结果完全符合最终检测精度,这种分析方法是合理的、正确的。     

轧制塑性加工中的摩擦力

本文依据轧制塑性加工中的滚一滑摩擦机理建立一个新的摩擦力概念,并在此基础上给出一个相应的摩擦力计算公式。文中用该公式对轧制咬入过程中的摩擦力进行了计算。并以实验对其计算结果进行了验证。同时还对计算结果进行了分析。文中的结论可供有关研究人员参考。     

Experimental study and numerical modeling of arc and weld pool in stationary GTA welding of pure aluminum

In this study, a 2D mathematical model was developed for both arc and weld pool in stationary GTA welding. In arc model, current continuity equation has been solved in both arc and cathode regions without any assumption of fixed current density on the cathode surface which was essential in most previous works. The results of arc model were presented for both copper and aluminum anodes to investigate the effect of anode material on arc properties. It was seen that aluminum anode has lower maximum anode current density and heat flux but the distributions are wider than copper anode. Furthermore, shear stress on anode surface is higher in the case of aluminum anode. Also, calculated results of this study were compared with other available theoretical and experimental results. It has been shown that the agreement between calculated and experimental results was fairly good. The necessary information to simulate the weld pool, including the anode current density and heat flux to the workpiece were taken from the arc model. In this model, due to high thermal conductivity of pure aluminum, fluid flow into the weld pool was ignored. Effects of arc variables, i.e., arc length, applied current and welding time on the shape and size of the weld pool were investigated as well. In order to check the validity of the weld pool model, a comparison between calculated results and the results of our experimental tests was conducted. Generally, these comparisons reveal an acceptable agreement between calculated results and experimental data.     

The Analysis of Multi-Layer Conductor-Backed Coplanar Waveguide for Moisture Sensor Application

The analysis of conductor-backed coplanar waveguide moisture sensor by using numerical method is described. The effective dielectric constant, characteristic impedance and dielectric loss of this multi-layer structure are calculated at various moisture contents with respect to protective layer thickness. The analysis shows that calculated values are drastically affected by a small thickness of the protective layer. The experimental results of the attenuation of sensor at various moisture contents agree reasonably with the theoretical data based on the above analysis. The information available from this study is important for estimating of the dynamic range and optimal design of the sensor.     

基于特征模型的柴油机机体有限元结构分析

这里以某柴油机机体为研究对象,建立了机体的特征实体模型,对其进行了三维有限元自由振动模态分析和有限元强度分析,为增压改进提供了理论依据。在同一实体模型的基础上,以高精度的振动模态计算模型来验证实体模型简化的合理程度是一种既经济又快捷的手段。     

航天高压氦气节流效应分析

通过经典气体状态方程和经验公式法推导计算了航天高压氦气节流过程的焦耳-汤姆逊系数,并将计算与实验结果进行了对比.计算结果表明:航天领域高压氦气在节流过程中产生热效应,经典VDW和R-K气体状态方程计算氦气焦耳-汤姆逊系数误差较大,经验公式法计算氦气焦耳-汤姆逊系数精度较高;根据氦气焦耳-汤姆逊系数经验公式,积分求解了氦...     

采用计算化学方法比较四种核苷的第一电离能

腺苷、胞苷、鸟苷和尿苷四种核苷在一定光频率辐照情况下会发生电离。本研究采用Gaussian03程序中的DFT/B3LYP/6-311G（基组）方法分别计算每个核苷的第一电离能Ei,根据Einstein光电效应公式计算电离时光辐射频率ν。计算结果为：腺苷、胞苷、鸟苷和尿苷电离频率分别是1.9384×1015Hz,1.9693×1015Hz,1.7640×1015Hz和2.0640×1015Hz。安全光辐照波长数值经计算是大于169.950nm。电离频率数据表明,尿苷具有最好光稳定性,鸟苷光稳定性最差。从而自计算化学角度开辟一条探寻发病机制新途径。