AZ31镁合金变形与强韧化研究

研究了AZ31镁合金组织的演变过程和力学性能,结果表明：通过挤压变形及动态再结晶,可以显著细化合金晶粒,其尺寸可由约100μm减少到5 μm;二次变形可以提高镁合金的抗拉强度.可见塑性变形是同时实现镁合金构件成形和强韧化的有效途径.     

纳米级XY微定位平台的设计与研究

为了实现二维平面纳米级定位,研制了一台压电陶瓷驱动和弹性铰链导向的一体化微定位平台.该微定位平台具有高刚度、高响应速度和高分辨率等优点.为了克服压电陶瓷驱动器伸长量较小的不足,采用杠杆放大机构增加微定位平台的位移输出.考虑驱动电路的影响,建立了微定位平台的机电耦合模型.通过试验研究了微定位平台的静动态特性,试验结果表明微定位平台的分辨率为5nm,固有频率分别为143Hz和180Hz.该微定位平台可应用于纳米级的微定位.     

基于遗传算法优化铣削用量的数控加工仿真系统的研究

遗传算法是一种模拟生物界自然选择和自然遗传机制的自适应搜索和优化方法,在搜索优化问题的全局或全局附近的最优解上具有良好的优势条件.文章建立了基于遗传算法思想的铣削用量多目标智能优化的数学模型及其数控加工动态仿真系统,运用遗传优化方法对铣削加工实例进行优化,并在数控加工动态仿真系统上验证了铣削用量多目标智能优化的数学模型的正确性和实用性.     

汽车半轴楔横轧机机架动态特性有限元法分析

目前,对楔横轧机机架的研究多集中在静力学分析,而动力学分析研究较少。本文应用ANSYS有限元动力学分析模块,求出了汽车半轴楔横轧机机架在现有边界条件下的固有频率和振型,并对机架的整体模态、谐响应以及机架上影响轧制精度的点在给定的激励下的位移响应进行了详细分析,结果表明该轧机在现有参数下的设计是可靠的。     

电液伺服阀静动态特性及其远程测控系统研究

介绍在液压综合实验平台上，应用虚拟仪器LabVIEW技术实现电液伺服阀动静态特性的测试。并将虚拟仪器技术与网络技术相结合实现了电液伺服阀远程测试功能。     

动力学法晶粒细化技术的进展及在高温合金中的应用

晶粒细化是一种提高高温合金低周疲劳性能的有效方法,因而细晶铸造技术成为高温合金的重要研究方向。本文简要介绍了动力学法晶粒细化技术的原理和特点,综述了动力学法晶粒细化技术的工艺方法及其在高温合金中的国内外研究现状,对高温合金动力学法晶粒细化技术的发展前景进行了展望。     

Dynamic Young’s modulus and internal friction in polycrystalline copper

An attempt has been made to measure the temperature dependence of dynamic Young’s modulus together with the related variation of internal friction in polycrystalline copper. A mechanical spectroscopy study was employed using a standard servo hydraulic fatigue testing machine equipped with a scanning laser extensometer. Dynamic Young’s modulus and internal friction were measured over a temperature range of 298 to 873 K at very low frequencies of 0.1, 0.05, and 0.01 Hz. One internal friction peak was observed over the ranges 450 to 700 K, together with marked decreases in the dynamic Young’s modulus in the same temperature range. From a quantitative analysis of the experimental data with the relaxation strength, relaxation time, and activation energy, it is concluded that the peak phenomenon is due to grain-boundary sliding relaxation.     

自动线计算机图形监控系统的研究

介绍一种通过与PLC进行实时通讯，将自动线各部分工作状态动态地显示在计算机窗口界面上的图形化监控系统。该系统的运用，使整个加工过程的监控更为有效、直观。     

Localized shear deformation during shear band propagation in titanium considering interactions among microstructures

Closed-form analytical solutions of plastic shear strain and relative plastic shear displacement during shear band propagation are proposed under dynamic loadings based on gradient-dependent plasticity considering the effect of microstructures due to heterogeneous texture of Ti. According to the differences in shear stress levels, Ti specimen is divided into three regions: residual region, strain-softening region and elastic region. Well-developed shear band is formed in the residual region and the relative plastic shear displacement no longer increases. In the normal and tangential directions, the plastic strain and the displacement are nonuniform in the strain-softening region.At the tip of shear band, the shear stress acting on the band is increased to shear strength from the elastic state and the shear localization just occurs. Prior to the tip, Ti remains elastic. At higher strain rates, the extent of plastic strain concentration is greater than that under static loading. Higher strain rate increases the relative plastic shear displacement. The present analytical solution for evolution or propagation of shear localization under nonuniform shear stress can better reproduce the observed localized characteristics for many kinds of ductile metals.     

基于广义预测控制的液压弯辊控制系统

针对液压弯辊控制这一随机干扰严重、滞后、时变的伺服系统,提出一种基于广义预测控制的液压弯辊控制系统。借助平稳随机序列预报思想建立系统输出误差预报模型,预报液压弯辊力未来序列输出误差并用以补偿系统的预测输出,从而提高了液压伺服控制系统的精度和抗干扰能力。仿真结果表明:采用广义预测控制并用预报误差代替一般的误差校正算法,液压弯辊板形控制系统精度和鲁棒性明显提高。