基于刚柔多体动力学的桥梁检测车受力分析和改善研究

运用ANSYS和ADAMS软件联合建立桥梁检测车刚柔多体动力学模型,对各液压缸受力情况和最大应力区域进行分析,得出初始时刻举升油缸受到的动载荷最大。通过添加辅助气缸,确定推力的大小和作用时间,改善了举升油缸初始时刻振动状况,为桥梁检测车的设计和改进提供了理论依据,具有参考价值。     

矫直机工作辊渐开线花键轴头设计分析

针对宽厚板矫直机工作辊的传动特点、受力条件,特别是整体换辊时操作要简单迅速,定位准确,并具有自动定心作用的要求,介绍了工作辊渐开线花键轴头的设计方案,包括花键的参数、承载能力、强度校核,换辊时配套使用的花键位置控制样板。     

三角股绳索建模及几何特性分析

针对三角股绳索进行建模方法和几何特性研究,基于三角直股内外层中心轨迹的参数方程,以及螺旋股单位矢量矩阵,推导三角股绳索内部钢丝矢量表达式,并通过Pro/E软件构建了三角股绳索实体模型。分析三角股绳索内部螺旋钢丝的曲率和挠率等几何特性。通过对三角股与圆股绳索内部螺旋钢丝几何特性进行对比,结果表明:三角股绳索侧股螺旋钢丝曲率和挠率随着自身旋转角的变化均以360°周期变化,侧股钢丝内侧绳芯的曲率和挠率最大,外侧最小,内层钢丝曲率和挠率大于外层,这些与圆股绳索几何特征一样;三角股绳索侧股螺旋钢丝曲率和挠率大小变化剧烈、且挠率方向发生变化。     

基于快速原型的转移涂料法制作模具技术

将快速原型制造与转移涂料精密铸造结合,对复杂曲面金属模具的快速制作方法进行了探索。该方法用三维造型软件设计模具,用分层制作技术快速得到模具原型,再基于原型直接采用转移涂料工艺,制作出近净型金属模具毛坯。该工艺流程短,成本较低,特别适合砂型铸造或消失模铸造用的小型金属模具的快速制作。     

电液位置伺服系统的高精度神经网络控制研究

提出了一种采用CMAC神经网络的自学习控制器,以解决具有参数不确定和时变外扰动的电液位置伺服系统的高精度控制问题,该控制器采用动态误差作为CMAC的激励信号,从而使基于CMAC的控制器跟踪连续变化的信号成为可能。仿真结果证明了该控制器不仅是有效的,而且具有很强的鲁棒性。     

Application of neural networks to laser ultrasonic NDE of bonded structures

The purpose of this study is to develop artificial neural networks for the nondestructive evaluation of a bounded structure using laser generated surface waves. The radial basis model is employed and the inputs of the networks are the sampled dispersion curves while the output is the thickness of the bonding layer or unbond ratio. Numerical simulated dispersion curves with noises were used to train and test the neural networks. The dispersion curves of laser ultrasonic experiments acquired by spectral analysis method were also utilized to test the systems. For comparison, simplex inverse method was also introduced. The results demonstrate that neural networks are well suited for on-line evaluation of bonding thickness and unbond ratio of a bonded layered structure.     

Fracture toughness of superplastic formed/diffusion bonded interfaces

The present paper is concerned with the interfacial fracture problem of bi-material interfaces of superplastic forming/diffusion bonding (SPF/DB) components. It has been known that the interfacial fracture toughness is a strong function of the mode mixture of crack tip, which is the most important characteristic of interfacial problems. Micromechanical models have been proposed to understand this trend of interfacial toughness curves, based on which a modified criterion for fracture under mixed-mode loading is advanced in this paper to predict phenomenological functional forms of toughness curves. On the ground of linear elastic fracture mechanics (LEFM), mode I and mode II interfacial fracture toughnesses of SPF/DB components formed under different processing conditions have been measured in this paper using the double cantilever beam (DCB) and end-notched flexure (ENF) specimens, respectively. It is found that, just as is the general trend of interfacial fracture toughness curves, the experimental results of mode II toughness values are much greater than those of mode I toughness values, and the fluctuation of mode II toughness values under different processing conditions is much greater than that of mode I toughness values. On the basis of the experimental results, the four basic parameters in the modified criterion are obtained and the interfacial toughness curve of Ti-50A/Ti-6Al-4V SPF/DB components is determined using the modified criterion for fracture under mixed-mode loading. Comparison between the results shows that the agreement between experiment and theory is excellent.     

INVESTIGATION ON THE VALENCE STATE OF Ce ATOM IN BULK AND NANOCRYSTAL CeO2 BY X-RAY ABSORPTION AND PHOTOEMISSION

1. IntroductionRare earth oxides are potentially useful Inaterials for various optical and electronicapplications such as optical waveguides, optical filters, and capacitors. Nanocrystallinerare earth oxides, RE.Oy, where RE=Ce, Pr, Tb etc. x=1 or 2 and y=2 or 3, are playingan increasingly important role in solid state physics, chemistry, materials science, and evenbiologylll. The ability to synthesis nanocrystals of high quality and to understand themicrostructure properties in the nanocr…     

化工自控系统维护管理综述

随着4C(Computer、Control、Communication、CRT)技术的发展,控制系统在化工生产过程中得到了广泛应用,而控制系统的可靠性和可用性是生产企业关心的重点.本文阐述了化工自动控制系统的资料管理、日常维护保养、检修及备件管理的方法和重要性,说明控制系统的维护和管理是生产装置安、稳、长、满、优运行的...     

矿用无极绳绞车绳道道岔装置的设置及应用

为保证煤矿井下轨道运输的安全以及道岔的正常使用,针对无极绳绞车绳道配套气动道岔装置的制作工艺以及保护设置展开分析.经实践应用证明,无极绳绞车绳道道岔装置结构简单,布置灵活,安装便捷,适应性强,可靠性高,为轨道运输提供了较高的安全保障.