Optimal design of butterfly-shaped linear ultrasonic motor using finite element method and response surface methodology

A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 mm/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.     

Train-induced vibration on elevated railway station

Results of in-situ vibration measurement carried out at Tianjin West Elevated Railway Station which has the trains running on the station structure were reported. The main excitation source is the train passing through the station. Vibration measurements were recorded in the vertical direction of the supporting track beam, the platform and the steel truss beam of the waiting hall, as well as in the vertical, longitudinal and transverse directions of the roof arch base of the station. Acceleration time responses were obtained. The maximum value, vibration level and one-third octave band RMS spectra of the measured accelerations were studied. The propagation of vibration in different structural floors was discussed. The influence of train speed, distance to the vibration source and the type of train on the structural vibration were analyzed. Results show that the vibration level increases with the train speed, while it attenuates with the distance to the track. Furthermore, the vibration responses of different structural floors were compared, and it is noted that the vertical vibration of the bottom slab of the platform is most severe and the transverse vibration of the roof arch base is the smallest. The results provide reference on the vibration characteristics and vibration energy distribution of this type of ＂Train on building frame＂ system used as an elevated railway station.     

气体钻井钻柱损伤疲劳寿命预测模型研究

针对气体钻井钻柱频繁断裂失效问题,以现代损伤力学研究为基础,分析钻柱损伤演化过程,建立气体钻井钻柱损伤疲劳寿命预测模型。由钻柱损伤疲劳寿命模型得出损伤度是影响钻柱疲劳寿命的主要因素,引入损伤梯度并进一步通过算例研究钻柱所受轴向载荷、损伤度及应变之间的关系。根据理论与算例分析可得,随着轴向载荷增大,损伤度与应变逐步由空间周期关系转变为类周期关系,出现损伤局部化,导致钻柱的疲劳失效。     

基于轴向振型差变化率的空间刚架结构损伤研究

通过结构动态特性参数对损伤位置和损伤程度的敏感性分析,提出以轴向振型差变化率为标示量的空间刚架损伤识别方法。应用ANSYS建立了空间刚架结构无损伤和有损伤的有限元模型,选取轴向振型差变化率作为损伤标示量进行结构损伤识别。结果表明：一阶轴向振型差变化率不但能很好地对单一或多个损伤的损伤位置进行识别,而且可以初步识别损伤程度。将此方法应用到实验刚架模型中,实现了对刚架损伤位置的识别。轴向振型差变化率具有敏感性高、回避空间振动方向性、减少工作量等优点,是一种较理想的空间刚架损伤标示量。     

徽州古民居无损检测技术与方法研究

无损检测技术是对徽州古民居结构构件检测的一种方便有效的方法.本文通过采用超声波技术对某栋徽州古民居的主要构件检测其存在的缺陷,并对无损检测方法和检测内容进行了归纳总结.通过检测得到数据,并对数据进行统计分析与归纳,提出了对徽州古民居检测的一些有益建议,为今后徽州古民居的检测、鉴定、修复提供技术参考.     

大跨径钢箱梁在温度影响下的振型分析

近年来,大跨径钢箱梁桥得到了飞速的发展,同时,在施工中发现温度对它的影响不容忽视．钢箱梁桥在太阳照晒下,箱梁顶部与底部会产生较大的温差,由此而产生的温度应力,会给该桥梁带来初始缺陷,并影响钢箱梁桥的振型变化．自振频率是桥梁结构动力特性的模态参数,也是评价桥梁动力性能的重要依据．以大跨度连续刚箱桥为例,进行建模分析,得出在温度荷载影响下的振型变化情况,对桥梁的设计与施工具有一定的参考价值．     

响应面法优化超声波提取迎春花总黄酮工艺的研究

首次研究利用响应面法优化迎春花总黄酮的提取工艺,在单因素试验基础上,利用中心组合设计响应面试验,考察了超声波提取温度、液料比、提取时间对总黄酮提取率的影响,并建立回归模型.优化后的工艺参数为:提取温度55℃,液料比50 1 mL/g,超声时间25 min,在此条件下总黄酮提取率为16.03%.与传统溶剂浸提法相比,提取时间大大缩短且节约了能耗.     

矿山救援钻孔定位精度和施工误差

为了指导矿山救援,提出了确定救援钻孔精度应采集的参数,用误差理论分析了影响救援钻孔精度的因素,对救援钻孔施工误差的合理值进行了研究,对传统的钻孔施工误差的确定方法进行了改进和优化,通过实例说明了其应用.研究表明,在人员位置和钻孔放样精度一定的情况下,钻孔施工误差必须控制在合理范围内.     

无土相淀粉聚合物饱和盐水钻井液体系在伊朗油田的应用

伊朗某油田钻井施工在三开井段遇到石膏层、岩盐层和高压盐水层时,采用低固相聚合物饱和盐水钻井液体系继续钻进。石膏侵和盐水侵会导致钻井液黏度难以控制、流动性变差、动切力较大、循环水动力不足,因此研究改用无土相淀粉聚合物饱和盐水钻井液体系。该钻井液体系改善了钻井液的流变性,减缓了地层钙离子对钻井液性能的影响,确保了钻进的正常进行,并取得了很好的经济效果。