1 汇报安排

题 目：参加 IMECE 2015国际会议总结报告会

时 间：2015年11月25日（周三）下午19：00–21:00

地 点：西二楼 振噪所会议室

报 告 人：

博1320班 刘学婧 学号：4113001082 指导教师：贾书海 教授

博1214班 陈 喆 学号：4112001044 指导教师：吴九汇 教授

博1214班 邢 宇 学号：4112001048 指导教师：徐 华 教授

2 参加国际会议信息

会议名称：IMECE 2015

会议日期：13-19 November, 2015

会议地点：Houston, Texas, USA

会议简介：ASME’s International Mechanical Engineering Congress and Exposition (IMECE) is the largest interdisciplinary mechanical engineering meeting in the world. IMECE plays a significant role in stimulating innovation from basic discovery to translational application. It fosters new collaborations that engage stakeholders and partners not only from academia, but also from national laboratories, industry, research settings, and funding bodies. Among the 4,000 attendees from 75+ countries are mechanical engineers in advanced manufacturing, aerospace, advanced energy, fluids engineering, heat transfer, design engineering, materials and energy recovery, applied mechanics, power, rail transportation, nanotechnology, bioengineering, internal combustion engines, environmental engineering, and more.

3 参会论文信息

Title：Experimental Study on Electromechanical Failure of Dielectric Elastomer Actuator

Author：Xuejing Liu, Shuhai Jia, Hualing Chen, Bo Li and Yu Xing

Abstract—The dielectric elastomer (DE) is an insulating membrane with extra-ordinary properties which can meet various electromechanical failures during the actuation. In the current work, we measured breakdown voltage in DE membrane with special focus on the varying boundary stress during the actuation process. The boundary stress tuned deformation state, causing the membrane to deform out-of-plane before breakdown. A theoretical model is presented, involving the strain-stiffening effect in material and boundary stress effect in geometry, to estimate the dielectric breakdown voltage. The results agree with the experiments. Then, another set of experimental investigation is conducted to study the voltage- induced wrinkling of DE membrane. Steady wrinkles, without an accompany of electrical breakdown are attained and three different failure modes of DE membrane are classified into a phase chart. Finally, a qualitative theoretical explanation on wrinkling mechanism of DE membrane is presented and verified by experimental observations.

Title：Experimental Study on Screech Supperssion of Supersonic Free Jet Through Rectangular Nozzle

Author：Zhe Chen, Jiuhui Wu, Xin Chen, Hao Lei and Adan Ren

Abstract—The paper conducted a series of experimental study on V-shaped grooves influence of supersonic free jet through rectangular nozzles, such as two different screech modes, changing rules of sound pressure level of the screech mode, 3D-dynamic spectrum of sound pressure and schlieren photographs of the flow field. The experimental results show that V-shaped grooves on rectangular nozzle could reduce the acoustic feedback of shock wave from jet flow, so as to eliminate one mode of screech completely). It is also suggest that V-shaped grooves performed differently on rectangular nozzle compared with circular one at high frequency when jet pressure was high. Several fundamental frequency differentials exist in both two rectangular nozzles at the same pressure, whereas fundamental frequency in non V-grooved nozzle is much smoother than the V-grooved one. The nozzle with V-shaped grooves had a significant noise suppression effect below 0.55MPa. An instantaneous spectrum comparison between V-grooved and non V-grooved nozzles in scope of 0.25~0.40MPa was given. The SPL (Sound Pressure Level) differential increased at beginning, then decreased with the decline of jet pressure in low frequency below 10kHz. Nozzle with V-shaped grooves had a lower SPL. Nevertheless, an entirely different phenomenon was discovered in high frequency above 10kHz. When jet pressure was 0.40MPa, V-grooved rectangular nozzle had a higher SPL, and it approached to SPL of non V-grooved nozzle with decline of jet pressure until below it. Moreover, differentials gradually became obvious due to the mixing effect with different nozzle structure. Noise pressure in V-grooved nozzle dropped rapidly in range of 0.40~0.80MPa, as well as lower SPL and widely frequency distribution. Impact of V-shaped grooves on schlieren photographs was analyzed. Flow at nozzle exit was strengthened by impact of V-shaped grooves. An obviously density gradient could be found in first shock-cell and length of cell was smaller than the one without grooves. The flow was more stable in other cells but in a weaker intensity. The V-shaped grooves could increase length of jet path as well as decrease expansion of the cells. In general, V-shaped grooves in rectangular nozzle performed differently from circular nozzle, which could suppress and even eliminate jet flow screech. During engineering application, the matching of V-shaped grooves in rectangular nozzle and pressure of jet flow should be taken into consider.

Title：A New Method to Model Spherical Roller Bearings Due to Self-aligning

Author：Yu Xing, Hua Xu, Shiyuan Pei, Xin Guo, Xuejing Liu and Fengcai Wang

Abstract—This research presents an analytical model to describe the indeterminate contact status and analyze the loaded condition, then acquire the key design parameters so as to improve the carrying capacity of spherical roller bearings. The model based on the non-Hertzian contact theory is applied to reflect the indeterminate contact status due to the self-aligning feature. The loaded condition, which is including the load distribution, the size of the contact region and the maximum contact pressure, is calculated according to the force analysis of spherical roller bearings. The non-linear equations are solved by using secant method and the proposed model is validated by comparing with the published reference. The importance of the indeterminate contact status is illustrated by comparing with the computing results of the Hertzian contact model. The fitted method based on the least square method is used to obtain the equivalent stiffness and the load-deformation exponent, whereby the computing procedure is simplified. In view of the operating condition and the lubricated effect, properly increasing the osculation number or the number of the rollers will obviously improve the carrying ability of spherical roller

bearings.

欢迎有兴趣的同学届时参加。