Grain size effect on cyclic deformation behavior and springback prediction of Ni-based superalloy foil

In order to clarify the influence of grain size on cyclic deformation response of superalloy sheets and springback behavior,cyclic loading-unloading and shearing tests were performed on the superalloy foils with 0.2 mm in thickness and diverse grain sizes.The results show that,the decline ratio of elastic modulus is weakened with increasing grain size,and the Bauschinger effect becomes evident with decreasing grain size.Meanwhile,U-bending test results determine that the springback is diminished with increasing grain size.The Chaboche,Anisotropic Nonlinear Kinematic(ANK)and Yoshida-Uemori(Y-U)models were utilized to fit the shear stress-strain curves of specimens.It is found that Y-U model is sufficient of predicting the springback.However,the prediction accuracy is degraded with increasing grain size.

自通风型电机气动噪声计算方法的研究

本文基于计算气动噪声声类比混合计算理论,提出了一种适用于自通风电机气动噪声预测的方法,该方法先通过对自通风型电机进行瞬态流场仿真,输出流场中的速度、密度等信息,之后将流场信息加载到声学网格上转换为声源,再进行声场计算,通过将仿真得到的结果与试验结果对比,发现误差仅为1.7dB,在工程计算的可接受范围之内,从而证明了本文所提出的自通风型电机气动噪声预测的方法可适用于在电机技术设计阶段对噪声进行预测计算。

基于相似设计理论的自通风型牵引电机风扇降噪优化

本文详细论述了风扇相似设计理论在牵引电机风扇性能及噪声优化应用中的方法,依据某气动性能较好的参考风扇设计了适合自通风型牵引电机的低噪声新风扇来替换原有风扇。同时基于自通风型牵引电机的非定常流场仿真结果,建立有限元声学计算模型,仿真计算了该电机在最高转速下的气动噪声,获取了由电机风扇产生的气动噪声幅值与频谱特性。通过对安装原风扇与优化后风扇电机的气动噪声计算结果进行对比,表明安装相似理论设计风扇的电机在高转速时有非常明显的降噪效果,达到了优化设计的目的。同时表明风扇相似设计理论在自通风型牵引电机降噪设计中具有一定的应用前景与推广价值。