共查询到17条相似文献,搜索用时 421 毫秒
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鉴于风力发电机组主轴的复杂工作情况和疲劳断裂失效形式,提出一种基于表面强化技术的超声辅助滚压加工系统;首先基于运动合成原理,获得了滚轮接触线的运动轨迹特征,并应用ANSYS/LS-DYNA软件分析了加工过程的特点;之后,基于一维振动理论、等效波长理论与牛顿迭代理论,推导了并求解了复合变幅杆的频率方程,实现了该复合变幅杆的纵向振动。通过对该变幅杆进行有限元仿真分析与振动特性测试,结果表明二者相对设计频率的偏差仅在0.817%以内。最后,通过对40Cr主轴进行超声辅助滚压测试,结果获得了粗糙度Ra 0.085μm和表面硬度32.2HRC的加工表面,较普通滚压加工粗糙度降低了69.1%,显微硬度提高了60%。 相似文献
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鉴于风力发电机组主轴的复杂工作情况和疲劳断裂失效形式,提出一种基于表面强化技术的超声辅助滚压加工系统。首先基于运动合成原理,获得了滚轮接触线的运动轨迹特征,并应用ANSYS/LS-DYNA软件分析了加工过程的特点。之后,基于一维振动理论、等效波长理论与牛顿迭代理论,推导并求解了复合变幅杆的频率方程,实现了该复合变幅杆的纵向振动。通过对该变幅杆进行有限元仿真分析与振动特性测试,结果表明二者相对设计频率的偏差仅在0.817%以内。最后,通过对40Cr主轴进行超声辅助滚压测试,获得了粗糙度Ra 0.085μm和表面硬度32.2 HRC的加工表面,较普通滚压加工粗糙度降低了69.1%,显微硬度提高了60%。 相似文献
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为了获得大负载平行砂轮复合变幅器的设计方法,将复合变幅器简化为复合变幅杆与多阶环盘组成。利用Mindlin中厚板理论,求解了各振动环盘的位移、转角、弯矩和剪力解析表达式,并通过复合变幅杆各振动单元间的力、位移的边界条件和连续条件,以及复合变幅杆和环盘两者结构间力与位移的耦合条件,建立了复合变幅器的数学模型和频率方程。针对频率方程进行编程求解 ,设计了平行砂轮复合变幅器。通过有限元仿真分析、实物阻抗特性试验、谐振试验验证。试验结果表明:平行砂轮复合变幅器的试际谐振频率、节圆位置与理论设计的误差小于5%,验证了其理论设计方法的正确性。为研制大负载平行砂轮复合变幅器提供了一种有效的设计方法。 相似文献
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本文对指数型纵-扭复合振动模式的复合超声变幅杆进行了理论及实验研究,该变幅杆由均匀截面直棒及指数型截面杆组成。文中推出了变幅杆中纵向振动及扭转振动的共振频率方程,通过发迹指数型变截面棒的截面变化规律,实现了同一变幅杆中纵向振动与扭转振动的同频共振。 相似文献
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针对低温微量超声雾化声学系统中的关键部件单波长超声雾化喷嘴进行研究。首先基于等效电路原理和传输矩阵法分别建立了带中心孔换能器和带中心孔复合变幅杆的频率方程,并应用数学分析软件获得了准确的数值解,实现了超声雾化喷嘴的全谐振。然后,对其进行有限元动力学分析和振动特性测试,结果表明二者相对于设计频率25 kHz的偏差率在0.6%以内,且空载超声振幅达13.5μm。之后,应用流体仿真分析软件对砂轮-工件磨削区进行流场特性分析,结果表明低温微量超声雾化声学系统可以解决磨削区涡流现象的产生。最后,通过对该系统使用前后两种润滑方式的磨削结果进行测试发现:低温微量超声雾化润滑不仅切削液使用量少,而且可以避免工件表面出现烧伤和硬度降低。 相似文献
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超声弯曲模式变幅杆的振动分析 总被引:5,自引:0,他引:5
介绍了用传递矩阵分析超声弯曲变幅杆的方法,推导了变幅杆的频率方程、放大系数、形状因子的表达式。作为方法的应用例,对圆锥形变幅杆进行了一些数值计算。最后进行了验证。结果表明传递矩阵法是弯曲变幅杆分析的有效方法。 相似文献
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An analysis is presented for the free vibration of joined conical-cylindrical shells. The governing equations of vibration of a conical shell, including a cylindrical shell as a special case, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the matrix has been determined, the entire structure matrix is obtained by the product of the transfer matrices of the shells and the point matrix at the joint, and the frequency equation is derived with terms of the elements of the structure matrix under the boundary conditions. The method has been applied to a joined truncated conical-cylindrical shell and an annular plate-cylindrical shell system, and the natural frequencies and the mode shapes of vibration calculated numerically. The results are presented. 相似文献
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研究了一种锥形剖面径向复合超声换能器。该换能器由一个等截面内金属圆环、一个轴向极化的压电陶瓷圆环和一个锥形剖面外金属圆环沿径向复合而成,且换能器的径向尺寸远大于高度。锥形剖面外金属圆环满足关系式h=h0r,h0为厚度变化常数。基于平面应力径向振动理论,推导了换能器的机电等效电路,得到了共振频率方程和反共振频率方程,进而研究了换能器的振动特性。并将理论计算的第1阶、第2阶径向共振频率和反共振频率与数值仿真结果相比较,二者结果一致。研究表明:锥形剖面换能器第1阶、第2阶径向共振频率、反共振频率、有效机电耦合系数不仅与换能器各部分的材料、径向几何尺寸有关,还与h0有关。h0越大,第1阶径向共振频率、反共振频率越大,有效机电耦合系数先增大后减小。与等截面相比,锥形剖面换能器沿径向向外辐射声波,辐射面积更大,辐射声功率更高,指向性更好。 相似文献
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本文根据光线在球面上的折射公式及光线微分方程,研究了光线经两端面为球面的锥形梯度折射率透镜的传播和变换,基于光线传递ABCD矩阵,提出了球面端面的锥形梯度折射率透镜的一种等效光学系统.文中给出了该透镜的主平面、焦平面和焦距计算公式,以及近轴成像高斯公式.当锥度为零时即得到球面端面的柱形或径向梯度折射率透镜的相应结果. 相似文献
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Lin S 《Ultrasonics》2007,46(1):51-59
A new type of radial composite piezoelectric transducer in radial vibration is developed and analyzed. The radial composite transducer consists of a piezoelectric ceramic thin ring polarized in the thickness direction and a metal thin circular ring. They are connected together and excited to vibrate in the radial direction. The radial vibrations of a piezoelectric ceramic thin ring and a metal thin circular ring are analyzed, respectively. Their radial electro-mechanical equivalent circuits are obtained. Based on the electro-mechanical equivalent circuits and using the boundary conditions between the piezoelectric ceramic thin ring and the metal thin circular ring in the radial direction, the electro-mechanical equivalent circuit of the radial composite piezoelectric transducer is derived out and the resonance frequency equation is obtained. The relationship between the resonance frequency and the geometrical dimensions of the transducer is analyzed. Some radial composite piezoelectric transducers are designed and manufactured. The resonance frequencies and the anti-resonance frequencies, the electro-mechanical equivalent circuit parameters are measured. The effective electro-mechanical coupling coefficient and the mechanical quality factor are calculated. It is illustrated that the measured radial resonance frequencies are in good agreement with the theoretical results from the resonance frequency equation. 相似文献
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Analysis on vibration characteristics of large-size rectangular piezoelectric composite plate based on quasi-periodic phononic crystal structure 下载免费PDF全文
Li-Qing Hu 《中国物理 B》2022,31(5):54302-054302
Based on the theory of composite materials and phononic crystals (PCs), a large-size rectangular piezoelectric composite plate with the quasi-periodic PC structure composed of PZT-4 and epoxy is proposed in this paper. This PC structure can suppress the transverse vibration of the piezoelectric composite plate so that the thickness mode is purer and the thickness vibration amplitude is more uniform. Firstly, the vibration of the model is analyzed theoretically, the electromechanical equivalent circuit diagram of three-dimensional coupled vibration is established, and the resonance frequency equation is derived. The effects of the length, width, and thickness of the piezoelectric composite plate at the resonant frequency are obtained by the analytical method and the finite element method, the effective electromechanical coupling coefficient is also analyzed. The results show that the resonant frequency can be changed regularly and the electromechanical conversion can be improved by adjusting the size of the rectangular piezoelectric plate. The effect of the volume fraction of the scatterer on the resonant frequency in the thickness direction is studied by the finite element method. The band gap in X and Y directions of large-size rectangular piezoelectric plate with quasi-periodic PC structures are calculated. The results show that the theoretical results are in good agreement with the simulation results. When the resonance frequency is in the band gap, the decoupling phenomenon occurs, and then the vibration mode in the thickness direction is purer. 相似文献
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Theoretical analysis and experimental validation of radial cascaded composite ultrasonic transducer 下载免费PDF全文
《中国物理 B》2021,(4)
A radial cascaded composite ultrasonic transducer is analyzed.The transducer consists of three short metal tubes and two radially polarized piezoelectric ceramic short tubes arranged alternately along the radial direction.The short metal tubes and the piezoelectric ceramic short tubes are connected in parallel electrically and in series mechanically,which can multiply the input sound power and sound intensity.Based on the theory of plane stress,the electro-mechanical equivalent circuit of radial vibration of the transducer is derived firstly.The resonance/anti-resonance frequency equation and the expression of the effective electromechanical coupling coefficient are obtained.Excellent electromechanical characteristics are determined by changing the radial geometric dimensions.Two prototypes of the transducers are designed and manufactured to support the analytical theory.It is concluded that the theoretical resonance/anti-resonance frequencies are consistent with the numerical and experimental results.When R_2 is at certain values,both the anti-resonance frequency and effective electromechanical coupling coefficient corresponding to the second mode have maximal values.The radial cascaded composite ultrasonic transducer is expected to be used in the fields of ultrasonic water treatment and underwater acoustics. 相似文献