共查询到20条相似文献,搜索用时 187 毫秒
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《功能材料与器件学报》2015,(4)
高频宽带全向换能器是水声换能器研究的发展方向,PZT压电复合材料圆环既能够水平全向发射和接收水声信号,同时又使换能器的带宽得到扩展。利用ANASYS有限元仿真软件对2-2型压电复合材料圆环结构进行模态仿真,得到带宽和结构尺寸的关系曲线。在仿真模拟的基础上,形成设计方案,将压电陶瓷圆环沿轴向方向均匀切割,把环氧树脂浇注于切槽,经打磨和被覆电极,制成2-2型压电复合材料圆环。对压电复合材料圆环的压电和介电性能进行测试,结果为谐振频率388k Hz,带宽11.2k Hz,声阻抗18.05Mraly,相对介电常数859,声速3200m/s,d33常数480 p C/N,振动位移89.5pm。该压电复合材料圆环适合做水平全向宽带换能器。 相似文献
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结构动力特性被广泛应用于结构振动控制、结构可靠性设计和健康监测,由此涉及到一些动力学基本概念的理解问题尚待深入探讨。采用一简支梁横向振动算例以及分别通过模态位移法和模态加速度法对多自由度系统的响应振幅进行分析计算,探讨结构位移响应与第一阶固有频率的关系、结构各阶位移模态的贡献与模态应变能的关系。基于模态正交性,通过分析多自由度振动系统的位移响应,论述了系统共振的必要条件,即在保证系统振动频率(某阶固有频率)等于激励频率的同时,其位移响应还应呈现出相应模态的形态;实现多自由度系统纯模态共振,可用于精确识别结构的模态参数。 相似文献
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为研究螺旋离心泵转子对流固耦合作用的动态响应信息,以ZJ200-25型双叶片螺旋离心泵为研究对象,利用CFD软件CFX12.1和有限元软件ANSYS Workbench对其进行了考虑流场变载荷和结构相互作用的两场交替联合求解。得到转子受到的激励力以及位移响应频谱特点,结果表明:叶轮受到流场变载荷激励,发生了弯曲及拉伸振动;叶轮径向位移随流量增大而减小,其主频率与径向力主频率同为48.3Hz,轴向力以低频随机波动为主,但轴向位移仅在200Hz以内有较明显的响应,且振幅随频率增加而减小;叶轮质心位移在低阶频率处的振幅不高,高阶频率的振幅逐渐减小,轴向及径向位移均没有振幅过大的情况出现,说明螺旋离心泵转子正常工作时未发生共振,稳定性良好。本文研究结果对螺旋离心泵转子系统的设计改良及振动分析具有一定的参考意义。 相似文献
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目的 减小共振疲劳对摩擦焊接机构的影响,提高砖块打包机的可靠性、性能及使用寿命。方法 建立摩擦焊接机构模型,分析不同振动频率下的摩擦振动臂位移振幅与应力振幅。以理想焊接温度为基础,焊接时间为参数,确定振动频率与马达转速。结果 在所测试的频率范围内,随着振动频率不断增加,Z方向位移振幅较大于X、Y方向,Y方向应力振幅较大于X、Z方向,3个方向位移振幅与应力振幅均呈上升趋势。振动频率为440 Hz时,焊接时间至少需要2.0 s;振动频率为450 Hz和460 Hz时,焊接时间至少需要1.9 s。摩擦振动臂底端温度分布基本一致且均达到理想焊接温度,最终选取振动频率为450 Hz,马达转速设定为27000r/min。结论 最终确定的转速不仅需要满足共振疲劳影响最小化,还需结合砖块打包机实际焊接温度及效率因素,以此提高砖块打包机的可靠性与使用寿命。 相似文献
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基于Ansys Workbench对卸料装置的动态性能分析与优化 总被引:1,自引:1,他引:0
目的研究振动电机的激励对卸料装置在满载工况下卸料时产生的影响,并对卸料装置振动特性进行优化。方法采用Solid Works对卸料装置建模,运用Ansys Workbench软件分析其前8阶固有频率和模态振型,找到其结构薄弱区,对比分析外部激振频率与卸料装置固有频率是否共振,以卸料装置薄弱区为参考,来优化振动电机的安装位置。结果由模态分析得,卸料装置第7阶固有频率在共振区内,可能会导致卸料装置共振;结合谐响应分析确定了卸料装置第1,4,5阶固有频率附近的振幅位移最大,同时得出振动电机在E,F,G处安装位置下,卸料装置响应构件的最大振幅位移分别为1.8,1.86,1.9 mm。结论通过综合分析得出,在卸料装置上施加外界激振频率时应避开16 Hz和33 Hz,同时可知振动源安装在F处最优,为卸料装置在实际设计和制造过程中提供必要的依据。 相似文献
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以车用316L不锈钢作为基材,对其实施等离子喷涂处理使其表面生成Mo-Al膜,分析表面温度变化、电弧特征以及形成的磨痕特点,对比了不同喷涂频率下得到的膜载流摩擦磨损特性。研究结果表明:当频率20 Hz时,在磨痕的表面区域形成了一层具有均匀尺寸的磨粒。元素分布表明Al元素发生了少量转移,跟膜层组织成分较为接近。在频率20 Hz下形成了具有完整结构的摩擦膜,此时在表面区域形成了尺寸均匀的磨粒。提高喷涂频率后,会引起摩擦副的大幅冲击并发生明显震动,温度迅速上升,更易发生氧化。当提高喷涂频率后,摩擦系数以及磨损率都发生了先减小再升高的变化规律,转折点在喷涂频率20 Hz,此时取值分别为0.326和68.5。 相似文献
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Finite element simulations of ultrasonically assisted turning 总被引:1,自引:0,他引:1
A. V. Mitrofanov V. I. Babitsky V. V. Silberschmidt 《Computational Materials Science》2003,28(3-4):645-653
Ultrasonically assisted turning is a promising machining technology, where high frequency vibration (f≈20 kHz) with an amplitude a≈10 μm is superimposed on the movement of the cutting tool. Ultrasonic turning yields a noticeable decrease in cutting forces, heat and noise radiation, as well as a superior surface finish, comparing to the conventional machining technology. The present study utilizes both experimental techniques and numerical (finite element) simulations to analyze the microstructural processes at the cutting tool–chip interface. High-speed filming of the chip–tool interaction zone during cutting and microstructural and nanoindentation analyses of the machined surfaces are used to compare process zones and deformation processes for both conventional and ultrasonically assisted technologies. The suggested finite-element (FE) model, which utilizes MSC Marc/Mentat general FE code, provides a transient analysis for an elasto-plastic material, accounting for the frictionless contact interaction between a cutter and workpiece as well as material separation in front of the cutting edge. A detailed analysis of cutting for a single cycle of ultrasonic vibration is carried out for isothermal conditions. Differences between conventional and ultrasonic turning in stress distribution in the process zone and contact conditions at the tool/chip interface are investigated. 相似文献
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为了了解纵轴式掘进机的纵向振动特性,提高机器工作的可靠性,分析并确定截割头随机载荷的数学模型,利用拉格朗日方法建立了该型掘进机的纵向动力学模型,通过拉氏变换法对动力学方程解耦,得到了其3阶固有频率和振型.为进一步探究截割头与悬臂、悬臂与机体的刚度对截割头和悬臂振动的影响,利用虚拟激励法求得截割头、悬臂的纵向位移响应,并在ADAMS中对整机多刚体动力学模型仿真,验证了该方法的可靠性.研究结果表明:系统的纵向振动固有频率在6 Hz内,通过增加悬臂与机体的刚度能明显减小外随机激励作用下截割头和悬臂的振动.所得结论为改进掘进机设计和参数优化提供理论依据. 相似文献
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超精密飞刀切削是一种重要的超精密加工手段,安装大飞刀盘的超精密铣床能够加工大口径超精密光学元件,加工表面具有很高的面形精度和很低的表面粗糙度值.但是加工表面普遍存在中频微波纹(空间周期从100μm到300μm,幅值低于0.1μm),极大影响了光学元件的使用.超精密铣床的主轴旋转精度对加工工件影响很大,尤其是主轴轴线偏转会使安装在大飞刀盘外缘处的刀具产生很大位移.为此,建立了适用于空气静压轴承支撑的立式主轴角位移欧拉动力学方程,推导出方程解析解,得出主轴运动规律及其对表面中频微波纹的影响,并设计实验进行验证.最终给出了抑制中频微波纹的工程措施. 相似文献
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螺纹旋风铣削的多刀具断续切削方式将加剧刀盘与工件间的交互冲击,引起刀盘系统的扭振,影响加工质量。以旋风铣削刀盘系统为研究对象,针对其在周期性切削力矩下发生扭振的特点,提出在铣削刀盘上安装硅油式减振器的抑振方案,进而建立基于硅油式减振器的旋风铣削刀盘系统动力学模型,对模型进行幅频特性分析,并对有无减振器两种方案下旋风铣削刀盘系统的动力学响应特性进行分析,以研究硅油式减振器对旋风铣削刀盘系统的减振效果。结果表明:硅油式减振器可有效地减小旋铣刀盘系统在不同切削频率下的振幅。当系统发生共振时,基于硅油式减振器的旋铣刀盘系统的响应幅值可降至7.10×10-4rad,降低了刀盘系统的扭振对螺纹工件加工质量和刀具寿命等的影响。 相似文献
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In the present study, finite element formulation based on higher order shear deformation plate theory is developed to analyze nonlinear natural frequencies, time and frequency responses of functionally graded plate with surface-bonded piezoelectric layers under thermal, electrical and mechanical loads. The von Karman nonlinear strain–displacement relationship is used to account for the large deflection of the plate. The material properties of functionally graded material (FGM) are assumed temperature-dependent. The temperature field has uniform distribution over the plate surface and varies in the thickness direction. The considered electric field only has non-zero-valued component Ez. Numerical results are presented to study effects of FGM volume fraction exponent, applied voltage in piezoelectric layers, thermal load and vibration amplitude on nonlinear natural frequencies and time response of FGM plate with integrated piezoelectric layers. In addition, nonlinear frequency response diagrams of the plate are presented and effects of different parameters such as FGM volume fraction exponent, temperature gradient, and piezoelectric voltage are investigated. 相似文献
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为适应微创手术的要求,设计了频率为55.5 kHz的细长结构超声手术刀。采用有限元方法对其进行模态分析和谐振分析,获取振幅大小、应力分布等参数。通过对手术刀刀身结构进行二次优化,使所设计的手术刀在50~60 kHz频段内以纵振模式为主,刀头和刀身应力分布均匀,最大应力由577 MPa降到375 MPa,远小于医用钛合金材质的超声手术刀的最大抗拉强度。为验证有限元分析结果,分别试制结构优化前后的手术刀模型并进行实验。结果表明:结构优化之后的手术刀工作时,应力分布均匀,径向无明显扰度,轴向输出振幅可以满足生物组织切割的要求。 相似文献
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The formation mechanism of surface texture for feed-direction ultrasonic vibration?assisted milling (UVAM) was investigated in this study by establishing a kinematic model and a pressing model of UVAM. The kinematic model showed that the cutter tip, which was supposed to be totally sharp, produced closed scratches by crossed trajectories. The variation trends of the interval for closed textures were of sine function. A comparative experiment was carried out by UVAM and conventional milling. A dividing line close to the X coordinate divides the surface feature into two parts. The pressing model showed that the tool minor cutting edge left clear traces with certain width because of the tool minor cutting edge angle. Scratches by tool minor cutting edge were intermittent and regularly varied when feed-direction vibration was introduced. All the surface feature changes are in the radial direction and the trajectory intersections shall always be the scratch grooves or ridges. The ratio between ultrasonic vibration frequency and spindle speed, tool radius, and the located cutter rotation angle affected the changing rule of scratches by tool minor cutting edge. The analytical models and the experimental results proved to each other reasonable. 相似文献
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A. Agic M. Eynian S. Hägglund J. -E. Ståhl T. Beno 《Journal of Superhard Materials》2017,39(4):259-270
The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavorable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. Under some circumstances the radial depth of cut in combination with milling cutter geometry might give unfavorable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon is originated from the geometrical features that affect the rise time of the cutting edge engagement into workpiece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult-to-cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the workpiece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behavior is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using the root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design. 相似文献