首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
The evolution of the planar vibrations of a rectangular piezoceramic plate as its aspect ratio is changed starting with 1 is studied. Experimental data are obtained using an integrated technique based on Meson’s circuit, Onoe’s circuit, and a piezotransformer transducer. As the aspect ratio increases (square plate becomes rectangular), the intensity of electromagnetic vibrations rapidly increases at the first longitudinal resonance and gradually decreases in the first radial mode. When the aspect ratio is changed so that the length of one of the plate sides remains constant, the resonant frequencies of all vibration modes change too __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 7, pp. 98–106, July 2007.  相似文献   

2.
3.
An attempt is made to systematize experimental data for a rectangular piezoceramic plate and to compare them with those on planar vibrations of a thin piezoceramic half-disk. Experimental data on planar vibrations of a half-disk are discussed for the first time. Neighboring vibration modes of a rectangular plate with solid electrodes demonstrate strong superposition and coupling __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 5, pp. 89–96, May 2007.  相似文献   

4.
The electroelastic problem for a transversely isotropic prolate ceramic spheroid is solved explicitly. The spheroid surface is free from external forces. The case is considered where the piezoceramic body is subjected to a given potential difference between electrodes partially covering the surface at the vertices. The normal component of electric-flux density is equal to zero on the noneletroded portion of the surface. Plots of normal stresses in the symmetry plane of the piezoceramic body are given __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 58–67, July 2005.  相似文献   

5.
The influence of the curving and twisting of an elongated blade on its vibrations during complex rotation is studied. It is shown that these geometrical factors may cause additional resonant vibrations__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 4, pp. 126–132, April 2005.  相似文献   

6.
The transverse vibrations of a circular disk of uniform thickness rotatingabout its axis with constant angular velocity are analyzed. The resultsspecialized to the linear case of disks clamped at the center and free atthe periphery are in good agreement with those reported in the literature.The natural frequencies of spinning hard and floppy disks are obtained for various nodal diameters and nodal circles. Primary resonance is shown to occur at the critical rotational speed at which, in the linear analysis, the spinning disk is unable to support arbitraryspatially fixed transverse loads. Using the method of multiple scales, wedetermine a set of four nonlinear ordinary-differential equations governingthe modulation of the amplitudes and phases of two interacting modes. Thesymmetry of the system and the loading conditions are reflected in thesymmetry of the modulation equations. They are reduced to an equivalentset of two first-order equations whose equilibrium solutions aredetermined analytically. The stability characteristics of thesesolutions is studied; the qualitative behavior of the response isindependent of the mode being considered.  相似文献   

7.
An approach is proposed to calculate the natural frequencies and modes of vibrations of cylindrically anisotropic piezoelectric cylinders. The frequency equation is derived, and the frequency spectrum is analyzed __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 68–72, July 2005.  相似文献   

8.
The paper proposes a method to solve the problem of vibrations of a radially polarized piezoelectric cylinder subject to nonstationary electric excitation. The dynamic electromechanical state of the cylinder is analyzed. The time-dependences of electric and mechanical characteristics are plotted. The distribution of these characteristics over the cross section of a short cylinder is examined. The region of end disturbances in a long cylinder is identified __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 3, pp. 73–79, March 2007.  相似文献   

9.
Steady precession vibrations of a single-support thin-walled rotor whose rotation axis is forced to make an additional rotation are simulated numerically. It is established that compared with double-support rotors, single-support rotors are more dynamically compliant and undergo two precession resonances over the range of rotation speeds being considered. Mode shapes of precession vibrations are drawn  相似文献   

10.
The results from studies into the vibrations and dynamic stability of thin elastic shells with initial geometric imperfections are analyzed. The corresponding dynamic problems are solved in both linear and nonlinear formulations. The influence of initial axisymmetric and nonaxisymmetric deflections on natural, forced, parametrically excited, and self-excited vibrations (flutter) is studied. The dynamic buckling of imperfect shells under short-term impulsive loading is examined. Some aspects of experimental investigation into the vibrations of shells with small geometric imperfections (deviations from the design shape) are considered  相似文献   

11.
Radial vibrations and dissipative heating of a polarized piezoceramic ring plate are studied. The plate is excited by a harmonic electric field applied to nonuniformly electroded surfaces of the plate. The viscoelastic behavior of piezoceramics is described in terms of complex quantities. An analytical solution is found in the case of quasistatic harmonic loading. The dynamic nonlinear problem of coupled thermoviscoelasticity is solved with regard for the temperature dependence of the properties of piezoceramics by step-by-step integration in time, using the numerical methods of discrete orthogonalization and finite differences. A numerical analysis is conducted for TsTStBS-2 piezoceramics to study the influence of partial electroding on the stress–strain distribution, natural frequency, and amplitude–frequency and temperature–frequency characteristics  相似文献   

12.
The flexural vibrations and dissipative heating of a circular bimorph piezoceramic plate are studied. The plate is excited by a harmonic electric field applied to nonuniformly electroded surfaces. The viscoelastic behavior of piezoceramics is described in terms of temperature-dependent complex moduli. The nonlinear coupled problem of thermoviscoelasticity is solved by step-by-step integration in time, using the discrete-orthogonalization method to solve the mechanics equations and the finite-differences method to solve the heat-conduction equations. A numerical analysis is conducted for TsTStBS-2 piezoceramics to study the influence of the nonuniform electroding on the resonant frequency, amplitude, and modes of flexural vibrations and the amplitude- and temperature-frequency characteristics of the plate __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 9, pp. 94–100, September 2005.  相似文献   

13.
本文用边界元法对销钉接触角及销钉孔半径对三种电流输入方式下紧凑拉伸试样的电位函数影响进行了分析。结果证明,人们在电位法测试中常用的电流输入方式容易引起误差,并非最佳方案.最佳方案是另一种同样方便的电流输入方式.  相似文献   

14.
The resonance synchronization of the vibrations of a system of shells is studied. It is established that the vibrations of isolated components excite the vibrations of the whole system, consisting of three cylindrical shells on a common elastic base.__________Translated from Prikladnaya Mekhanika, Vol. 40, No. 12, pp. 134–137, December 2004.  相似文献   

15.
Suweken  G.  van Horssen  W. T. 《Nonlinear dynamics》2003,31(2):197-223
In this paper the weakly nonlinear, transversal vibrations of aconveyor belt will be considered. The belt is assumed to move witha low and time-varying speed. Using Kirchhoff's approach a singleequation of motion will be derived from a coupled system ofpartial differential equations describing the longitudinal andtransversal vibrations of the belt. A two time-scalesperturbation method is then applied to approximate the solutionsof the problem. It will turn out that the frequencies of the belt speed fluctuations play an important role in the dynamic behaviourof the belt. It is well-known in linear systems that instabilitiescan occur if the frequency of the belt speed fluctuations is thesum of two natural frequencies. However, in the weakly nonlinearcase as considered in this paper this is no longer true. It turns out that the weak nonlinearity stabilizes the system.  相似文献   

16.
A technique and results of experimental determination of vibrational stresses in a system of two truncated conical shells joined by three thin plates are presented. An analysis of the data obtained shows that the stress peaks near the added point mass at resonance __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 9, pp. 93–97, September 2007.  相似文献   

17.
管道超声导波检测专用探头的研制   总被引:4,自引:0,他引:4  
何存富  于海群  吴斌 《实验力学》2003,18(4):500-505
结合常规超声探头的研制技术,根据检测对象——管道的特殊性,从敏感元件、背衬材料、保护层以及外型等各方面详细介绍了一种管道超声导波检测专用探头的研制过程;利用这种探头分别在板和管中进行了激励接收超声导波的实验,结果表明,这种探头能够激励接收超声导波。  相似文献   

18.
薄膜润滑中双电层效应的理论分析与实验研究   总被引:1,自引:0,他引:1  
建立了考虑双电层效应的有限宽组合滑块薄膜润滑数学模型,并利用组合滑块与圆盘的滑动摩擦试验对双电层效应进行研究,利用实验结果修正了润滑过程中双电层效应的计算,给出电粘度的计算公式并进行数值分析.结果表明:在薄膜厚度较薄的情况下,双电层效应使得流体的等效粘度随膜厚减小而迅速增加;随着膜厚增加,双电层的电粘度效应逐渐减弱;随着电场强度增加,双电层的电粘度效应增加,当电场强度达到一定程度时,双电层的电粘度效应开始减弱.  相似文献   

19.
Anlas  Gunay  Elbeyli  Ozer 《Nonlinear dynamics》2002,30(1):1-28
The nonlinear response of rectangular and square metallic plates subjectto transverse harmonic excitations is studied. The nonlinearitiesoriginate from the use of Von Kármán strains. The method of multiplescales is used to solve the system of differential equationsapproximately. Frequency response curves are presented for both squareand rectangular plates for primary resonance of either mode in thepresence of a one-to-one internal resonance. Stability of steady statesolutions is investigated. Bifurcation points and their types arediscussed.  相似文献   

20.
在自制摩擦磨损试验机上考察了黄铜表面电极电势的变化对氮化硅 /黄铜滑动摩擦副摩擦磨损特性的影响 .结果表明 ,在不同的电势区间内 ,摩擦系数表现出不同的变化趋势 ,特别是在 - 1.4~ - 1.0 V电势区间内摩擦系数表现出可控性 .利用扫描电子显微镜观察发现 ,在摩擦系数可控区摩擦系数有所增大但磨损并未加剧 .根据黄铜在润滑液中的循环伏安曲线可以初步推断 ,在不同的电势区间内 ,电化学反应的不同是引起摩擦系数变化的主要原因  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号