Papers by Keyword: Vibration Test

Abstract: In this paper there are presented determination methods of longitudinal elasticity modulus based on processing and analysis of vibration signals which are the results of an impulse from a small rigid ball applied on some samples of hydroxyapatite with discoid form. Hydroxyapatite is a bioactive bioceramics used, usually in implants, rods and screws covering, in order to allow human tissue to adhere to implant surface. In order to improve mechanical properties of hydroxyapatite it is doped with magnesium. This chemical element exists in normal bone tissue; it doesnt create any compatibility problem and has a stabilizing role in heat treatments stopping undesirable phase transformations.

Abstract: The DGZX - 1425 high-speed milling motorized spindle which is made and designed independently by Hao Zhi electrical and mechanical company in Guangzhou China is made as the research object, the method of establishing numerical simulation model for the spindle units dynamic performances is established, and the design of the spindles structure has been verified reasonable. Modal analysis of the spindle has been completed in ANSYS Workbench to get the first six natural frequencies and mode shapes. Harmonic analysis of the spindle is also completed to obtain the dynamic stiffness at the highest speed. Modal test and vibration test of the assembled spindle are also processed, which have verified the accuracy of the finite element method. The paper has provided a theoretical basis for the motorized spindles design, structural optimization and the improvement of the dynamic performances.

Abstract: Multi-exciter vibration test control system is the core of the multiple shaker vibration test, and multi-exciter vibration test control technology has become the hot point of vibration test field. Based on coherence principles, the coherence of two exciters control system was tested, the introduction of noise signal reduces the control coherence between the response spectrum and partial coherence between response and the corresponding drive signal. By means of increasing the coherence between drive signals, the control coherence between the response spectrum can be raised and control performance of system can be Improved. The above means could provide technical support for multi-exciter vibration test system development.

Abstract: In this paper, a cable reinforcement structure for small scale horizontal axial wind turbines is proposed. Shock-vibration tests were performed on the cable reinforced structure with different parameters of cable installation. The first order frequency of the blade was chosen to represent the stiffness of the blade rotor. According to the results, an optimum location of cable reinforcement exists at around 1/3 length of the wind turbine blade, and the first order frequency of the blade rotor will rise with the tension of the cable in a certain range. Further analysis showed that besides improving the reliability of the wind turbine rotors, the cable reinforcement structure also provides a possibility to use cheaper materials for blade manufacturing and also control the noise level of small scale horizontal axial wind turbines.

Abstract: The 3d model of miter gate has been set up based on skeleton model of Pro/E, and it has been imported into ANSYS Workbench module for static structure analysis and modal analysis. In the process of finite element simulation, the rotational constraints has been imposed on the top and bottom pivot according to the actual operation situation of the miter gate, and obtain the first several order frequencies and corresponding modal vibration mode of the miter gate, which can show the hydrodynamic vibration stress and strain distribution. According to the results of the finite element simulation analysis, the prototype vibration test of the miter gate has been done. The test results show that the vibration amplitude and the stress and strain distribution of each part of the miter gate are corresponding to the vibration test.

Abstract: This paper deals with effects of damage on Carbon FRP (CFRP) elements subjected both to defects and micro-cracking due to static tensile loading through an investigation of CFRP elements under natural vibration tests. The correlation between the response and frequency decrease due to damage for cross section reduction of CFRP cantilever beam elements has been analysed. Successively, the response of CFRP subjected to different values of tensile force has been investigated; experimental frequency values are compared with theoretical values and discussed.

Abstract: This paper devotes to vibration test based on digital videometrics. The new non-contact measuring technology has good dynamic performance and high accuracy. It is applied to the suspension cable of an indoor scaled model of FAST telescope and successfully gets the identified modal parameters such as natural frequency and damping ratio. Special focus is put on the principle of digital videometrics and the testlayout. Besides, the related signal processing before parameter identification is also discussed.

Abstract: In order to overcome the disadvantages of traditional instrument for performance test of vibration damper, a power dissipation characteristic measurement system based on virtual instrument was developed. A fully digital test platform was constructed through the use of modular and networked data acquisition equipment. Real-time display and automatic analysis of various measuring parameters were realized. The system has higher efficiency than traditional instrument. Moreover, it is easy to expand base on this existing modular system for further testing requirement.

Abstract: The inconsistency of the projectile's seizing-bore stroke of the large caliber gun during feeding process will lead to differences of the volume of propellant chamber and starting pressure of projectiles.It will also affect guns' muzzle velocity and firing accuracy.In order to improve the positioning accuracy of projectiles in an arm-type autoloader,first of all,high speed photography was used and only to find that there will be vibrations of projectiles in the direction of gravity.The vibrations will consume kinetic energy of the projectile and contribute to inconsistency of the retaining force.By means of analyzing the working mechanism of the rammer,the motion relationship among the parts during ramming process came to clear eventually.Then the position of the exciting source which causes vibrations of the projectile can be determined by analyzing the force situation of the rammer in the stationary state and the state of motion,and next,testing the amplitude and frequency of the position using laser displacement sensor.Finally,the improved scheme was raised to eliminate the impact of the vibration on stability of ramming.

Abstract: The increase in the number of electronic and electric systems used in the automotive industry necessitates a high level of electric power. To respond to this high electric power demand, it will be necessary to increase the voltage of the batteries and the current and to use new power connectors. A connector provides a separable interface between two subsystems of an electronic system. The main function of the connector is to transmit a signal or distribute power. For power connectors, heating can lead to an increase in contact resistance and sometimes even to contact surface melting and thus to connector damage. In this study, vibration tests and heat evolution of a commercial power connector used in the automotive industry was undertaken. The connector includes two spring lamellas on each side and the pin is flat. The pin is introduced between the two lamella springs and is submitted to vibration tests. Using an experimental set-up, the mechanical insertion force, the temperature and the resistance evolution can be measured. To quantify these parameters at the contact zone, a numerical modeling, using the finite element software Ansys, is used to give the change of the insertion force during several insertion-extraction cycles and to solve the differential equations for heat transfer in a transitory mode.