Vibration welding of glass-filled poly(styrene-co-maleic anhydride)

Vibration welding is used to assess the weldability of 16 wt% glass-filled poly(styrene-comaleic anhydride) (16-GF-SMA). Data are presented on the strengths of butt welds for two specimen thicknesses and T-welds for one specimen thickness. The maximum weld strength of butt joints is shown to be only 35% of the tensile strength of the material. T-joints are shown to have only 61% of the strength of butt joints. The relative butt-weld strengths of 16-GF-SMA are much lower than those measured in other glass filled resins: 71% in a 20-wt% glass-filled modified poly(phenylene oxide); 68 and 60%, respectively, in 15- and 30-wt% glass-filled grades of poly(butylene terephthalate); and 58% in a 40-wt% glass-filled polyamide 6,6.     

APPLICATION OF FRF ESTIMATOR BASED ON ERRORS.IN-VARIABLES MODEL IN MULTI-INPUT MULTI-OUTPUT VIBRATION CONTROL SYSTEM

The FRF estimator based on the errors-in-variables(EV)model of multi-input multi-output (MIMO)system is presented to reduce the bias error of FRF H1 estimator.The FRF H1 estimator is influenced by the noises in the inputs of the system and generates an under-estimation of the true FRF. The FRF estimator based on the EV model takes into account the errors in both the inputs and outputs of the system and would lead to more accurate FRF estimation.The FRF estimator based on the EV model is applied to the waveform replication on the 6-DOF (degree-of-freedom) hydraulic vibration table.The result shows that it is favorable to improve the control precision of the MIMO vibration control system.     

Method for Detecting Multi-Modal Vibration Characteristics of Landmines

The acoustic vibration characteristics of landmines are investigated by means of modal analysis. According to the mechanical structure of landmines, a certain n...     

Optimal vibration attenuation of an adhesively-bonded cantilevered single-lap joint

In this study the three-dimensional transient vibration attenuation of an adhesively-bonded cantilevered single-lap joint was controlled using actuators. First, the vibration attenuation of the adhesive joint, which was disturbed by applying a concentrated load to the free edge of the lower adherend, was determined without a control force. In order to reduce displacement level and vibration attenuation time, a variable transverse control force was applied to a point on the lower adherend surface using an actuator. The transient variation of the control force was expressed by a periodic function so that the damped vibration of the adhesive joint was decreased. The optimal transient variation of the control force applied by the actuator is an optimization problem requiring the minimization of the objective function including the total elastic strain and kinetic energies, and the actuator work. In addition, the optimum placement of the actuator on the surface of the lower adherend is the second optimization problem. Optimal transient control force history and optimal actuator position were determined using the Open Loop Control Approach and Genetic Algorithm. The peak displacement reduced by 69.6% and the attenuation time decreased by 33%. In addition, the control performance of two actuators was investigated. Thus, the first actuator was located at the optimal position of a single actuator case, and then the optimal transient variations of the control forces applied by both actuators and the optimal position of the second actuator were determined. An additional decrease of 30% in the total energy of the adhesive joint and in the total work of both actuators in comparison to the single actuator case was found, whereas the difference in the vibration attenuation time of the adhesive joint was minor.     

同步提高A／D转换的分辨率和精度

通过外部电路提高Ａ／Ｄ转换的分辨率，必须和提高Ａ／Ｄ转换的精度同步，否则，提高分辨率的意义就非常有限。外部电路不仅会引入误差，还会引起振荡。本文分析了外部电路应具有的精度指标，并给出了一种不会引起振荡的简单方法     

Charpy toughness and microstructure of vibrated weld metal

Abstract

Vibration during welding can be used to obtain certain changes in mechanical properties of weld metal. Research work on the influence of vibration on the secondary microstructure of welds and hence on the Charpy toughness was performed. Vibration during welding exhibits positive effects on the microstructure constituent formation. Multipass welding was simulated with reheating of the original single pass weld in order to obtain similar microstructure to multipass welds. Microstructures were examined with an optical microscope. Additionally, fractographic examination of the rupture of Charpy specimens was performed. Changes in the microstructure according to vibration were observed which affect toughness of the weld metal. Vibration during welding was rated more effective in the case of reheating the weld metal, which is the case in multipass welding.     

ACTIVE VIBRATION SUPPRESSION VIA LINEARIZING HYSTERESIS OF PIEZOCERAMIC ACTUATORS

A novel active vibration control technique on the basis of linearized piezoelectric actuators is presented.An experimental apparatus consisting of a cantilever beam to which are attached strain patches and piezocoramic actuators to be used for active vibration suppression is described.A dy- namical model of the cantilever beam using Lagrange's equation and two coordinate systems are presented.Based on the Lyapunov's direct method,an active vibration controller with hysteresis compensation is designed.The controller is designed so that it guarantees the global stability of the overall system.The controller developed is assessed experimentally.     

Design and Characterization of a Low-Cost Piezoelectric Vibration Energy Harvester with Bulk PZT Film

To improve the efficiency of MEMS piezoelectric vibration energy harvesters(PVEHs), the bulk lead zirconate titanate(PZT) has been used to substitute the thin f...     

Production of Fe based bulk metallic glasses using electromagnetic vibrations

Abstract

It is known that cooling rate from the liquid state is an important factor for producing the bulk metallic glasses. However, little work has been conducted on the influence of other factors such as electric and/or magnetic fields. The authors have previously reported that the glass forming ability of Mg–Cu–Y and Fe–Co–B–Si–Nb alloys is enhanced with increasing electromagnetic vibration force. The present study aims to investigate effect of the electromagnetic vibrations on the crystal particles in Fe–Co–B–Si–Nb bulk metallic glasses. As a result, the electromagnetic vibrations were found to act mainly on decreasing the number of crystal nuclei.     

Precise trajectory control of a redundant flexible manipulator on a space platform

In this paper, we propose a trajectory control method for a redundant flexible space manipulator with slewing and deployable links on a space platform. This method consists manipulator tip position feedback with a transposed Jacobian matrix and local vibration control. We newly derive the Jacobian matrix for a flexible manipulator considering link deformation with the assumed modes method. Simulation results show the effectiveness of this method. We use dynamics consisting of an order N algorithm for N bodies, based on the non-recursive Lagrangian approach, to simulate the dynamics of an orbiting manipulator with an arbitrary number of slewing and deployable flexible links.