Vibration, Structural Engineering and Measurement I

Volumes 105-107

doi: 10.4028/

Paper Title Page

Authors: Li Chao Xu, Ru Hai Ge
Abstract: Transmission load was one of the important parameters for engineering vehicle powertrain system, on the basis of calculating drive shaft torque values and ascertaining the measurement point positions, we selected resistance strain guages to design torque sensors and also chose a signal telemetry system, after using a self-made torque calibration bench to statically calibrate torque sensors, we developed a test system for loader drive shaft load. According to the given test program, we performed an actual loader experiment to measure torque at the loader drive shaft measurement points and analyzed the test waveforms. The results of bench calibration and actual loader test showed that the designed torque sensors had a high sensitivity and a good linearity, and the developed test system was correct and effective.
Authors: Hao Jie Lv, Guo Qing Hu, Xing Ye Wang
Abstract: In order to reveal the temperature dependence of a touch mode capacitive pressure sensor, temperature dependence of material parameters of the sense have been studied. Using Finite Element Method (FEM) to simulate and solve capacitance, the results show that the relation of capacitance and temperature is almost linear in touch state of the sensor. At the same time, temperature sensitivities under different pressure are slight difference, which are 0.0056pF/K and 0.0040pF/K, respectively. Therefore, the high-temperature performance of the sensor is greatly outstanding.
Authors: Kamal Jahani
Abstract: Resistance spot welding is one of the mostly used methods in joining different pieces of complex sheet metal structures such as automotive BIW. Some manufacturing inaccuracies, accessibility difficulties to some locations and large quantity of spot welds, may lead to missed out substantial number of spot weld connections. In present work, it is tried to find suitable Indexes to detect the locations of omitted spot welds in a structural joint using finite element method and modal analysis. Two different special modal indexes derived that can be used to detect the missed out location of a spot weld in a lap joint of two flat plates. One modal index derived from computations on high range natural frequencies of the structure and the other one was achieved by searching on a special case of MAC values of modal vectors at joint region. Finally, using artificial neural networks and the developed indexes in present work, the location of an absent spot weld in the investigated structure detected successfully.
Authors: Gui Ling Li
Abstract: Datum are the key of “Digital Earth”.In measurement, dealing with nonlinear models of observation datum, we may take their approximate values at observation values by Taylor series expansion, say, taking first-order item as a linear function of classical adjustment. But requirements of observation data, processing and accuracy assessment are higher and higher with today's fast-growing of high-tech mapping and surveying. So study on nonlinear least squares adjustment has been paid more and more attention. Damping least squares, as a modified algorithm of Gauss-Newton’s algorithm, is necessary to add a damping factor to improve the nature of a coefficient matrix. But it is difficult to choose a suitable damping factor, and needs to solve a group of linear equations repeatedly. In this paper, an improved damping least square was utilized for the non-linear processing of measurement datum in order to reduce a lot of computational workload.
Authors: Yu Jie Cui
Abstract: This paper presents a modular robot called RBT-6T/S01SM. This robot composed of 6 basic modules which could composed 5 kinds of robot. Each module owns one rotational degree of freedom. The total combined robot RBT-6T/S01SM features an easy-to-build mechanical structure. A formulation of this robot is educed based on Denevit and Hartenberg in this paper.The kinematics is studied and inverse kinematics is obtained based on algebraic method. The kinematics simulation of RBT-6T/S01SM is presented based on Matlab. The effectiveness of kinematics equations is verified by the simulation results.
Authors: Jin Hua Li
Abstract: NC machine monitoring system is built based on the wireless data acquisition. All kinds of the complicated information can be collected, and the test server can process the information. Some important information can transmit by the network, and the client and web can browse them and feedback to the NC machine. The experiment was done on the system platforms, and basic functions were realized. It provides a new method that it can solve the key problem of the NC machine remote monitoring.
Authors: Xiang Cao, Zhe Feng Yu, Hai Wang
Abstract: A data acquisition (DAQ) system for the low velocity impact tests is presented. The DAQ system is comprised of transducers, DAQ card, personal computer and self-manufactured impact equipment. The whole impact signal acquisition system has capability of sampling time history of contact force and optical signal which is employed to calculate the falling velocity, and it also generates the control signal for the equipment which catches the drop-weight after its rebound. The test data are presented, which shows the proposed DAQ system is applicable to the test setup for low velocity impact damage pre-set of composites in the aircraft structural industries.
Authors: Bin He
Abstract: The study about the direction-of-arrival (DOA) estimation for wideband signals is a basic topic of Signal Processing. The method called test of orthogonality of projected subspaces (TOPS) does not require initial values to form focusing matrix compared with the coherent signal subspace method (CSSM), but it has poor performance for coherent wideband signals at low signal-to-noise ratio (SNR). Based on the lack of the conventional TOPS, this paper reconstructs a set of new matrices with the narrowband correlated matrices coming from the DFT decomposition of the array output and modifies the method frame of the conventional TOPS. So we get a set of reconstructed matrices with full rank corresponding to each frequency bin, and which have no array aperture loss. The improved TOPS can estimate the DOA for coherent wideband sources at low SNR, and enhances the performance of the conventional TOPS. Simulation results show that the improved TOPS is effective, and the total performance of which is similar to the rotational signal-subspace (RSS) method.
Authors: Wen Hou, Peng Fei Xue, Tie Hua Ma
Abstract: A new method and equipment based on compound pendulum was designed for measuring moment of inertia (MOI). The measurement principle of the system, being quite different from the traditional method which records the swing period of the compound pendulum, records the “Angle-time” curve and conducts a series of computation featuring phase-plane to obtain the MOI of the object being measured. The proposed method could effectively eliminate the friction moment’s influence on the measurement results and enhance the precision up to 0.12%. The method is suitable for the heavy and large-scale objects, especially those with large length/diameter ratio.
Authors: Dong Zi Pan, Hai Qian Han, Ying Li
Abstract: Tidal bore is a series of waves propagating upstream as the tidal flow turns to rising. The Qiantang Bore has aroused the curiosity of scientists and tourists all over the world in the past centuries as a strong turbulent bore. We consider here tidal bore impact measurements, recorded in the Qiantang River using pressure transducers. Based on the empirical mode decomposition (EMD) algorithm, a signal processing method for impact test due to the Qiantang Bore is proposed. As a self-adaptive approach, EMD method can be used to decompose the local characteristics of the no-stationary and nonlinear signals into several fluctuations and trend items with different time scales step by step. The separation of the quasi-static and dynamic pressures is conducted by using the empirical mode decomposition method.

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