Papers by Keyword: Dynamic Response

Paper TitlePage

Authors: Yang Bo Guo, Zhi Ping Tang
Abstract: Shock-induced phase transition under intensive impact loading can strongly change the dynamic behavior of materials and wave propagation features. Dynamic constitutive modeling is one of the key problems in this area. We established a 3D dynamic incremental constitutive equation of phase transition with N transforming phases considering pressure, shear stress and temperature based on the Gibbs free energy. We also proposed an evolution equation for the product phase taking account both the over driving force and the growing space. The dynamic stress-strain response predicted by the model for TiNi specimen undergoing martensitic transition fitted the experimental result well, which demonstrates the present model can describe the dynamic deformation behavior of materials during phase transition process under impact loading.
422
Authors: Joanna Dulinska
Abstract: The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.
1324
Authors: Joanna M. Dulinska, Anna Galuszka
Abstract: The paper indicates the role of 3D modeling of concrete gravity dams in evaluation of dynamic response of dams to mining tremors which occur in mining activity regions. 2D and 3D models of a concrete gravity dam were prepared in order to compare two-and three-dimensional analysis of the dynamic response of dam to mining shock. Firstly, values of natural frequencies obtained for 2D and 3D models occurred to be very similar, but only the 3D model allowed to predict the dam behaviour under longitudinal kinematic excitation. Secondly, the comparison of the maximal principal stresses obtained for 2D and 3D models indicates that the simplified 2D analysis underestimates the values of dynamic response on about 20 %. Three-dimensional dynamic analysis allows to assess internal stresses resulting from mining shock more precisely, since the amplitudes of ground vibrations during mining tremors are comparable in three directions.
2015
Authors: Wei Min Wang, Feng Gang Tao, Jian Fei Zhang, Jun Yao
Abstract: A new hexagonal actuator arrangement continuous face-sheet MEMS deformable mirror is proposed, a mirror array with 19 elements is fabricated by a surface micromachining process. This design has a good fitting capability and a fast dynamic response. The fabricated sample is tested by an optical profiler. Simulation and test results indicate that it has a small aperture size, a high fill factor, a fast response time and a high working bandwidth. This new device provides a possibility of manufacturing a large-actuator-count DM for high speed wavefront control.
169
Authors: Gui Xi Jia, He Jiang
Abstract: To improve the disadvantage of DC-DC converter output voltage fluctuation when output current changes in wide range, a compensation circuit for improving DC-DC converter dynamic response was presented. The circuit was based on the theory of parallel or anti-parallel capacitor. A charged capacitor was paralleled when output current positive jumped. A charged capacitor was anti-paralleled when output current negative jumped. It worked when output current changed. So DC-DC converter dynamic response was improved and efficiency could be high in the same time. The simulation results proved that the effect of compensation circuit in improving the converter dynamic response and stabilizing the output voltage.
3133
Authors: Hui Lan Ren, Ping Li
Abstract: The dynamic response of polycrystalline alumina were investigated in the pressure range of 0-13Gpa by planar impact experiments. Manganin gauges were employed to obtain the stress-time histories. From the free surface particle velocity profiles indicate the dispersion of the “plastic” wave for alumina. Using path line principle of Lagrange Analysis the dynamic mechanical behaviors for alumina under impact loading are analyzed, such as nonlinear, strain rate dependence, dispersion and declination of shock wave in the material. A damage model applicable to ceramics subjected to dynamic compressive loading is developed. The model is based on the damage micromechanics and established on wing crack nucleation and growth. The results of the dynamic damage evolution model are compared to the experimental results and a good correlation is obtained.
289
Authors: Hui Cui Chen, Pu Cheng Pei
Abstract: An equivalent circuit model of the PEM fuel cell is built to study the voltage dynamic response during load change. A mathematical model is built to simulate the voltage response during load change. The simulation results fit the test results very well. Then the model is applied to predict the limiting operation condition of the fuel cell. The model also provides a reference to design PEM fuel cell control modes.
194
Authors: Jun Liao, Da Fu Xu, Bing Yan Jiang
Abstract: A numerical procedure to compute the mean and covariance matrix of the random response of stochastic structures modeled by FE models is presented. With the help of Gegenbauer polynomial approximation, the calculation of dynamic response of random parameter system is transformed into an equivalent certainty expansion order system's response calculation. Non-stationary, non-white, non-zero means, Gaussian distributed excitation is represented by the well-known Karhunen-Loeve (K-L) expansion. The Precise Integration Method is employed to obtain the K-L decomposition of the non-stationary filtered white noise random excitation. A very accurate result is obtained by a small amount of K-L vectors with the vector characteristic of energy concentration, especially for the small band-width excitation. Correctness of the method is verified by the simulations.
119
Authors: Rong Qiao Wang, Wu Lin Si, Dian Yin Hu
Abstract: A method for computing dynamic response considering joint dry friction has been developed based on equivalent linearization and micro-slip model. Computational simulation model was established by linking corresponding contact nodes with Matrix27 elements which simulate additional stiffness and damping effects on structure caused by dry friction nonlinear force. Equivalent stiffness and damping coefficient formula was deduced to calculate real constants of Matrix27 elements. An iterative program was created to compute maximum slip displacements of Coulomb contact nodes on interface and dynamic response and vibration stress were calculated then. An experimental verification has also been carried out which testified the accuracy of the method. Evidently attenuation of vibration is revealed which certifies the effectiveness of joint dry friction damper. Better attenuation effect occurs when exciting frequency is nearer natural frequency.
152
Authors: Qi Li, Wei Rong Chen, Zhi Xiang Liu, Shu Kui Liu, Wei Min Tian
Abstract: A nonlinear model of proton exchange membrane fuel cell (PEMFC) based on an adaptive neuro-fuzzy inference system (ANFIS) is proposed to study different operational conditions effect on the dynamic response of Ballard 1.2kW Nexa power module. A hybrid learning algorithm combining back propagation (BP) and least squares estimate (LSE) is adopted to identify the parameters of input and output membership functions for the improvement of training efficiency in the ANFIS. The comparisons with the experimental data demonstrate that the obtained ANFIS model can efficiently approximate the dynamic output response of Nexa power module and is capable of predicting dynamic performance in terms of stack output voltage with a high accuracy.
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Showing 1 to 10 of 445 Paper Titles