共查询到20条相似文献，搜索用时 31 毫秒
1.
Considering the relationships of coupling movement and compatible displacement among bonding layer, piezoelectric layer, damping layer, and base structure, a finite element dynamic model of coupled systems for vibration reduction plates is established. The model combined with piezoelectric theory, finite element theory and ADF model of viscoelastic damping material can be suitable for vibration model of complex SCLD structure. The dynamics parameters for clamped-clamped steel plate with partially treated smart constrained layer damping are obtained by theoretical calculation, ANSYS modal analysis and modal experiment. The results show that theoretical values are closer to the test results and ANSYS analysis, and the methods proposed is more accurate and effective. 相似文献
2.
It is difficult to obtain the globe optimum solution by applying conventional sizing and geometrical optimization methods. Evolutionary topology optimization is conducted for the lower stable of a hydraulic press using a bi directional evolutionary structure optimization (BESO) method based on ratio of stress changes, and the evolutionary history and index are analyzed. The presented algorithm obtains the simultaneous optimization on both geometry and topology, and a new topology of the lower stable of the press is evolved which possesses a reasonable topological structure. The results of finite element analysis show that the new structure has decreased maximum stress, uniform stress distribution and good material usage. 相似文献
3.
The accuracy of modal parameters identification has the influence on the quality of dynamic characteristics analysis of mechanical structure directly. And the precision of the frequency response function estimation has the great influence on the accuracy of modal parameters identification. In the engineering the frequency response function can be estimated by the average power spectrum and cross-power spectrum with the hel Pof FFT. As the result of limited frequency resolution in the course of FFT and the noise, the accuracy of modal parameters identification is influenced by the frequency response function estimation. This paper has put forward a least-square-based optimization of frequency response function estimation in modal parameters identification. According to the optimized frequency response function, the peak value can be searched to identify the damped natural frequencies and damping ratio directly. An experiment has been made to validate the proposed method. The result indicates that the damped natural frequencies and damping ratio identified by the optimized frequency response function are closer to the true results than which without the optimized frequency response function. So the accuracy of modal parameters identification can be improved by adopting the proposed method. 相似文献
4.
Based on the modal assurance criterion, using simulated annealing algorithm, the dynamic characteristic data of cable-stayed bridge are extracted, optimal acceleration sensor layout scheme of main beam is obtained. According to this optimization scheme, we carry out a dynamic characteristics test on one cable-stayed bridge. The results between test data and finite element modal calculation are very closely. Theory technique research and field modal test demonstrated that the simulated annealing algorithm based on modal assurance criterion is effective and viable for optimal acceleration sensors placement of cable-stayed bridge. 相似文献
5.
The design method of parameter optimization of nonlinear viscous dampers for dissipation structure was analyzed based on response surface methods. The method included experimental design, finite element analysis, fitting the response surface function and parameter optimization. Taking a reinforced concrete frame structure for an instance, the mathematical model of parameter optimization of viscous dampers for dissipation structure was established by taking the minimum all damping force as objective function and taking the interlayer maximum displacement less than limits as constraints, and then the damper parameters were optimized using the method of nonlinear programming optimization. The results show that the method of parameter optimization of viscous dampers based on response surface method can ensure the structural displacement is less than limit and the construction cost can be reduced. 相似文献
6.
The mountain hazards like snow avalanches, landslides, rock falls, debris flows and so on all have strong power of destruction which seriously threaten human’s lives and belongings. Therefore, it is necessary to study more the development of these disasters in order to prevent them. Setting up obstacles is the primary measure to control the movement and deposition process of mountain hazards. For the study of the influence of this measure on the development of disasters, the numerical simulation calculation aiming at the flow and deposition process of the granulars flowing past different built obstacles was made by the theory of SH granular flow and the method of finite volume discretization based on Roe's Scheme. Futhermore, the influence of different settings of obstacles on the granular flow is discussed. The numerical results show that the settings of obstacles have a great effect on the process of granular flow. That is, the effective precaution against the disasters is no other than setting up the obstacles correctly. As the numerical simulation calculation can optimize the setting of obstacle, it provides a reasonable and economic reference scheme of disaster prevention and planning of mountain area. 相似文献
7.
Dan Bin Xu Mingtao 《保鲜与加工》1990,(3)
In this paper, a-method using the complex modal theory to identify physical parameters of system with viscous damping is discussed. A procedure is present to calculate the mass, clamping, and stiffness matrices from the measured data in time and frequency domains. The double least squares approach is used to identify modal parameters. In identification of physical parameters, the data of different measured point is used in calculation for more accurate results. 相似文献
8.
Zhang Xiangwei Xu Meihe 《保鲜与加工》1991,(2):47-55
A simplified procedure is presented for the determintion of rates of change of frequency response function matrix of system for the non-proportional changeable damping ,by means of the second order perturbation technique in conjunction with complex modal analysis. Consequently, when excitation information in frequency domain is known,the sensitivity of the response power spectra and the response time history can be obtained. 相似文献
9.
The drawing process of the front side panel of autobody is simulated by using the finite element software, Dynaform. The drawing surface is designed, focusing on the optimization of the addendum and the drawbead layout. By comparing the stress/strain conditions and the FLD in two types of addendum (stepped and slope) and three types of drawbead layout (closed, discontinuous and oblique drawbead), the slope addendum is chosen as the optimized addendum and the oblique drawbead is chosen as the optimized drawbead layout. The simulation results show the material flow in the corner and the quality of the part can be improved effectively with the optimized drawing surface. The optimized parameters are employed in production and acceptable quality parts are produced. Therefore, the optimized drawing surface is verified to be effective. 相似文献
10.
Lei Jiyao Wang Yanchun 《保鲜与加工》1989,(3):8-13
A method is presented in this paper which uses an incomplete set of complex modal parameters identified from the experimental date to modify the structural dynamic model. The method, not requiring iteration and being programed easily,is suitable for the complex structures with general viscous damping in improving the analytical mass, damping and stiffness matrix madel of a structure with a set of minimum changes in the analytical matrics, so as to force the eigensolutions to agree with the test measurement. An example is given to demonstrate the validity of this proposed method. 相似文献
11.
Perturbation Analysis of Complex Modes for Vibration System with Viscous Damping and Its Application
Deng Zhaoxiang Liang Xichang He Yusheng 《保鲜与加工》1997,(2):1-9
The sensitivity characteristics of the undamped natural frequencies and complex mode shapes of vibration system with the non-proportional viscous damping with respect to structural mass, stiffness and damping modifications are analyzed in this paper using the matrix perturbation of complex modes. The general principles for the selectivity of the design and the most sensitive positions of the structural perturbation modifications are shown thereby. This is of importance to a great computational savings in the dynamic characteristic improvement of large or complex structures. By the dynamic characteristic sensitivity analysis of a test device type RDT-1,the optimal structural design for its especial requirement of dynamic characteristics is obtained easily and the principles presented in this paper are confirmed by the numerical results of perturbation analysis. 相似文献
12.
Size, shape and topology optimizations are involved in the structural design of partial single layer reticulated shells. To meet the requirements of computation efficiency during preliminary design, a uniform design method was adopted to achieve multi level optimization. Only existing software packages for reticulated shells were used in the experiment design. By regressing the computing data, approximate functional relations between the indexes (steel weight, deflections, basic frequency, and minimal nonlinear buckling load) and variables (rise of the shell, single layer area, and design stress ratio for single layer members) were obtained. The best combination of the variables was acquired by solving a simple programming problem. Comparative design of a multipoint supported hexagonal reticulated shell verified the efficiency and reliability of this approach. 相似文献
13.
Vibration control of active constrained layer damping structure 总被引：1，自引：0，他引：1
A finite element dynamic model for plates with active constrained layer damping (ACLD) treatments is derived based on the constitutive equations of elastic, viscoelastic and piezoelectric materials by application of Hamilton principle. The closed loop control system considering displacement and velocity feedback of self sensing voltage from sensor layer is developed. The dynamic behaviors of active constrained layer damping (ACLD) plates including nature frequencies, loss factors and responses in frequency domain are investigated. The influence of control gains on vibration suppression is discussed. Numerical examples demonstrate the validity of the finite element model and the control strategy approach. The proposed control strategy can be widely used to structure vibration control with ACLD patches due to its simple scheme and easy implementation. 相似文献
14.
Under multi-support earthquake excitation, the damping is proportional to the relative velocity in relative motion method, While the damping is proportional to the absolute velocity in method of direct solving absolute displacement, and the damping assuming difference may cause the calculation errors on structural responses. The structural response errors of the dynamic component of power spectral density between the two solving methods are derived by random vibration theoretical analysis in Rayleigh damping model, which include damping ratio and the ratio between excitation frequency and fundamental frequency of the structures. Based on probability theory, the variation errors of dynamic component response between the two solving methods are also derived by theoretical analysis, and some numerical examples are provided to verify the error analysis. At last, it is pointed out that the calculation errors between the two solving methods decrease with damping ratio, and it is negligible when the damping ratio of structure is less than 5%. 相似文献
15.
For a ISA HEV,the transmission gear shaft dynamic model is established and the 3-D modal analysis is carfled out. Based on above work, the structure of the gear shaft is analysed, then the diameter of the gear shaft is taken as a design variable. With first order optimization,low inherent frequencies are optimized in order to avoid resonance and decrease NVH. 相似文献
16.
We address damage detection based on dead loads in monitoring the health of beams and bridges. We discuss the damage characteristics of statically indeterminate beams under dead loads and analyze monitoring parameters and sensor placement in monitoring. We used an amended genetic algorithm to solve the optimization problem under constrained parameters. Damage in a beam was detected successfully based on dead loads with limited sensor allocations. We present a way to detect damage based on dead loads in bridge health monitoring. 相似文献
17.
There are three working modes of electro rheological(ER) damper, flow mode of fixed electrode, shear mode of slide electrode, mixer mode of slide electrode. The damping force is analyzed for gas-filled ER damper of flow mode of fixed electrode. There are three sections of damping force, and they are background damping force of a fluid viscosity, electric damping force of applied electric field and pressure of gas. The characteristic of ER damper is adjustable by electric filed strength for electric damping force. At the same time, some structure factors of ER damper are discussed. 相似文献
18.
The finite element model is developed for the multi stage planetary gearbox housing in shield tunnelling machine (STM), and the the eigenvalue problem is solved by using block Lanczos method, and then the low order natural frequencies and corresponding modes are extracted. Based on the theory of experimental modal analysis, the modal testing is made for the gearbox housing by pulse excitation method. The least squares complex frequency domain (LSCF) estimation method is used to analyze the modal data, and the natural characteristics of housing is obtained. According to the modal assurance criterion (MAC), the experimental modal parameters are validated. Modal analysis shows that the experimental data is coincided with analytical results, which indicates the accuracy of the theoretical model and testing method. The coupling sympathetic vibration is disappearing between the gears train and housing, the local vibration is large at the high speed side of gearbox housing, and the torsional mode is outstanding under operating condition. The research results provide theoretical basis and experimental support for the structural optimization of the gearbox of STM. 相似文献
19.
The tuned liquid damper(TLD),as a passive energy dissipation system,has been applied in structural vibration absorption in recent years.In this paper,the achievements in the study on the principle of damping,influencing factors,analysis and design methods are generalized.The trend of the TLD development is discussed.The researches including numerical emulation technology of TLD,non-linearity analysis,research of control-TLD,effect of damping under seismic shock and construction design methods considering the TLD are the future emphases. 相似文献
20.
The two-way branch exhaust pipe shield is the main source of surface radiate noise of a vehicle's engine.(Using) the finite element analysis software ANSYS,a finite element model of the shield is established,and then the(modal) analysis is done theoretically with this model,the result is consistent with the experiment.The result shows that this finite element model can be used for the next structual dynamic characteristics analysis.With this model,the relationship of structural parameter,structural style of the shield and the corresponding vibrative modal is analyzed.The(optimal) improved measures are adopted which is based on the practical structure of the shield.The analysis of the(improved) structure shows that the increase of natural vibration frequency is visible,the vibration noise of the shield is suppressed distinctly. 相似文献