Dynamic Modal Response Analysis of Composite Laminates

1995 ◽  
pp. 2557-2562
Author(s):  
J. Zhu ◽  
A. H. Shah ◽  
S. K. Datta
Keyword(s):  
Composite Laminates ◽  
Response Analysis ◽  
Modal Response

Random Response Analysis for Nonlinear Systems of Composite Laminates

2011 ◽  
Vol 415-417 ◽  
pp. 56-61
Author(s):  
Feng Xiang You ◽  
Fei Zhang ◽  
Buo Lei Zuo
Keyword(s):  
Nonlinear Systems ◽  
Composite Laminates ◽  
Response Analysis ◽  
Random Response ◽  
Random Parameters ◽  
Engineering Structures ◽  
Central Difference ◽  
Central Difference Method ◽  
Random Responses ◽  
Random Nature

Geometric parameters of composite materials often have a random nature in engineering structures. How to study random response and statistical properties of nonlinear systems with random parameters has a very important significance for reliability and optimization of structural design. In this paper, perturbation method and random central difference method are explored to establish composite nonlinear vibration equations and computational model to study random responses of nonlinear systems with random parameters under deterministic loading of the composite laminates, numerical examples illustrate the correctness of the algorithm.

Dynamic Modeling and Stability Analysis of a Dual-Rotor Wind Turbine

2018 ◽  
Author(s):  
Oliver T. Filsoof ◽  
Morten H. Hansen ◽  
Anders Yde ◽  
Xuping Zhang
Keyword(s):  
Wind Turbine ◽  
Dynamic Modeling ◽  
Wind Turbines ◽  
Floquet Theory ◽  
Equations Of Motion ◽  
Response Analysis ◽  
Modal Response ◽  
Asymmetric Rotor ◽  
Modal Property ◽  
Fidelity Model

Various modal analysis methods are available for single-rotor wind turbines, but there is no report and guidance on the modal property analysis of multi-rotor wind turbines. This paper presents a dynamic modeling method for the modal response analysis of a wind turbine with two three-bladed isotropic rotors. The equations of motion are derived using Lagrange’s equations and are further linearized at a steady-state equilibrium. To avoid using Floquet Theory to remove the periodic coefficients, multi-blade coordinates are utilized. Comparison between the numerical simulations and a high-fidelity model in HAWC2 shows agreements in terms of modal frequencies. The results shows that the whirling modes splits into symmetric and asymmetric rotor modes.

scholarly journals Modal response analysis of non-uniform and asymmetric DL under plane-wave illumination

2019 ◽  
Vol 13 (4) ◽  
pp. 553-562
Author(s):  
Jinpeng Yang ◽  
Xiaoying Sun ◽  
Yu Zhao ◽  
Jian Chen ◽  
Tiegang Sun
Keyword(s):  
Plane Wave ◽  
Response Analysis ◽  
Modal Response

Accurate Wind-Induced Response Analysis of Long-Span Structure Based on Quick Modal Response Estimate for Mode Selection

2011 ◽  
Vol 243-249 ◽  
pp. 844-853
Author(s):  
Li Gang Zhang ◽  
Wen Juan Lou ◽  
Ming Feng Huang
Keyword(s):  
Wind Loads ◽  
Induced Response ◽  
Response Analysis ◽  
Frequency Domain Method ◽  
Superposition Method ◽  
Relative Significance ◽  
Similarity Factor ◽  
Long Span ◽  
Mode Superposition Method ◽  
Modal Response

By the combination of POD method and mode superposition method, the eigenvector similarity factor is introduced on the representation of the similarity between the load spacial distribution and the structural mode. Meanwhile, the eigenvalue got from the wind pressure field decomposition indicates the relative ratio of the energy associated with the corresponding load spacial distribution to the total of the wind load energy. It is proved that the eigenvector similarity factor and the eigenvalues are two of most important factors when measuring the relative significance of each modal response. So the quick estimates of the modal responses are provided, which predominates in picking structural modes to obtain wind-induced dynamic response of long-span roof structure with frequency-domain method. Then, by arranging the estimative response of each mode in reduced-order and truncating higher modes to expedite computations, the accurate wind-induced response is calculated by ACQC method, which has taken into account the partial correlation of wind loads and the quad-spectra (imaginary parts of XPSD) of the generalized wind loads. Finally, utilizing the rigid model wind tunnel test data of some large railway station platform, the effectiveness of the scheme proposed is verified.

Modal response analysis of multi-support structures using a random vibration approach

2015 ◽  
Vol 44 (13) ◽  
pp. 2241-2260 ◽  
Author(s):  
Ernesto Heredia-Zavoni ◽  
Sandra Santa-Cruz ◽  
Francisco L. Silva-González
Keyword(s):  
Random Vibration ◽  
Response Analysis ◽  
Support Structures ◽  
Modal Response

Low-Velocity Impact Damage Prediction of Composite Laminates Using Linearized Contact Law

2007 ◽  
Vol 334-335 ◽  
pp. 261-264
Author(s):  
Ik Hyeon Choi
Keyword(s):  
Failure Criterion ◽  
Composite Laminates ◽  
Impact Damage ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Response Analysis ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Impact ◽  
Delamination Area

Recently, author had presented that impact force history of composite laminates subjected to low-velocity impact could be well analyzed using linearized contact law instead of the modified Hertzian contact law. If the linearized contact law concept is applied in impact response analysis, the impact problem can be transformed as a general structural analysis problem, so general purpose FEM software can be used in this kind of impact response analysis. In the present study it will be shown that impact damage, specially delamination area, as well as impact response can be well analyzed using the linearized contact law concept. In order to accurately predict delamination area, geometrical nonlinear analysis considering large deflection effect of plate has been performed and thermal stress analysis to consider thermal residual strain induced in curing process has been performed. Also, a proper failure criterion for delamination estimation has been used. In this failure criterion, in-situ strength values, obtained through matrix crack onset analysis have been used. Finally, analytically predicted delamination areas have been compared with experimental results. It shows that this analytical procedure can well predict delamination area of composite laminates subjected to the low-velocity impact.

Forced Response of a Large Civil Fan Assembly

2008 ◽  
Author(s):  
J. S. Green
Keyword(s):  
Ground Plane ◽  
Time History ◽  
Forced Response ◽  
Operating Conditions ◽  
Response Analysis ◽  
Analysis Tool ◽  
Flow Distortion ◽  
Modal Response ◽  
Engine Order ◽  
Compressor Inlet

Forced response analysis has become commonplace for predicting the vibration amplitude of turbomachinery blading. These analyses are usually limited because they rely on predicting a well defined source of flow distortion, such as blade wakes and shocks etc. However, the sources of excitation of civil fans are not well defined and yet are able to produce high levels of force. The objective of the work described in this paper is to investigate the forced response of a large civil fan assembly using CFD. An unsteady, time accurate, 3D CFD model of the complete low pressure compression system has been used to calculate the modal response of a large civil fan. The mesh consists of the ground plane, intake, fan, OGV, bypass duct and compressor inlet stator, with every aerofoil passage modelled. The analysis tool allows calculation of a time history of modal response for a range of modes simultaneously to provide a description of the overall vibration behaviour. The results of the analyses have been used to investigate the modal contributions to the off-resonant first engine order response at a range of operating conditions to assess the contribution of various geometric features. The response is shown to compare well with measured strain gauge data for both ground and altitude conditions. The response of the majority of resonances was found to be heavily influenced by the presence of the ground plane, which is consistent with the available experimental data.

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