A Modified MSE Method for Viscoelastic Systems: A Weighted Stiffness Matrix Approach

1995 ◽  
Vol 117 (2) ◽  
pp. 226-231 ◽  
Author(s):  
B.-G. Hu ◽  
M. A. Dokainish ◽  
W. M. Mansour
Keyword(s):  
Stiffness Matrix ◽  
Strain Energy ◽  
Real Eigenvalue ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Damped System ◽  
Modal Damping ◽  
Weighted Matrix ◽  
Error Index

The conventional Modal Strain Energy method (MSE is briefly discussed. Several indices are proposed to characterize a viscoelastically damped system. An Overall Error Index is proposed to assess the accuracy of the solution. A Modified MSE method is developed for a better evaluation of modal damping. Instead of neglecting the damping stiffness matrix in the determination of the eigenvectors, as is the case in the conventional MSE method, the authors used a weighted matrix to solve a real eigenvalue problem. With such modification the estimation of the modal damping is often improved. Numerical simulation of multi degree-of-freedom systems are reported using the proposed Modified MSE method and the indices.

scholarly journals Effect of lamination schemes on natural frequency and modal damping of fiber reinforced laminated beam using Ritz method

2021 ◽  
Vol 12 ◽  
pp. 15
Author(s):  
Somi Naidu Balireddy ◽  
Pitchaimani Jeyaraj ◽  
Lenin Babu Mailan Chinnapandi ◽  
Ch V.S.N. Reddi
Keyword(s):  
Natural Frequency ◽  
Ritz Method ◽  
Laminated Composite ◽  
High Strength ◽  
Fiber Reinforced ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Modal Damping ◽  
Method Effects ◽  
Thin Beams

The current study focussed on analysing natural frequency and damping of laminated composite beams (LCBs) by varying fiber angle, aspect ratio, material property and boundary conditions. Ritz method with displacement field based on the shear and normal deformable theory is used and the modal damping is calculated using modal strain energy method. Effects of symmetric angle-ply and cross-ply, anti symmetric cross-ply, balanced and quasi-isotropic lay up schemes on modal damping are presented for the first time. Results revealed that influence of lay-up scheme on natural frequencies is significant for the thin beams while the modal damping of the thin beams are not sensitive to lay-up scheme. However, the lay-up scheme influences the damping significantly for the thick beams. Similarly, high strength fiber reinforced LCBs have higher natural frequency while low strength fiber reinforced LCBs have higher damping due to the better fiber-matrix interaction.

Infrastructure Sustainability

2011 ◽  
pp. 186-201
Author(s):  
Hoi Wai Shih ◽  
David Thambiratnam ◽  
Tommy Chan
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Health State ◽  
Modal Strain Energy ◽  
Structural Health ◽  
Modal Strain Energy Method ◽  
Modal Flexibility ◽  
Before And After ◽  
Composite Bridges ◽  
Strain Energy Method

Assessing the structural health state of urban infrastructure is crucial in terms of infrastructure sustainability. This chapter uses dynamic computer simulation techniques to apply a procedure using vibration-based methods for damage assessment in multiple-girder composite bridges. In addition to changes in natural frequencies, this multi-criteria procedure incorporates two methods, namely, the modal flexibility and the modal strain energy method. Using the numerically simulated modal data obtained through finite element analysis software, algorithms based on modal flexibility and modal strain energy change, before and after damage, are obtained and used as the indices for the assessment of structural health state. The feasibility and capability of the approach is demonstrated through numerical studies of a proposed structure with six damage scenarios. It is concluded that the modal strain energy method is capable of application to multiple-girder composite bridges, as evidenced through the example treated in this chapter.

Influence of Sandwich Damping on the Loss Factor of Multi-Plies Bellows

2010 ◽  
Vol 44-47 ◽  
pp. 2998-3002 ◽  
Author(s):  
Wei Ma ◽  
Yong Chao Lu ◽  
Yong Gang Liu ◽  
Ji Shun Li ◽  
Yu Jun Xue
Keyword(s):  
Finite Element ◽  
Loss Factor ◽  
Strain Energy ◽  
Vibration Isolation ◽  
Mechanical Performance ◽  
Finite Element Models ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Thin Walled ◽  
Strain Energy Method

Multi-plies bellows is a kind of cylindrical thin-walled container with curved shape. It is effective in seal, energy storage and vibration isolation. In the paper, the modal loss factor of multi-plies bellows was analyzed based on the modal strain energy method. Then the finite element models of multi-piles bellows were given by ANSYS. The mechanical performance of bellows was analyzed in detail. The strain energy distribution of multi-plies bellows and viscoelsticity layer were given. According to the strain energy, the influence of sandwich damping on the loss factor was studied. The results show that the loss factor can be improved by employing the sandwich damping with big thickness and elastic modulus 200MPa.

Research on Detection of Distribution and Collision of Wireless Sensor Nodes Based on Radio-Frequency Technique

2014 ◽  
Vol 602-605 ◽  
pp. 2089-2092
Author(s):  
Jin Cheng Zhou ◽  
Zhen Yang
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Large Scale ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Detection Accuracy ◽  
Structural Components ◽  
Modal Strain Energy ◽  
Wireless Sensor Nodes ◽  
Modal Strain Energy Method

many factors need to be considered in layout and distribution of wireless sensor nodes; in addition to the general features of common monitoring sensors, such as economic factors, environmental factors, detection accuracy factor, etc, some particular features should be fully considered, such as intensity, large-scale rapid layout, early warning and monitoring of critical structural components and important areas, as well as its redundancy. Basing on the Modal Energy Method, the paper proposes an optimal sensor layout algorithm available in improvement of modal strain energy method, and such the method is simple and quick, with certain practical value.

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