scholarly journals Vibration Analysis of Viscoelastically Damped Sandwich Shells

1996 ◽  
Vol 3 (6) ◽  
pp. 403-417 ◽  
Author(s):  
Ji-Fan He ◽  
Bang-An Ma
Keyword(s):  
Asymptotic Solution ◽  
Strain Energy ◽  
Natural Frequencies ◽  
Governing Equations ◽  
Modal Strain Energy ◽  
Simply Supported ◽  
Modal Strain Energy Method ◽  
Sandwich Shells ◽  
Method Accuracy ◽  
Loss Factors

The simplified governing equations and corresponding boundary conditions of vibration of viscoelastically damped unsymmetrical sandwich shells are given. The asymptotic solution to the equations is then discussed. If only the first terms of the asymptotic solution of all variables are taken as an approximate solution, the result is identical with that obtained from the modal strain energy method. By taking more terms of the asymptotic solution with successive calculations and use of the Padé approximants method, accuracy of natural frequencies and modal loss factors of sandwich shells can be improved. The lowest three or four natural frequencies and modal loss factors of simply supported cylindrical sandwich shells are calculated.

Viscoelastic Damping Calculations Using a p-Type Finite Element Code

1992 ◽  
Vol 59 (3) ◽  
pp. 696-699 ◽  
Author(s):  
C. J. Wilson ◽  
P. Carnevali ◽  
R. B. Morris ◽  
Y. Tsuji
Keyword(s):  
Finite Element ◽  
Strain Energy ◽  
Natural Frequencies ◽  
Computation Time ◽  
Viscoelastic Damping ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Solution Convergence ◽  
Cantilevered Beam ◽  
P Type

Damping factors of viscoelastically damped structures can be calculated using the modal strain energy method, implemented with a sequence of undamped modal analysis computations. There are significant advantages in performing these calculations using p-type finite element codes. These include ease of mesh design, an indicator of degree of solution convergence, modest computation time, and an insensitivity to element aspect ratio. Capitalizing on these advantages an algorithm is defined, which is effective in solving for the natural frequencies and modal loss factors of damped structures. The algorithm is demonstrated using a sandwiched cantilevered beam as an example.

Study on Damage Identification of Simply Supported-Beam Based on Modal Strain Energy Method

2014 ◽  
Vol 578-579 ◽  
pp. 1204-1207
Author(s):  
Yong Qiang Gu ◽  
Chun Feng Mao
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Damage Identification ◽  
Energy Index ◽  
Modal Strain Energy ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Modal Strain Energy Method ◽  
Analysis Of Results ◽  
Strain Energy Method

In present study, ANSYS finite element method was utilized to analyze the modal of simply supported beam and then the study on damage identification was performed based on modal strain energy method. The comparative analysis of results obtained by modal strain energy changes rate method and modal strain energy index demonstrates that modal strain energy index is an effective damage identification parameter.

Analysis of Modal Parameters of Adhesively Bonded Double-Strap Joints by the Modal Strain Energy Method

1993 ◽  
Author(s):  
Mohan D. Rao ◽  
Krishna M. Gorrepati
Keyword(s):  
Strain Energy ◽  
Natural Frequencies ◽  
Structural Parameters ◽  
Flexural Vibration ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Adhesively Bonded ◽  
Modal Strain Energy ◽  
Joint System ◽  
Damping Material

Abstract This paper presents the analysis of modal parameters (natural frequencies, damping ratios and mode shapes) of a simply supported beam with adhesively bonded double-strap joint by the finite-element based Modal Strain Energy (MSE) method using ANSYS 4.4A software. The results obtained by the MSE method are compared with closed form analytical solutions previously obtained by the first author for flexural vibration of the same system. Good agreement has been obtained between the two methods for both the natural frequencies and system loss factors. The effects of structural parameters and material properties of the adhesive on the modal properties of the joint system are also studied which are useful in the design of the joint system for passive vibration and noise control. In order to evaluate the MSE and analytical results, some experiments were conducted using aluminum double-strap joint with 3M ISD112 damping material. The experimental results agreed well with both analytical and MSE results indicating the validity of both analytical and MSE methods. Finally, a comparative study has been conducted using various commercially available damping materials to evaluate their relative merits for use in the design of these joints.

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.

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