Modal Strain Energy based Crack Inspection in Mono Composite Leaf Spring

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.

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Looseness localization for bolted joints using Bayesian operational modal analysis and modal strain energy

Advances in Mechanical Engineering ◽

10.1177/1687814018808698 ◽

2018 ◽

Vol 10 (11) ◽

pp. 168781401880869 ◽

Cited By ~ 3

Author(s):

Yu-Jia Hu ◽

Wei-Gong Guo ◽

Cheng Jiang ◽

Yun-Lai Zhou ◽

Weidong Zhu

Keyword(s):

Modal Analysis ◽

Strain Energy ◽

Damage Index ◽

Operational Modal Analysis ◽

Modal Identification ◽

Bolted Joints ◽

Mode Shapes ◽

Bolted Connections ◽

Modal Strain Energy ◽

Beam Structures

Bayesian operational modal analysis and modal strain energy are employed for determining the damage and looseness of bolted joints in beam structures under ambient excitation. With this ambient modal identification technique, mode shapes of a damaged beam structure with loosened bolted connections are obtained based on Bayesian theory. Then, the corresponding modal strain energy can be calculated based on the mode shapes. The modal strain energy of the structure with loosened bolted connections is compared with the theoretical one without bolted joints to define a damage index. This approach uses vibration-based nondestructive testing of locations and looseness of bolted joints in beam structures with different boundary conditions by first obtaining modal parameters from ambient vibration data. The damage index is then used to identify locations and looseness of bolted joints in beam structures with single or multiple bolted joints. Furthermore, the comparison between damage indexes due to different looseness levels of bolted connections demonstrates a qualitatively proportional relationship.

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A Two Step Damage Prognosis Method for Beam-Like Truss Structures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.578-579.1092 ◽

2014 ◽

Vol 578-579 ◽

pp. 1092-1095

Author(s):

Hao Kai Jia ◽

Ling Yu

Keyword(s):

Finite Element Method ◽

Strain Energy ◽

Truss Structure ◽

Truss Structures ◽

Second Step ◽

The Finite Element Method ◽

Modal Strain Energy ◽

Damage Prognosis ◽

Modal Curvature ◽

Simulation Results

In this study, a two step damage prognosis method is proposed for beam-like truss structures via combining modal curvature change (MCC) with modal strain energy change ratio (MSECR). Changes in the modal curvature and the elemental strain energy are selected as the indicator of damage prognosis. Different damage elements with different damage degrees are simulated. In the first step, the finite element method is used to model a beam-like truss structure and the displacement modes are got. The damage region is estimated by the MCC of top and bottom chords of a beam-like truss structure. In the second step, the elemental MSECR in the damage region is calculated and the maximum MSECR element is deemed as the damage element. The simulation results show that this method can accurately locate the damage in the beam-like truss structure.

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