Research on Feasibility and Applicability of Delamination Localization Methods for Composite Laminated Beams

2014 ◽  
Vol 599-601 ◽  
pp. 92-95
Author(s):  
Hang Ma ◽  
Ping Lu ◽  
Tao Jiang ◽  
Sheng Feng Shi ◽  
Jian Bin Wei ◽  
...  
Keyword(s):  
Strain Energy ◽  
Damage Index ◽  
Energy Difference ◽  
Laminated Beams ◽  
Modal Strain Energy ◽  
Laminated Beam ◽  
Modal Strain Energy Method ◽  
Response Method ◽  
Strain Energy Ratio ◽  
Delamination Damage

The feasibility and applicability of delamination damages localization methods with various defined damage indexes for the damaged composite laminated beam were studied. The results indicate that, for the modal strain energy method, damage indexes defined by strain energy difference are more effective to locate the delamination damage than that of strain energy ratio. For energy response method, damage index defined by the second difference can effectively locate the delamination damage in the composite laminated beams.

Nondestructive Damage Detection of Two Dimensional Plate Structures Using Modal Strain Energy Method

2008 ◽  
Vol 24 (4) ◽  
pp. 319-332 ◽  
Author(s):  
H.-W. Hu ◽  
C.-B. Wu
Keyword(s):  
Energy Method ◽  
Strain Energy ◽  
Damage Index ◽  
Mode Shapes ◽  
Two Dimensional ◽  
Plate Structures ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Before And After ◽  
Strain Energy Method

AbstractA nondestructive detection method of surface cracks in two dimensional plate structures using modal strain energy method is investigated in this paper. Experimental modal analysis (EMA) is conducted on an aluminum alloy 6061 thin plate to obtain the mode shapes before and after damage under a completely free boundary condition. The measured mode shapes are used to compute the strain energy of the plate. Limited by the measured points, a differential quadrature method is employed to compute the partial differential terms in strain energy formula. A damage index is then defined based on strain energy ratio of the plate before and after damage. This damage index is employed to identify the location of surface crack in plate structure. A finite element analysis (FEA) is also performed to access this approach and demonstrate a feasible process for the experimental work. Good correlation between FEA and EMA results is obtained. The damage index obtained from both FEA and EMA successfully identify the location of surface crack in the aluminum plate. Only few measured mode shapes of the plate are required in this method, which provides a quick, flexible, inexpensive and nondestructive technique to identify the damagein local and global 2D plate structures.

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

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880869 ◽  
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.

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.

Damage Modes Detection of Composite Laminates Using Improved Modal Strain Energy Method

2011 ◽  
Vol 338 ◽  
pp. 375-379
Author(s):  
Jia Hui ◽  
Xiao Peng Wan ◽  
Mei Ying Zhao
Keyword(s):  
Composite Laminates ◽  
Strain Energy ◽  
Composite Laminate ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Damage Index ◽  
Qualitative Description ◽  
Mode Shapes ◽  
Modal Strain Energy ◽  
Damage Level

Damage causes changes in structural parameters, which in turn, modify dynamic properties, such as natural frequencies and mode shapes. Based on this assumption, this paper presents a new approach to detect different damage modes of composite laminates. Finite element modal analysis is performed on the composite laminate to obtain the modal mode shapes used to compute the modal strain energy. Consequently, an improved damage index is defined by using the ratio of modal strain energies of composite laminates before and after damage. The proposed method is validated using a numerical simulation of a composite laminate with damages in some elements, which are simulated by reducing elements’ material stiffness properties under a combined material properties degradation rule. The result shows that six kinds of damage modes of composite laminates can be detected by this method preferably and give a qualitative description for the damage level.

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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