scholarly journals Damage Detection in Different Types of 3D Asymmetric Buildings Using Vibration Characteristics

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Yi Wang ◽  
Ziru Xiang ◽  
Zhenyuan Gu ◽  
Chenhui Zhu ◽  
Wangping Qian
Keyword(s):  
Damage Index ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Reinforced Concrete Structure ◽  
Modal Strain Energy ◽  
Damage Scenarios ◽  
Asymmetric Buildings ◽  
Modal Strain Energy Method ◽  
Modal Flexibility ◽  
Different Types

This paper treats the vibration characteristics of three different types of asymmetric buildings and investigates the feasibility of applying an innovative vibration-based multicriteria approach-based damage index (MCA-DI) technique to detect the damage. This technique combines a modified form of the traditional modal strain energy method (MSEM) developed by decomposing the mode shapes into lateral and vertical components together with a modified form of the modal flexibility method to define a new damage indicator. Lastly, the dynamic behavior of three asymmetric building instances, including a 10-storey L-shaped structure, a 10-storey setback structure, and a 6-storey reinforced concrete structure with an unsymmetrical distribution of columns, was studied under five different damage scenarios. The results showed that despite different vibration characteristics of these three asymmetric buildings, the proposed method was able to accurately and effectively locate all damages and eliminate the confusion when more than one index is simultaneously used by using only the first a few modes.

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.

FEM Free Damage Detection of Beam Structures Using the Deflections Estimated by Modal Flexibility Matrix

2021 ◽  
pp. 2150128
Author(s):  
Wen-Yu He ◽  
Wei-Xin Ren ◽  
Lei Cao ◽  
Quan Wang
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Damage Index ◽  
Element Model ◽  
Mode Shapes ◽  
Beam Structures ◽  
Flexibility Matrix ◽  
Damage Quantification ◽  
Modal Flexibility ◽  
The Cost

The deflection of the beam estimated from modal flexibility matrix (MFM) indirectly is used in structural damage detection due to the fact that deflection is less sensitive to experimental noise than the element in MFM. However, the requirement for mass-normalized mode shapes (MMSs) with a high spatial resolution and the difficulty in damage quantification restricts the practicability of MFM-based deflection damage detection. A damage detection method using the deflections estimated from MFM is proposed for beam structures. The MMSs of beams are identified by using a parked vehicle. The MFM is then formulated to estimate the positive-bending-inspection-load (PBIL) caused deflection. The change of deflection curvature (CDC) is defined as a damage index to localize damage. The relationship between the damage severity and the deflection curvatures is further investigated and a damage quantification approach is proposed accordingly. Numerical and experimental examples indicated that the presented approach can detect damages with adequate accuracy at the cost of limited number of sensors. No finite element model (FEM) is required during the whole detection process.

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.

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.

Damage Detection of Wood Beams Using the Modal Flexibility Curvatures

2012 ◽  
Vol 538-541 ◽  
pp. 1815-1820
Author(s):  
Chuan Shuang Hu ◽  
Wei Wen ◽  
Hong Yun
Keyword(s):  
Modal Testing ◽  
Mode Shapes ◽  
Damage Scenarios ◽  
Statistical Algorithm ◽  
Wood Construction ◽  
Modal Flexibility ◽  
Wood Beams ◽  
Before And After ◽  
Damage Indicators ◽  
Axial Moment

Local damages such as knots, decay, and cracks can be translated into a reduction of service life due to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and detect damage at the earliest possible stage to avoid the future catastrophic failure. In this study, modal testing was conducted on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract the damage indicator by computing the modal flexibility curvature before and after damage in timbers. Different damage severities, damage locations, and double damages were simulated by removing mass from intact beams to verify the algorithm. The results have shown that the proposed statistical algorithm is effective and suitable to the designed damage scenarios. The proposed algorithm can qualitatively identify the damage existence and its location although there is no linear correlation between damage indicators and damage severities. The peak values of the damage indicators increase when the losses of the second axial moment of area increases. It is also reliable to detect multiple damages.

Network-Conscious Damage Tracing Method for Beam Structures Based on Measurements Acquired by Distributed MEMS Gyroscopes

Aerospace ◽  
2004 ◽  
Author(s):  
Arata Masuda ◽  
Akira Sone
Keyword(s):  
Damage Index ◽  
Mode Shapes ◽  
Beam Structures ◽  
Vibratory Gyroscopes ◽  
Damage Indices ◽  
Mode Separation ◽  
Modal Flexibility ◽  
Mems Gyroscopes ◽  
Evaluation Algorithm ◽  
Tracing Method

The aim of this conceptual paper is to develop a damage tracing method to detect and track the evolution of structural damages in aerospace structures, in particular, large beam structures, considering the applicability in a decentralized computing environment of wireless sensor networks. We first present a modal flexibility-based damage indices that have simple and intuitive physical interpretation. Since the damage indices are computed using angular mode shapes of the lowest several modes, vibratory gyroscopes are adopted as the sensing device in this approach. The damage evaluation algorithm is then modified to a decentralized form, which is to be implemented as the local computation of mode separation at each sensor unit and the global computation of the damage index at the central monitoring station. Some illustrative experiments simulating both stationary damages and sudden damages are conducted to show that the proposed method is capable to indicate the location of the damages and the time when they occur.

Assessment of Modal Strain Energy Method: Advantages and Limitations

2012 ◽  
Author(s):  
Hasan Koruk ◽  
Kenan Y. Sanliturk
Keyword(s):  
Mode Shape ◽  
Energy Method ◽  
Strain Energy ◽  
Reference Method ◽  
Mode Shapes ◽  
Complex Eigenvalue ◽  
Modal Strain Energy ◽  
Modal Strain Energy Method ◽  
Shape Complexity ◽  
Strain Energy Method

The Modal Strain Energy Method (MSEM) is widely used in practice for the prediction of damping levels in structures. MSEM is based on a fundamental assumption that the damped and the undamped mode shapes of a structure are identical. Therefore, when MSEM is to be used, it is essential to ensure that this assumption is an acceptable assumption. However, detailed information on the accuracy of the method as a function of the system parameters including modal (or mode shape) complexity is quite limited. In this paper, the performance of MSEM is assessed in terms of the damping levels of the structure, proportionality of damping distribution and/or the modal complexity. To do so, an effective finite element based MSE approach is proposed first. Then, a proportionally damped structure with different damping levels is modeled and the performance of MSEM is assessed as a function of the structural damping level. After that, a non-proportionally damped structure is studied in order to examine the performance of the method with respect to mode shape complexity. In all cases, a more accurate reference method, based on complex eigenvalue approach, is used for comparison purposes. Furthermore, a few definitions of mode shape complexity are utilized in order to quantify the mode shape complexity. The results show that as long as the mode shapes are real or close to being real, MSEM can predict the damping levels as well as the natural frequencies of a damped structure with good accuracy. However, the accuracy that can be achieved with MSEM decreases as mode shape complexity increases.

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