Assessment of Internal Damage in Sandwich Structures by Post-Processing of Mode Shapes Using Curvelet Transform

Identification and quantification of structural damage is one of the crucial aspects of proper maintenance of mechanical and civil structures, which is directly related to their integrity and safety. The paper presents a novel approach for detecting various types of damage in sandwich structures by processing the mode shapes using a hybrid algorithm based on the curvelet transform and the standardized damage index concept. The proposed approach uses the properties of directional selectivity, absence of the boundary effect, typical of such a class of transforms, and excellent filtration capabilities of the curvelet transform as well as the classification hypothesis in the standardized damage index, which allows the exclusion of irrelevant information and emphasizes proper damage location and shape. The proposed hybrid algorithm allowed to successfully identify a subsurface core damage in sandwich structures, such as local lack of a core or its debonding from facings. The performed quantification study aimed to evaluate the correctness of identified damage shape confirmed the validity and accuracy of the proposed algorithm not only for the damage detection and localization but also for the estimation of the size of structural damage.

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

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455421501285 ◽

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.

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Non-model-based damage identification of plates using measured mode shapes

Structural Health Monitoring ◽

10.1177/1475921716655974 ◽

2016 ◽

Vol 16 (1) ◽

pp. 3-23 ◽

Cited By ~ 18

Author(s):

Yongfeng Xu ◽

Weidong Zhu

Keyword(s):

Structural Damage ◽

Damage Identification ◽

Damage Index ◽

Thickness Reduction ◽

Aluminum Plate ◽

Mode Shapes ◽

Identification Method ◽

Model Based

Mode shapes (MSs) have been extensively used to detect structural damage. This paper presents a new non-model-based damage identification method that uses measured MSs to identify damage in plates. A MS damage index (MSDI) is proposed to identify damage near regions with consistently high values of MSDIs associated with MSs of different modes. A MS of a pseudo-undamaged plate can be constructed for damage identification using a polynomial of a properly determined order that fits the corresponding MS of a damaged plate, if the associated undamaged plate is geometrically smooth and made of materials that have no stiffness and mass discontinuities. It is shown that comparing a MS of a damaged plate with that of a pseudo-undamaged plate is better for damage identification than with that of an undamaged plate. Effectiveness and robustness of the proposed method for identifying damage of different positions and areas are numerically investigated using different MSs; effects of crucial factors that determine effectiveness of the proposed method are also numerically investigated. Damage in the form of a machined thickness reduction area was introduced to an aluminum plate; it was successfully identified by the proposed method using measured MSs of the damaged plate.

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Damage Identification in Collocated Structural Systems Using Structural Markov Parameters

Volume 2: Control, Monitoring, and Energy Harvesting of Vibratory Systems; Cooperative and Networked Control; Delay Systems; Dynamical Modeling and Diagnostics in Biomedical Systems; Estimation and Id of Energy Systems; Fault Detection; Flow and Thermal Systems; Haptics and Hand Motion; Human Assistive Systems and Wearable Robots; Instrumentation and Characterization in Bio-Systems; Intelligent Transportation Systems; Linear Systems and Robust Control; Marine Vehicles; Nonholonomic Systems ◽

10.1115/dscc2013-3758 ◽

2013 ◽

Author(s):

Ramin Bighamian ◽

Hamid Reza Mirdamadi ◽

Jin-Oh Hahn

Keyword(s):

Structural Damage ◽

Damage Identification ◽

Mode Shapes ◽

Structural Systems ◽

Structural System ◽

Computationally Efficient ◽

Markov Parameters ◽

Novel Approach ◽

Stiffness Matrices ◽

Stiffness Characteristics

This paper presents a novel approach to damage identification in a class of collocated multi-input multi-output structural systems. In the proposed approach, damage is identified via the structural Markov parameters obtained from a system identification procedure, which is in turn exploited to localize and quantify damage by evaluating relative changes occurring in the mass and stiffness matrices associated with the structural system. To this aim, an explicit relationship between structural Markov parameters versus mass and stiffness matrices is developed. The main strengths of the proposed approach are that it is capable of quantitatively identifying the occurrence of multiple damages associated with both mass and stiffness characteristics in the structural system, and it is computationally efficient in that it is solely based on the structural Markov parameters but does not necessitate costly calculations related to natural frequencies and mode shapes, making it highly attractive for structural damage detection and health monitoring applications. Numerical examples are provided to demonstrate the validity and effectiveness of the proposed approach.

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Damage Identification in Collocated Structural Systems Using Structural Markov Parameters

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4028786 ◽

2014 ◽

Vol 137 (4) ◽

Cited By ~ 3

Author(s):

Ramin Bighamian ◽

Hamid Reza Mirdamadi ◽

Jin-Oh Hahn

Keyword(s):

Structural Damage ◽

Damage Identification ◽

Mode Shapes ◽

Structural Systems ◽

Structural System ◽

Computationally Efficient ◽

Markov Parameters ◽

Novel Approach ◽

Stiffness Matrices ◽

Stiffness Characteristics

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Novel TQWT Algorithm for Structural Damage Identification

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d8332.118419 ◽

2019 ◽

Vol 8 (4) ◽

pp. 5136-5146

Keyword(s):

Input Signal ◽

Structural Damage ◽

Damage Identification ◽

Damage Index ◽

Identification Problem ◽

Oscillatory Behavior ◽

Mode Shapes ◽

Q Factor ◽

Stiffness Loss ◽

Beam Damage

In this paper tunable Q-factor wavelet transform is implemented into damage identification. Fixed – Fixed beam damage identification problem is demonstrated. Translation and Rotational mode shapes are used as an input signal, the TQWT algorithm depends Q-factor and asymptotic redundancy, when it matches with the oscillatory behavior of the input signal it is tuned. This method decomposes a signal into a high-Q-factor and low-Q-factor component, and it can be used to differentiate the damaged and undamaged mode shapes of the beam structure. TQWT coefficient is used as damage index to locate and quantify the damage. Proposed method evaluated experimentally and results shows TQWT algorithm has a potential to detect even a small damage (10% stiffness loss) present in the structure.

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A novel damage index for damage detection and localization of plate-type structures using twist derivatives of laser-measured mode shapes

Journal of Sound and Vibration ◽

10.1016/j.jsv.2020.115448 ◽

2020 ◽

Vol 481 ◽

pp. 115448

Author(s):

Wei Xu ◽

Weidong Zhu ◽

Maosen Cao ◽

Hao Wu ◽

Ruihu Zhu

Keyword(s):

Damage Detection ◽

Damage Index ◽

Mode Shapes ◽

Detection And Localization ◽

Derivatives Of ◽

Plate Type

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Damage Detection and Localization on Real Structures Subjected to Strong Motion Earthquakes Using the Curvature Evolution Method: The Navelli (Italy) Case Study

Applied Sciences ◽

10.3390/app11146496 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6496

Author(s):

Rocco Ditommaso ◽

Chiara Iacovino ◽

Gianluca Auletta ◽

Stefano Parolai ◽

Felice Carlo Ponzo

Keyword(s):

Damage Detection ◽

Structural Damage ◽

Evaluation Method ◽

Empirical Relationship ◽

Computing Time ◽

Damage Index ◽

Strong Motion ◽

Critical Event ◽

Curvature Variation ◽

Detection And Localization

In recent years, structural health monitoring (SHM) has received increasing interest from both research and professional engineering communities. This is due to the limitations related to the use of traditional methods based on visual inspection for a rapid and effective assessment of structures and infrastructures when compared with the great potential offered by newly developed automatic systems. Most of these kinds of systems allow the continuous estimation of structural modal properties that are strictly correlated to the mechanical characteristics of the monitored structure. These can change as a result of material deterioration and structural damage related to earthquake shaking. Furthermore, a suitable configuration of a dense sensor network in a real-time monitoring system can allow to detect and localize structural and non-structural damage by comparing the initial and a final state of the structure after a critical event, such as a relevant earthquake. In this paper, the modal curvature evaluation method, used for damage detection and localization on framed structures, considering the mode curvature variation due to strong earthquake shaking, is further developed. The modified approach is validated by numerical and experimental case studies. The extended procedure, named “Curvature Evolution Method” (CEM), reduces the required computing time and the uncertainties in the results. Furthermore, in this work, an empirical relationship between curvature variation and damage index has been defined for both bare and infilled frames.

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Baseline-Free Structural Damage Identification for Beam-Like Structures Using Curvature Waveforms of Propagating Flexural Waves

Sensors ◽

10.3390/s21072453 ◽

2021 ◽

Vol 21 (7) ◽

pp. 2453

Author(s):

Y. F. Xu ◽

J. S. Kim

Keyword(s):

Structural Damage ◽

Damage Identification ◽

Damage Index ◽

Mode Shapes ◽

Experimental Investigations ◽

High Signal ◽

Flexural Waves ◽

Local Regression ◽

Local Effects ◽

Structural Damage Identification

Curvatures in mode shapes and operating deflection shapes have been extensively studied for vibration-based structural damage identification in recent decades. Curvatures of mode shapes and operating deflection shapes have proved capable of localizing and manifesting local effects of damage on mode shapes and operating deflection shapes in forms of local anomalies. The damage can be inversely identified in the neighborhoods of the anomalies that exist in the curvatures. Meanwhile, propagating flexural waves have also been extensively studied for structural damage identification and proved to be effective, thanks to their high damage-sensitivity and long range of propagation. In this work, a baseline-free structural damage identification method is developed for beam-like structures using curvature waveforms of propagating flexural waves. A multi-resolution local-regression temporal-spatial curvature damage index (TSCDI) is defined in a pointwise manner. A two-dimensional auxiliary TSCDI and a one-dimensional auxiliary damage index are developed to further assist the identification. Two major advantages of the proposed method are: (1) curvature waveforms of propagating flexural waves have relatively high signal-to-noise ratios due to the use of a multi-resolution central finite difference scheme, so that the local effects of the damage can be manifested, and (2) the proposed method does not require quantitative knowledge of a pristine structure associated with a structure to be examined, such as its material properties, waveforms of propagating flexural waves and boundary conditions. Numerical and experimental investigations of the proposed method are conducted on damaged beam-like structures, and the effectiveness of the proposed method is verified by the results of the investigations.

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Structural Damage Assessment Using Output-Only Measurement: Localization and Quantification

Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting ◽

10.1115/smasis2013-3008 ◽

2013 ◽

Author(s):

Chin-Hsiung Loh ◽

Min-Hsuan Tseng ◽

Shu-Hsien Chao

Keyword(s):

Damage Detection ◽

Damage Assessment ◽

Structural Damage ◽

Damage Identification ◽

Model Updating ◽

Null Space ◽

Singular Spectrum Analysis ◽

Damage Index ◽

Computation Efficiency ◽

Output Only

One of the important issues to conduct the damage detection of a structure using vibration-based damage detection (VBDD) is not only to detect the damage but also to locate and quantify the damage. In this paper a systematic way of damage assessment, including identification of damage location and damage quantification, is proposed by using output-only measurement. Four level of damage identification algorithms are proposed. First, to identify the damage occurrence, null-space and subspace damage index are used. The eigenvalue difference ratio is also discussed for detecting the damage. Second, to locate the damage, the change of mode shape slope ratio and the prediction error from response using singular spectrum analysis are used. Finally, to quantify the damage the RSSI-COV algorithm is used to identify the change of dynamic characteristics together with the model updating technique, the loss of stiffness can be identified. Experimental data collected from the bridge foundation scouring in hydraulic lab was used to demonstrate the applicability of the proposed methods. The computation efficiency of each method is also discussed so as to accommodate the online damage detection.

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An Effective Method of Modeling the Deformation Behavior of Polymer Sandwich Structures with Adhesive Joints

Applied Composite Materials ◽

10.1007/s10443-021-09948-1 ◽

2021 ◽

Author(s):

László Takács ◽

Ferenc Szabó

Keyword(s):

Deformation Behavior ◽

Sandwich Structures ◽

Experimental Tests ◽

Mechanical Tests ◽

Adhesive Joints ◽

Core Material ◽

Full Vehicle ◽

Novel Approach ◽

Stiffness Matrices ◽

Layered Shells

AbstractPolymer sandwich structures have high bending stiffness and strength and also low weight. Therefore, they are widely used in the transportation industry. In the conceptual design phase, it is essential to have a method to model the mechanical behavior of the sandwich and its adhesive joints accurately in full-vehicle scale to investigate different structure partitioning strategies. In this paper, a novel approach using finite element modeling is introduced. The sandwich panels are modeled with layered shells and the joint lines with general stiffness matrices. Stiffness parameters of the face-sheets and the core material are obtained via mechanical tests. Stiffness parameters of the joints are determined by using the method of Design of Experiments, where detailed sub-models of the joints serve as a reference. These models are validated with experimental tests of glass-fiber reinforced vinyl ester matrix composite sandwich structure with a foam core. By using two joint designs and three reference geometries, it is shown that the method is suitable to describe the deformation behavior in a full-vehicle scale with sufficient accuracy.

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