Experimental Damage Identification of Carbon/Epoxy Composite Beams Using Curvature Mode Shapes

2004 ◽  
Vol 3 (4) ◽  
pp. 333-353 ◽  
Author(s):  
Cole S. Hamey ◽  
Wahyu Lestari ◽  
Pizhong Qiao ◽  
Gangbing Song
Keyword(s):  
Damage Identification ◽  
Epoxy Composite ◽  
Composite Beams ◽  
Mode Shapes

Detection of Embedded Damage Growth by Analysing Its Structural Dynamic Response

2009 ◽  
Author(s):  
Mohammad Mehdizadeh ◽  
Krishna Oruganti ◽  
John Sabu ◽  
Michael Bannister ◽  
Israel Herszberg
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Dynamic Response ◽  
Crack Growth ◽  
Epoxy Composite ◽  
Composite Beams ◽  
Mode Shapes ◽  
Structural Dynamic ◽  
Damage Site ◽  
Damage Types

The primary focus of this paper is to report on the technique developed to extend a simulated damage site (such as a delamination) without inducing other extraneous damage modes. This was done in order to assess the suitability of curvature mode shape analyses in detecting damage types which are similar in type but different in severity or size. This paper highlights the use of vibration based testing on Carbon/Epoxy composite beams for damage detection. Such composites are commonly used in the aerospace and marine industry. The study comprises of testing carbon/epoxy composite beams with various embedded delaminations with a mechanical actuator and a Scanning Laser Vibrometer (SLV) as a sensor for recording the frequency response and the subsequent analyses of the acquired dynamic response based on Displacement and Curvature Mode Shapes. The paper also discusses the Finite Element Method (FEM)-based Analysis to validate the experimental results. In order to assess the effect of an increasing damage zone on a particular damage configuration, it was necessary to extend the damage without inflicting other damage types in the process. This paper reports on an innovative way of extending an existing delamination by a fatigue crack-growth technique. The ASTM E399-90 standard was used for the experiment and a carefully designed fatigue crack growth routine was implemented to advance the delamination in a controlled manner.

Damage Detection in Composites Using Vibration Signatures and Mode Shapes

2008 ◽  
Author(s):  
K. Oruganti ◽  
M. Mehdizadeh ◽  
S. John ◽  
I. Herszberg
Keyword(s):  
Damage Detection ◽  
Epoxy Composite ◽  
Composite Beams ◽  
Matrix Cracking ◽  
Mode Shapes ◽  
Laser Vibrometer ◽  
Modern Times ◽  
Marine Industry ◽  
Service Operation ◽  
Vibration Signatures

Composite materials are supplanting conventional metals in aerospace, automotive, civil and marine industries in modern times. However, despite these advantageous properties, they are prone to delamination or matrix cracking. Thus, necessitating the early detection of the crack or flaw before it initiates into a serious defect. An offline approach was commonly used where in the parts examined away from service/operation. This not only consumed a lot of time but risked damage to the part during operation and handling. A detailed understanding of the various proven methods and techniques and their applicability in the analysis of vibration signatures obtained from damaged structures under dynamic conditions is essential to develop a reliable Structural Health Monitoring System (SHMS). This paper includes Vibration based damage detection testing on Carbon/Epoxy composite beams. Such composites are commonly used in the aerospace and marine industry. This material type is gaining acceptance not only in the aerospace industry but also in the automotive and construction industries. The paper reports the processing of the vibration signatures from healthy and damaged composite beams upon excitation and analysis of the mode shapes acquired. The study comprises of testing carbon/epoxy composite beams with various embedded delaminations with a mechanical actuator and a scanning laser vibrometer (SLV) as a sensor for recording the frequency response and analysing the acquired signatures based on Displacement and Curvature Mode Shapes.

Vibration-based delamination evaluation in GFRP composite beams using ANN

2021 ◽  
pp. 096739112110033
Author(s):  
TG Sreekanth ◽  
M Senthilkumar ◽  
S Manikanta Reddy
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Composite Structures ◽  
Composite Beams ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Aviation Industry ◽  
Frequency Data ◽  
Fiber Reinforced ◽  
Back Propagation Algorithm

Delamination is definitely an important topic in the area of composite structures as it progressively worsens the mechanical performance of fiber-reinforced polymer composite structures in its service period. The detection and severity analysis of delaminations in engineering areas like the aviation industry is vital for safety and economic considerations. The existence of delaminations varies the vibration characteristics such as natural frequencies, mode shapes, etc. of composites and hence this indication can be effectively used for locating and quantifying the delaminations. The changes in vibration characteristics are considered as inputs for the inverse problem to determine the location and size of delaminations. In this paper Artificial Neural Network (ANN) is used for delamination evaluationof glass fiber-reinforced composite beams using natural frequency as typical vibration parameter. The Finite Element Analysis is used for generating the required dataset for ANN. The frequency-based delamination prediction technique is validated by finite element models and experimental modal analysis. The results indicate that the ANN-based back propagation algorithm can predict the location and size of delaminations in composites with good accuracy for numerical natural frequency data but the accuracy is comparitivelyless for experimental natural frequency data.

Vibration of Beams with a Single Delamination under Axial Loading

2011 ◽  
Vol 675-677 ◽  
pp. 477-480
Author(s):  
Dong Wei Shu
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Analytical Solutions ◽  
Axial Load ◽  
Natural Frequencies ◽  
Axial Loading ◽  
Composite Beams ◽  
Mode Shapes ◽  
Equilibrium Conditions ◽  
Monotonic Relation

In this work analytical solutions are developed to study the free vibration of composite beams under axial loading. The beam with a single delamination is modeled as four interconnected Euler-Bernoulli beams using the delamination as their boundary. The continuity and the equilibrium conditions are satisfied between the adjoining beams. The studies show that the sizes and the locations of the delaminations significantly influence the natural frequencies and mode shapes of the beam. A monotonic relation between the natural frequency and the axial load is predicted.

Effect of Delamination on Natural Frequencies of E-glass and S-glass Epoxy Composite Plates

2021 ◽  
Author(s):  
P. K. Karsh ◽  
Bindi Thakkar ◽  
R. R. Kumar ◽  
Abhijeet Kumar ◽  
Sudip Dey
Keyword(s):  
Natural Frequencies ◽  
Epoxy Composite ◽  
Orientation Angle ◽  
Laminated Composite ◽  
Composite Plates ◽  
Mode Shapes ◽  
Transverse Shear Deformation ◽  
The Finite Element Method ◽  
Modes Of Failure ◽  
Ply Orientation

The delamination is one of the major modes of failure occurring in the laminated composite due to insufficient bonding between the layers. In this paper, the natural frequencies of delaminated S-glass and E-glass epoxy cantilever composite plates are presented by employing the finite element method (FEM) approach. The rotary inertia and transverse shear deformation are considered in the present study. The effect of parameters such as the location of delamination along the length, across the thickness, the percentage of delamination, and ply-orientation angle on first three natural frequencies of the cantilever plates are presented for S-glass and E-glass epoxy composites. The standard eigenvalue problem is solved to obtain the natural frequencies and corresponding mode shapes. First three mode shape of S-Glass and E-Glass epoxy laminated composites are portrayed corresponding to different ply angle of lamina.

Free Vibration of Damaged Beam Structure with a Notch Defect

2012 ◽  
Vol 226-228 ◽  
pp. 44-47 ◽  
Author(s):  
Jiang Yi Chen ◽  
Li Ge Fan ◽  
Dong Chen Qin
Keyword(s):  
Damage Identification ◽  
Delta Function ◽  
Theoretical Background ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Beam Structure ◽  
Arbitrary Boundary ◽  
Numerical Examples ◽  
Elastically Supported ◽  
Universal Expression

In this paper, we derive the universal expression of the modal parameters for a damaged beam under arbitrary boundary conditions. The delta function is first employed to describe a notch damage in the beam and consequently to derive the governing equation for the damaged beam. Second, by virtue of the perturbation method, the eigenvalues and the corresponding mode shapes are obtained for the damaged beam. Finally, numerical examples are given for an elastically supported beam. It is believed that the proposed approach could provide the necessary theoretical background for damage identification in beam structures.

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