Calculation of the Response of a Composite Plate to Localized Dynamic Surface Loads Using a New Wave Number Integral Method

2005 ◽  
Vol 72 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Sauvik Banerjee ◽  
William Prosser ◽  
Ajit Mal
Keyword(s):  
Wave Field ◽  
Composite Laminates ◽  
Impact Damage ◽  
Propagation Distance ◽  
Computational Effort ◽  
Point Load ◽  
Guided Wave ◽  
Wave Number ◽  
Element Analysis ◽  
Dynamic Surface

This study is motivated by the need for an efficient and accurate tool to analyze the wave field produced by localized dynamic sources on the surface or the interior of isotropic plates and anisotropic composite laminates. A semi-analytical method based on the wave number integral representation of the elastodynamic field is described that reduces the overall computational effort significantly over other available methods. This method is used to calculate the guided wave field produced in a thin unidirectional graphite/epoxy composite laminate by a dynamic surface point load. The results are compared with those obtained from a finite element analysis, showing excellent agreement, except for minor differences at higher frequencies. A recently discovered feature of the calculated surface motion, namely, a spatially periodic “phase reversal” of the main pulse with propagation distance, is observed in both cases. The present work is expected to be helpful in developing impact damage monitoring systems in defect-critical structural components through real time analysis of acoustic emission wave forms.

scholarly journals Modeling Analysis of Guided Ultrasonic Waves in Composite Plates with Impact Damage

2018 ◽  
Vol 7 (4.26) ◽  
pp. 175
Author(s):  
Noorfaten Asyikin Ibrahim ◽  
Bibi Intan Suraya Murat
Keyword(s):  
Composite Structures ◽  
Impact Damage ◽  
Composite Plates ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Fe Model ◽  
Element Analysis ◽  
Damage Area ◽  
Guided Ultrasonic Waves ◽  
The Impact

This paper investigates the propagation of guided ultrasonic waves and the interaction with impact damage in composite plates using a full three-dimensional Finite Element analysis. Impact damage in the composite plate was modeled as rectangular- and T-shaped delaminations. In order to provide guidelines for extending the modeling of realistic multimode impact damage, the impact damage was modeled as a combination of the delamination and reduced materials properties. The information obtained from these methods was compared to the experimental results around the damage area for a validation. There was a reasonable similarity between the experimental and FE results. The FE simulations can effectively model the scattering characteristics of the A0 mode wave propagation in anisotropic composite plates. This suggests that the simplified and easy-to-implement FE model could be used to represent the complex impact damage in composite plates. This could be useful for the improvement of the FE modeling and performance of guided wave methods for the in-situ NDE of large composite structures. 

Predicting low-velocity impact damage in composites by a quasi-static load model with cohesive interface elements

2012 ◽  
Vol 116 (1186) ◽  
pp. 1367-1381 ◽  
Author(s):  
X. Zhang ◽  
F. Bianchi ◽  
H. Liu
Keyword(s):  
Impact Load ◽  
Impact Damage ◽  
Computational Effort ◽  
Low Velocity Impact ◽  
Cohesive Failure ◽  
Low Velocity ◽  
Element Analysis ◽  
Interface Elements ◽  
Velocity Impact ◽  
Matrix Cracks

AbstractA numerical model is developed for predicting low-velocity impact damage in laminated composites. Stacked shell elements are employed to model laminate plies with discrete interface elements in pre-determined zones to model the onset and propagation of matrix cracks and delamination. These interface elements are governed by a bi-linear cohesive failure law. Cohesive element zone size is determined by a separate finite element analysis using solid elements to identify the stress concentration sites. In order to save the computational effort, low-velocity impact load is modelled by quasi-static loading. Influence of contact force induced friction on shear driven mode II delamination is modelled by a friction model. For a clustered cross-ply laminate, calculated impact force and damage area are in good agreement with the test results. It is shown that matrix cracks should be included in the model in order to simulate delamination in adjacent interface. The practical outcome of this research is a validated modelling approach that can be further improved for predicting low-velocity impact damage in other stacking sequences.

Prediction of Ultrasonic Guided Wave Dispersion in Bent Pipes Using Finite Element Analysis and 2-D Fourier Transform

2005 ◽  
Vol 297-300 ◽  
pp. 2065-2070 ◽  
Author(s):  
Sung Jin Song ◽  
Young H. Kim ◽  
Joon Soo Park ◽  
Hyung Ju Yu ◽  
Yong Moo Cheong ◽  
...  
Keyword(s):  
Finite Element ◽  
Fourier Transform ◽  
Wave Dispersion ◽  
Angular Frequency ◽  
General Purpose ◽  
Guided Wave ◽  
Wave Number ◽  
Element Analysis ◽  
Finite Element Program ◽  
Mode Identification

In this paper, the dispersion curves of a bent cylindrical pipe are obtained by using the 3-dimensional finite element modeling and 2-dimenstional Fourier transform. The transient responses of the bent pipe are calculated by using a general-purpose finite element program, and the displacements are extracted at a series of sequential points as a function of spatial position and time, u(x,t). Then 2-dimentional FFT of u (x,t) offers U (k,ω), the relation between wave number and angular frequency so that the phase velocity and group velocity can be calculated. In addition, verification of the result is made by the mode identification using wavelet transform. The modes invoked by both methods agree very well.

Theoretical calculation of circular-crested Lamb wave field in single- and multi-layer isotropic plates using the normal mode expansion method

2019 ◽  
Vol 19 (2) ◽  
pp. 357-372 ◽  
Author(s):  
Lingfang Li ◽  
Mohammad Faisal Haider ◽  
Hanfei Mei ◽  
Victor Giurgiutiu ◽  
Yong Xia
Keyword(s):  
Wave Field ◽  
Normal Mode ◽  
Lamb Wave ◽  
Response Spectrum ◽  
Excitation Frequency ◽  
Expansion Method ◽  
Guided Wave ◽  
Element Analysis ◽  
Mode Expansion ◽  
Isotropic Plates

The guided wave technique is commonly used in the health monitoring of thin-walled structures because the guided waves can propagate far in the structures without much energy loss. However, understanding of the wave propagation in bounded layered structures is still lacking. In this study, the Lamb wave field of single- and multi-layer plates excited by surface-mounted piezoelectric wafer active sensors is theoretically analyzed using the normal mode expansion method, which is based on the elastodynamic reciprocity relation and utilizes the orthogonality relations of the Lamb wave modes. The mode participation factors of Lamb wave in single- and multi-layer isotropic plates are derived. The time domain responses are obtained through the inverse Fourier transform of the structural response spectrum, which is obtained by multiplying the transfer function with the excitation frequency spectrum. The developed normal mode expansion method is first applied to an aluminum single-layer plate. The obtained analytical tuning curves and out-of-plane velocity of the plate are in good agreement with the numerical and experimental results. Finally, the analytical wave responses of an aluminum–adhesive–steel triple-layer plate are verified through comparison with the finite element analysis and experiment. The proposed normal mode expansion method provides a reliable and accurate calculation of the wave field in single- and multi-layer plates.

Modelling Anisotropy Influence on Guided Wave Scattering at Composite Delaminations

2021 ◽  
Author(s):  
Flora Hervin ◽  
Paul Fromme
Keyword(s):  
Composite Laminates ◽  
Guided Waves ◽  
Impact Damage ◽  
Scattered Wave ◽  
Unidirectional Composite ◽  
Guided Wave ◽  
Parameter Study ◽  
Laser Vibrometer ◽  
Composite Panels ◽  
Isotropic Composite

Abstract Carbon fibre reinforced composite laminates are widely used in aerospace structures but are prone to barely visible impact damage (BVID). Depending on impact severity, delaminations can form below the surface of the laminate, reducing the load bearing capacity. Efficient structural health monitoring (SHM) of composite panels can be achieved using guided waves propagating along the structure. Propagation and scattering of the A0 Lamb wave mode in a quasi-isotropic composite laminate was modelled using full three-dimensional (3D) Finite Element (FE) simulations. Individual ply layers were modelled using homogeneous unidirectional composite material properties to accurately capture the anisotropy effects. FE predictions for scattering and energy trapping at delaminations were compared to experimental measurements. Noncontact, full-wavefield guided wave measurements were obtained using a laser vibrometer. Good agreement was found between experiments and FE predictions. The effect of delamination shape and depth was investigated through a numerical parameter study. The angular dependency of the amplitude of the scattered wave was calculated. The influence of ply layer anisotropy on wave propagation in an undamaged laminate was investigated numerically. The sensitivity of guided waves for the detection of delaminations due to barely visible impact damage (BVID) in composite panels has been verified.

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