Fundamentals of Vibrations

Vibrations of straight and curved composite beams: A review

Impact damage identification in composite laminates using vibration testing

https://hal.archives-ouvertes.fr/hal-02126019/document

On the use of in-situ piezoelectric sensors for the manufacturing and structural health monitoring of polymer-matrix composites: A literature review

Summary

In this paper, a mode shape curvature-based method for detection and localization of damage in plate-like structures is described. The proposed algorithm requires only the mode shape curvature data of the damaged structure. The damage index is defined as the absolute difference between the measured curvature of the damaged structure and the smoothed polynomial representing the curvature of the healthy structure. To examine the advantages and limitations of the proposed method, several sets of numerical simulations are carried out. Simulated test cases considering different levels of damage severity, measurement noise and sensor sparsity are studied to evaluate the robustness of the method under the noisy experimental data and limited sensor data. Applicability and effectiveness of the proposed damage detection method are further demonstrated experimentally on an aluminium plate containing mill-cut damage. The modal frequencies and the corresponding mode shapes are obtained via finite element models for numerical simulations and by using a scanning laser vibrometer for the experimental study. Copyright © 2016 John Wiley & Sons, Ltd.

Mode shape‐based damage detection in plate structure without baseline data

Vibration based Structural Health Monitoring of a composite T-beam

The feasibility of a vibration-based damage identification approach for impact damage in two advanced composite skin-stiffener structures is investigated in this paper. Mode shape curvatures combined with the modal strain energy damage index (MSE-DI) algorithm are utilized to identify the damage. Special attention is paid to the effective application of this vibration-based methodology by investigating the relation between the damage location, the structural design, and the dynamic behavior. The performance of a 1D and 2D formulation of the MSE-DI algorithm is compared for several damage scenarios. Experiments demonstrated the capabilities of the MSE-DI algorithm to detect, localize, and roughly quantify the size of barely visible impact damage in advanced composite structures. It is concluded that the method is particularly effective for health monitoring of skin-stiffener connections. The most effective results were obtained by considering the 1D formulation in the direction of the stiffeners for the stiffener mid-section and perpendicular to the stiffeners for the stiffener run-out. The method remained inconclusive in the case of pure skin-related damage. The results obtained in this study contribute to the development of guidelines for vibration-based structural health monitoring of advanced composite skin-stiffener structures.

Impact Damage Identification in Composite Skin-Stiffener Structures Based on Modal Curvatures

Nonlinear dynamic behavior of an impact damaged composite skin–stiffener structure

A vibration based damage identification algorithm is implemented to assess the damage of a thin-walled composite structure. The structure analysed is a skin with stiffeners, as frequently applied in aircraft components. Both experimental and numerical studies on a single composite skin--stiffener structure showed that the modal strain energy damage index (MSE--DI) algorithm is a suitable method for the detection and localization of a delamination of the stiffener from the skin. A recent study on a strip with a single stiffener and an artificial delamination is extended to a study on a plate with two stiffeners and an impact induced delamination damage.

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Vibration based structural health monitoring of a composite plate with stiffeners

A Finite Element based numerical model for a vibration based damage identification method for a thin-walled slender composite structure is discussed in this chapter. The linear dynamic response of an intact and a locally delaminated 16-layer unidirectional carbon fibre PEKK reinforced T-beam is analysed. The capabilities of the modal strain energy damage index algorithm to detect and localize a delamination is assessed. Both bending and torsion modes of the structure are used in the algorithm. Both an experimental set-up and a numerical model are discussed. Measurements are performed on an intact and an artificially delaminated structure, using a laser-vibro measuring system to determine the response to a force excitation. A commercially available Finite Element package is employed for the numerical model. The aim of the numerical model is to perform a parametric study. The study is preceded by an experimental verification of the numerical model. Subsequently, it is used to analyse the effect of the size and location of a delamination, as well as the number of data points employed, on the damage index.

T.H. Ooijevaar

Papers

Vibration based Structural Health Monitoring of a composite T-beam

Impact Damage Identification in Composite Skin-Stiffener Structures Based on Modal Curvatures

Nonlinear dynamic behavior of an impact damaged composite skin–stiffener structure

Vibration based structural health monitoring of a composite plate with stiffeners

Vibration Based Structural Health Monitoring and the Modal Strain Energy Damage Index Algorithm Applied to a Composite T-Beam