Damage Assessment in Thin Materials: Finite Element Investigation

This thesis describes the process of detection, and if possible, also localization of the damage in non structural sheet-like materials. Simulation and analysis is carried out in ABAQUS with a FE model that has the same dynamic characteristics as the corresponding real material. Three types of damage forms are investigated: crack, hole and local weakness. Results presented in the report show that global damage detection and localization in sheet-like structure by monitoring changes in the modal parameters is possible. Based on the results, this thesis provides a basis for development of global non-destructive health monitoring methods for materials having no bending stiffness.


1 Notation
2 Introduction
3 Overview of Defects
3.1 Types of defects
3.1.1 Local Weakness
3.1.2 Hole
3.1.3 Crack
4 Theoretical Analyses
5 Available Experimental Results
5.1 Experimental Procedure
5.2 Results
6 Overview of Numerical Analysis
6.1 The Finite Element Method
6.2 Methods for Crack Analysis
6.2.1 Virtual Crack Extension: Stiffness Derivation Formulation
6.2.2 Virtual Crack Extension: Continuum Approach
7 Simulation
7.1 Problem Formulation
7.1.1 Eigenvalue Technique
7.1.2 Definition of the Models
7.1.3 Elements
7.1.4 Convergence Study
7.1.5 Boundary Conditions
7.2 Material Details and Assumptions
7.3 Modelling and Post-processing
7.3.1 Crack
7.3.2 Hole
7.3.3 Local Weakness
8 Results and Interpretation
8.1 Crack
8.2 Hole
8.3 Local Weakness
8.4 Spatial Distribution of Some of the Modes
9 Conclusion and Further Work
10 References

Author: Mirza Mohammed Yousuf Baig

Source: Blekinge Institute of Technology

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