Numerical and experimental analyses about SHM metrics using piezoelectric materials

Author(s)

Medeiros, R. ; Sartorato, M. ; Ribeiro, M. L. ; Vandepitte, D. ; Tita, V. ; Sas, P ; Moens, D ; Jonckheere, S

• Document type: Journal article
• Source: PROCEEDINGS OF INTERNATIONAL CONFERENCE ON NOISE AND VIBRATION ENGINEERING (ISMA2012) / INTERNATIONAL CONFERENCE ON UNCERTAINTY IN STRUCTURAL DYNAMICS (USD2012); v. N/A, p. 15-pg., 2012-01-01.

Abstract

Aircraft are composed by different complex systems, for example: structural, hydraulic, propulsion, electronic and avionic elements. Such complex systems normally require maintenance plans with inspection periods. Structural Health Monitoring (SHM) can provide a diagnosis of the material state and the structure situation, constantly during the aircraft life, as well as a prognostic for the residual strength of the structure. Thus, SHM can reduce the maintenance costs, avoiding useless inspections. This study presents numerical and experimental analyses about health monitoring metrics and techniques for detecting damage in a cantilever beam. Studies used an aluminum beam with two piezoelectric patches attached in suitable positions. A pulse signal is used to produce the excitation on the structure and the piezoelectric patches are used as sensors for data acquisitions. A theoretical model for structural structure containing active piezoelectric layers was presented and used to formulate a plate quadratic finite element with eight nodes for large displacements and curved structures; the element was implemented into the finite element commercial package Abaqus through its UEL (User Element) Fortran subroutine. The used finite elements allow fully coupled electromechanical analyses. Experimental vibration tests are carried out using patches Mide QP10n. Different types of techniques and metrics can be found in the literature. In this work, the approach based on Frequency Response Function (FRF) is used, because there is a natural relation between stiffness, mass and natural frequency, which changes with changes in stiffness and/or mass. Therefore, it is possible to identify damage through modal methods applied for undamaged and for damaged structure. Thus, first, an undamaged cantilever aluminum beam is modeled by Abaqus. Then natural frequencies and Frequency Response Functions are obtained by finite element analyses. After that, holes are created in the finite element model in order to simulate damage. The new natural frequencies and Frequency Response Functions for different degree of damage severity are obtained. Furthermore, experimental analyses are performed not only for undamaged beams, but also for damaged beams with the same damage simulated by Abaqus. Numerical and experimental results are analyzed using the metrics, which are compared in terms of their capability for damage identifying. Finally, there is a comparison between numerical and experimental approaches in order to show the limitations and advantages for each one. (AU)

• FAPESP's process: 09/00544-5 - STUDY OF DAMAGE AND PROGRESSIVE FAILURE MODELS FOR COMPOSITE STRUCTURES
• Grantee: Volnei Tita
• Support Opportunities: Regular Research Grants