Fault detection and passive and active structural patches

Abstract

The global objective of this research project is to integrate the competence of different research groups into an interdisciplinary research effort at UNICAMP for the development of structural fault detection analysis tools and design of structural patches, both active and passive. The aeronautical, Gil, and civil construction industries demand efficient techniques for the detection of structural faults and the design of structural patches, which this project will develop with the participation of researchers from the Faculties of Mechanical and Civil Engineering. Existing collaboration with the Faculty of Electrical Engineering end Physics Institute will also be fostered with this project. This research effort will unfold into three main aspects of the problem: The first considers primarily the detection of structural faults through experimental methods. The investigation methods are all related with the measurement of noise and vibration with high spatial resolution that have the potential to detect and locate faults. Under this approach, optical and acoustical measurement techniques will be investigated. In the processing of the experimental data, energy flow techniques will be used. The techniques under investigation have in common the fact that they are spatially dense and are, generally, made at relatively high frequencies, above the first tens of modes of the structures under investigation. The second refers to the development of numerical and semi-analytical prediction tools. These tools are based upon the analysis and synthesis of structures consisting of plates and shells made of bonded composites. The goals here is the analysis of cracked and delaminated structures by the bonding of composite material patches. Boundary and Finite Element formulations will be used to model such structures. Such formulations must be able to treat plates and shells with shear stresses in the planes normal to their surface, while in the model of the patches, such stresses are neglected. Structural optimization procedures will be used in lhe design of lhe shape and topology of the patches. Conventional numerical methods in structural mechanics are not well suited for dynamic analysis at high frequencies. Even with the most up-to-date computer facilities, some analysis and optimization problems cannot be treated, or are not economically viable. In recent times, methods that can be classified as semi-analytical are getting the attention of the engineering community. In these methods, the three-dimensional problem is solved in two dimensions analytically while the third dimension is treated numerically... (AU)