Accession Number : ADA470797


Title :   Characterization and Detection of Delamination in Smart Composite Structures


Descriptive Note : Final rept. 1 Aug 2002-31 Dec 2006


Corporate Author : CALIFORNIA STATE UNIV LONG BEACH


Personal Author(s) : Chen, Hsin-Piao ; Chattopadhyay, Aditi


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA470797


Report Date : 31 DEC 2006


Pagination or Media Count : 50


Abstract : A multidisciplinary procedure has been developed for damage diagnosis or interrogation based on the concept of analyzing temporal relations between values of critical variables. Some observable variable of the system is traced through time from a specific initial state. The dynamics of the degradation process can be described by a time-variant mathematical model of this relationship. A novel neural-network-based approach to damage diagnosis and prognosis for nonlinear dynamic systems has been developed. High quality response surface approximations are developed to the progressive damage model. A neural network is trained to model the multi-dimensional response surface that relates the dependent variables to the independent variables. The main advantage of neural networks is that much more complex nonlinear relationships can be modelled, potentially incorporating high order interactions between predictive variables. A distinct feature of the proposed technique for constructing the response surface approximations is that it permits explicit treatment of the dynamics of the process under observation - in this case, structural damage that evolves in time. Assessing and quantifying existing damage may be treated as a static problem and its solution can be summarized by a mapping from parametric descriptions of damage attributes and measured structural response data.


Descriptors :   *COMPOSITE STRUCTURES , *APPROXIMATION(MATHEMATICS) , *DELAMINATION , MATHEMATICAL MODELS , NEURAL NETS , NONLINEAR SYSTEMS , GENETIC ALGORITHMS , DIAGNOSIS(GENERAL) , PIEZOELECTRIC MATERIALS , STRUCTURAL RESPONSE , PARAMETRIC ANALYSIS , DETECTION


Subject Categories : NUMERICAL MATHEMATICS
      STRUCTURAL ENGINEERING AND BUILDING TECHNOLOGY


Distribution Statement : APPROVED FOR PUBLIC RELEASE