Accession Number : ADA296673

Title :   Non-Destructive Inspection of Composite Structures Using Modal Analysis.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Matthews, Timothy S.

PDF Url : ADA296673

Report Date : MAR 1995

Pagination or Media Count : 117

Abstract : Anomalies from manufacturing variability or in-service damage are manifested as subtle differences in the inertial and stiffness matrices of otherwise identical components. Modal analysis seeks to model these constitutive relations by examining a structure's dynamic response to applied vibrations. In this investigation, characterization of anomalies in composite structures is attempted through multi-input, multi-output modal analysis. Two graphite-epoxy specimens manufactured by different processes are subjected to random excitation and frequency response functions are obtained. The dynamic behavior of the structures is compared through modal parameter extraction techniques. Dynamic solutions from a finite element model are used to validate the results. Finally, observations are made concerning the feasibility of extending the procedure to quality assurance and damage detection applications. (MM)

Descriptors :   *AIRCRAFT, *NONDESTRUCTIVE TESTING, *LAMINATES, *COMPOSITE STRUCTURES, *GRAPHITE EPOXY COMPOSITES, MATHEMATICAL MODELS, ANOMALIES, VIBRATION, NAVAL AVIATION, COMPOSITE MATERIALS, FINITE ELEMENT ANALYSIS, DYNAMIC RESPONSE, STIFFNESS, DAMAGE ASSESSMENT, DISPLACEMENT, DEFLECTION, THESES, STRENGTH(MECHANICS), DEFECTS(MATERIALS), CALIBRATION, INERTIAL SYSTEMS, GRAPHITED MATERIALS, FREQUENCY RESPONSE, AXIAL LOADS, POISSON RATIO, SHEAR STRENGTH.

Subject Categories : Aircraft
      Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE