A NEW APPROACH FOR SEVERITY ESTIMATION OF TRANSVERSAL CRACKS IN MULTI-LAYERED BEAMS

Abstract

NOWADAYS, THE DAMAGE SEVERITY EVALUATION IN MECHANICAL STRUC-TURES MADE OF BEAMS IS MOSTLY PERFORMED BY ANALYZING THE NATURAL FREQUENCY SHIFT. THE NON-ISOTROPIC MATERIALS, AS THE MULTI-LAYERED ONES, ARE WIDE-SPREAD IN INDUSTRIAL APPLICATIONS, FOR INSTANCE DUE TO THEIR INTERESTING PHYSIC-MECHANICAL PROPERTIES. THUS, A DEEPER APPROACH OF MULTI-LAYERED BEAMS BECOMES AN IMPORTANT REQUEST IN THE RESEARCH DOMAIN. IN THIS PAPER, THE ACCOMPLISHMENT OF DAMAGE SEVERITY IN MULTI-LAYERED BEAMS IS MORE COMPREHENSIVELY CHARAC-TERIZED BY INTRODUCING A NEW WAY TO HIGHLIGHT THE CRACK EVOLUTION AS A FUNCTION OF STORED ENERGY. IT IS WELL KNOWN THAT THE ENERGY STORED IN A BEAM WITHOUT DAMAGE IS GREATER THAN THE ENERGY OF THAT DAMAGED BEAM. AS A CONSEQUENCE, THE BEAM DEFLECTION CAN BE RELATED TO THE STORED ENERGY. IN THIS REGARD, THE POSSIBILITY TO SPLIT THE DAMAGE LOCALIZATION AND THE DAMAGE SEVERITY ASSESSMENT HAS BEEN PROVEN, AND ALSO THE GRAPHICAL EVOLUTION OF THE NATURAL FRE-QUENCY SHIFT HAS BEEN ACHIEVED AS A FUNCTION OF THE CRACK DEPTH. THE RESULTS ACHIEVED BY THE FINITE ELEMENT METHOD (FEM) AND EXPERIMENTAL TESTS ARE GIVEN IN TABLES AND GRAPHICS. FOR THE FIRST FIVE VIBRATION MODES, A COMPARISON WAS MADE BETWEEN FREQUENCIES ACCOMPLISHED BY ANALYTICAL, NUMERICAL AND EXPERIMENTAL ANALYSES, IN ORDER TO GIVE MORE CREDIBILITY TO THE ACCURACY OF THE RESEARCH DATA PRESENTED IN THIS PAPER.