STATIC AND DYNAMIC STRUCTURAL ANALYSIS OF ALUMINIUM CRAFT DECK STRUCTURES, SUBJECTED TO REPEATED IMPACT LOAD

Abstract

THIS PAPER PRESENTS THE RESULTS OF AN INVESTIGATION ON THE RESPONSE OF THE DECK STRUCTURE OF A HIGH-SPEED ALUMINIUM CRAFT TO THE REPEATED IMPACT LOAD. THIS TYPE OF LOAD IS PRODUCED BY OPERATING THE EQUIPMENT WHICH IS INSTALLED ON THE DECK STRUCTURE, REINFORCED BY THE LONGITUDINAL STIFFENERS AND TRANSVERSE FRAMES. FINITE ELEMENT METHOD IS USED TO ANALYSE THE STRESS DISTRIBUTION ON THE DECK STRUCTURE. USING THE COMMERCIAL FEM-BASED SOFTWARE ANSYS, A CERTAIN REGION OF THE DECK IS MODELLED. THE IMPACT LOAD IS SIMULATED AS A REACTION OF THE STIFFENED DECK. DIFFERENT ANGLES OF THE IMPACT LOAD ARE CONSIDERED IN RELATION TO THE VERTICAL PLANE, WHICH LED TO THE CRITICAL LOADING CONDITIONS. THE STRESS DISTRIBUTIONS AND DEFLECTION PATTERNS WITHIN THE DECK INDUCED BY THE REPEATED IMPACT LOAD ARE OBTAINED THROUGH TRANSIENT DYNAMIC FE ANALYSES. FURTHERMORE, THE RECOMMENDATION OF ONE OF THE SHIP CLASSIFICATION AGENCIES CONCERNING SUCH CASES IS PURSUED AND INVESTIGATED. IT WAS CONCLUDED THAT THE STATIC ANALYSIS BASED ON THIS RECOMMENDATION DOES NOT EXPLAIN THE BEHAVIOUR OF THE DECK STRUCTURE SUBJECTED TO SUCH LOCAL IMPACT LOADS WELL. THE DETAILED RESULTS OF DYNAMIC TRANSIENT ANALYSIS SHOW VERY COMPLEX MODES OF DEFLECTION AND STRESS CONTOURS AT EACH INTERVAL OF LOADING. THE RESULTS ALSO INDICATE THAT THE ACCUMULATION OF INDUCED STRESSES OVER TIME MAY FINALLY LEAD TO THE COLLAPSE OF THE DECK STRUCTURE. THE HORIZONTAL DIRECTION OF THE REPEATED IMPACT LOAD GENERATES THE MOST CRITICAL STRESSES AND DEFLECTIONS IN THE DECK STRUCTURE.