DEFORMATION PATTERN AND ENERGY ABSORPTION CHARACTERISTICS OF A FOURTUBE NESTED SYSTEM UNDER LATERAL AND OBLIQUE LOADINGS

Abstract

THE PRESENT RESEARCH INTRODUCES A NEW CONFIGURATIONS OF THIN-WALLED NESTED TUBE STRUCTURE AS A POSSIBLE ENERGY ABSORBER SUBJECTED TO LATERAL COMPRESSION. THE NESTED-TUBE STRUCTURES WERE CONFIGURED IN A SYSTEM COMPRISING OF FOUR TUBES ARRANGED IN DIFFERENT WAYS. ALL THE NESTED SYSTEMS WERE QUASI-STATICALLY COMPRESSED IN THE LATERAL DIRECTION ON A UNIVERSAL MECHANICAL TESTER TO OBTAIN THEIR ENERGY ABSORPTION CHARACTERISTICS. QUASI-STATIC TESTS WERE ALSO PERFORMED ON THE FOUR-TUBES NESTED SYSTEMS ROTATED BY 10 DEGREE TO INVESTIGATE THE EFFECT OF OBLIQUE LOADING. THE RESULTS OF A THREE-TUBES NESTED SYSTEM, USED AS BASELINE, WERE COMPARED WITH RESULTS OF THE FOUR-TUBES NESTED SYSTEMS. TWO MODES OF DEFORMATION, ASYMMETRIC MODE REFERRED TO AS “OVERLAP” AND SYMMETRIC MODE REFERRED TO AS “SIDE-BY-SIDE”, WERE IDENTIFIED IN THE FOUR-TUBES NESTED SYSTEMS. THE RESULTS SHOWED THAT THE INNER TUBES OF THE INVERTED FOUR-TUBES SYSTEMS WERE FOUND TO ADJUST THEIR LOCATIONS TO RESIST COMPRESSION AND THUS PROVIDED BETTER ENERGY ABSORPTION PERFORMANCE. THE SPECIFIC ENERGY ABSORBED BY THE INVERTED FOUR-TUBES SYSTEMS WAS LARGER THAN THAT OF THE THREE-TUBES NESTED SYSTEMS BY 20%. THE EXPERIMENTS WERE ALSO MODELLED USING ABAQUS V6.13. GOOD CORRELATIONS WERE OBTAINED FOR THE DEFORMATION MODES AND THE CORRESPONDING LATERAL CRUSH FORCE-DISPLACEMENT. THE VALIDATED MODEL WAS THEREAFTER USED IN PARAMETRIC STUDY TO INVESTIGATE THE EFFECTIVENESS OF THE NESTED SYSTEM UNDER TWO DIFFERENT BOUNDARY CONDITIONS; ROTATION OF THE SPECIMEN BY DIFFERENT ANGLES AND IMPACT AT DIFFERENT ANGLES.