COMPARISON BETWEEN A LINEAR AND CUBIC FIBER ANGLE VARIATION ON BUCKLING RESPONSE OF VARIABLE ANGLE TOW COMPOSITE PANELS

Abstract

ADVANCES IN MANUFACTURING TECHNIQUES HAVE ALLOWED MORE FLEXIBILITY TO THE DESIGN AND NEW POSSIBILITIES TO APPLY COMPOSITES MATERIALS IN LIGHTWEIGHT STRUCTURES. NOVEL TECHNIQUES SUCH AS THE AUTOMATED FIBER PLACEMENT ALLOW THE FIBERS TO FOLLOW CURVILINEAR PATHS, MAKING POSSIBLE LAMINATE PROPERTIES THAT VARY WITHIN THE LAMINATE PLANE. THESE TYPE OF LAMINATES ARE KNOWN AS VARIABLE STIFFNESS LAMINATES OR VARIABLE ANGLE TOW. IN THIS WORK, THE IN-PLANE AND BUCKLING RESPONSE OF COMPOSITE PANELS WITH VARIABLE STIFFNESS THROUGH A SPATIALLY VARYING FIBER ORIENTATION HAS BEEN ANALYZED FOR TWO DIFFERENT BOUNDARY CONDITIONS. THIS WORKS COMPARES THE OUTCOMES OF IN-PLANE STRESS AND CRITICAL BUCKLING LOAD FOR LINEAR AND CUBIC FIBER ANGLE CONSIDERING FOUR ASPECT RATIOS. MANUFACTURING CONSTRAINT HAS BEEN CONSIDERED IN THE ANALYSIS OF THE LAMINATES. THE FINITE ELEMENT METHOD HAS BEEN APPLIED TO SOLVE THE SYSTEM ELLIPTIC PARTIAL DIFFERENTIAL EQUATIONS THAT GOVERN THE IN-PLANE BEHAVIOR OF THESE PANELS. THE RITZ METHOD HAS BEEN USED TO FIND THE BUCKLING LOADS FOR THE VARIABLE STIFFNESS PANELS. RESULTS FOR FOUR DIFFERENT ASPECTS RATIOS ARE PRESENTED. IMPROVEMENTS IN THE BUCKLING LOAD OF UP TO 18% FOR CUBIC FIBER ANGLE VARIATION OVER LINEAR FIBER ANGLE VARIATION WERE FOUND.