STRAIGHT FOLD ANALYSIS FOR AXISYMMETRIC CRUSHING OF THIN WALLED FRUSTA AND TUBES

Abstract

A STRAIGHT FOLD MODEL WITH PARTLY INSIDE AND PARTLY OUTSIDE FOLDING IN AXISYMMETRIC CRUSHING OF THIN METALLIC FRUSTA HAS BEEN PRESENTED. THE FIRST FOLD OF THE MODEL ENDS AT THE MEANDIAMETER AND ALL SUBSEQUENT FOLDS INITIATE AND END AT THE MEAN DIAMETER. SOME PARAMETERS HAVE BEEN INTRODUCED FOR MAKING THE EXPRESSIONS VALID FOR ALL THE FOLDS. EXISTING TOTAL OUTSIDE FOLD MODEL OF FRUSTA AND PARTLY INSIDE AND PARTLY OUTSIDE FOLD MODEL OF TUBE CAN BE DERIVED FROM THE PRESENT MODEL. THE RELATIONS FOR OBTAINING THE INSIDE AND OUTSIDE FOLD LENGTHS IN TUBES ARE DERIVED. DIFFERENT VALUES OF YIELD STRESS OF THE MATERIAL IN COMPRESSION AND TENSION HAVE BEEN TAKEN IN THE ANALYSIS. THE VARIATION OF CIRCUMFERENTIAL STRAIN DURING THE FORMATION OF A FOLD HAS BEEN TAKEN INTO ACCOUNT FOR THE PURPOSE OF COMPUTING THE VARIATION OF CRUSHING LOAD. THE RESULTS HAVE BEEN COMPARED WITH EXPERIMENTS AND GOOD AGREEMENT HAS BEEN OBSERVED.