SIMPLIFIED ANALYTICAL APPROACH TO EVALUATE THE NONLINEAR DYNAMICS OF ELASTIC CYLINDRICAL SHELLS UNDER LATERAL BLAST LOADS

Abstract

THIS PAPER PRESENTS AN ANALYTICAL SOLUTION TO PREDICT THE NONLINEAR FORCED VIBRATIONS OF THIN-WALLED CYLINDRICAL SHELLS UNDER SUDDENLY APPLIED LOADS. INTEREST IN THIS PROBLEM IS MOTIVATED BY EFFECTS DUE TO EXPLOSIONS ON FLUID-STORAGE METAL TANKS. THE MODEL IS BASED ON THE ENERGY CRITERION DUE TO LAGRANGE, IN WHICH THE KINEMATIC NONLINEAR RELATIONS ARE ASSUMED USING DONNELLÂS SIMPLIFIED SHELL THEORY. SOLUTION IS ACHIEVED AS A SERIES SUMMATION IN TERMS OF TRIGONOMETRIC FUNCTIONS IN THE AXIAL AND CIRCUMFERENTIAL DIRECTIONS, WHEREAS THE DEGREES OF FREEDOM DEPEND ON TIME. A BLAST LOAD IS ASSUMED TO REPRESENT EFFECTS DUE TO EXPLOSIONS ON THE SHELL AS TIME-DEPENDENT PRESSURES WITH A GIVEN CIRCUMFERENTIAL DISTRIBUTION (A COSINE SQUARE DISTRIBUTION IN TERMS OF THE CENTRAL ANGLE). THE PROCEDURE IS VALIDATED BY COMPARISON WITH A NONLINEAR FINITE ELEMENT MODEL UNDER THE SAME LOAD CONDITIONS. THE INFLUENCE OF LOAD LEVEL AND SHELL GEOMETRY ON THE TRANSIENT RESPONSE IS INVESTIGATED BY MEAN OF PARAMETRIC STUDIES. GOOD ACCURACY IS FOUND IN THE RESULTS FOR THE RANGE OF SHELLS WHICH ARE REPRESENTATIVE OF HORIZONTAL, FUEL STORAGE TANKS IN THE OIL INDUSTRY.