PERIPHERAL DEFORMATION AND BUCKLING OF STAINLESS STEEL HEMISPHERICAL SHELLS COMPRESSED BY A FLAT PLATE

Abstract

AN EXPERIMENTAL INVESTIGATION WAS PERFORMED ON STAINLESS STEEL HEMISPHERICAL SHELLS UNDER AXIAL COMPRESSION. EIGHT KINDS OF SHELLS WITH RADIUS-TO-THICKNESS RATIOS THAT RANGE FROM 57.1 TO 125 WERE DESIGNED AND MANUFACTURED FOR THIS STUDY. THE SHELLS WERE COMPRESSED TO MORE THAN 50% OF THEIR RADII BY A SOLID FLAT PLATE. TO AVOID CONTACT BETWEEN THE BASE PLATE AND THE DEFORMED CENTRAL PART OF THE SHELLS, MOST OF THE SHELLS WERE PLACED ON A PLATE WITH A HOLE IN THE CENTER. NONETHELESS, ONE TYPE OF SHELL WAS PLACED ON A SOLID BASE PLATE WITHOUT A HOLE TO ANALYZE THE EFFECT OF THE BASE PLATE. AS PER AN OBSERVATION OF COLLAPSE MODES AND LOAD-DEFORMATION SHELL RELATIONS, THE DEFORMATION PROCESS OF A HEMISPHERICAL SHELL THAT IS COMPRESSED BY A FLAT PLATE CAN BE DIVIDED INTO FOUR STAGES: LOCAL FLATTENING (STAGE I), AXI-SYMMETRIC INWARD DIMPLING (STAGE II), NON-SYMMETRIC MULTIPLE LOBES (STAGE III), AND PERIPHERAL DEFORMATION AND BUCKLING STAGE (STAGE IV). THE PRESENT STUDY MAINLY STUDIES STAGE IV, WHICH CAN BE CATEGORIZED INTO PERIPHERAL COMPRESSION (STAGE A), PERIPHERAL BUCKLING (STAGE B), BUCKLING EXPANDING (STAGE C), AND OVERALL COLLAPSE (STAGE D).