engleski

FINE MESH ANALYSIS OF FLOOR OPENINGS IN BULK CARRIER - Technical Report

The objective of the analysis is to investigate the structural strength of the 3-hold model of the bulk carrier 51 000 TDW (project 972) in fulfillment of requirements for direct calculation of the classification society American Bureau of Shipping (ABS). 3D FEM MAESTRO model for critical structural holds is generated in accordance with ABS safety factors and recommendations. 3D FEM model has approximately 77 570 DOF and 9340 macro- elements. Nine loadcases : LC1-LC9 from ABS Rules are generated using given weight distribution and adjusted to the required bending moment distribution. The Report describes global model usage in providing boundary conditions for fine mesh analysis of floors in double bottom structure. Critical values of shear and von Mises stresses in global analysis are obtained at Fr 128 in ABS loadcases 2 and 4 . 3D fine mesh model for Detail Stress Analysis (DSA) using "top down approach" is developed (Fr 127-129, 70296 DOF, 11716 Q4 shell element groups). The displacement boundary conditions are automatically transferred from the MAESTRO global model to DSA models as well as local loads. High stress areas are clearly identified in global and DSA model. Structural modifications (stiffening) are suggested. Model, boundary conditions and permmited stress levels are adjusted to ABS requirements. This report covers the results of Detail Stress Analysis (DSA) of the critical floors required modifications. Modifications include closing of openings between longitudinals and and collar stiffening of holes between stiffeners. Obtained von Mises and shear stress levels are presented. They are at ABS permited levels for material grades applied.

Bulk carrier; finite elements; MAESTRO modeling

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