Failure Behavior Analysis of Crack Propagation in Ship Sandwich Structures

Damage to ship structures leads to a reduction in strength, which increases the risk of structural failure. The vulnerability of damage in sandwich panel structures made of low-density steelpolyurethane elastomer needs to be evaluated and predictions made regarding failure modes, particularly crack propagation through the core thickness. Variations in structure thickness and the size of the initial crack are evaluated to determine the impact of structural design on damage under the ship’s operational loads. Finite element analysis, validated with experimental data, is used to simulate the dynamics of crack propagation. It was found that a thicker core and a smaller initial crack length result in slower crack propagation rates and shorter crack extensions. Increasing the core thickness from 15 mm to 24 mm reduced the crack propagation rate by up to 28% and improved crack extension resistance by as much as 54%. Thicker face and bottom plates further contributed an additional reduction in crack growth rate, providing an extra margin of structural toughness. Shorter initial cracks also proved significant, with propagation rates decreasing by about 73% when comparing a 25 mm crack to a 75 mm crack. These factors lowered the strength reduction factor (SRF ) and extended crack growth times, confirming that thicker cores and smaller initial cracks improve damage resistance in ship sandwich structures.