PSI - Issue 81

Dhanies Wahyu Ardyrizky et al. / Procedia Structural Integrity 81 (2026) 458–464

459

compromising the essential function of the double hull (Prabowo et al., 2016;2018;2023; Fatt and Sirivolu, 2017; Klanac et al., 2005; Theulen and Peijs, 1991). One of the critical aspects in evaluating the capability of sandwich panels is under fire scenarios (Anjang et al., 2015; Galgano et al., 2009). During such events, mechanical and thermal loading act simultaneously. In VLCCs, the structure constantly bears the weight of the oil cargo. When a fire accident occurs, the material strength deteriorates, and residual stress develops after cooling, reducing the structural integrity of the ship hull (Kamal et al., 2025; Du et al., 2022). Predicting the mechanical response of the sandwich panel aims to assess its behavior under these conditions before it is adopted as an alternative to the double-hull structure. The finite element method (FEM) provides an accurate prediction of the structural response through numerical discretization. FEM accuracy depends strongly on mesh discretization, where the mesh size can influence the simulation results (Kim et al., 2023; Wang et al., 2016). Typically, a finer mesh improves the accuracy of FEM results; however, in some cases, it only increases computation time without significant improvement in precision. Therefore, a mesh convergence study is crucial for obtaining accurate results that closely approximate real-world conditions. Although many studies have investigated explosions and fires in sandwich panels (Fitri et al., 2025; Nurcholis et al., 2024; Zheng and Xu, 2021), research combining static mechanical loading with thermal loading remains limited. The purpose of this study is to observe the mechanical response of the sandwich panel and to conduct a mesh-convergence analysis under fire conditions.

Nomenclature c p

specific heat at constant pressure convective heat transfer coefficient

h c

thermal conductivity

k

internal heat generation rate

Q

heat flux

q”

temperature

T

hot gas temperature surface temperature

T g T s

exposure time

t

emissivity

ε ρ σ

density

Stefan –Boltzmann constant (5.67 × 10 -8 )

2. Fire – Structure Interaction Fire – structure interaction is a continuous phenomenon in which a structure's thermal and mechanical responses are coupled when exposed to fire. A fire scenario typically involves three heat transfer mechanisms: conduction, convection, and radiation, each playing a specific role depending on the environmental and fire configuration conditions. Drysdale (2011) explained that conduction dominates in massive sections, while transient thermal behavior becomes important in layered structures, where the temperature gradient between layers governs the rate of heat transfer and the reduction in stiffness. The conduction equation is given by Eq. (1). Convection occurs through the surrounding fluid medium and continues to the exposed structural surface. The convection heat transfer equation is expressed in Eq. (2). According to the Society of Fire Protection Engineers (SFPE) Handbook of Fire Protection Engineering (Quintiere, 2016), the convection rate is significantly influenced by gas velocity and turbulence intensity near the flame region. Meanwhile, radiation often dominates in high-temperature fire conditions. The radiative heat flux is represented by Eq. (3). Drysdale ( 2011) stated that radiation becomes dominant when flame temperatures exceed 800 °C and must always be considered in thermal – structural coupling analysis. ρc p ∂ ∂ T t =∇∙(k∇T)+Q (1) q = h c (T g -T s ) (2) q̈=εσ(T g 4 -T s 4 ) (3) 3. Design and Material The model in this study is based on the sandwich panel geometry proposed by Klanac et al. (2005). Fig. 1(a) illustrates the configuration of a core layer sandwiched between two face plates that act as stiffeners. For the overall geometry, dimensions of 5550 × 4050 × 360 mm were set, corresponding to the equivalent weight for a ship structure (Fig. 1(b)). Weld connections were