PSI - Issue 72

Gusti Kid Faiq Syah et al. / Procedia Structural Integrity 72 (2025) 401–408

403

This analysis focuses on the mesh variation performed on the designed sandwich panel to determine the optimal mesh size in further research based on considering the convergence of the results and the total computation time. In addition, the impactor is positioned to hit the target plate. For simplification, boundary conditions are applied to the sandwich panel with mesh variations performed with mesh sizes (0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 13 mm, 14 mm, and 1.5 mm). 2.1. Material properties Unalloyed aluminum, specifically Aluminum 1100-H12, is the material chosen for this simulation. Various material properties are carefully outlined in Table 1. These properties are essential for accurately modeling the material's behavior under different loads and environmental conditions. Aluminum 1100-H12's simulations reflect real-world scenarios, allowing for a comprehensive analysis of the material's structural response. This approach not only enhances the validity of the simulation results but also aids in identifying potential areas for improvement in design and application. Table 1. Material parameters of Aluminum 1100-H12.

Description

Unit

Numerical Value

Modulus of elasticity, E

GPa

65.76

Density, ρ

Poisson’s ratio, v

0.30 2.71

g/cc MPa MPa

Yield stress constant, B Strain hardening constant, B

102.75 168.11 0.1012

N

Strain sensitivity coefficient, C Thermal softening constant, m Reference strain rate, ε̇ 0 Melting temperature, θ melting Transition temperature, θ transition Fracture strain constants: D1

0.001 0.859

1

K K

1800

293

0.071 1.248 -1.142 0.0097

D2 D3 D4 D5

0

A reference point is established for the projectile to facilitate ballistic impact testing. The material utilized for this simulation is EN-24 steel, modeled as an analytical rigid body to enhance computational efficiency during the simulation process. The shell is fixed at the rear, meaning that all degrees of freedom for the elements located at the back are constrained. A generalized contact algorithm is employed to model the interaction between the shell surfaces, enabling the shell structure to interact with itself effectively. All dynamic explicit numerical simulations are conducted using the LS-DYNA/Explicit simulations. 2.2. Meshing strategy and boundary conditions All the target plates were made of 1100-H12 aluminum with a plate thickness of 1 mm. The target plate was cut into circles with a total diameter of 315 mm and had nine holes with a diameter of 8 mm used for plate holders, which were the constrained spots during the experiment given in Figure 2. The mesh size is divided into three sizes distributed evenly to decrease the computing load on the simulations while maintaining better results. Mesh sizing for the contact zone is the defined value for the simulation; the mesh size for the outer part is multiplied by two for each transition as a noncontact zone, as shown in Figure 3. The projectile was driven using a compressed-air pneumatic gun with a