PSI - Issue 72

Muhammad Zainnal Mutaqin et al. / Procedia Structural Integrity 72 (2025) 445–452

450

Investigation on flexural behavior sandwich panels with aluminum honeycomb core embedded by thin-ply carbon-glass fibers/epoxy face (Kazemian et al., 2024) . Fatigue behaviour of composites honeycomb materials with aramide fibre core using four-point bending tests (Abbadi et al., 2010) . Failure behavior of sandwich GLARE face-sheets and aluminum honeycomb core under three-point bending (Zhang et al., 2022a) .

2024

Aluminum alloy 5052 Carbon fabric prepregs

Aramide fibres (ECA)

Aluminium (AlMg3)

2010

Glass Laminate Aluminum Reinforced Epoxy (GLARE)

Aluminum alloy 2024 T3

2022

The results of previous research conducted a three-point bending test showed a tendency for damage in the form of deflection on the entire layer. In the core layer, fatigue shear crack occurs, while damage to the face sheet layer consists of matrix cracking, delamination and fiber fracture. Therefore, it can be assumed that the damage in the face sheet at specimen failure is only caused by the microcracks in the matrix (Ma et al., 2021). The failure mechanism of the sandwich structure in the three-point bending load test on the face sheet layer is divided into three stages, the rapid decline stage, the steady decline stage and the failure stage in the form of cracks in the core layer. Plastic deformation in the sandwich structure causes debonding in the core layer and face sheet layer (Palomba, Crupi and Epasto, 2019).

(a) (b) Fig 5. Bending loading experimental testing: (a) results from Ma et al. (2021); and (b) results from Palomba et al. (2019).

The test validation with numerical method uses the Allen Beam theory approach, adopting sandwich beam deflection analysis. Three layers beam with honeycomb structure with three-point bending loading, ignoring the small effect of the shear force (Słonina et al., 2023) . Deflection/bending stiffness ( δ F ) at the midpoint can be expressed in Equation 4: = ͵ Ͷͺ (4) where F (N) bending force, L (mm) distance between supports (beam span), D (Nmm 2 ) flexural stiffness of the beam. = ͵ ͳʹ = ͵ ͸ + ( + ) ʹ ʹ + ͵ ͳʹ (5) where E x , E fx , E cx (MPa) are the elastic module of the beam, facings, and core, respectively, t, tc, tf (mm) the thickness of the beam, core, and facing, respectively, b (mm) beam width. This equation can be simplified assuming that the bend of the facing around the beam center of gravity is the dominant term and taking into account that first and third terms amount to less than 1 % of this when (Petras and Sutcliffe, 1999).