This study investigated the mechanical performance of the edge-closed honeycomb sandwich structure with face/core debonding under compressive load by experimental and numerical methods. Uniaxial compression tests of asymmetric sandwich structures with various debonding sizes between the carbon/epoxy face sheets and the honeycomb core were conducted. The experimental results showed that the failure of debonding specimens was mainly caused by the local buckling of face sheets at the debonding area. The failure zone of sandwich structures gradually translated from the edge-closed beveled area to the debonding area with the increase of debonding sizes correspondingly, Meanwhile, the stability and the load carrying capacity of sandwich structures were in a downtrend. Compared with the nondestructive specimens, the residual strength of two kinds of defective specimens decreased by 9.9% and 22.1%, respectively. The simulation of the developed numerical model based on the linear buckling theory and the continuum damage mechanics agreed well with the experimental data. The study has guide to assess on the damage tolerance of edge-closed honeycomb sandwich panels with face/core debonding.

How to simulate fracture mode and crack propagation path in a plate with multiple cracks is an attractive but dicult issue in fracture mechanics. Peridynamics is a recently developed nonlocal continuum formulation that can spontaneously predict the crack nucleation, branch and propagation in materials and structures through a meshfree discrete technique. In this paper, the peridynamic motion equation with boundary traction is improved by simplifying the boundary transfer functions. We calculate the critical cracking load and the fracture angles of the plate with multiple cracks under uniaxial tension. The results are consistent with those predicted by classical fracture mechanics. The fracture mode and crack propagation path are also determined. The calculation shows that the brittle fracture process of the plate with multiple cracks can be conveniently and correctly simulated by the peridynamic motion equation with boundary conditions.

This study focuses on AG-80 epoxy resin, using 5228A and BA9916-II as representative examples. Saturated moisture absorption tests and dynamic mechanical analyses (DMA) were conducted to investigate its physical properties. The saturated moisture absorption rates and diffusion coefficients for 5228A and BA9916-II were measured. Their distinct molecular structures were found to lead to different moisture–absorption behaviors. A hygro-thermal–mechanical constitutive model for AG-80 resin (represented by 5228A) was developed, taking into account the effects of temperature and moisture content on mechanical properties. The model was validated by DMA tests on 5228A/CCF300 composites. The research findings of this study enhance the understanding of AG-80 epoxy resin and provide a theoretical basis for its application in high-temperature-resistant industrial environments.

To evaluate the energy absorption ability of composite beams with corrugated web under impact, the drop tests were conducted to demonstrate the fracture modes and obtain the load and energy history curves. Based on the drop tests, a finite element (FE) model was proposed with a weak link designed to trigger crushing, developed using Abaqus/Explicit, which integrates cohesive elements and employs the improved Hashin criterion along with the Choi–Chang criterion to accurately predict the onset and progression of delamination. The model accounts for the anisotropy and progressive damage in composite laminates. The periodic boundary conditions (PBCs) were integrated into the single-wave corrugated web beam model, the inherent limitations of which were corrected, enabling it to simulate the crushing process with the same effectiveness as the multi-wave model. As a result, the proposed model can accurately depict the progressive crushing behavior of corrugated web beams under impact loads while maintaining high computational efficiency.

Composite laminates possess complex anisotropic behavior, motivating the development of simplified yet accurate modeling approaches. In this paper, we present a study that introduces a stiffness-invariants-based constitutive model for symmetric, balanced composite laminates, highlighting a novel “quasi-Poisson’s ratio” parameter as a key innovation. The proposed method reconstructs the laminate stiffness matrices using invariant theory (trace of stiffness tensor) and a Master Ply concept, thereby reducing the number of independent material constants. The methods and assumptions (e.g., neglecting minor bending-twisting couplings) are outlined, and the model’s predictions of critical buckling loads are compared to classical laminate theory (CLT) results. Good agreement is observed in most cases, with a consistent conservative bias of CLT. The results confirm that the invariant-based model captures the dominant stiffness characteristics of the laminates and can slightly overestimate stability margins due to its idealizations. In conclusion, this work provides an efficient constitutive modeling framework that can be integrated with finite element analysis and extended to more general laminates in future studies.

Carbon fiber reinforced polymer (CFRP) is widely used in aircraft crashworthiness structures, but its unstable failure modes limit its energy absorption capability. This study proposes a hybrid aluminum/CFRP (Al/CFRP) corrugated web beam to enhance the energy absorption and progressive collapse under axial impact. Quasi-static crushing experiments were performed on CFRP and Al/CFRP corrugated web beams with 45° crushing triggers. Results revealed that the initial peak load and the total energy absorption of the Al/CFRP corrugated web beam increased by 16.68% and 34.62%, respectively, compared to those of the CFRP corrugated web beam. The specific energy absorption and the crushing force efficiency also improved by 13.22% and 1.51%, respectively. The CFRP corrugated web beam underwent transverse shearing, brittle fracture, and bending failures during crushing, resulting in a decline in energy absorption after a 40 mm displacement due to crack propagation. In contrast, the Al/CFRP corrugated web beam exhibited stable progressive collapse with sustained energy absorption up to a 60 mm displacement, benefiting from the plasticity of the aluminum layer. Detailed finite element models were validated against the experimental results, with the simulated failure morphologies and the energy absorption being consistent with the measured results. The proposed Al/CFRP corrugated web beam demonstrated superior crashworthiness, progressive collapse, and energy absorption capabilities under impact.