Multiscale Transfer of Cohesive-Zone Parameters for Opening-Dominated Interlaminar Fracture in Carbon-Fiber-Reinforced Aluminum Laminates

Abstract

Specimen-scale fitting can reproduce interlaminar fracture in carbon-fiber-reinforced aluminum laminates (CARALL) but obscures the physical origin of cohesive-zone parameters. We present a multiscale framework integrating molecular dynamics (MD), a representative volume element (RVE), finite element (FE) modeling, and opening-dominated asymmetric double-cantilever-beam (DCB) tests. At modeled high rates, an ideal nonbonded Al/epoxy interface exhibited normal and tangential strengths of 470.09 and 352.93 MPa, respectively. Across 0.001–0.005 Å/fs, normal and tangential peak tractions increased by 5.93% and 5.82%, respectively, whereas traction-separation integrals varied nonmonotonically. These single-atomistic-realization descriptors were transferred to an RVE containing Al/matrix and fiber/matrix interfaces. In this morphology, fiber/matrix debonding preceded Al/matrix damage in all three realizations, and the RVE yielded mean effective normal and tangential strengths of 27.42 ± 0.33 and 39.04 ± 0.65 MPa, together with mean Mode I and Mode II fracture energies of 0.36 ± 0.02 and 0.81 ± 0.04 N/mm, respectively, where the means and standard deviations are taken over the three stochastic fiber realizations. The RVE-derived strengths and fracture energies were assigned directly to the DCB model without fitting the experimental response. The FE peak load was 44.48 N, 5.50% above the four-specimen mean of 42.16 ± 1.22 N, and the predicted damage location was qualitatively consistent with the observed Al/matrix interfacial damage. Because the interface model is idealized and the comparison rests on load–displacement data without synchronized crack-length measurements or independent fracture-resistance data, these results are reported as a configuration-specific assessment of the transfer procedure rather than as a quantitative validation; the transferred parameters are not intended to predict the chemically and structurally complex anodized interface.