Basalt, carbon and Kevlar hybrid laminates

We explored how the order of carbon, Kevlar and basalt plies shapes the mechanical response of hybrid epoxy laminates. The study combines laminate fabrication, tensile and flexural testing, and SEM examination of selected fracture surfaces.

Figure 1. Graphical abstract of the hybrid laminate study.

Ply order and fabric structure

Each laminate contained ten plies. All seven hybrids used four carbon, four Kevlar and two basalt plies, arranged symmetrically about the mid-plane. We varied the surface material, carbon position and number of transitions between dissimilar plies.

Carbon and basalt were twill fabrics; Kevlar was plain weave. The hybrid proportions refer to ply counts.

Ply order and fabric structure — Figure 2. Single-fiber references and hybrid stacking sequences. C = carbon, K = Kevlar and B = basalt. Dashed lines mark the mid-plane; each block represents one ply.

Tensile and flexural testing

We used uniaxial tension and three-point bending to examine the laminates under different loading conditions. The schematic and test photographs show the loading directions, specimen geometry and visible damage during testing.

Test photographs — Figure 4. Tests at KUET MERC: (a) three-point bending, showing the loading nose, support rollers, compression face and tension face; (b) tensile loading, showing the grips and failure zone.

Selected mechanical response

The selected plots show the flexural stress–strain response and the tensile strength comparison across laminate configurations.

Selected fracture surfaces

SEM observations add a closer view of ply separation, exposed fiber bundles and fracture features in selected flexural specimens.