Machine learning-based analysis of energy absorption and punch shear behavior in Kevlar/glass/carbon/MWCNTs composite laminates for aerospace applications

This study develops and evaluates lightweight hybrid Kevlar–glass–carbon/epoxy laminates reinforced with multi-walled carbon nanotubes (MWCNTs) for improved energy absorption and punch shear performance in aerospace structures. Composite plates were fabricated using a quasi-static stacking sequence (45° Kevlar/45° carbon/0° glass/45° carbon/45° Kevlar) and nanoparticle loadings of 0, 1.5, 3, 4.5, and 6 wt.% MWCNTs, followed by mechanical testing under ASTM tensile, flexural, interlaminar shear, and quasi-static punch shear configurations. Among all formulations, the laminate containing 4.5 wt.% MWCNTs exhibited the best overall performance, achieving tensile strength of 215.58 MPa, flexural strength of 320.18 MPa, puncture strength of 110.8 MPa, and interlaminar shear strength of 28.49 MPa. Under punch shear loading, this optimal laminate also reached a maximum net energy absorption of 15.45 J and a specific energy absorption of 0.44 J/g, representing an improvement of more than 15% in puncture resistance and energy absorption relative to the baseline laminate without MWCNTs. Convolutional neural network (CNN) models were trained on the experimental dataset to predict punch shear strength and energy absorption, yielding low error metrics (e.g., a mean absolute error of 1.243 MPa for punch shear strength and 0.0224 J/g for specific energy absorption) and confirming 4.5 wt.% as the optimal nanoparticle loading. Scanning electron microscopy of fractured specimens corroborated these macroscopic trends by revealing improved fiber–matrix interfacial bonding, effective crack-bridging, and reduced delamination at intermediate MWCNT contents, whereas agglomeration and microstructural defects at 6 wt.% diminished mechanical gains. The combined experimental and machine learning results demonstrate that judicious MWCNT incorporation in Kevlar–glass–carbon laminates can significantly enhance strength-to-weight efficiency and impact tolerance, supporting their application in high-performance aerospace components.