A Novel <scp>3D</scp> Model for Describing Interlayer Intimate Contact During the Processing of Thermoplastic Composite

ABSTRACT This study presents a novel 3D interlayer contact model based on fractal theory to quantify the evolution of intimate contact during thermoplastic prepreg processing. The rough surface is modeled as a 3D Cantor set embedded in a 2D plane, and the 3D deformation of asperities under processing conditions is described using a creeping squeeze flow model in polar coordinates. Key parameters, including fractal dimension, scaling factor, and a dimensionless surface roughness ratio, are calibrated and used to predict interlayer contact in three‐layer prepregs under various thermoforming conditions. Experimental validation using metallographic and C‐scan analysis confirms the model's accuracy, with most prediction errors within 5%. Compared to conventional 2D models, the 3D model provides improved accuracy by accounting for the 3D flow of asperities, particularly under higher temperature and pressure. Finally, the independent impact mechanisms of the processing parameters and surface geometry on intimate contact are analyzed, with temperature and fractal dimension exerting the greatest impact on the rate of contact development. This model serves as an effective tool for predicting intimate contact evolution in thermoplastic composite processing and provides theoretical support for interlaminar strength prediction and manufacturing process optimization.