Hybrid Finite Element Model for Predicting the Interface Pressure of Medical Compression Stockings.

Abstract

Accurate prediction of interface pressure is essential for optimising product design and ensuring the therapeutic effectiveness of medical compression stockings. Finite-element (FE) methods are commonly used for this purpose, allowing for the integration of specific mechanical and dimensional properties of both fabric and body. However, existing models rely on homogenisation approaches to model the fabric, neglecting its mesoscale architecture and the individual mechanical contributions of yarn systems. This study presents a hybrid FE model that combines discrete and continuous elements to represent local fabric architecture and yarn behaviour. A mesoscale unit cell couples 1-D connectors for the inlay yarn with 3-D shell elements for the loop structure, with mechanical parameters identified from uniaxial tensile tests. Two compression zones (ankle and calf) of a class-II stocking were modelled with zone-specific course densities, directly linking local architecture to macroscopic response without homogenisation. Interface pressure was predicted in several in-use configurations by simulating garment placement over rigid leg cylinders. The model was validated against Laplace's law and PicoPress sensor data. Predicted average pressures differed by 5.1%-20.5% from Laplace estimates, and by ≤ 20% from sensor measurements on 3-D-printed legs. Local pressure profiles reproduced the therapeutic gradient (ankle > calf) and remained numerically stable after mesh-ratio optimisation (8:1). The proposed framework enables precise integration of structural and mechanical parameters and represents a significant improvement over homogenised models for pressure prediction and garment design.