Measurement and Modelling of the Stiffness, Deformation and Constitutive Behaviour of Biomedical Textile Implants

Abstract

Composite materials and technical textiles are increasingly used in biomedical applications. In the past few decades, research on artificial biomedical scaffolds manufactured from technical textiles have attracted much attention. Among many types of technical textiles, those made from PET fibres are most commonly used to repair knee ligaments due to their advantages including biocompatibility, biodegradability and suitable mechanical properties. The woven structure of a textile influences its the mechanical properties in many aspects, such as its tensile behaviour and shear behaviour, both of which being the main deformation modes that knee ligaments must sustain within human bodies. The aim of this thesis is to analyze the tensile and shear behaviours of three types of PET implantable artificial textile ligaments provided by manufacturer Neoligaments®.

The first part of the work consists in applying tensile and shear loads on the three types of artificial textile ligaments and deriving the value of tensile stiffness and shear stiffness. Then, the experimental results were analyzed, and they were compared with the behaviour of real knee ligaments in order to assess whether the artificial textile ligaments provide adequate behaviour and stiffness.

The second part of the work introduces early work done towards modelling the mechanical behaviour of the artificial textile ligaments. Finite element models were constructed from geometric models of the textiles built using textile modelling software TexGen. After applying tensile loads in ANSYS, stresses, strains and deformations in the models were analyzed. Based on the results, tensile stiffness of the models could be calculated. Although some limitations to the models lead to differences between these results and experimental values, the work enabled the identification of features of the models to be maintained in future work, and of features to be improved, towards the analysis of the mechanical properties of technical textiles and other non-linear, non-rigid structures.