Predicting the elastic properties of two dimensionally braided tubular composite structures towards the design of braid-reinforced polymer medical catheters

Two-dimensionally (2D) braided tubular composites have been utilized in a wide range of applications including medical equipment such as braided stents and catheters.;An analytical model that accounts for the effect of diameter of a braided tubular product on the elastic properties, needed for catheter design, was developed. Parametric studies were conducted to highlight the effects of the change in radius on elastic properties of braided composites. Case studies that underline the important geometrical parameters that affect predictions were conducted and findings discussed.;Effect of increased undulation length on elastic properties of braided composites was also investigated. The findings were compared to experimental work using three different fiber/matrix system composites. As predicted by the model, a decrease in the properties was observed experimentally; however, this decrease was found to be more important than predicted. Possible reasons for this behavior are discussed in the view of composite materials and geometrical factors.;The experimental findings of the open-mesh composites were also used to further validate a regression based model available in the literature. Lower linearity limit values for the regression based model were calculated for longitudinal elastic and shear moduli predictions.;Catheters are long flexible tubes used in catheterization procedures, such as angiography and ablations. In this thesis, angiographic catheters were specifically targeted; which are referred as "catheters" for the remaining of the document. Catheters are typically used with guidewires which provide structural support to the often low rigidity catheters. In some catheterization procedures, it may be beneficial to use a 2D braided catheter for increased control and maneuverability in the body. The 2D braided catheter, if designed properly, may provide all the required rigidities for a successful procedure and decrease the dependency to the guidewire compared to conventional catheters. Hence, use of 2D braided catheters may decrease the procedure time, may provide superior control of the device due to its design, and may also decrease the inherent patient discomfort. A thorough understanding of 2D braided composites is of absolute necessity considering the delicate use of medical equipment, such as catheters, in the human body. The aim of this PhD thesis is to address the shortcomings of the available models in the literature by developing an analytical model geometrically consistent with small braided tubular structures and provide all the necessary tools possible to design a target specific braided catheter.