Buckling analysis of medical guidewires based on the modified couple stress theory

This paper investigates the behavior of a medical guidewire within a vessel with a specific focus on its buckling, commonly known as tip load. The guidewire is simulated as a variable section microshaft embedded in an elastic environment, and a comprehensive buckling analysis is carried out based on the modified couple stress theory (MCST). The fundamental frequency is determined by applying Hamilton’s principle and Rayleigh’s method. A formula for calculating the buckling force is subsequently introduced. Numerical simulations were conducted to analyze the impact of the material properties, tapered tip length, core thickness, slenderness ratio, and material length scale parameter on the tip load and penetration force. Furthermore, a comparative study was carried out to validate the proposed formulation. The findings derived from this research can provide valuable insights for the optimization and exploration of various parameters related to medical guidewires. The findings indicate that coronary guidewires with lengths exceeding 10 cm exhibit minimal variations in tip load, whereas those with lengths below this threshold experience a substantial decrease of 65–75% in both tip load and penetration force when the length is doubled. In addition, nitinol guidewires demonstrate greater flexibility, with their tip load being nearly 75% lower than that of stainless steel guidewires of equivalent dimensions. Moreover, there is a notable increase in penetration force with an expanding radius, with tapered tips resulting in an approximate 20–30% increase in penetration force.