## 1 Introduction
[4] carried out a mechanical protocol to characterise horse urethral tissues and structures, including distal and proximal regions and circumferential and longitudinal directions. They performed tensile and stress-relaxation tests to investigate the response of the tissues and inflation tests to study the behaviour of urethral structures. With the elastic and viscous parameters obtained from this work, [PERSON] et al. [20] investigated the mechanical interaction of urethra tissues under occlusion with a prosthesis. They developed a computational model and assumed that equine and human urethra are similar. They were able to characterise the nonlinear mechanical behaviour, using an hyperelastic formulation, and proposed preliminary constitutive parameters. From the same group, [PERSON] et al. [21] also studied the mechanical behaviour of the lower urinary tract, performing inflation tests on segments of horse penile urethrae. From the experimental results, a computational model was developed to interpret the response in pressure-volume-time of the structures. They obtained an elastic modulus of 0.677 \(\pm\) 0.026 and 0.262 \(\pm\) 0.006 kPa for the proximal and distal regions, respectively. Concerning the viscous component, the results were \(\tau_{1}\) = 0.153 \(\pm\) 0.018 s, \(\tau_{2}\) = 17.458 \(\pm\) 1.644 s and \(\tau_{1}\) = 0.201 \(\pm\) 0.085, \(\tau_{2}\) = 8.514 \(\pm\) 1.379 s for the proximal and distal regions, respectively. Using and comparing with rabbit urethrae, [PERSON] et al. [22] and [PERSON] et al. [23] studied the mechanical properties and biocompatibility of several biomaterials, such as polyglycolic acid, to be used as scaffolds. Their final goal was to consider them for urethral regeneration and reconstruction, respectively. Focusing on porcine tissues, [PERSON] et al. [24] evaluated the effects of cryopreservation on the mechanical properties of porcine urethra samples. They performed uniaxial tension and inflation tests and measured the elastic modulus and ultimate tensile strength. In addition, [PERSON] et al. [25] characterised human urethral tissue in terms of the mechanics, composition and gross structure in order to produce a more biomimetic scaffold. The mechanical characterisation was made using pressure-diameter and uniaxial extension testing. They concluded that the tissue stiffens as intraluminal pressure is applied. Moreover, the response of the tissue, regarding the elastic and viscous components, was independent of the regional or directional variance. In the current study, the porcine urethra will be investigated as a possible replacement model for the human urethra, mainly concerning the mechanical behaviour. The mechanical properties of the porcine urethra, obtained through experimental tests in the longitudinal and circumferential directions, will be used as input data for the finite element method (FEM) simulations. Moreover, the hypothesis of using the mechanical properties of the porcine urethra as a proxy for the mechanical characterisation of the human urethra will be critically evaluated. Following the principles outlined above, the samples of the porcine urethra were collected from crossbreed male animals (85 kg; 6 months old) within a maximum of two hours after slaughtering. The urethral samples were then mechanically characterised under low-cycle fatigue conditions. The experimental protocol, which comprises the first part of this research, was followed by the numerical simulations. Their outputs (the FEM simulation results) were then compared with the experimental mechanical behaviour observed under fatigue loading conditions. This comparison intends to evaluate how close to reality the numerical (FEM) models are given the experimental protocol conditions.