With the introduction of 3D elastic-plastic deformation, and strip plastic flow factor concept, to analysis of the influence of strip local high points on the ridge-buckle behaviour in coiling process, an elastic-plastic coiling stress and ridge-buckle value model that can be used for online calculation was established. According to comparison and analysis of the influencing factors, uneven distribution of radial and circumferential stress caused by local waves is an important cause of strip ridge-buckle, and the ridge-buckle value increases with increases of local wave size, coil diameter and coiling tension, and significantly with decreases in the strip thickness. The influence of waves with different locations on the ridge-buckle value was analysed. Based on comparison of analysis results obtained by an elastic ridge-buckle value model and ANSYS FEM (finite element method), the accuracy and feasibility of this model have been proved, which will provide theoretical and model support for subsequent reduction of the ridge-buckle defects brought by local waves.
Fluid-structure interaction (FSI) is a common phenomenon in biological systems. FSI problems of practical interest, such as fish/mammalian swimming, insect/bird flight, and human cardiac blood flow and respiration often involve multiple 3D immersed bodies with complex geometries undergoing very large structural displacements, and inducing very complex flow phenomena. Simulation of heart valve FSI is a technically challenging problem due to the large deformation of the valve leaflets through the cardiac fluid domain in the atrium and ventricular chambers. Recently, we developed a FSI computational framework [1] for modeling patient-specific left heart (LH) dynamics using smoothed particle hydrodynamics (SPH) for the blood flow, and non-linear anisotropic finite element analysis for heart valve tissues. SPH is a meshless, statistical method that relies on sampling neighboring particles to calculate fluid field variables. SPH's mesh-free and Lagrangian nature makes it particular suitable for numerical problems where there are 1) moving boundaries and 2) large deformations, which are the conditions seen in heart valve FSI applications. In this presentation, I will explain under which scenarios that heart valve FSI simulations are needed, and give a few examples of our FSI applications. Briefly, we utilized the SPH-FE based, fully-coupled FSI modeling techniques to investigate the pathological LH dynamics under primary and secondary mitral regurgitation (MR) conditions [2], and examine the underlying biomechanics of various minimally-invasive mitral valve (MV) repair techniques. The FSI model was also used to investigate the impact of transcatheter aortic valve replacement (TAVR) on LH dynamics under bicuspid aortic valve (BAV) stenosis and concomitant significant MR [3].
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