A COMPARATIVE-STUDY OF LINEAR AND NONLINEAR SIMULATIONS OF THE LEAFLETS IN A BIOPROSTHETIC HEART-VALVE DURING THE CARDIAC CYCLE

Two geometrically identical models of the leaflets of a bicuspid biopr osthetic heart valve have been constructed using finite elements. The boundary conditions applied to the models were also identical but a li near material model has been used in one and a nonlinear elastic model in the other. The models were full-scale and contained 2600 Belytschk o-Lin-Tsai shell elements which allowed the variation of stress throug h the thickness of the leaflet to be modelled. A time-varying, spatial ly-uniform pressure differential was applied across the leaflets to mo del their behaviour during a complete cardiac cycle. The simulation wa s performed using a dynamic, explicit, time-stepping, finite element c ode. A comparison of the two models showed that the nonlinear model wa s more responsive to the time-varying pressure wave, and deformed into more complex shapes during the opening and closing phases which induc ed lower compressive but higher tensile stresses in the leaflets.