Analysis and Improvement of Virtual Work Criteria for Structure Optimization
An improvement of virtual work criteria for structure optimization is presented to overcome the shortcomings caused by the neglect of dead weight and inertial load of structure in solution of criteria equations. Deduction of criteria equations is analyzed to prove that the shortcomings lead to the error of structure optimization. Therefore, new criteria equations are formulated using the displacement representation of algebraic sum and matrices. According to the characteristics of the improved criteria equations, an improved Aitken algorithm is applied to solve the equations in order to implement the complete automatization of iterative solution for structure optimization. The algorithm is proved to be an accelerated iterative method, and its convergence order is estimated. The feasibility of improved criteria equations and the merits of improved Aitken algorithm are demonstrated by an illustrative example showing five-bar truss. The results show that the improvement of virtual work criteria provides a structure optimization method for precision machine.
Comparison of theories for stability of truss structures. Part 2: Computation of critical solution of stability
Abstract Critical solution of stability is the optimum solution of cross-sectional area with stability constraint. By applying the linear Eulerian theory of stability, the critical solution with discrete variables for general truss structures is computed in this paper. Then, in order to compare the results with the ones in previous publications and to reveal the applicability of various theories of stability, the critical solutions with continuous cross-sectional areas are computed for several examples by applying various theories of stability.
Balloon assisted translocation of the mitral anterior leaflet to prevent left ventricular outflow obstruction (BATMAN): A novel technique for patients undergoing transcatheter mitral valve replacement
Transcatheter mitral valve replacement (TMVR) is an option for patients at high risk for mitral valve replacement or repair via sternotomy or left thoracotomy approach. TMVR carries up to 22% risk of left ventricular outflow tract (LVOT) obstruction. Severe LVOT obstruction can have devastating hemodynamic and clinical consequences.