Rapid manufacturing techniques in the development of an axial blood pump impeller
Abstract This paper presents a comparison of manufacturing techniques used in the development of an axial blood pump impeller. In this development process the impeller was designed and its performance was evaluated with the aid of computational fluid dynamics (CFD). Prototypes of those designs where the CFD results show promise were needed in sufficient quantities at a low cost for experimental validation of the CFD results. As the impeller is less than 16 mm in diameter with a maximum blade thickness of about 1.5 mm, innovative manufacturing techniques are explored in this paper to determine the best process for quick fabrication of prototypes that are dimensionally accurate, structurally robust and low in cost. Four rapid prototyping techniques were explored. The completed parts were compared on the basis of manufacturing time, quality and strength of parts obtained, manufacturing cost and also in vitro performances. Based on these studies, it was concluded that selective laser sintering (SLS) is the most appropriate method for the quick production of prototype parts for evaluation of pump performance.
Analysis of interaction between geometry and efficiency of impeller pump using rapid prototyping
Design aids available today might have helped the pump designers to bring about theoretically the most efficient pumps, but the production technology and quality control during manufacture has not kept pace with such achievements in realizing the goals of developing energy efficient pumps. Pump designers often face the problem of selecting and optimizing a number of independent geometrical parameters whilst aiming at the desired efficiency from the pump. The only option is to approximate the theoretical design with experimental findings iteratively until the end result is achieved. Tremendous development of advanced manufacturing technology and computer technology has made rapid prototyping and computational fluid dynamics (CFD) techniques the right alternative method of reaching the target. Centrifugal pump impeller geometry, which contributes maximum complexity in flow during pump design, has been analysed in this work based on the parameters derived through computer-aided design (CAD) and CFD analysis. Using selective laser sintering, technique the impeller designed by CAD and two standard impellers commercially available for the same duty requirement is manufactured and their performance is tested to know their hydraulic efficiency. Results obtained from this work are useful for standardising pump impeller design and for developing energy-efficient pumps.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.