OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
STRESS DISTRIBUTION ANALYSIS OF A ROTATING HYPER
ELASTIC VANE WITH THE FINITE ELEMENT METHOD
Pratik D Upadhyay 1 ,Akshay J Patel 2
1 B.Tech Mechanical Engineering, SASTRA University, Tamil Nadu, India, Email: upadhyay.pratik24@gmail.com
2 Sr. Development Engineer, Xylem Water Solutions, Gujarat, India, Email:akshay.patel@xyleminc.com
Abstract
Improving the Impeller life is one of the most significant steps in improving the sustainability of the Flexible Impeller Pump.
For the same purpose it is necessary to know the stress distribution on the impeller vane at specific conditions when
failure is most likely to occur. Also it is necessary to identify the specific locations of failure on the vane. This process is
difficult to carry out by hand calculation or by experimentation due the hyper elastic nature of the impeller
material and also due to the high running speed of the pump. This paper proposes a solution to the above problem by
simplification of the impeller geometry and subsequent discretization of the equations involved in vane deformation
using the finite element method. This approach gives us stress distributions and points of expected failure over the entire
vane geometry at instant when the pump starts. The points of failure are then experimentally verified.
1. Introduction
The flexible impeller pump is a relatively unknown product used primarily in the food processing and marine industries.
This pump has a polymer impeller which is deformed during rotation by an internal cam profile. The pump uses the change in
impeller shape during deformation to get the pumping action and cause transport of fluids. The constantly improving
industrial technology has created newer applications for these types of pumps which require longer pump sustainability
and lower current consumptions. It is obvious that the impeller characteristics such as deformation, material
stiffness and the speed of rotation control the life of impeller as well as the current consumption. Thus to improve the
impeller life it is necessary to first have an in-depth understanding of the stress distributions over the impeller. Furthermore it
is necessary to identify the instants of time during the running of the pump when the stress is highest and failure is most likely.
One way to do it would be to use experimental methods to test the pump for failure of impeller in various conditions.
However this is a lengthy and expensive procedure without prior knowledge of expected failure times or points of failure
extensive testing would be required and the results might still be inconclusive. Also this problem does not lend itself easily to
hand calculations due to the complex nature of the geometry and the multiple forces involved. Thus the best
possible solution is to carry out a finite element analysis to find out the stress distributions and the expected locations of
failure and then verify this data experimentally.
PROBLEM DESCRIPTION
Fig 1. Actual Impeller Geometry
The above shown geometry is the actual shape of the impeller; this impeller rotates at 2800 rpm, and the vane
deformation takes place by contact with a stationary cam profile inside the pump bore. Figure 2 and Figure 3
together illustrate the pump construction and situation during operation of the pump.
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