(345g) A Spinning Device for the Mechanical Characterization of Soft Tissues and Polymers

Nondestructive evaluation of the elastic properties of soft tissues and polymers may be achieved by spinning a sample about an axis of symmetry. If the angular velocity is known, the centrifugal body force can be determined at each point in the sample. Sample deformation may be measured by comparing high resolution digital photographs at rest and at known velocities using image analysis algorithms. Here, we present an automated testing method which offers repeatable measurements by photographing the sample at eight fixed angular locations both at rest and at speed.  The apparatus and imaging methods are validated using a rigid sample of known dimensions.  A climate control system which allows modulation of both temperature and humidity is also detailed. 

An analysis method was developed which allowed estimation of the linear elastic properties of general spheroidal elastic bodies using a separable response surface method.  This method computed deformations in the sample as a function of nondimensionalized parameters related to the sample geometry and mechanical properties, apparatus geometry, and angular velocity.

Further validation of the device was achieved using a multi-level, full factorial experimental design and corresponding analysis.  Here, we measured the effects of storage (duration and solution) and testing (temperature, humidity, and angular velocity) conditions on the geometry and mechanical properties of 99 porcine ocular lenses.  Confocal scanning laser microscopy was used to determine the critical angular velocity above which structural damage to the lens occurred.