Radial Force Characterization of Stainless Steel Stents
Radial force is an important aspect in stent performance and design.
Loop and other experimental test results can be calibrated to anticipated in-vivo conditions using detailed FEA.
Strain contoured plots from analysis of self expanding stents
Moire Interferometry for Nitinol Material Calibration
Phase-shifted Moiré interferometry is an excellent photomechanics technique for producing detailed displacement and strain fields in superelastic materials.
These are fringe patterns of the opening mode displacement fields at
a) partial loading below transformation stress and
b) the corresponding strain field
c) full loading,
d) nearing full unloading showing the recoverable nature of Nitinol.
Approach is ideal for verifying finite element models and for guiding the development of more comprehensive material models.
Phase Transformations Behavior in Nitinol
The unique ability of Nitinol to repeatedly recover large strains (up to 8%) is a direct result of Austenite to Martensite phase transformations occurring at the material level.
The transformation behavior is dependent on the material processing and texture as shown in the two different behaviors seen in material X and Y using Moire Interferometry.
Stent expansion and strain contours from a finite element analysis
Multiscale Stochastic Modeling
Localized grain transformations act as stress raisers and can significantly influence fatigue life.
Martensite plasticity + Polycrystalline modeling can accurately predict expected variations and increases in amplitude and mean stresses.
Prediction of lesion formation
Mechanical-thermal-electrical finite element analysis of cardiac muscle in contact with bi-polar RF electrodes.
Trans-renal portion of a AAA device
Trans-renal portion of a AAA device and detailed
view of diamond design element.
Photomechanical measurements
Photomechanical measurement of thermal strain in
surface mounted electronic package.
Detail of solderball.
