A torsion test for the study of the large deformation recovery of shape memory polymers

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. ABSTRACT:A torsion device was designed and built for testing the shape fixity and shape recovery of shape memory polymers at large deformation. A simple thermal chamber was used to regulate the thermal environment during testing and a CCD camera was used for recording the deformation. Such a torsion testing system provided a quantitative estimate of the kinematics and kinetics of shape recovery for samples submitted to large deformations at moderate strains that are more likely expected in actual shape memory applications. In addition, such measurements are complementary to those obtained from large strain uniaxial tension tests usually run for during traditional shape memory effect characterization. As a result, the torsional shape memory testing device and testing method described is expected to contribute building complementary data for the thermomechanical modeling of shape memory polymers.

Reversible plasticity shape memory effect in carbon nanotube/epoxy nanocomposites: Shape recovery studies for torsional and bending deformations

“…The sample is fixed at one end and the other end is twisted at a constant rate of 3 rpm (18°/s). The advantage of cold programming can be observed from the simplicity of the test set‐up as compared to set‐ups used for conventional programming in which the entire set up is to be inside a thermal chamber. The RPSM properties of the samples are evaluated for three different twist angles (180°, 270°, 360°) and for four relaxation times (0, 10, 20, and 30 min).…”

Pattern transformation of thermo-responsive shape memory polymer periodic cellular structures

“…The bulk modulus is taken as a constant value K 0 =3.1GPa in the present study. With experimental DMA data in Diani et al (Diani et al, 2011;Diani et al, 2012) and using a timetemperature superposition principle, the storage modulus in the frequency domain was expressed as follows:…”

“…Among these models, the generalized Maxwell model proposed by Diani et al is more popular and can be easily adopted (Diani et al, 2012). In this model, the time-temperature dependence of the viscoelastic properties of the SMPs was determined using a dynamic mechanical analysis procedure of relatively small-strain large-deformation torsion tests (Diani et al, 2011); no other experiments or fitting parameters were needed. Implementation of the model in numerical analysis was based only on a combination of standard features from commercially available finite element codes and did not call for the contribution of any additional elaborate complex routines.…”

Characterization of unconstraint and constraint shape recoveries of an epoxy based shape memory polymer

“…Baer et al have examined the thermomechanics and shape-memory behavior for thermoset polyurethanes intended for medical applications as a function of curing temperature and deformation strain [17]. Diani et al have recently developed a torsional testing apparatus to evaluate the shape recovery of the SMPs under torsional loads [18].…”