A thermoviscoelastic model for amorphous shape memory polymers: Incorporating structural and stress relaxation

Thermally actuated shape-memory polymers: Experiments, theory, and numerical simulations

“…Considering the temperature and strain-rate dependence of ϕ * , it is expected to decrease with increasing 11 Instead of the VFT form, other authors (e.g. Richeton et al, 2007;Nguyen et al, 2008) have recently used a WilliamsLandel-Ferry (WLF)-type temperature-dependent expression for the plastic shear strain rate to extend to the applicability of their theories to temperatures ϑ > ϑg. The WLF equation (Williams et al, 1955) can be written as (6.21) where C 1 and C 2 are constants with dimensions of temperature.…”

“…In the past few years several efforts at experimental characterization of the thermo-mechanical stressstrain response of a wide variety of shape-memory polymers have been published in the literature (e.g., Tobushi et al, 1996;Baer et al, 2007a;Gall et al, 2005;Yakacki et al, 2007;Safranski and Gall, 2008;Qi et al, 2008). Significant modeling efforts have also been published (e.g., Liu et al, 2006;Chen and Lagoudas, 2008;Qi et al, 2008;Nguyen et al, 2008).…”

“…Significant modeling efforts have also been published (e.g., Liu et al, 2006;Chen and Lagoudas, 2008;Qi et al, 2008;Nguyen et al, 2008). However, at this point in time, a thermo-mechanicallycoupled large-deformation constitutive theory for modeling the response of thermally-actuated shape-memory polymers is not widely agreed upon -the field is still in its infancy.…”

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

“…Previous experimental work revealed complicated dependency of the SM performance on thermo-temporal conditions in an SM cycle. For example, the recovery of SMPs programmed under the same conditions strongly depends on the recovery temperature and heating rate in the recovery step 43,[46][47][48][49][50][51][52] ; in addition, the programming temperature has been shown to affect significantly the free recovery behaviour for SMPs under the same thermo-temporal recovery conditions 31,[53][54][55][56][57] . To date, because the recovery behaviour of an SMP depends on the aforementioned multiple thermo-temporal input parameters, there is no clear understanding how these input parameters can affect the SM performance individually or collectively.…”

Three-dimensional constitutive model for shape memory polymers using multiplicative decomposition of the deformation gradient and shape memory strains

“…For example, the temporarily fixed shape of SMPs has ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T 5 been modeled using their crystallization behavior (Barot and Rao, 2006) and, in particular, strain-or stress-induced crystallization processes (Barot et al, 2008;Li and Shojaei, 2012;Rao and Rajagopal, 2001;Richard and Lisa Mauck, 2008;Westbrook et al, 2010). Shape memory has also been modeled on the temperature-induced changes in SMP microscopic structures Srinivasa, 2013, 2014;Gu et al, 2015;Nguyen et al, 2008;Nguyen et al, 2010;Srivastava et al, 2010;Westbrook et al, 2011;. These temperature-dependent models were based on the well-known Arruda-Boyce model (Arruda and Boyce, 1993), which includes detailed microscopic features of SMPs.…”