Coupled Thermo-chemo-mechanical Model for the Large Deformation of Shape Memory Gels

Description

Shape memory gel (SMG) is one of the most interesting hydrogels which can rememberits original shape, keep the temporary deformed shape at low temperature and recoversto the original shape spontaneously by heating. Many thermo-mechanical models havebeen proposed to describe the shape memory behavior of SMGs in dry state. However,very little work has been done on SMGs in wet environment in which SMGs are softwith predominant water, and a thermo-chemo-mechanical coupled large-deformationcommonly occurs. Hence, the proposed project aims to develop a constitutive theory forthe thermo-chemo-mechanical coupled large-deformation and a meshless numericaltechnique for modelling the response of SMGs in wet environment. In order to provide acomprehensive insight into the mechanism for shape memory effect, this research willconduct experimental, theoretical and numerical investigations on the multi-fieldcoupling behaviours of SMGs.First, a series of experiments on a representative SMG will be conducted at differenttemperatures and chemical environments for the quantitative characterization of themulti-field responses.Secondly, based on the experimental data, a coupled thermo-chemo-mechanicalconstitutive theory for large deformations will be formulated to characterize theresponse of thermally actuated SMGs within the framework of thermodynamics; thematerial parameters appearing in our constitutive model will be calibrated using thestress-strain data from the compression experiments.Thirdly, a numerical technique which is suitable for the large deformation analysiswill be developed by implementing the developed constitutive model into the meshlessmethod.Finally, representative experiments will be conducted to validate the predictivecapability of the proposed theoretical model and its numerical implementation incomplex three-dimensional geometries of SMGs.It is worth noting that, so far, relatively little work on the constitutive theory andnumerical simulation of hydrogels with shape memory effect was reported in literature,and the proposed research will result in a constitutive model for the thermo-chemo-mechanicallycoupled large-deformation and a mesh-free numerical technique for thedesign of more complicated SMG-based structures and devices.