Simulation Of Shape Memory Properties For Resin And Their Fiber Reinforced Composites Based On Viscoelasticity

Shape memory polymers are able to fix a temporary shape and recover to their permanent shape when exposed to external stimuli such as heat, light, moisture, electric or magnetic field. Compared with shape memory alloys (SMAs) and shape memory ceramics (SMCs), shape memory polymers (SMPs) and their composites have lots of advantages such as light weight, low cost, good processability, high shape deformability, high shape recoverability and tailor-able switch temperature. Hence, they are promising smart materials which can be used in many fields, such as sensors and actuators in aerospace, packaging, smart textiles and bioengineering.SMPs and their composites attracted lots of attentions in the last thirty years. There are lots of theoretical researches for SMPs and their composites along with lots of experimental researches. Physical fields during shape memory processes includ displacement field and temperature field due to SMPs complicated shape memory mechanisms. The displacement field is closely related to the viscoelasticity of resin, and this result in the complication of the whole solution processes. The researches of shape memory properties of SMPs and their composites should be deepen as the modeling analysis for SMPs and their composites still in early stage. There are still in lacking of publications of theoretical researches for continuous fiber reinforced composites which are used in the morphing wing. For this reason, it is meaningful to establish the mathematical models of resin and its continuous fiber reinforced composites under the support of National Key Basic Research Program of China.Taking the shape memory properties of SMPs and their continuous fiber reinforced composites as the study project, using viscoelasticity, composite thermoelastic theory, composite constitutive theory, numerical heat transfer theory and finite element simulation method, the project attempts to carry out the study of shape memory properties and their influencing factors. Then, the shape memory mechanisms are analyzed, the evolution of shape memory processes are simulated, the influencing factors and influencing pattern of material parameters and technological parameters on shape memory processes are analyzed. It is a comprehensive problem of geometric nonlinearity, material nonlinearity and boundary nonlinearity for shape memory simulations.The main contents and conclusions were as follows:Simulation of shape memory thermal cycles and recovery stresses of pure resin using Maxwell-Weichert model are based on viscoelasticity. As the simulation results show, Maxwell-Weichert model can be used to describe stress relaxation, creep, and shape memory processes of SMPs. And the comparisons of stress relaxation curves between experimental results and simulated results are very good. Furthermore, the influencing factors of shape memory processes and recovery forces are discussed.Simulation of shape memory thermal cycles and recovery stresses of continuous fiber reinforced composites using Maxwell-Weichert model are based on viscoelasticity and composites mesomechanics. The macro-mechanical properties of composites can be obtained through composites mesomechanics, and then shape memory thermal cycles and recovery stresses of continuous fiber reinforced composites are calculated using Maxwell-Weichert model. Furthermore, the influencing factors of shape memory processes and recovery forces are discussed.