软智能材料的动力学过程及其调控

Two classes of coupling time-dependent process in soft active materials and their control are investigated in this project. One is the coupling between the diffusion and viscoelasticity in the hydrogel when the length of the specimen approaches to the material-specific length. The other is the self-oscillatory process occurred by the coupling between the nonoscillatory reaction and the swelling dynamics in the polyelectrolyte gel. For the first case: the nonlinear field theory for time-dependent coupling process is constructed on the basis of finite deformation theory and nonequilibrium thermodynamic theory as well as viscoelastic theory. The effect of the incompressibility and the mechanical constraint on the constitutive relations is considered. An effective and stable numerical method is developed for solving the nonlinear partial differential equations undergoes inhomogeneous and large deformations. The instability due to the evolution of the swelling process is also studied. For the second case: the nonlinear field theory is constructed for analyzing the time-dependent process coupling between the nonoscillatory reaction and the large deformation swelling dynamics. The condition of self-oscillatory and the oscillatory process are analyzed. The control of the time-dependent coupling process in soft active materials is explored. The outcome can serve as the theoretical basis and technical support for the development and design of the new soft devices with self-sensing and self-adjusting functions.

针对两类耦合动力学过程开展软智能材料的动力学过程及其调控研究，一类是凝胶的尺寸与材料特征尺度相当情形的扩散过程与粘弹性过程相耦合的凝胶动力学行为研究；另一类是非振荡的化学反应动力学过程与溶胀过程相耦合的自激振荡动力学行为研究。对于第一类情形：在有限变形理论和非平衡热力学理论的基础上，考虑粘弹性效应，建立凝胶大变形的扩散和粘弹性耦合的非线性理论体系，考察凝胶的不可压缩性、特定方向受到机械约束等因素对本构关系的影响。发展非均匀大变形耦合非线性动力学偏微分控制方程组的高效、稳定求解方法。研究凝胶在演化过程出现的表面失稳现象。对于第二类情形：建立考虑凝胶化学反应动力学过程和凝胶大变形溶胀过程相耦合的理论体系，对凝胶的自激振荡形成条件及振荡过程进行精确分析。研究软智能材料动力学过程的调控方法，为自我感知和自我调节的新一代智能凝胶器件开发和研制提供理论依据和技术支持。

软智能材料在小激励下能实现大变形，在驱动器、智能假肢、生物组织工程、药物控释、仿生机器人等领域具有重要的应用前景。对软智能材料力学行为的分析和预测，由于涉及多场耦合且建立的力学模型的偏微分方程组是强非线性的，求解难度非常大。. 本项目系统研究了软智能材料的动力学过程及其调控的途径和方法。在有限变形理论和非平衡热力学理论的基础上，建立考虑粘弹性效应的软智能材料的非线性动力学演化问题的控制方程，发展了高效、稳定的求解非均匀大变形耦合非线性动力学偏微分方程组的方法。在不考虑溶胀效应情形，针对球形和锥形的软智能材料驱动器，当考虑电场耦合效应的影响，给出了在常机械和电载荷作用下的蠕变效应和在周期机械和电载荷作用下的粘弹性动力学行为。在考虑溶胀效应情形，研究了球形凝胶的在力-化学耦合作用下的溶胀响应。完成了丁苯橡胶（styrene-butadiene rubber, SBR）在正十六烷（hexadecane）有机溶剂中的溶胀动力学实验研究以及在不同吸十六烷溶胀程度下的断裂性能研究和预测。利用考虑了表面能情形Gibbs自由能函数，分析了饱和及非饱和吸水球形凝胶的双稳态行为。完成了球形和块体凝胶溶胀失稳的实验研究。建立考虑凝胶化学反应动力学过程和凝胶大变形溶胀过程相耦合的场方程，对块体凝胶的自激振荡过程进行精确描述和分析。探讨了软智能材料动力学过程的调控方法，为自我感知和自我调节的新一代软智能器件开发和研制提供理论依据和技术支持。. 本项目共发表基金标注论文14篇，其中SCI收录论文（或SCI源期刊）论文12篇，期刊包括Soft Matter, J Appl Phys, Polymer Testing, Int J Solids Struct, Int J Mech Sci, Appl Math Model, Smart Mater Struct等。培养博士毕业生2名，培养硕士毕业生5名，在读博士研究生1名。