聚硅氧烷硅胶的黏超弹性力学行为研究

STUDY ON THE VISCO-HYPERELASTIC BEHAVIOR OF POLYSILOXANE RUBBER

聚硅氧烷硅胶是一类以Si—O键为主链、硅原子上直接连接有机基团的无色透明高分子聚合物,因其具有优异的超弹性性能而广泛应用于精密减震结构、柔性电子器件等领域.在聚硅氧烷硅胶减震结构和柔性电子器件的设计中,材料在大变形和动态加载下的黏超弹性力学行为的精确描述至关重要.本文针对该问题进行了系统的研究:首先,将该硅胶的超弹性和黏弹性行为进行解耦,确定其黏超弹性本构方程的基本框架;其次,基于单轴拉压、平面拉伸试验确定其准静态超弹性模型的各项参数;再次,利用霍普金森压杆冲击试验确定其黏弹性模型的各项参数;在此基础上,将超弹性和黏弹性模型合并为适用于大应变和大应变率的黏超弹性动态本构模型;最后,利用落锤冲击试验对该硅胶薄片的冲击变形行为进行了研究,并利用上述建立的动态本构模型对落锤冲击过程进行了有限元模拟.结果表明:本文建立的黏超弹性本构模型可有效预测该硅胶在冲击载荷下的力学行为,从而为聚硅氧烷硅胶减震结构和柔性电子器件的优化设计提供了理论和应用基础.

Polysiloxane rubber is a kind of typical polymer material which is usually colorless and transparent.The molecular structures of Polysiloxane rubber consist of Si—O bonds as the main chain and organic groups directly connected to the silicon atoms,respectively.Owning to the outstanding hyperelastic property derived from the intertwined molecule chains,the polysiloxane rubber is widely used for fabrication of damping structures and stretchable electronics.In engineering application it is crucial to precisely describe the visco-hyperelastic behavior of materials under dynamic and large deformation for the design of polysiloxane rubber based damping structures and flexible electronic devices.Therefore,the visco-hyperelastic property of polysiloxane rubber is systematically investigated in this work.For the first step,the hyperelastic behavior and viscoelastic effect are decoupled to propose the basic forms of the visco-hyperelastic constitutive model.Secondly,the hyperelastic model of the material is established based on quasi-static uniaxial tension,uniaxial compression and planar tension tests,respectively.Then,the strain rate effect is quantified by Hopkinson pressure bar tests,based which the viscoelastic model is established.Accordingly,the visco-hyperelastic constitutive model is finally proposed by combing the two decoupled models.Besides,the proposed visco-hyperelastic constitutive model is used to simulate the drop-weight impact behavior of polysiloxane rubber specimens by finite element method.The well agreement between the simulations and tests show that the viscoelastic constitutive model established in this paper can effectively predict the mechanical behavior of the polysiloxane rubber under impact load,which provides a theoretical and applied basis for the optimal design of polysiloxane rubber based shock absorption structure and flexible electronic devices.