电驱动连续碳纤维增强形状记忆复合材料镂空结构设计

Hollow structure design of electrically driven continuous carbon fiber reinforced shape memory composite

电驱动连续碳纤维增强形状记忆复合材料(continuous carbon fiber reinforced shape memory composites,CFSMPC)是一种利用电信号驱动实现可控变形的形状记忆复合材料。本工作提出一种电驱动连续碳纤维增强形状记忆聚乳酸复合材料镂空结构,通过对温度均匀性的控制,可实现结构变形的精确控制和力学性能的提升。采用3D打印方法制备复合材料镂空结构,利用实验探究几何参数对镂空结构力学性能和形状回复性能的影响。结果表明:镂空结构较非镂空结构的拉伸强度有所提高,且胞宽越小强度提升越明显;CFSMPC镂空结构的形状记忆回复速度和最大回复力均有明显上升,这是因为镂空结构可以有效避免碳纤维热扩散导致的低温区,从而保证结构整体的温度均匀性;提出基于黏弹性本构的CFSMPC镂空结构电-热-力耦合有限元模型,预测的温度分布和回复时间与实验结果吻合较好。采用该模型进行分析,发现胞宽越小,回复时单胞的温度越均匀,内部应力释放越快,因此,结构的形状回复越快。

Electrically driven continuous carbon fiber reinforced shape memory composite(CFSMPC)is a kind of shape memory composite driven by electrical signal to realize controllable deformation.The lightweight cellular structure of continuous carbon fiber reinforced composites is a kind of high-performance structure with low density.In this work,an electrically driven continuous carbon fiber reinforced shape memory poly(lactic acid)composite hollow structure was proposed.By controlling the temperature uniformity,the precise control of structural deformation and the improvement of mechanical properties were realized.3D printing method was used to fabricate hollow composite structures.The effects of geometric parameters on mechanical properties and shape recovery performance of hollow composite structures were investigated by experiments.The results show that the tensile strength of hollow structure is improved compared with that of non-hollow structure,and the smaller the cell width,the more obvious the tensile strength increases.With the carbon fiber reinforced,the strength of hollow structure is significantly improved,and the strength of CP-3 sample is 66%higher than that of non-hollow PLA.Hollow cell width determines the carbon fiber volume fraction of hollow structure,which affects the mechanical properties of CFSMPC.Moreover,the interfacial properties between printing layers of composite materials are higher.The results show that the volume content of single cell fiber is closely related to tensile strength.In addition,the shape memory recovery speed and the maximum recovery force of CFSMPC hollow structure are obviously increased,and the fastest recovery is completed in 11s.The recovery force of samples is significantly improved.The results show that hollow structure can further release the shape memory performance of structure and obtain higher quality structure-function integrated intelligent material.This is because the hollow structure can effectively avoid the low temperature zone caused by the thermal diffusion of carbon fiber,which can ensure the temperature uniformity of the whole structure.Finally,a coupled electro-thermal-mechanical finite element model of CFSMPC hollow structure is proposed based on viscoelastic constitutive model.The predicted temperature distribution and recovery time are in good agreement with the experimental results,and the error is within 15%.The distribution of internal stress during the recovery process of hollow structure deformation can be obtained by simulation analysis,and it proves that cell width affects the stress release of single cell,which is the difference of shape recovery performance at macro level.Therefore,the model can guide the optimization of CFSMPC structure design.