Fabrication And Study Of SMP Composite Tubes With Two-way And Self-assembly Effects

Shape memory polymers (SMPs) over shape memory alloys and shape memory ceramics have many advantages, such as low density, high fixture strain, easy processing, wide shape transition temperature, the potential applications of SMPs include biomedical engineering. But the inherent defects of SMP shave restricted its development, such as unsystematic experimental study. Soft matter science has developed rapidly in recent years, the membrane structure of surface instability based on self assembled complex microstructure formation in planar mapping technology, function surface fabrication, flexible electronic devices have important prospects. But now the membrane structure reported about the shape change are irreversible one-way, rather than two-way. Combining the characteristics of two aspects and problems, this paper presents a two-dimensional surface mechanical assembly function method. In this study, thermo-mechanical experiments, the behaviors and evolvement of morphology control were carried out.The SMP film/substrate composites with high critical transition temperature and low critical temperature were frozen at the initial axial compression. In the process of thermos-mechanical experiments, they will buckle from the smooth surface and recover back to the smooth shape. Essentially, the film buckling was due to external stimulus (such as temperature field, electric field, biological tissue growth etc.).The film buckling was caused by the deformation mismatch between the surface and soft substrate. Then the residual stress generated by deformation mismatch was released by the further stimulus. And the deformation was recovered.Firstly, the basic concept of stability problem of cylindrical model was introduced in theoretical part, and the theoretical framework of membrane structure was deduced. The effects of geometric and material parameters on the buckling parameters were analyzed, such as the ultimate buckling modulus, the critical film thickness. Then the SMP membrane composite tubes were prepared. And thermo-mechanical experiments, real-time detections of the deformation field were carried out. Through the experimental studies of different loading methods, it was decided to join the cylindrical core as the internal support loading. Through the contrast with the effect of a variety of buckling, the ideal loadings were determined. The membrane buckling effect was good and the integral process of two-way self-assembly method was realized. Finally, some simplifications based on the existing boundary conditions were brought in finite element simulation. Compared the results of the finite element simulation with theoretical solution, the effects of various geometric and material parameters on the buckling form were analyzed. It provided an important basis for further quantitative control of buckling behavior of composite tube.The results of the paper revealed that the two-way self-assembly of SMPs composite tube was feasible, and also controllable.