Cylinder hydrogel is simple in geometry and easy to synthesize,therefore was widely used to investigate the swelling/shrinking instability of hydrogel and many instability patterns were accumulated in the literature.The mechanism of instability pattern formation of this unique configuration,nevertheless,is far from being fully understood.We applied and extended the recently developed nonlinear theory of polymer gels into cylindrical coordinates,and performed linear perturbation analysis of swelling-induced stability of a constrained cylinder hydrogel.We derived the incremental formulations of stresses and the associated equilibrium equations.We obtained the critical conditions for the onset of instability and probed in details the effects of various parameters on the stability diagram of the hydrogel.The physical meaning of the variation of stability diagram was also interpreted.
A novel method for calculating the magnetic stiffness matrix was proposed for the numerical analysis of the magneto-elastic stability of complicated current-carrying structures aim- ing for application in the magneto-elastic behavior of the tokamak system. A code based on the proposed method was developed and applied to the numerical analysis of two typical current- carrying structures. The good consistency of the numerical and analytical results validated the proposed method and the related numerical code.
In periodic cellular structures,novel pattern transformations are triggered by a reversible elastic instability under the axial compression.Based on the deformation-triggered new pattern,periodic cellular structures can achieve special mechanical properties.In this paper,the designed architecture materials which include elastomer matrixes containing empty holes or filled holes with hydrogel material are modeled and simulated to investigate the mechanical property of the periodic materials.By analyzing the relationship between nominal stress and nominal strain of periodic material,and the corresponding deformed patterns,the influence of geometry and shapes of the holes on the mechanical property of architecture material is studied in more details.We hope this study can provide future perspectives for the deformation-triggered periodic structures.
