On compacting pattern control of finite-size 2D soft periodic structures through combined loading

2D soft periodic structures can produce reversible compaction and relaxation behaviors with complex and diverse compacting patterns during loading and unloading. The (trans)formation and control of the recoverable and adjustable compacting pattern are essential in their wide range of application prospects. In addition to the traditional schemes, this paper proposes and discusses the possibility of using combined loading to control the compacting pattern of finite-size 2D soft periodic structures. Based on the detailed analysis and design of the loading schemes, the buckling and post-buckling behaviors of four kinds of 2D soft periodic structures with finite size under biaxial loading and combined normal and shear loading are investigated by a validated ABAQUS finite element analysis. The buckling model shapes of each structure under each loading combination are discussed and classified in detail to determine the Representative Compacting Patterns (RCPs) and the Critical Points of model transformation Controlled by Loading (CPCL) on the loading plane. Of course, some new modes have been found. Moreover, the CPCL between RCPs without conversion relationship is found to have a corresponding relationship with the variation of the difference between the first eigenvalue and the second eigenvalue of the structure on the loading plane. By using the rotation angle of the hole walls as an index, the compacting behavior and charac-teristics of each pattern in the process of post-buckling are analyzed quantitatively. The research ideas and results of this paper will provide a new design space for various application fields of finite-size 2D soft periodic structures.