# Design and Optimization of Origami-Inspired Orthopyramid-Like Core Panel for Load Damping  
[PERSON]  
1 State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China; [EMAIL_ADDRESS] (Y.F.); [EMAIL_ADDRESS] (K.L.); [EMAIL_ADDRESS] (H.Q.); [EMAIL_ADDRESS] (J.L.  
of cuts and creases. [PERSON] [33] presented a method, which output a set of nonlinear differential equations governing the parametrization, metric, and curvature of surfaces that the initially discrete structure could fit. Employing the Miura pattern, [PERSON] [34] studied the sandwich beam with the origami-inspired core and found it has unique mechanical properties that can be used as programmable materials to fit specified engineering demands. [PERSON] [35] presented the experimental investigations and finite element analysis (FEA) simulation of the effect of the base material on the mechanical properties and the impact resistance of Miura-Origami sandwich cores. In another work [36], he studied the force allocation and energy dissipation properties of the Ron-Resch-like origami tessellations through compression and impact tests and FEA simulation. Inspired by the structures raised by [PERSON] [37] and [PERSON] [38], an orthopyramid-like core panel was proposed by [PERSON] et al. [39] based on origami geometry. They also studied the evaluative mechanism of it, by changing the parameters of the folded element to make it adapt to different circumstances. Using the same geometry, [PERSON] et al. [40] proposed a computational solution to develop a shape that meets some design performance criteria. Another study by [PERSON] [41] investigated the shape recovery effect in different 3D-printed honeycomb shapes. In addition, studies on the different aspects of origami materials were highlighted and the challenges ahead discussed [42; 43]. [PERSON] [44] proposed a method for programming the deformation of a temperature-driven bilayer structure, which provided a great possibility for fabricating complex origami and foldable structures.  
In the present work, we investigate various orthopyramid-like core panels by changing the similarity parameter value and the number of edges. Three-, four-, and six-edged folded origami elements were studied with three different similarity parameters (1/2, 3/4, and 5/6). The flat panels were formed by the selected geometries. The orthopyramid-like origami elements are periodic in the planar direction. The panel material, panel thickness, and element thickness are considered constants in this study. The models of panels were fabricated by the method of 3D printing with the material of PLA (polylactic acid). To study the compressive properties of the prepared samples, a compression and impact test was conducted. The results revealed that the panels can resist high stress in compression during the collapse. The impact test shows that the panels can exhibit a high degree of energy dissipation due to the deformation of the tips. Moreover, a simulation of the compression test of the models was conducted using ANSYS finite element package. The impact event was simulated by an explicit dynamics analyzer. In addition, the optimal similarity parameters for each element with a fixed edge were obtained through the finite element method integrated with the genetic algorithm.  
The main contribution of our paper to the field of sandwich core structure can be summarized in two parts. First, we investigated the load damping properties of the orthopyramid-like origami core, which was proposed in our previous work, for the first time. The other contribution that makes our paper novel is that the orthopyramid-like origami cores' load damping properties were studied not only in conventional ways but also in a joint simulation method, which inherits the advantages of the Genetic Algorithm (GA) and the strong solution ability of FEA software.