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## 1. chinaXiv:202012.00059 [pdf]

Subjects: Mechanics >> Applied Mechanics

 In order to enhance the overall structural stability of 3D printed concrete wall, we propose a novel scheme to produce a wavy wall with curvature along its contour direction. To validate the idea of the scheme, a single wave wall is set as a cylindrical wall and its mechanical performances are analyzed. The mathematical 3D printing model of the wavy wall is formulated by the shell theory while taking into account of additional parameters of the printing processes, the model will be used to analyze the two failure mechanisms of the cylindrical wall: elastic buckling and plastic collapse. Compared with the results of Suiker’s straight wall, it is found that when the parameters were same, the stability of the cylindrical wall is more than twice of the rectangular wall. Our studies indicate that it’s a feasible scheme to improve the printed structural stability by increasing curvature.

## 2. chinaXiv:202012.00019 [pdf]

Subjects: Mechanics >> Applied Mechanics

 对于打印墙结构往往因为稳定性而失效的问题,本文提出了采用直立波纹墙的方法,即适当增加墙体沿轮廓方向的曲率,以求提高打印墙稳定性.本文通过将波纹墙的单个波纹视为单胞进行研究,取曲率为常数,并进行结构闭合处理,以求稳定性最大化,即分析柱壳形直立墙在3D打印进程中的力学性能.此模型利用 Goldenveizer-Novozhilov壳体理论,加入打印进程参数,包括打印速率、打印材料固化特征、柱壳几何特征、以及自重作用影响,对圆柱壳的两种破坏机理:弹性屈曲和塑性破坏进行分析.利用Suiker[22] 首次提出的无量纲参数 (暂称Suiker数),对柱壳形直立墙弹性屈曲与塑性破坏间的竞争关系进行描述.将结果与文献[22]进行比较,发现当参数完全相同情况下,将柱壳形直立墙比矩形直墙结果对比发现,稳定性提升了两倍有余.同时给出了通过曲率的改变达到此类参数下柱壳结构稳定性最大化的方法,即通过拟合的手段,得到失效高度随曲率变化函数,据此对失效机制区域进行划分.这表明该模型可用于探讨打印进程中曲率对直墙结构的力学性能影响,并可通过调整参数对结构作出优化.同时,通过引入曲率,将直立墙沿轮廓方向打印成波纹墙,对于提高打印墙结构稳定性是一个简单可行的方案.