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1. chinaXiv:202012.00059 [pdf]

Analysis of mechanical performances of cylindrical wall in 3D printing processes.pdf

刘轩廷; 孙博华
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.

submitted time 2020-12-18 Hits380Downloads209 Comment 0

2. chinaXiv:202012.00019 [pdf]

3D打印进程中曲率对直立墙结构力学的影响

刘轩廷; 孙博华
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.

submitted time 2020-12-10 Hits1850Downloads278 Comment 0

3. chinaXiv:202008.00090 [pdf]

可乐易拉罐在轴-侧-扭-内压联合作用下的屈曲地貌

宋广凯; 孙博华
Subjects: Mechanics >> Applied Mechanics

本文利用非线性有限元分析程序 ABAQUS 研究了柱壳曲屈问题,并应用到了可乐易拉罐的曲屈分析。首先从数值模拟上验证了Virot 等学者的可乐易拉罐曲屈实验结果,然后为了获得曲屈的一些普适结果,进一步考察了柱壳的曲屈表现。对柱壳结构在不同荷载组合、不同几何参数作用下进行了细致的分析。为了讨论的直观,本文绘制了柱壳结构在受到侧压-轴压荷载作用下外力-曲屈荷载-位移三维地貌图(称为landscape)。结果表明:在侧压-轴压-扭转荷载作用下试件力-位移曲线出现了“cliff”(断崖)现象;扭转荷载的施加不利于试件整体稳定性,并造成了试件对初始缺陷的敏感性;对于受到轴压-扭转试件,本文定义承载力为零的平面为“sea level” (海平面) 来区分试件破坏模式;通过对不同边界条件的试件进行分析,发现试件两端固接可以有效地整加结构的承载能力,提高稳定性。对柱壳结构内部充气可以大幅度提升结构的承载能力和稳定性,减小对初始缺陷的敏感度。

submitted time 2020-08-25 Hits3244Downloads606 Comment 0

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