大学生结构设计大赛材料力学性能试验研究

为研究大学生结构大赛采用的白卡纸、竹皮、桐木的力学性能,应用LDS-5电子拉力试验机对222个试件进行轴向拉伸试验,探讨白卡纸、竹皮、桐木3种材料在不同厚度、宽度、长度条件下的受力性能。研究表明,对于竹皮、桐木、白卡纸3种材料,试件均会发生正截面断裂,少量竹皮、桐木试件发生斜截面断裂。在对试件进行加载过程中,由于施加的拉力存在偏心,削弱了试件的极限承载能力。对于白卡纸试件,长度改变对试件极限承载力无明显影响。竹皮材料随着厚度的增加,极限承载力呈非线性增长。综合强度和结构重量等因素,厚度为0.35 mm的竹皮材料最为适合制作拉索构件。最后获得不同材料的弹性模量、极限抗拉强度,并得到受拉构件极限承载能力Pu与构件宽度D的关系拟合公式,为学生进行结构设计提供较为科学的设计依据,为结构仿真分析提供较为精确的材料性能数据。

Experimental study on mechanical properties of materials for structure design contest for college students

In order to study the mechanical properties of white cardboard, bamboo skin and paulownia used by structure design contest for college students, the LDS-5 electronic tensile testing machine was used to carry out the axial tension test on 222 specimens, to investigate the stress performance of white cardboard, bamboo skin and paulownia in the condition of different thickness, width and length. The results showed that the breakage of all specimens of the three materials occurred at the normal section, and the breakage of a few specimens of the bamboo skin and paulownia occurred at the oblique section. In the course of the specimens'' loading, because the tension was exerted eccentrically, the ultimate bearing capacity of specimens was weakened. White cardboard specimens'' length change had no significant effect on ultimate bearing capacity of the specimens. Bamboo skin materials'' ultimate strength showed a nonlinear growth with thickness increases. Considering the strength, structural weight and other factors, the 0.35 mm-thickness bamboo skin materials were most suitable for the production of cable structures. Elastic modulus and ultimate tensile strength of different materials, as well as the fitting formula of relationship between ultimate bearing capacity of tension member (P_u) and widget width (D) were obtained, to provide a more scientific design basis for students'' structure design and to provide a more accurate performance data for structure simulation analysis.