关于瓜多竹集成材在不同纤维方向剪切特性的实验研究与数值模拟
摘 要
本文通过实验与数值模拟相结合的方法，在考虑竹纤维三个不同正交方向的情况下研究了瓜多竹集成材（LGB）所具有的剪切强度和裂纹特性。分三种情况分别进行测试：（1）当加荷方向平行于纤维方向时；（2）当加荷方向垂直于纤维方向且不穿过面积缩减平面时；（3）当加荷方向垂直于纤维方向并穿过面积缩减平面时。当板之间的接触面平行于面积缩减平面时，对LGB板的取向和结构进行了试验研究，并在二者相互垂直时进行试验。同样地，测试板与板之间的接触面与面积缩减平面之间匹配的情况，如果不匹配，则进行试验。有限元数值模型是基于复合材料的强连续性方法和纤维破坏过程的韦布尔概率模型。数值模拟中获得的裂纹方向与在相应的试验中观察到的裂纹方向大体一致，并与板的布置无关。平行于加载方向的LGB纤维表现出与面积缩减平面匹配的裂纹。垂直于加载方向且不穿过面积缩减平面的LGB纤维出现的裂纹相对于加载方向呈斜45°。在纤维垂直于加载方向并与面积缩减平面相交的LGB中，垂直于加载方向并平行于纤维方向形成了多道裂纹。
关键词：瓜多竹集成材；剪切特性；有限元法；裂纹模式
Experimental and numerical modeling of shear behavior of laminated Guadua bamboo for different fiber directions
ABSTRACT
The shear strength and the crack pattern of laminated Guadua bamboo (LGB) are studied in this work, by means of both experimental tests and numerical simulation, considering the three different orthogonal directions of the fibers: (i) when the fiber is parallel to the loading direction, (ii) when the fiber is perpendicular to the loading direction without crossing the reduced area plane, and (iii) when the fiber is perpendicular to the loading direction and crossing the reduced area plane. The slats orientation and disposition in LGB were experimentally studied, when the contact surface between slats is parallel to the reduced area plane and when it is perpendicular. Likewise, the cases when the contact surface between slats matches with the reduced area plane is tested and when it is not. The numerical model of finite elements is based on the continuum strong discontinuity approach for composite materials and the Weibull probability model for the failure progressive of fibers. The crack direction obtained in the numerical simulation is approximately equal to the one observed in the corresponding experimental test, regardless of the disposition slats. LGB with fibers parallel to the loading direction exhibits a crack that matches with the reduced area plane. In LGB with fibers perpendicular to the loading direction that do not cross the reduced area plane, the crack is inclined 45 degrees with respect to loading direction. In LGB with fibers perpendicular to the loading direction and crossing the reduced area plane, several cracks are made up perpendicularly to loading direction and parallel to the fiber orientation.
Key words：Laminated Guadua bamboo；Shear mechanical behavior；Finite elements methods；Crack pat
目 录
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