重组竹顺纹冲击力学性能研究

重组竹是一种新型竹基复合材料，其力学性能优于落叶松等木材。为评价重组竹在动态加载下的顺纹抗冲击力学性能，以密度1.06 g/cm3、含水率8.52%、龄期3～5年的毛竹基重组竹为研究对象，通过准静态单轴压缩和循环加卸载以及动态加载实验，研究了重组竹加载变形过程、各项力学性能指标以及对应变率的敏感性。结果表明:重组竹顺纹压缩过程可以分为弹性变形和弹塑性变形阶段，破坏类型为延性破坏，其各项强度指标随应变率的提高而提高，动态增长因子与应变率之间呈现线性关系，斜率为0.0024；重组竹压缩过程中的应变比能与应变之间呈线性关系，且随应变率的增长而增大，证明其吸能能力随着应变率的增大而提高。实验结果证明，重组竹顺纹具有良好的抗冲击力学性能和显著的应变率效应。

A study of impact mechanical properties of the bamboo scrimber along the grain

Bamboo scrimber is a new type of bamboo-based composite materials with outstanding mechanical properties which is more effective than some wood such as pine. In order to evaluate the impact mechanical properties of the bamboo scrimber along the grain under impact loading, this study made the samples by commercial bamboo scrimber as the research object with the density about 1.06 g/cm3 and the moisture content about 8.52%, manufactured by Moso bamboo with the age of 3?5 years. The quasi-static uniaxial compression, cyclic loading and unloading, and dynamic loading tests were all carried out to explore its loading deformation process, various mechanical performance parameters, and the strain rate effect under different strain rates, as obtained by the MTS universal material testing machine and the split Hopkinson pressure bar (SHPB) testing system, respectively. The results show that the compression process of the bamboo scrimber along the grain can be divided into an elastic deformation stage and an elastic-plastic deformation stage. The failure type of bamboo scrimber under compression load was ductile failure with much better energy absorption capacity than brittle failure. Its various strength indexes, including elastic ultimate strength, yield strength and failure strength showed high strain rate sensibility, all go up with the increase of the strain rate. A linear relationship exists between the dynamic increase factor (DIF) and strain rate, with a slope of about 0.0024. The strain energy density during the compression process of the bamboo scrimber also exhibits a linear relationship with the strain, and it increases with the increase of strain rate, indicating that the energy absorption capacity of bamboo scrimber increases with the increasing strain rate. In summary, as verified by tests, the impact mechanical properties of the bamboo scrimber along the grain are good and its strain rate effect is significant.