Experimental study and numerical simulation on the macro and micro mechanical properties of bamboo

With the increasing scarcity of natural resources and human beings' emphasis on the ecological environment, bamboo is a type of renewable and environmentally friendly structural material with excellent mechanical properties, which has the characteristics of fast growth, high yield, and excellent mechanical properties, so that it has wide engineering application potential. It is of great significance to accurately obtain the mechanical properties of each component of bamboo structure because its mechanical properties and failure rules depend on its mechanical properties. In this study, a calculation method for determining the mechanical properties of bamboo fiber and matrix material was presented by combining the methods of meso-mechanics and material mechanics, and the macroscopic mechanical properties of bamboo specimens under different loading conditions were obtained by quasi-static compression, tension and bending tests. Then, the mechanical properties of bamboo fiber and matrix were obtained by means of the mesomechanical and material mechanical analysis. Based on the macroscopic tests and mechanical properties of the bamboo fiber and matrix, the finite element analysis model was established, and numerical simulations for the compression and tensile tests were carried out. The results showed that the bamboo underwent a strengthening period after yielding during the longitudinal compression, and then the compressive stress decreased due to the buckling instability of the bamboo fibers, and then increased again after decreasing to a low value, and was gradually compacted. The mechanical properties of the transverse compression were similar to those of ordinary foam materials, which entered the linear weak strengthening stage after the elastic stage, and then into the densification stage. The tensile process of bamboo was a typical brittle material fracture. Under a bending load, the process could be approximated as the linear elastic process until the maximum load was reached, after the load decreased gradually with the increase of displacement. Based on the mechanical performance tests of the macroscopic compression, tension and bending, the mechanical performance parameters of each component of the bamboo specimens were obtained by combining the methods of micromechanics and mechanics of materials. According to the characteristics of bamboo, the finite element model of the bamboo compression and stretching was established, and the mechanical parameters of fibers and matrix materials were used for the simulation process. The simulation results were compared with the experiments, the errors of the stress-strain curve between simulation and test results were smaller than 10%, which verified the validity of the numerical simulation method and material parameters, and provided a reference for future research.