格构式腹板增强桐木夹芯复合梁弯曲疲劳性能试验研究

Paulownia sandwich composite beams reinforced with lattice webs have attracted more and more attention of engineering field because of its light weight, high strength and corrosion resistance. However, the fatigue properties of the sandwich structure are still seldom studied. The lattice-web reinforced paulownia core sandwich structure is the structural component which has the GFRP skins and a paulownia-web core. It can effectively improve the flexural and interfacial properties of the composite sandwich beams. Three point bending static load test and fatigue test were carried out on the reinforced paulownia wood sandwich beam with lattice web, and the fatigue failure mode, fatigue life and the cumulative damage development law of the sandwich beam were obtained. The exponential function model was used to fit the fatigue test results. The life prediction formulas of three types of specimens, namely exponential function formula, power function formula and effective defect type formula, were obtained. The development law of the deflection development of the sandwich specimens undergoes two stages of 'the slow and steady development of deflection and the acceleration of damage accumulation to failure'. The results show that compared with the sandwich beams without lattice-web, the lattice-web plays an important role in improving the bending fatigue interface performance of wood core sandwich lattice-web composite beam, and the sandwich lattice-web composite beams show obvious precursors before failure.