| In order to study the performance of FRP-wood bond interface fracture process zone,and establish FRP-wood interface fracture model.Three-point bending(I-type fracture test)and four-point shear(?-·type fracture test)were carried out on prefabricated notched beams with different notch height ratio.The complete development of FRP-wood interface cracks in fracture experiments was observed by two-dimensional digital image correlation observation technique(DIC).The crack opening displacement(CMOD),the crack tip opening displacement(CTOD)and the deflection were measured by a clip-type extensometer,and the load were measured by load sensor.The test results show that under the three-point bending test,the ultimate length of the fracture process zone(FPZ)was decreases with the increase of the initial notch height ratio.At the same time,the stress-strain softening process of FPZ contain micro crack propagation stage and fiber bridging stage.Based on the theory and method of fracture mechanics,this study analyzed the fracture properties of FRP-wood bonded interface.The fracture model is introduced to calculate the fracture parameters and the FRP-wood interface fracture model is established too.1)the turning point of the bilinear fracture softening model is determined,and the FRP-wood viscosity is calculated.The correlation between the fracture toughness and the fracture energy of the junction interface is established and a calculation formula is also established.2)During the four-point bending fracture process of FRP-wood bonding interface,the crack tip slip value is not related to the initial notch height ratio.After the crack length reaches a certain value,the interface take place type ? fracture.3)The prestressing loss formula and bearing capacity formula of prestressed FRP reinforced glulam beams are studied.The research results in this paper can help to improve the FRP-wood interface research theory and provide calculation theory for designing FRP-wood composite structures. |
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