Influence of notch shape on the quasi-static tensile behavior of 2.5D woven composite structure

The application of 2.5D woven composites (2.5DWC) in engineering structures has received increasing attention, but the mechanical behavior of the 2.5DWC notched structure (2.5DWC-NS) is not very clear, especially the effect of notch shapes. For this purpose, a full-thickness unit cell model, including its finite element model, of 2.5DWC is built in this work based on the actual mesoscale characterization of the material. Subsequently, the unit cell finite element model is spliced and modified, and several macro-meso combined models of 2.5DWC-NS with different notch shapes are constructed. Furthermore, a progressive damage model is derived and the corresponding user-defined subroutine (UserMat) in ANSYS is secondary developed, thus performing numerical simulations for the macro-meso combined models. Moreover, tensile experiments of different 2.5DWC-NS are implemented. Comparing with the experimental results, the maximum error of tensile stiffness and strength of 2.5DWC-NS is found to be only 6.34%, demonstrating the validity of the simulation models. On this basis, the mechanical behavior of 2.5DWC-NS with different notch shapes is compared, and the results show that the notch shape affects the initial stress concentration effect and damage propagation behavior of 2.5DWC-NS, while it has little influence on the structural stiffness and strength. This work provides the design direction of 2.5DWC-NS, which is highly critical for engineering guidance.