具有大倾斜角的纤维桥联分析

将基体作为纤维在垂直和水平方向的弹性支承,考虑基体剥落与纤维拉出的完全耦合,基于基体的支承刚度和破坏条件,利用杆件非线性弯曲模型和有限元法,分析了具有大倾斜角的层间短纤维的桥联力与层间裂纹张开位移的关系·数值算例表明,桥联纤维的弯曲变形是局部的,主要是拉伸,在基体剥落与纤维拉出的影响下,韧性较好的芳纶短纤维桥联张开位移较大,可以在桥联中产生较大的能量耗散和增韧作用

Analysis for Bridging of Fibers with Large Inclination Angle

In order to determine the effect of short chopped fibers between laminae on interlaminar toughening, a method was presented to analyze the bridging of short fibers with large inclination angle to crack surface. The short fibers were considered as geometrically non linear beams on elastic matrix foundation. The supporting stiffness and fracture load of unit length matrix in the vertical direction was computed by FEM based on a plane strain model. Because the interlaminar short fibers were embedded near crack surface, the solution of semi space subjected to shear load on the surface was approximately applied to estimate the supporting stiffness of matrix along fiber direction and the debonding condition. Considering the coupling of matrix spalling and fiber pull out, the relation of bridging force in short Kevlar or carbon fibers and crack opening displacement was obtained by FEM. The bending of fibers only occurs in a extremely small local area near spalling point, and fibers are basically in tension. Because of the better toughness, the bridging displacement of Kevlar fibers is much larger than that of carbon fibers. Therefore, the bridging of short Kevlar fibers between continuous fiber reinforced laminae accompanies larger energy dissipation and leads to interlaminar toughening.