A Sequential Fiber Failure Criterion for the Tensile Fracture in Notched Fiber Reinforced Composites

Abstract

A new criterion, which is named a sequential fiber failure criterion for the tensile fracture in notched fiber reinforced composite plates, is developed based on the combined micromechanical sequential fiber failure condition and the macroscopic Yeh-Stratton failure criterion. Since the sequential fiber failure behavior is considered, therefore, the failure mechanisms are included in this sequential fiber failure criterion. The fracture angle and damage zone can also be evaluated from this criterion. The fracture stresses predicted by the sequential fiber failure criterion are close to those stresses measured experimentally. The tensile failure of a laminate is governed by the failure of the plies having fibers parallel to the loading direction. These fibers fail sequentially by a process in which the failure of the fiber causes its neighbor to fail. Under the uniaxial tensile load, the fracture planes of all the plies are perpendicular to the tensile loading direction within the [90°/0°/±45°]s laminates containing a center crack.

Analytical Damage Zone Size Predictions for Notched Laminated Composites

“…These results are based on recalibrating the ply characteristic lengths, r, for each data point in [17], as opposed to using the average characteristic length as was done for the linear fracture models. Consequently, the predicted fracture stresses reported in [9,11] are very close to the experimental values. The data for required characteristic length provides significant insight into how the damage zone sizes predicted by the QSC and SFFC compare with the linear theories.…”

“…Both models fit the experimental results reasonably well, but the scatter in the data prohibits any substantiated relative assessment of the models. From Figure 3 it can be seen that removing just the one [9,11] for the data in [17]. These results are based on recalibrating the ply characteristic lengths, r, for each data point in [17], as opposed to using the average characteristic length as was done for the linear fracture models.…”

“…Comparing Equations (17) and (18) with (10) and (11) it becomes apparent that the damage parameter defined in [8] is in fact the characteristic length proposed in [4,5]. Unlike [4,5], Zhen explicitly states that the damage parameter directly represents the size of the damage zone ahead of the crack tip.…”

Stress Concentration in Symmetric Angle-Ply Laminates Studied by the Quadric Surfaces Criterion

“…Each quadrant has its own criterion function in the stress space. However, all of these criterion functions have the pattern as of Equation (8). It is reasonable for the concept of the piecewise failure surfaces since the composite materials are anisotropic and show different strengths in different directions or planes.…”

“…The point with the maximum stress is the fracture point and the applied stress is the fracture stress. The related works and discussion can be found in [8][9][10][11][12].…”