Numerical evaluation of the influence of porosity on bending properties of 2D carbon/carbon composites

Abstract

Numerical simulation with progressive damage criterion is implemented to investigate the effect of porosity on the bending properties of 2D cross-ply carbon/carbon (C/C) composites. The mechanical properties of Pyrocarbon matrix regarding the change of porosity are calculated by using Mori-Tanaka approach. Combining with the stiffness degradation scheme, the ultimate bending strengths are calculated in Abaqus though a user-defined subroutine (USDFLD). Delamination is modelled by inserting cohesive elements between two adjacent plies. A good agreement is obtained when the FEM results are compared to three-point bending experiments. The FEM results show that the bending strength decreases greatly with the increase of porosity. When the porosity reaches up to 18%, the bending strength is decreased by 57%. The major fracture behaviors are interlamination delamination and continuous crack damage in 90˚ plies. With the increase of porosity, more severe interlamination delamination will be slightly aggravated. In addition, the increase of porosity will also accelerate the damage in 90˚ plies.

Identification of voids and interlaminar shear strengths of polymer‐matrix composites by optical microscopy experiment and deep learning methodology

“…Void defects are important issues in polymer‐matrix composite structures because they significantly affect the mechanical properties of a polymer‐matrix composite by altering the stress field of the structure. Particularly, void defects affect the matrix‐dominated properties such as the interlaminar shear strength (ILSS), 1‐5 compressive strength and modulus, 6,7 and bending properties 8 . Among these, ILSS has attracted significant research interest owing to its high void sensitivity.…”

A novel method for generating random fiber distributions for fiber-reinforced materials

“…RSE generates fibers The following steps represent the procedure of the RSE algorithm. In addition, Figure 1 shows the outcome of these steps: [1] Generate a random coordinate (x 1 , y 1 ) within the RVE window (a*b) to serve as the first fiber; [2] Search randomly around the first fiber and generate the location of the second fiber (x 2, y 2 ). It is obvious that:…”

“…The direction of the second fiber (θ 1 ) is randomly obtained in the range of [0, 2π] (refer to Figure 2(a) and (b)); [3] Repeat steps [2] to search and generate the position of the third fiber (x 3 ,y 3 ) (as shown in Figure 2(c)), and so on, where the other fibers are continuously generated until the maximum search time N max (generally equal to 50) is reached. At this point, no new fibers can be generated around the first fiber (x 1 ,y 1 ).…”

“…Further, analytical calculations or numerical simulations have been shown to be meaningful alternatives to experimental methods. 2 The mesoscale mechanical analysis of fiber-reinforced composites is usually performed using their Representative Volume Element (RVE). Originally, Sun et al 3 conducted finite element analysis based on the RVE model to obtain the equivalent modulus of the unidirectional fiber composite.…”

Effect of Defects Part II: Multiscale Effect of Microvoids, Orientation of Rivet Holes on the Damage Propagation, and Ultimate Failure Strength of Composites

“…They also predicted the strength of the braided composite with the Mori-Tanaka method. Chao and et al [44] studied the effect of porosity on flexural properties of 2D carbon/carbon composites. The results showed that the increase of porosity may accelerate the damage in 90 plies and the severe delamination will thus be slightly aggravated.…”