A new damage model for composite laminates

Abstract

a b s t r a c tAircraft composite structures must have high stiffness and strength with low weight, which can guarantee the increase of the pay-load for airplanes without losing airworthiness. However, the mechanical behavior of composite laminates is very complex due the inherent anisotropy and heterogeneity. Many researchers have developed different failure progressive analyses and damage models in order to predict the complex failure mechanisms. This work presents a damage model and progressive failure analysis that requires simple experimental tests and that achieves good accuracy. Firstly, the paper explains damage initiation and propagation criteria and a procedure to identify the material parameters. In the second stage, the model was implemented as a UMAT (User Material Subroutine), which is linked to finite element software, ABAQUS™, in order to predict the composite structures behavior. Afterwards, some case studies, mainly off-axis coupons under tensile or compression loads, with different types of stacking sequence were analyzed using the proposed material model. Finally, the computational results were compared to the experimental results, verifying the capability of the damage model in order to predict the composite structure behavior.

A Delamination Propagation Model for Fiber Reinforced Laminated Composite Materials

“…Ribeiro, Tita, and Vandepitte [1] proposed an intralaminar failure model regarding composite lamina under plane stress and considering uniform damage through the thickness. The model has three damage variables, each of them related to fiber failure, matrix failure, and shear stress failure under tensile or compression loads, respectively.…”

“…Using these values, five TSLs (Table 3) can be generated by following the procedure described in Section 2.1. The maximum traction or critical nominal stress for each fracture mode is estimated with (1). From the plots, the damage variables are calculated by employing (8).…”

“…A corresponding damage variable was assigned for each stress: d 2 for transverse loading and d 6 for shear loading. The hypotheses of effective stress were employed to link damage variables to the stresses: Table 1 resumes the complete damage model and a full description can be found in [1]. The model has shown good potentiality by predicting progressive failure when loading has predominating in-plane stresses.…”

“…Ribeiro, Tita, and Vandepitte [1] proposed an intralaminar model that estimates the material degradation due to matrix and/or fiber failure for tensile or compression loads. The present work aimed at the complementation of Ribeiro's material model by describing the delamination propagation as a means of interlaminar fracture failure.…”

Development of a criterion for predicting residual strength of composite structures damaged by impact loading

“…The behaviour of the composite laminated structures depends on the behaviour of each homogenized lamina, including the damage mechanisms of the fibres and the matrix (epoxy resin). These damage mechanisms are represented by mathematical equations based on experimental observations performed by Ribeiro et al (2012aRibeiro et al ( , 2013b. The fundamentals of the damage model can be found at Ribeiro's PhD thesis (Ribeiro, 2013a).…”