Failure Progression and Mesh Sensitivity Analyses by the Plate Element-Failure Method

Abstract

Despite the fact that fiber-reinforced composite materials have been extensively used in aerospace, defense and marine structures for many years, the high stiffness and strength properties of these materials have not yet been fully exploited. In many instances, overly rigid adherence to conservative design rules based on ‘black aluminum’ (symmetric quasi-isotropic graphite-epoxy laminates) has eroded these advantages significantly. Efforts to better understand the failure mechanisms and develop efficient and robust computational tools will lend more confidence to designers and engineers to realize better weight savings and improve damage tolerance. The search for efficient computational tools for the modeling of progressive damage in composites should be coupled with sufficient fidelity to ensure that the mechanisms of the complex failure modes are accurately represented. In an effort towards this goal, the authors have proposed the element-failure method (EFM) using 3D solid finite elements, which has been successfully applied to failure analysis of composite laminates. The EFM has advantages over the traditional material property degradation method (MPDM) because the stiffness matrix of the element is not changed, thereby improving computational convergence and saving in computational efforts. In this article, a plate element-based EFM (PEFM) is presented for modeling progressive damage in fiber-reinforced composites. The implementation in plate elements further improves the efficiency of computation, when compared to analyses with 3D elements. In conjunction with several different failure theories, the plate EFM is applied to model progressive damage in quasi-isotropic composite laminates with open-holes, subjected to remote tensile loading. A mesh sensitivity study shows that the EFM results are relatively independent of mesh size effects. When compared with experimental data, the predicted ultimate strengths and damage patterns show good agreement.

Mitigating stress concentration through defense hole system for improvement in bearing strength of composite bolted joint, Part 1: Numerical analysis

“…It was observed that the failure pattern is comparable for all plies for fiber and matrix failures. In a study conducted by Liu et al, 23 the experimental failure load at the first fiber rapture was 30,259 N, while the failure load obtained from their progressive failure analysis was 27,477.7 N, which gave 9% variation from the experimental load. Nonetheless, in our model, it was found that the failure load was 28,170 N, which indicated only a 6.9% variation compared to the experimental failure load and a 2.4% variation from those models.…”

“…Further verification of the progressive failure model was carried out with a study that dealt with the progression of failure in an open-hole carbon/epoxy composite laminate with stacking sequence [45/0/ À 45/90] s subjected to tension. 23 The study used different failure theories, including the micromechanics of failure, maximum stress, Tsai-Wu, Hashin, and Puck theories with ABAQUS user subroutine, to analyze the open-hole laminate. The stress at the first load drop (first fiber rapture) was considered as the ultimate strength.…”

“…Nonetheless, in our model, it was found that the failure load was 28,170 N, which indicated only a 6.9% variation compared to the experimental failure load and a 2.4% variation from those models. 23 Subsequently, following the validation of nonlinear material behavior of the composite model, the progressive failure model was then included in the current analysis, comprising double-lap single-bolted composite joints of 8-plies balanced GFRP plain weave.…”

Modeling of composite plates with an arbitrary hole location using the variable separation method

“…the Equivalent Single Layer Models (ESL): the Reissner-Mindlin (FSDT, [9,10]) and higher-order models (TSDT, [11]) have been addressed. But, only global quantities can be obtained, and the integration of the equilibrium equations is needed to estimate the transverse shear stresses with accuracy.…”

Simulation on size effect of notched quasi-isotropic composite laminates under tensile loading

“…Over the past decades, many attempts have been made to investigate the progressive failure of composite laminates. The methods commonly seen in literature include the material property degradation method (MPDM), 2,3 continuum damage mechanics method (CDMM), 4–6 element failure method (EFM), 7–9 and so on. The MPDM assumes that the damaged material can be replaced by an equivalent one with degraded properties.…”