Title

Multi-Scale Modeling of Thermo-Oxidation Effects on the Flexural Behavior of Cross-Ply Bismaleimide Composites

Abstract

Mechanical properties of high-temperature polymer matrix composites deteriorate during their service. Oxidation plays a significant role in determining the residual elastic and strength properties of the composite. The present work investigates the oxidative aging damage of cross-ply bismaleimide composites, both experimentally and numerically. Also, this work introduces a better understanding of the significant damage mechanisms, and their respective time ranges. Micro/macro-scale thermo-oxidation behavior and flexural failure were simulated for 1,700 hours of aging. Thermo-oxidation behavior of the cross-ply laminates was simulated using a multi-fiber multi-layer representative volume element. Thermo-oxidation is a diffusion–reaction phenomenon that depends on temperature and oxidation state in time and space domains. In this work, the proportionality between oxidation state evolution and reaction rate was modeled using a new form of time-dependent parameter. Owing to aging damage, the required properties for the flexural test simulation were reduced in the meso-scale. The current study presents a damage state assuming proportionality between the average crack length and oxidized layer thickness based on a continuum damage mechanics approach. Scanning electron micrographs showed that the onset of the "blunt" transverse (through-thickness) micro-cracking/debonding in the superficial layers was at 500 hours under 176.7 °C (350 °F), where oxidative cracking dominates aging mechanisms. The "blunt" micro-cracks propagated in the transverse direction near 1000 hours rendering the crack faces in contact with the oxidative air. After about 1,700 hours of aging, the weight loss ratio was 0.5%, and the flexural modulus and strength reduced by 19% and 10%, respectively. Prior to 500 hours, where cracking was not noticeable in the "crack-free region", the strengths reduction was not significant based on the numerical simulations. In the crack-free and oxidative damage dominated regions, the elastic property numerical reduction was significant.

Department(s)

Mechanical and Aerospace Engineering

Comments

Article in Press

Keywords and Phrases

Concrete aggregates; Continuum damage mechanics; Laminated composites; Polymer matrix composites; Scanning electron microscopy; Thermal aging; Thermooxidation; Bismaleimide composites; High temperature polymer matrix composite; Multi-scale Modeling; Representative volume element (RVE); Scanning electron micrographs; Superficial layers; Time dependent parameter; Weight loss ratios; Cracks; 3D FEA; Continuum damage mechanics (CDM); Flexural of laminates; SEM; Thermal aging damage

International Standard Serial Number (ISSN)

1385-2000; 1573-2738

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Springer Verlag, All rights reserved.

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