Anisotropic oxidation prediction using optimized weight loss behavior of bismaleimide composites

Abstract

High-temperature polymer matrix composites are susceptible to thermo-oxidation, which accelerates their degradation and reduces the service life. This work presents the viability of using experimental weight loss for modeling the spatial distribution of oxidation when the oxidized polymer matrix is not discernible due to cracking. The oxidized layer thickness and weight loss were predicted at a microscale level by implementing a volumetric integral in finite element analysis and scaled to a macroscale level by respective area ratios. Weight loss was shown to have a spatial distribution following the three-zone model. The proportionality parameter was optimized by fitting the scaled finite element predictions to the experimental results using artificial neural networks and a generalized pattern search algorithm. Aging experiments have been conducted at the operating temperature range of BMIs, 176.67°C (350°F) and 200°C (392°F). Optical dark field images were acquired to monitor longitudinal and transverse oxidation. Microscale simulations were conducted using representative volume elements utilizing COMSOL Multiphysics. A novel characteristic index for describing the completely oxidized matrix was the weight loss per unit volume that equals 0.44 mg/lm 3 as shown by spatial distribution simulations. The orthotropic diffusivity resulted in a higher degree of anisotropy in the oxidized thickness compared to the weight loss %. At the representative volume element scale, the oxidized layer thickness simulations showed a higher degree of non-linearity at higher temperatures stemming from the cracking effect.

Influence of Reinforcement Structures and Hybrid Types on Inter-Laminar Shear Performance of Carbon-Glass Hybrid Fibers/Bismaleimide Composites under Long-Term Thermo-Oxidative Aging

“…In particular, carbon fiber (CF)/glass fiber (GF) hybrid composites, with excellent mechanical properties and stealth property, are frequently used in aircraft wing cover [7]. Meanwhile, bismaleimide (BMI) resin matrix composites are currently used as structural materials for both military and commercial aircraft, due to their high specific mechanical strength and stiffness under high service temperature [8,9]. This is especially the case of the future supersonic transport aircraft, which is expected to have a service life of around 80,000 h for a supersonic flight, with a maximum skin temperature of 180 °C [10,11].…”

Investigation of Polymer Aging Mechanisms Using Molecular Simulations: A Review

“…In order to fully analyze the aging mechanism, the combination of various simulation methods at different scales will become the choice of more researchers. In addition to the molecular simulation methods (RMD, MD, QM) described above, the Finite Element Analysis (FEA) method has also been applied to the aging simulation of polymers and their composites [129][130][131][132][133]. The results of the FEA simulation can provide a reference for constructing the connection between the experimental and simulation results.…”

Characterization on fatigue behavior and damage mechanism of C/BMI composites experienced thermal cycling

“…3,4 Nowadays, Bismaleimide (BMI) is regarded as a preferred matrix for advanced carbon fiber reinforced composites applied in the next generation of air-superiority fighters. [5][6][7] In addition to the exposure to high temperature and humidity environment, the C/BMI components of air superiority fighters are often subjected to thermal cycles during service. 8 For example, the exterior skins of the aircraft are exposed to a high amplitude temperature variation between À54°C (subsonic phase of flight) and 177°C (supersonic flight at Mach 2.4 cruise) cyclically.…”