Effect of depth-absorbed dose distribution on the flexural modulus of carbon fiber–reinforced plastics in a radiation environment in radio-astronomical satellite orbit

Abstract

Carbon fiber–reinforced polymers (CFRP) are used as structural materials for spacecraft due to their excellent physical properties. However, exposure in space to environmental factors, such as radiation, ultraviolet radiation, and thermal cycling, would alter these properties. Therefore, in order to ensure the safety and reliability of the spacecraft and the feasibility of the mission, it is necessary to evaluate the material’s space-environment resistance.The space environment consists of various types of energy and radiation, resulting in a non-uniform depth-absorbed dose distribution. This means that the absorbed dose is significantly higher at the surface of the material and lower with depth. However, reproducing this distribution in a ground-based test facility that typically uses a single energy irradiation is challenging. To overcome this challenge in ground-based testing, it is recommended that multiple radiation types and energies be irradiated to simulate the depth-absorbed dose distribution in a real space environment. However, there is a lack of understanding about the agreement between the depth-absorbed dose distribution obtained in real space environments and in ground-simulated tests. Additionally, the degree to which each depth region of the absorbed dose distribution affects material degradation is unknown. Hence, a faithful reproduction of the depth-absorbed dose distribution in a real space environment requires not only massive test facilities with significant financial investment but also a significant amount of time spent on irradiating those materials containing radiation that have practically no effect on material degradation.This study focused on analyzing the changes in the mechanical properties of CFRP due to radiation degradation using composite beam theory and mathematical models while considering the non-uniform depth-absorbed dose distribution in real space environments. The results of this study provide insight into which depth region of the depth-absorbed dose distribution is dominant for radiation-induced changes in mechanical properties when the CFRP plate thickness varies.