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 \(176.7~{}^{\circ}\mbox{C}\) (\(350~^{\circ}\mbox{F}\)), 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.

高温聚合物基复合材料的机械性能在使用过程中会降低。氧化在确定复合材料的残余弹性和强度特性方面起着重要作用。本工作从实验和数值两方面研究了交叉双马来酰亚胺复合材料的氧化老化损伤。此外，这项工作还可以更好地理解重要的损坏机制及其各自的时间范围。模拟了1700小时的老化过程的微观/宏观热氧化行为和弯曲破坏。使用多纤维多层代表体积元素模拟了交叉层压材料的热氧化行为。热氧化是一种扩散反应现象，它依赖于时空域中的温度和氧化态。在这项工作中 氧化态演变和反应速率之间的比例是使用一种新的时变参数形式建模的。由于老化的损害，弯曲试验模拟所需的性能在中观尺度上降低了。当前的研究基于连续损伤力学方法，提出了假设平均裂纹长度与氧化层厚度成比例的损伤状态。扫描电子显微镜照片显示，在表层下，“钝”的横向（贯穿厚度）微裂纹/脱胶的开始时间为500小时。当前的研究基于连续损伤力学方法，提出了假设平均裂纹长度与氧化层厚度成比例的损伤状态。扫描电子显微镜照片显示，在表层下，“钝”的横向（贯穿厚度）微裂纹/脱胶的开始时间为500小时。当前的研究基于连续损伤力学方法，提出了假设平均裂纹长度与氧化层厚度成比例的损伤状态。扫描电子显微镜照片显示，在表层下，“钝”的横向（贯穿厚度）微裂纹/脱胶的开始时间为500小时。\（176.7〜{} ^ {\ circ} \ mbox {C} \）（\（350〜^ {\ circ} \ mbox {F} \）），其中氧化裂化是老化机制的主导。“钝”微裂纹在近1000个小时的横向传播，使裂纹面与氧化空气接触。老化大约1,700小时后，失重率为0.5％，弯曲模量和强度分别降低了19％和10％。在500小时之前，在“无裂纹区域”中裂纹不明显的情况下，基于数值模拟的强度降低并不明显。在无裂纹和氧化损伤占主导的区域，弹性性能数值下降是显着的。