Ahmad Muhammad Ayaz, Ali Shah Syed Irtiza, Khan Sabih Ahmad, Khan Haris Ali, Shams Taimur Ali
Department of Aerospace Engineering, College of Aeronautical Engineering, National University of Sciences and Technology, Islamabad 44000, Pakistan.
Polymers (Basel). 2023 Mar 11;15(6):1402. doi: 10.3390/polym15061402.
The determination of suitable testing and qualification procedures for fiber-reinforced polymer matrix composite structures is an active area of research due to the increased demand, especially in the field of aerospace. This research illustrates the development of a generic qualification framework for a composite-based main landing gear strut of a lightweight aircraft. For this purpose, a landing gear strut composed of T700 carbon fiber/epoxy material was designed and analyzed for a given lightweight aircraft having mass of 1600 kg. Computational analysis was performed on ABAQUS CAE to evaluate the maximum stresses and critical failure modes encountered during one-point landing condition as defined in the UAV Systems Airworthiness Requirements (USAR) and Air Worthiness Standards FAA FAR Part 23. A three-step qualification framework including material, process and product-based qualification was then proposed against these maximum stresses and failure modes. The proposed framework revolves around the destructive testing of specimens initially as per ASTM standards D 7264 and D 2344, followed by defining the autoclave process parameters and customized testing of thick specimens to evaluate material strength against the maximum stresses in specific failure modes of the main landing gear strut. Once the desired strength of the specimens was achieved based on material and process qualifications, qualification criteria for the main landing gear strut were proposed which would not only serve as an alternative to drop test the landing gear struts as defined in air worthiness standards during mass production, but would also give confidence to manufacturers to undertake the manufacturing of main landing gear struts using qualified material and process parameters.
由于需求不断增加，尤其是在航空航天领域，确定纤维增强聚合物基复合材料结构的合适测试和鉴定程序是一个活跃的研究领域。本研究阐述了一种用于轻型飞机基于复合材料的主起落架支柱的通用鉴定框架的开发。为此，针对一架质量为1600千克的给定轻型飞机，设计并分析了一个由T700碳纤维/环氧树脂材料制成的起落架支柱。在ABAQUS CAE上进行了计算分析，以评估在无人机系统适航要求（USAR）和联邦法规法典FAA FAR Part 23中定义的单点着陆条件下遇到的最大应力和关键失效模式。然后针对这些最大应力和失效模式，提出了一个包括基于材料、工艺和产品的鉴定的三步鉴定框架。所提出的框架首先围绕按照ASTM标准D 7264和D 2344对试样进行破坏性测试展开，接着确定热压罐工艺参数并对厚试样进行定制测试，以评估材料强度抵抗主起落架支柱特定失效模式下的最大应力的能力。一旦基于材料和工艺鉴定达到了试样所需的强度，就提出了主起落架支柱的鉴定标准，这不仅将作为批量生产期间按照适航标准对起落架支柱进行落震试验的替代方法，还将使制造商有信心使用合格的材料和工艺参数来制造主起落架支柱。
