Holistic structural integrity process (HOLSIP) research for hybrid structure applications

该提案概述了研究和模拟导致疲劳载荷下“混合”结构失效的物理裂纹扩展过程的研究。混合结构在这里定义为使用粘合复合材料进行加固或修复的金属结构。这种复合“补强”（用于未破裂的金属结构）或“补强”（用于破裂的金属结构）通常是多层硼/环氧树脂或其他高刚度纤维增强材料。混合结构在各种应用（例如飞机、船舶、压力容器、生物医学植入物、车辆结构、航天器等）中具有巨大的潜力，但是它们在可靠性关键部件中的应用非常有限，因为目前还不存在用于可靠预测故障的准确分析工具。由于缺乏混合结构中多重和相互作用的失效过程机制的基本知识（这是为结构完整性评估创建准确的失效/寿命预测模型所必需的），限制了它们的广泛使用。本研究将利用UBC之前开发的知识、设施和专业知识来构建和测试小尺寸试样，以研究混合结构几何形状、疲劳裂纹扩展和脱粘率之间的机制和相互作用，从而正确识别和模拟破坏机制。获得的信息将用于创建混合结构的裂纹扩展模型，为这些复杂结构开发新的风险/可靠性分析策略所必需。这一新策略——整体结构完整性工艺（HOLSIP）——将特别侧重于金属飞机结构的粘合复合材料修复应用。目标是开发必要的知识和预测模型，以克服现有的障碍，使这项技术获得认证，用于修理民用飞机结构。这项研究对于从目前存在的大量老化民用飞机的寿命延长计划中获得经济效益至关重要，并且由于9/11事件后飞机采购的减少，未来将会增加。

This proposal outlines research to investigate and model the physical crack growth processes that lead to failure in a "hybrid" structure under fatigue loading. A hybrid structure is defined here as a metal structure that has been reinforced or repaired using a bonded composite material. This composite "reinforcement" (for an uncracked metal structure) or "patch" (in the case of a cracked metal structure) is typically a multi-layer boron/epoxy or other high stiffness fiber-reinforced material. Significant potential exists for the use of hybrid structures for a variety of applications (e.g. aircraft, ships, pressure vessels, biomedical implants, vehicle structures, spacecraft, etc.), however their use for reliability-critical components is extremely limited as accurate analytical tools for reliably predicting failure do not currently exist. It is due to a lack of basic knowledge of the multiple and interacting failure process mechanisms within the hybrid structure (required for the creation of an accurate failure/life prediction model for structural integrity assessment) that limits their widespread use. This research will utilize knowledge, facilities and expertise previously developed at UBC to construct and test small-scale specimens to investigate the mechanisms and interaction between hybrid structure geometry, fatigue crack growth and disbonding rate in order to properly identify and model the failure mechanisms. The information obtained will be used to create a crack growth model for hybrid structures, required for development of a new risk/reliability analysis strategy for these complex structures. This new strategy - the HOLolistic Structural Integrity Process (HOLSIP) - will be developed with a specific focus on the application of bonded composite repairs for metal aircraft structures. The goal is to develop the necessary knowledge and prediction models to overcome existing barriers to the certification of this technology for repairing civilian aircraft structures. This research is crucial to obtaining economic benefit from the life-extension programs for the vast fleets of ageing civilian aircraft that currently exist, and will be increasing in the future due to reductions in aircraft purchases after the events of 9/11.