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

这项建议概述了一项研究，以调查和模拟在疲劳载荷下导致“混合”结构失效的物理裂纹扩展过程。混合结构在这里被定义为使用粘结复合材料加固或修复的金属结构。这种复合材料“补强”(对于无裂纹的金属结构)或“补丁”(对于有裂纹的金属结构)通常是多层硼/环氧树脂或其他高硬度纤维增强材料。混合结构在各种应用(如飞机、船舶、压力容器、生物医学植入物、车辆结构、航天器等)中的应用潜力很大，但它们对可靠性关键部件的使用极其有限，因为目前还不存在可靠地预测故障的准确分析工具。这是由于缺乏对混合结构内多个相互作用的失效过程机制的基本知识(为结构完整性评估建立准确的失效/寿命预测模型所必需的)，从而限制了它们的广泛应用。这项研究将利用UBC先前开发的知识、设施和专业知识来构建和测试小规模试件，以研究混合结构几何形状、疲劳裂纹扩展和剥离率之间的机制和相互作用，以便适当地识别和模拟失效机制。获得的信息将用于建立混合结构的裂纹扩展模型，这是为这些复杂结构制定新的风险/可靠性分析战略所必需的。这一新战略-HOLLISTIC结构完整性过程(HOLSIP)-将特别侧重于金属飞机结构粘结复合材料修复的应用。目标是开发必要的知识和预测模型，以克服现有的障碍，证明这项修复民用飞机结构的技术。这项研究对于从目前存在的大量老化民用飞机机队的延长寿命计划中获得经济利益至关重要，而且由于9/11事件后飞机购买量的减少，这一研究将在未来增加。

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.