SBIR Phase II: Blind Fastener Inflation for Structural Joining of Aluminum

这个小型企业创新研究（SBIR）二期项目继续开发用于安装盲结构紧固件的高压流体脉冲系统。铆接是装配承重铝机身结构的首选方法。镦紧铆接需要使用冲击活塞或液压活塞对铆钉两端施加高载荷。一种可以从结构的一侧安装的结构紧固件——盲式紧固件——将简化飞机的组装和维修。现有的盲式紧固件价格昂贵、耗时长，而且与镦压铆钉的腐蚀和疲劳性能不匹配。该项目的第一阶段证明，一种紧凑的高压脉冲发生器可以使铝合金铆钉膨胀，其过盈配合和强度接近传统的镦粗铆钉。在无支撑的铝板上演示了盲紧固。第一阶段分析表明，可以使用更小的工具完成铆钉膨胀。第二阶段的工作将包括开发一种轻便的手持式工具，该工具具有增强的触发机制，可以提供可靠的紧固件安装所需的脉冲控制。这项工作将继续发展用铝销充气铆钉形成坚固的全铝紧固件的技术。第二阶段的目标是满足流体密封航空结构铆钉的性能规范。机体组装是军用和商用飞机成本的主要部分。即将开发的工艺将使手工机身制造成本减半，并可用于自动化柔性制造环境。超压脉冲技术还有多种其他潜在的应用，包括：紧固复合材料/钛机身；汽车铝板粘接；脉冲喷射喷丸在铝板应力消除和成形中的应用并研究材料在极端压力下动态加载的行为。

This Small Business Innovation Research (SBIR) Phase II project continues the development of a hyper-pressure fluid pulse system for installation of blind structural fasteners. Riveting is the preferred method of assembling load-bearing aluminum airframe structures. Upset riveting requires the application of high load to both ends of the rivet using impact or hydraulic pistons. A structural fastener that could be installed from one side of the structure - blind fastening - would simplify aircraft assembly and repair. Existing blind fasteners are expensive, time-consuming and do not match the corrosion and fatigue performance of upset rivets. Phase I of this project demonstrated that a compact, hyper-pressure pulse generator can inflate aluminum alloy rivets with an interference fit and strength approaching conventionally upset rivets. Blind fastening was demonstrated in unsupported aluminum panels. Phase I analysis showed that rivet inflation can be accomplished with a much smaller tool. The Phase II effort will involve the development of a lightweight, hand-held tool with an enhanced trigger mechanism that will provide the pulse control required for reliable fastener installation. The work will continue the development of techniques for inflating rivets with aluminum pins to form a solid, all-aluminum fastener. The objective in Phase II is to meet the performance specifications for a fluid-tight aerospace structural rivet.Airframe assembly represents a major portion of the cost of military and commercial aircraft. The process to be developed will halve the cost of manual airframe fabrication and can be used in an automated flexible-manufacturing environment. There are a variety of other potential applications of hyper-pressure pulse technology including: fastening composite/titanium airframes; automotive aluminum sheet bonding; pulsed-jet peening for stress-relief and forming of aluminum sheet; and research into the behavior of materials under dynamic loading at extreme pressures.