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

该小型企业创新研究（SBIR）第二阶段项目继续开发用于安装盲结构紧固件的超高压流体脉冲系统。 铆接是装配承载铝机身结构的首选方法。 顶锻铆接需要使用冲击或液压活塞在铆钉两端施加高载荷。 可以从结构的一侧安装的结构紧固件-盲紧固-将简化飞机组装和维修。现有的盲紧固件是昂贵的、耗时的，并且与镦粗铆钉的腐蚀和疲劳性能不匹配。 该项目的第一阶段表明，一个紧凑的，超高压脉冲发生器可以膨胀铝合金铆钉与干涉配合和强度接近传统的镦粗铆钉。在无支撑的铝板中证明了盲紧固。 第一阶段的分析表明，铆钉膨胀可以用更小的工具完成。 第二阶段的工作将涉及开发一种轻型手持工具，该工具具有增强的触发机制，将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技术，使铆钉与铝销膨胀，形成一个坚实的，全铝紧固件。 第二阶段的目标是满足流体密封航空航天结构铆钉的性能规格。机身装配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。 超高压脉冲技术还有其他各种潜在应用，包括：紧固复合材料/钛合金机身;汽车铝板粘合;用于消除应力和铝板成形的脉冲喷射喷丸;以及研究材料在极压动态载荷下的行为。

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.