Frangible Airframe Joiners for UAV Crash Energy Dissipation
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) face challenges in dissipating kinetic energy during collisions, which can lead to damage and safety risks due to the concentration of impact forces on structural components, particularly in crash landings.
Innovation Solution
The implementation of frangible mechanical joiners that decouple kinetic energy between linked structures by designed failure points, allowing controlled separation of high mass components from elongated airframe elements, thereby dissipating collision energy within the fuselage rather than directing it to the tips of booms or rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional rigid mechanical joiners are used to connect airframe structures, then structural strength and rigidity are improved, but kinetic energy concentration during collision leads to increased damage and safety risks
Solution Approach 1:
The airframe is divided into modular sections connected by frangible joiners that can selectively fail during impact. The joiners include separable components (e.g., insert and receiver elements) that allow the structure to segment into manageable sections, dissipating kinetic energy through controlled separation rather than concentrating forces on rigid connections.
Solution Approach 2:
The frangible joiners are designed to fail in a controlled manner during collision, converting the harmful impact force into beneficial energy dissipation through deliberate structural failure. The joiners incorporate features like shear pins, weak bonds, or frangible fasteners that break at predetermined points, transforming the harmful concentrated impact into distributed energy absorption across multiple separation points.
2Loss of energy
If frangible mechanical joiners with designed failure points are implemented, then kinetic energy is dissipated through controlled separation, but device complexity increases
Solution Approach 1:
The frangible joiners apply local quality by concentrating the energy dissipation function in specific localized components rather than throughout the entire airframe. Each joiner is a discrete element with specialized failure characteristics, allowing the rest of the airframe to maintain simple, robust construction. This localized approach enables controlled energy dissipation without requiring complex modifications to the overall airframe architecture.
3Reliability
If frangible joiners are used to protect critical components, then safety is improved, but manufacturing precision requirements increase
Solution Approach 1:
The frangible joiners incorporate predetermined failure points and characteristics that are established during manufacturing. Features such as pre-weakened sections, pre-installed shear pins, or pre-configured weak bonds are created in advance, ensuring that the joiners will fail in the desired manner during impact. This preliminary preparation allows for controlled energy dissipation without requiring high precision during actual operation, as the failure behavior is pre-programmed into the joiner design.
Data Source
AI summary
A mechanical joiner for an airframe includes a joiner core and first and second caps. The joiner core has a first side with a first cradle shaped to hold a first structural member and a second side with a second cradle shaped to hold a second structural member. The first cap is shaped to mate to the first side and clamp the first structural member into the first cradle. The joiner core includes a first hole for a first mechanical fastener to extend through and across the first cradle and secure the first cap to the joiner core. The second cap is shaped to mate to the second side and clamp the first structural member into the second cradle. The second cap includes second holes for second mechanical fasteners, distinct from the first mechanical fastener, to secure the second cap to the joiner core.