Separation Nut Eddy Current Damping for Near-Zero Release Shock
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Solution Overview
Problem
Existing separation nuts in launch vehicle, missile, and spacecraft applications generate significant shock and momentum transfer during payload release, which can damage sensitive electronics and affect the accuracy of released weapons due to high kinetic energy conversion and momentum transfer, and often require refurbishment after a single use.
Innovation Solution
A selectively releasable separation nut that dissipates over 99.99% of stored strain energy as heat using a combination of electromagnetic eddy current damping and mechanical friction, minimizing kinetic energy and momentum transfer, and can be reset for repeated use without refurbishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pyrotechnic actuators are used to release the separation nut, then release speed and reliability are improved, but shock and momentum transfer to the payload increase significantly
Solution Approach 1:
The patent converts the harmful kinetic energy and momentum of the released bolt into beneficial heat energy through electromagnetic eddy current damping. The bolt's motion induces currents in a conductive damper ring, which dissipate the energy as heat, reducing shock and momentum transfer to the payload while maintaining fast release
Solution Approach 2:
The patent replaces the purely mechanical bolt catcher system with an electromagnetic damping system. Instead of relying only on mechanical friction and deformation to stop the bolt, the system uses electromagnetic induction to create eddy currents that provide controlled damping, reducing shock and momentum transfer
2Reliability
If high preload force is applied to hold down the payload during launch, then holding reliability is improved, but stored strain energy increases leading to higher shock upon release
Solution Approach 1:
The patent converts the harmful strain energy stored in the preloaded bolt into beneficial heat energy through electromagnetic damping during release. The high preload force that creates large strain energy is the same energy that is then dissipated as heat through eddy currents, preventing shock transmission to the payload
Solution Approach 2:
The patent introduces an electromagnetic damper as an intermediary between the bolt and the payload. This damper absorbs and dissipates the energy from the preloaded bolt through electromagnetic induction, acting as a buffer that prevents direct transmission of shock and momentum to the payload
3Object-affected harmful factors
If a deformable pad is used to damp bolt impact in the bolt catcher, then some shock is reduced, but momentum transfer to the payload remains significant and the device requires refurbishment after single use
Solution Approach 1:
The patent replaces the mechanical deformable pad system with an electromagnetic damping system. Instead of using a consumable mechanical element that deforms and requires replacement, the system uses electromagnetic induction in a conductive damper ring that can be reset and reused without refurbishment
Solution Approach 2:
The patent recovers and resets the damping system after use. Instead of discarding or refurbishing a deformed mechanical pad, the electromagnetic damper components (conductive ring, magnets) can be reset to their original state and reused, eliminating single-use limitations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves near zero shock and momentum transfer, reducing tipoff velocity and maintaining performance over time, with less than 20 g shock and 1% momentum transfer compared to prior art, and allows for precise control of bolt release velocity and energy dissipation.
Implementation Method 1
a dynamically balanced rotor that converts a majority, greater than 50%, and more preferably a very large majority, greater than 90%, and even more preferably a nearly complete majority, greater than 99%, of the strain energy in the preload force loop into heat through a magnetic eddy current damper
Implementation Method 2
a magnetic eddy current damper that converts the kinetic energy into heat
Implementation Method 3
a combination of electromagnetic eddy current damping and mechanical friction
Data Source
AI summary
A selectively releasable separation nut for securing a payload and/or deployable equipment (hereafter “second body”) to a rocket, missile, or aircraft or spacecraft (hereafter “first body”) by way of a preloaded bolt, or other fastener, and releasing them on command. The separation nut may have magnetic eddy current damping components that dissipate as heat the strain energy stored in the separation nut, the bolt, and surrounding first body and second body structures during the bolt preload release. Energy not dissipated as heat during preload release may be stored as kinetic energy and dissipated as heat after the bolt mechanical release. The bolt acceleration and velocity are controlled throughout the release cycle. The bolt kinetic energy post release is less than 0.01% of the stored strain energy pre-release. Shock, impulse, and momentum transfer to the released second body are near zero.