Dual-Fracture Explosive Bolt for Reliable Missile Separation

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Solution Overview

Problem

Conventional explosively releasable bolts in the Mk41 Vertical Launching System have a single explosive charge and fracture plane, leading to costly restrained firing events if the energetic chain reaction malfunctions, resulting in failed separation of missiles.

Innovation Solution

A double-separating explosively releasable bolt design with two distinct energetic chains and fracture planes within a single bolt assembly, featuring a notched cylindrical bar with explosives and detonators, and anchors with helical threads to ensure reliable separation by concentrating stress waves for controlled fracture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single explosive charge and fracture plane is used in the bolt, then the device complexity is reduced, but the reliability of missile separation deteriorates due to potential malfunction of the energetic chain reaction

Engineering Contradiction:

Improvebolt structureVSAvoidmissile separation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The bolt is segmented into two independent fracture planes, each with its own explosive charge and detonator. This segmentation creates redundant separation paths, so if one fracture plane fails to activate, the other can still accomplish missile separation, thereby improving reliability without significantly increasing overall device complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dual-fracture-plane design provides beforehand cushioning against failure by pre-establishing redundant energetic chains. If the first explosive charge or detonator fails, the second fracture plane serves as a backup mechanism to prevent restrained firing events, ensuring reliable missile separation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If two separate explosive bolts are used to ensure redundancy, then the reliability of missile separation is improved, but the volume and complexity of the restraint system increase

Engineering Contradiction:

Improvemissile separationVSAvoidrestraint system

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

Two independent fracture planes are merged into a single bolt assembly, sharing common structural elements such as the bolt body, mounting features, and anchoring mechanisms. This merging achieves the redundancy of two separate bolts while consolidating the physical footprint, thereby maintaining reliability without proportionally increasing system volume

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If a single fracture plane is used in the bolt, then the manufacturing precision requirements are reduced, but the reliability deteriorates due to potential malfunction of the energetic chain reaction

Engineering Contradiction:

Improvefracture plane geometryVSAvoidmissile separation

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The single fracture plane is segmented into two distinct fracture planes, each with its own explosive charge and detonator. This segmentation creates redundant separation paths, so if one fracture plane fails to activate, the other can still accomplish missile separation, thereby improving reliability without significantly increasing overall device complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

This design enhances the reliability of missile separation by reducing the probability of restrained firing events, minimizing complexity and volume, and maintaining system functionality even if one bolt fails, thus preventing damage to the launch system.

Implementation Method 1

Each explosive correspondingly inserts into a corresponding bore to a corresponding depth end

Methodology Applied

Scientific EffectExplosion: Explosion

Implementation Method 2

concentrating stress waves for controlled fracture

Methodology Applied

Scientific EffectStress wave concentration: Shock Wave

Implementation Method 3

First and second notches reduce the thickness proximate to the corresponding depth ends

Methodology Applied

Scientific EffectStress concentration: Fracture Mechanics

Implementation Method 4

The longitudinal ends include helical male threads, and the anchors are nuts having helical female threads

Methodology Applied

Scientific EffectThreaded fastening: Screw

Data Source

PatentUS10989243B2Doubly-separating explosively releasable bolt

Publication Date: 2021.04.27 THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY

AI summary

An explosive bolt is provided for securing a brace in tension. The bolt includes a bar, a pair of explosives, a pair of detonators and a pair of anchors. The bar has opposing longitudinal ends and an outer thickness. Opposing bores extend inwardly from the longitudinal ends to corresponding depth ends. First and second notches reduce the thickness proximate to the corresponding depth ends. A center rod separates the notches from each other. Each explosive correspondingly inserts into a corresponding bore to a corresponding depth end. Each detonator correspondingly inserts into the corresponding bore. Each anchor secures the bar to the brace. In further embodiments, the longitudinal ends include helical male threads, and the anchors are nuts having helical female threads.