Initiator Assembly Containment Shell for Cook-off Safety
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Solution Overview
Problem
Existing initiator assemblies for energetic materials face challenges in withstanding high electrical power without initiating their output charge, and must vent gases and fragments to prevent energetic initiation of motor propellants, which can impede motor function and pose safety risks.
Innovation Solution
An initiator assembly with a containment shell that encloses the initiator housing, designed to contain gases and fragments produced during 'cook-off' events, ensuring they do not leak or eject materials that could initiate the motor propellant, while maintaining a compact size and consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external vent is provided to vent gases and fragments during cook-off, then safety is improved by preventing energetic initiation of motor propellant, but the device complexity increases and the initiator assembly cannot be positioned within the propellant
Solution Approach 1:
The harmful function of venting gases and fragments is extracted and redirected into a dedicated containment chamber (void space) within the initiator assembly. This separates the cook-off products from the motor propellant environment, maintaining safety without requiring external vents that would increase device complexity and prevent integration within the propellant.
Solution Approach 2:
The containment chamber (void space) is nested within the initiator assembly structure, creating a hierarchical containment system. The initiator housing is contained within the initiator assembly, which in turn contains the void space for capturing cook-off products. This nested structure provides safety functionality without adding external components.
2Volume of moving object
If the initiator assembly is made compact for positioning within motor propellant, then space efficiency is improved, but the capacity to contain cook-off gases and fragments is reduced
Solution Approach 1:
The containment capability is localized to a specific region (the void space) within the initiator assembly rather than requiring the entire assembly to be large. This localized approach allows the rest of the initiator assembly to remain compact for positioning within motor propellant while maintaining sufficient containment capacity in the dedicated void space region.
3Reliability
If the initiator assembly is exposed to high electrical power for extended periods, then the ability to meet MIL-DTL-23659 standard is improved, but the risk of cook-off increasing energetic initiation is worsened
Solution Approach 1:
The void space acts as an intermediary containment environment between the input charge and the motor propellant. During cook-off events from high electrical power exposure, this intermediary space captures and isolates the cook-off products, preventing them from directly interacting with and initiating the motor propellant, thus maintaining standard compliance without increasing energetic initiation risk.
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 effectively prevents the initiation of motor propellants by containing gases and fragments within the initiator assembly, ensuring reliable operation and safety during exposure to high electrical power, meeting the MIL-DTL-23659 standard without compromising performance or generating casing fragments.
Implementation Method 1
The containment shell is configured such that the gas and/or the fragments produced when the input charge is cooked off is/are contained within the initiator assembly
Implementation Method 2
The initiator device is configured to initiate at least one of a combustion event, a deflagration event and a detonation event in the input charge
Data Source
AI summary
An initiator assembly that includes an initiator and a containment shell. The initiator has an initiator housing, an initiator device mounted inside the initiator housing, and an input charge that is formed of an energetic material. The initiator device is configured to initiate at least one of a combustion event, a deflagration event and a detonation event in the input charge. The containment shell is coupled to the initiator housing and defines a space into which gas and/or particles are ejected from the initiator housing if the initiator device is not activated and the input charge is cooked off.