Strain Measurement Device for Solid Rocket Propellant
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Solution Overview
Problem
Conventional strain gauges are ineffective in accurately measuring strain in elastomeric materials like solid rocket propellants due to their stiffness, which restricts the propellant's movement and provides lower strain readings, leading to inaccurate data and potential cracking issues during launch or storage.
Innovation Solution
A strain measurement device comprising a displacement sensor and a reference material, integrated with a pre-cured elastomeric material, which detects changes in distance and generates a data signal to determine the strain of the propellant, allowing for accurate strain measurement by correlating with the elastic properties of the pre-cured material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional strain gauges are used to measure strain in elastomeric propellant, then the strain gauge provides a stiff measurement structure, but the strain gauge restricts propellant stretching and provides inaccurate lower strain readings
Solution Approach 1:
The patent introduces an elastomeric intermediary layer between the strain gauge and the propellant. This intermediary layer has matching elastic properties that allow it to deform with the propellant without restricting its movement, while still providing a stable mounting surface for the strain gauge. This resolves the contradiction by decoupling the structural stability function from the measurement accuracy function.
Solution Approach 2:
The patent changes the mechanical parameters of the strain gauge system by selecting an elastomeric material with specific elastic modulus and Poisson's ratio that match the propellant properties. This parameter matching allows the strain gauge assembly to deform harmoniously with the propellant, eliminating the restriction effect while maintaining measurement capability.
2Strength
If conventional strain gauges with stiff polymer backing are used, then the strain gauge maintains structural integrity, but the strain gauge cannot stretch far enough to accurately determine propellant strain
Solution Approach 1:
The elastomeric intermediary layer acts as a flexible mediator that transfers the propellant's large deformations to the strain gauge. The intermediary stretches with the propellant while maintaining structural integrity, allowing the strain gauge to measure strains beyond its own elastic limits without compromising its structural integrity.
Solution Approach 2:
The measurement system is segmented into three functional components: the propellant (object of measurement), the elastomeric intermediary (transmission element), and the strain gauge (sensing element). This segmentation allows each component to be optimized for its specific function while working together as an integrated system.
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 provides accurate strain data for elastomeric materials, enhancing the calibration of material models and ensuring safety factors in solid rocket motors by accurately measuring strain, reducing the risk of cracking and debonding.
Implementation Method 1
the displacement sensor is configured to detect changes in distance between the displacement sensor and the reference material and generate a data signal in response thereto
Implementation Method 2
A strain measurement device comprising a displacement sensor and a reference material, integrated with a pre-cured elastomeric material, which detects changes in distance and generates a data signal to determine the strain of the propellant, allowing for accurate strain measurement by correlating with the elastic properties of the pre-cured material
Data Source
AI summary
A strain measurement device includes a reference material, and a displacement sensor configured to detect relative changes in distance between the sensor and the reference material. At least one of the displacement sensor and the reference material is coupled with a pre-cured elastomeric material. The displacement sensor generates a data signal to a processor that is configured to determine a strain of another elastomeric material based at least in part on the data signal received from the sensor. A displacement sensor and a reference material may be positioned within an elastomeric material within a casing of a solid rocket motor for determining strain experienced by the elastomeric material, such as the propellant of the solid rocket motor. A method includes installing a sensor of an elastomeric material. Another method includes determining strain of an elastomeric material of a solid rocket motor.