Optical Radial Strain Measurement for Granular Powder Under Triaxial Loading
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Solution Overview
Problem
Measuring radial strain in powders and granular materials under compressive axial and radial loading is challenging due to the inherent nature of these materials, which requires triaxial loading and results in strains that conventional strain gauges cannot accurately measure, especially when strains exceed 50%.
Innovation Solution
A system and method utilizing a cylindrically shaped pliable sleeve with end caps and hydraulic confinement, where optical sensing measures the change in diameter of the specimen by interrupting a light beam, allowing for accurate radial strain measurement under axial and radial loading conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional strain gauges are used to measure radial strain, then the measurement device is simple and easy to use, but the measurement precision deteriorates when strains exceed 50%
Solution Approach 1:
The patent replaces conventional mechanical strain gauges with an optical measurement system. A light source emits light through the specimen, and a photodetector measures the transmitted light intensity. The radial strain is calculated from the change in light transmission, enabling accurate measurement of large radial strains (exceeding 50%) that would saturate conventional strain gauges.
Solution Approach 2:
The patent introduces an optical intermediary (light beam) to measure radial strain indirectly. Instead of directly attaching a strain gauge to the specimen surface, the system uses light transmission through the specimen as an intermediary measurement mechanism, where the light intensity change correlates with radial dimension changes.
2Measurement precision
If triaxial loading is applied to powder specimens, then the constitutive properties can be determined, but the measurement of radial strain becomes challenging
Solution Approach 1:
The patent replaces mechanical contact-based strain measurement with an optical transmission method. The light beam passes through the specimen in the radial direction, and changes in light intensity provide information about radial strain without requiring mechanical contact or attachment to the specimen surface.
Solution Approach 2:
The patent measures radial strain by observing changes in the light transmission path through the specimen. Instead of measuring surface deformation in the radial direction directly, the system uses light transmission along the radial dimension to infer strain, effectively using optical path information to measure dimensional changes.
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
Enables precise quantification of radial strain in powders and granular materials, facilitating the determination of constitutive properties essential for predicting material behavior in various applications, such as simulating penetration events or asteroid impact responses.
Implementation Method 1
optical sensing measures the change in diameter of the specimen by interrupting a light beam
Data Source
AI summary
A method and system for measuring radial strain on powder or other granular material while the powder is subject to compressive axial and radial loading. The powder is contained within a pliable sleeve. As pressure is applied to the powder, the sleeve changes diameter. An optical emitter emits a beam of light, which is intersected by the entire diameter of the sleeve. An optical sensor receives the intersected beam, and generates a response signal that indicates the diameter of the sleeve. This change in diameter can be related to a constitutive property such as strain.