Strain Sensing Compositions for 3D Spatial Strain Measurement
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Solution Overview
Problem
Current technologies fail to provide direct and accurate measurements of 3D spatial strain distribution during high-speed and high-strain rate impact events, particularly in soft materials like human tissues, due to limitations such as altered stress fields, poor data quality, and inability to measure internal strain distributions.
Innovation Solution
Development of strain sensing compositions comprising a polymeric matrix material and a mechanophore component that undergoes a visible color change, allowing for a continuous 3D spatial strain distribution to be visualized upon impact, including the use of a mechanophore component like spiropyran covalently bonded to a polymeric matrix material, which changes color in response to strain, enabling direct measurement of strain and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to the specimen surface, then strain measurement is enabled, but the local stress field is altered resulting in inaccurate strain measurement
Solution Approach 1:
The patent replaces traditional mechanical strain gauges with a photochromic material-based optical sensing system. The photochromic material undergoes reversible color changes in response to strain, allowing strain measurement without mechanical attachment that would alter the stress field. This substitution of mechanical measurement with optical detection resolves the contradiction between enabling measurement and avoiding stress field disturbance.
Solution Approach 2:
The patent utilizes photochromic materials that exhibit reversible color changes when subjected to strain. The color intensity or wavelength shifts correlate with the applied strain, providing a non-contact, non-intrusive measurement method. This color-based sensing mechanism enables accurate strain measurement without the need for physical strain gauges that would disturb the local stress field.
2Measurement precision
If 2D-DIC is used for soft materials, then surface strain can be captured, but marking inks are needed and compatibility with specimen surface is not always possible
Solution Approach 1:
The patent incorporates photochromic materials directly into the soft material matrix, eliminating the need for external marking inks. The photochromic material is integrated during material fabrication, ensuring compatibility with the specimen surface and eliminating the separate marking step required by 2D-DIC methods.
Solution Approach 2:
The patent creates a composite material system where photochromic molecules are dispersed or embedded within the soft material matrix. This composite approach allows the sensing functionality to be inherently part of the material structure, avoiding the need for separate marking layers and ensuring compatibility with the base material properties.
3Measurement precision
If high-speed X-ray is used for bulk strain measurement, then 3D strain distribution can be measured, but very complex instrumentation and complicated pre-test sample tracer mounting are required
Solution Approach 1:
The patent replaces complex X-ray instrumentation with a simple optical detection system. The photochromic material provides inherent 3D strain visualization through color changes that can be captured with standard optical cameras, eliminating the need for sophisticated X-ray equipment and tracer mounting procedures.
Solution Approach 2:
The photochromic material automatically indicates strain distribution through its intrinsic color-changing property without requiring external tracers or complex preparation. The material serves its own sensing function, eliminating the need for pre-test sample preparation with tracers and reducing instrumentation complexity.
4Measurement precision
If split Hopkinson pressure bar test is used, then uniform stress/strain field can be established, but low wave speed in soft materials makes this not always feasible resulting in poor data quality
Solution Approach 1:
The patent replaces the mechanical wave-based measurement approach with an optical sensing method. The photochromic material responds locally to strain regardless of wave propagation characteristics, allowing accurate strain measurement in soft materials with low wave speed without requiring the uniform stress field establishment that characterizes split Hopkinson pressure bar tests.
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 direct visualization and quantification of 3D strain and stress distributions within impacted materials, improving the design of protective equipment and allowing for repeated use without additional steps or cleanup, enhancing the assessment of impact damage and protective gear effectiveness.
Implementation Method 1
the mechanophore component undergoes a visible color change
Implementation Method 2
the strain sensing composition exhibits a continuous three-dimensional (3D) spatial strain distribution including at least one color gradient upon direct or indirect impact by an object
Data Source
AI summary
Strain sensing compositions including a polymeric matrix material and a mechanophore component distributed throughout the polymeric material and covalently bonded to the polymeric material are provided. The mechanophore component undergoes a visible color change and the strain sensing composition exhibits a continuous three-dimensional (3D) spatial strain distribution including at least one color gradient upon direct or indirect impact by an object. Methods of forming strain sensing compositions are also provided. Methods of evaluating a strain distribution associated with an impact of a surrogate material comprising a mechanophore component are also provided.