X-Ray Contrast Gage for Internal Strain Measurement in Headform Surrogates
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Solution Overview
Problem
Current diagnostic systems for evaluating internal traumatic injuries, particularly in soft-tissue anthropomorphic test devices, fail to accurately measure dynamic strains and shear stresses, leading to inadequate prediction of injury levels and material failure in protective equipment certification.
Innovation Solution
A gage integrated with x-ray contrast agents within tissue-simulating materials, monitored using fluoroscopic techniques for time-resolved deformation measurement, enabling full-field strain analysis and identification of high deformation/strain regions linked to potential injury outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accelerometer-based diagnostic systems are used to measure rigid body mechanics, then the measurement system is simple and readily available, but the ability to measure dynamic strains in soft materials and predict injury levels is insufficient
Solution Approach 1:
The patent replaces mechanical measurement systems (accelerometers, load cells) with an optical measurement system using digital image correlation. This substitutes the mechanical field with an optical field to capture full-field deformation, enabling precise measurement of dynamic strains in soft materials while avoiding the limitations of point-measurement mechanical sensors.
Solution Approach 2:
The patent transitions from point-measurement diagnostics (zero-dimensional) to full-field two-dimensional measurement capabilities. By using digital image correlation to track deformation across entire surfaces, the system captures spatial distribution of strains, providing comprehensive injury prediction data that point sensors cannot obtain.
2Measurement precision
If localized single-point measurements using pressure transducers or accelerometers are used, then the measurement system is simple, but the ability to capture full-field deformation and measure shear stresses is limited
Solution Approach 1:
The patent applies digital image correlation to transform point measurements into full-field two-dimensional deformation mapping. By tracking the motion of patterns across entire surfaces, the system captures spatial distribution of deformations, strains, and shear stresses, providing comprehensive injury prediction data.
Solution Approach 2:
The patent replaces mechanical sensors (pressure transducers, accelerometers) with an optical measurement system. This substitution enables non-contact, full-field measurement of deformation, allowing visualization and quantification of strain distribution throughout soft tissue materials without the limitations of point-measurement devices.
3Measurement precision
If hollow metal headforms are used for helmet certification testing, then the rigid body mechanics can be measured accurately, but the internal deformation of skull and brain cannot be captured
Solution Approach 1:
The patent changes the material parameters of the headform from rigid metal to soft tissue-simulating materials with appropriate viscoelastic properties. This material parameter change enables the headform to deform in a manner similar to human tissue under impact, allowing accurate measurement of internal deformation patterns that predict brain injury.
Solution Approach 2:
The patent replaces traditional rigid body mechanics measurement with optical deformation mapping using digital image correlation. This substitution enables direct visualization and measurement of internal tissue deformation, providing the data needed to accurately predict injury outcomes in soft tissue materials.
4Ease of operation
If point measurements are used to study rigid body mechanics, then the measurement approach is simple, but full-field measurement is necessary to capture deformation in soft-tissue headforms
Solution Approach 1:
The patent applies digital image correlation to transition from point measurements to full-field two-dimensional deformation mapping. By tracking the motion of patterns across entire surfaces, the system captures spatial distribution of deformations, providing comprehensive injury prediction data that point sensors cannot obtain.
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
Enhances the reliability of injury predictions and certification standards for personal protective equipment by providing direct measurements of internal strain histories, replacing accelerometer-based methods with more accurate deformation metrics.
Implementation Method 1
The gage consists of a substrate integrated or coated with x-ray contrast agents that can be introduced into the tissue-simulants of an ATD
Implementation Method 2
monitored using fluoroscopic techniques (multiple x-ray images or x-ray videography) to determine the time-resolved motion of the contrast materials
Implementation Method 3
Taking multiple images with the fluoroscopic configuration, the relative motion of these distinct spots between successive images and the deformation history within the tissue-simulants can be obtained through existing speckle correlation algorithms
Data Source
AI summary
A diagnostic gage (12) that can be implemented into a tissue-simulating headform (17) or other anthropomorphic surrogate test device (11) as a means of determining the internal strain within the test surrogate. One embodiment of the gage consists of a matrix or substrate embedded with x-ray contrast agents (14) and a series of holes within the substrate (15) that provide contrasting markers in an x-ray image and a means of closely coupling the gage to the test specimen. The relative motion of these contrasting markers can be monitored using x-ray fluoroscopy equipment (e.g., source (10) and detector (13)). This gage provides a means of determining the internal strain within a headform surrogate model for the purpose of evaluating the performance of helmets in terms of reducing the occurrence of concussion among other biomechanical injuries from trauma.