Viscoelastic Foam Recovery Measurement Using Optical Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for measuring viscoelastic foam compression recovery times are inaccurate due to the 'finger nailing' phenomenon, which causes delayed recovery at shallow indentations, and are limited by the retraction rate of the compression plate, making it difficult to compare foams accurately and measure response times less than 3 seconds.
Innovation Solution
An apparatus and process that includes a compression plate with an aperture and a sensor to continuously measure the height of the viscoelastic foam upon retraction, allowing for faster retraction of the compression plate and accurate recording of recovery rate and time, which can be contact or non-contact based, using a piston, rod, or laser displacement sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the compression plate retracts slowly according to ASTM methodology, then the measurement process is simple and equipment requirements are basic, but the total recovery time measurement becomes inaccurate due to finger nailing phenomenon and the method cannot measure response times less than 3 seconds
Solution Approach 1:
The patent replaces the mechanical contact-based height measurement with optical measurement systems. A laser displacement sensor or camera system continuously measures the foam height during retraction without mechanical contact, eliminating the finger nailing effect and enabling accurate measurement of response times below 3 seconds while maintaining relatively simple apparatus requirements
Solution Approach 2:
The patent implements continuous height measurement throughout the entire retraction process rather than discrete measurements. The sensor continuously records foam height as the compression plate retracts, capturing the complete recovery curve including the initial rapid recovery phase, thereby providing accurate total recovery time measurements without the limitations of intermittent sampling
2Loss of time
If the compression plate retracts faster to capture short response times, then response times below 3 seconds can be measured, but the measurement system becomes more complex and requires more sophisticated sensors
Solution Approach 1:
The patent uses optical measurement systems (laser displacement sensors or camera-based systems) that can capture height changes at very high frequencies without mechanical inertia limitations. This enables accurate measurement of rapid recovery events with response times below 3 seconds while keeping the actual measurement apparatus relatively simple and non-intrusive
3Measurement precision
If continuous height measurement is implemented during retraction, then accurate recovery rate and total recovery time can be obtained, but the apparatus becomes more complex
Solution Approach 1:
The patent employs optical sensors that continuously measure foam height during retraction without requiring complex mechanical measurement mechanisms. The laser displacement sensor or camera system provides continuous height data through non-contact optical fields, achieving high measurement precision while adding minimal complexity to the apparatus
Solution Approach 2:
The patent introduces an optical field as an intermediary between the compression system and the measurement system. The laser beam or camera field acts as a mediator that can penetrate through the compression plate aperture to continuously measure foam height without mechanical contact, enabling accurate recovery rate measurement with minimal added complexity
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
Provides accurate measurement of recovery rate and time, eliminating the finger nailing effect and enabling precise comparison of viscoelastic foams, and allows for measurement of response times below 3 seconds, offering a more accurate representation of the foam's feel and properties.
Implementation Method 1
a laser displacement sensor aligned to measure a position of the viscoelastic foam sample
Implementation Method 2
Flexible, viscoelastic polyurethane foam (also known as 'slow recovery' foam,' memory' foam or 'high damping' foam) is characterized by slow, gradual recovery from compression
Data Source
AI summary
An apparatus and process for measuring recovery rate and total recovery time of viscoelastic foam samples. This apparatus will record the change in height with time to fully define how a viscoelastic foam responds to compression. The process generally includes compressing a compression plate against a surface of the viscoelastic foam sample from a nominal height to a pre-determined compressed height, maintaining the pre-determined compressed height for a period of time; retracting the compression plate at a rate greater than a recovery rate so as to disengage the compression plate from the viscoelastic foam sample, and measuring displacement as a function of time to provide a viscoelastic response profile. Measuring the displacement may be contact based or non-contact based.