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Development and testing of a modular strain measurement clip.
Gabrielle Whan1, John Phillips, Stacy Bullock
1School of Engineering, University of Guelph, Guelph, Ont. N1G 2W1, Canada.
Journal of Biomechanics
|October 3, 2003
Summary
A new, affordable strain measurement clip offers versatile, low-stiffness in vitro strain analysis. This modular transducer provides accurate results comparable to traditional methods, even at high strains where others fail.
Area of Science:
- Biomedical Engineering
- Materials Science
- Mechanical Engineering
Background:
- Existing in vitro strain measurement techniques are often costly, complex, or lack versatility for multi-use applications.
- There is a need for a low-cost, adaptable transducer for accurate strain analysis in various experimental settings.
Purpose of the Study:
- To develop and evaluate a novel, low-stiffness, modular transducer for in vitro strain measurement.
- To assess the accuracy, versatility, and cost-effectiveness of the new strain measurement clip compared to traditional methods.
Main Methods:
- A stainless-steel modular strain measurement clip was designed with adjustable extension arms and instrumented with four axial strain gauges in a Wheatstone bridge configuration.
- Calibration was performed to determine linearity and response range across different amplifier settings.
- Validation involved comparing the clip's measurements with surface-mounted strain gauges and theoretical values in an aluminum rod under tensile load, and in an equine metacarpal specimen.
Main Results:
- The clip demonstrated a linear response (R(2)>0.99) over a minimum of 1.04 mm at high gain and up to 30.5 mm at reduced gain.
- Clip stiffness was measured at 0.6 N/mm, minimizing instrumentation artifact.
- Validation tests showed results within 6% of the known modulus of elasticity for aluminum and comparable performance to bonded strain gauges in biomechanical testing, successfully measuring strains beyond the failure point of traditional gauges.
Conclusions:
- The developed modular strain measurement clip is a low-cost, versatile, and accurate alternative to existing methods for in vitro strain analysis.
- Its low stiffness and ability to measure high strains make it particularly suitable for biomechanical applications where traditional methods may fail.
- Further investigations into its diverse applications and potential design improvements are recommended.