High-Speed Planar Biaxial Tester

Background

A fundamental goal in constitutive modeling is to predict the mechanical behavior of a material under a generalized loading state. To achieve this goal, rigorous experimentation involving all relevant deformations is necessary to obtain both the form and material constants of a strain energy density function.

	Picture of a newly developed, high-speed biaxial tester

For both natural biological tissues and tissue-derived soft biomaterials, there exist many physiological, surgical, and medical device applications where rigorous constitutive models are required. Since biological tissues are generally considered incompressible, planar biaxial testing allows for a two-dimensional stress-state that can be used to characterize fully their mechanical properties.

Device Operation

This device was designed to perform biaxial tests at strain rates above 1000% per second in order to effectively reproduce the strain rates

		custom specimen mounting hardware was designed to balance suture tension
		Close-up.

experienced by native heart valves in vivo. The device features 4 ball screw-driven linear actuators and lightweight polycarbonate carriages in order to minimize inertial effects related to rapid acceleration and high speed motion. Specimen strains are obtained using a sub-specimen imaging system that features a high speed digital camera, capable of acquiring up to 1000 frames per second.

For more information, please see the following article for more information:

M.S. Sacks, “Biaxial mechanical evaluation of planar biological materials,” Journal of Elasticity, vol. 61, pp. 199-246, 2000

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