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Tissue Sample Mechanical Test
Material test was performed in compression and tension on swine, lamb and human tissues with different experimental setups.
Three experimental setups were used:
- A custom made Micro Testing Machine “MTM” with ±2mN load resolution and ±1mm stroke capacity,
- The ELF-3100
- Testing Instrument with ±22N and ±2.5mm ranges and a 100L Dynamic Material Testing Machine with ±50N and ±25mm ranges.
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Experimental setup for ex vivo soft tissue compression test. Three compression mechanisms are shown
- General configuration and indentation mechanism 1
- Compression mechanism 2 (Simple constant load)
- Compression mechanism 3 (Pre-stretched)
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Mechanical property of soft tissue:
Stress-strain results for muscle, fat, skin and fascia from tensile and compression material test.
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Fitting hyperelastic material models to the experimental data:
The strain energy potentials were fitted to the experimental data. The material was assumed as in compressible.
The tested material models included:
- Arruda-Boyce
- Marlow
- Van Der Waals
- Reduced Polynomial (N=1: Neo-Hooken, 2, and 3: Yeoh)
- Polynomial (N=1: Mooney Rivilin, and 2)
li>Ogden (N=1, and 3)
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Findings:
Generally, material behaviors for skin and fat were favorably represented by the fitted strain energy potentials. However, material behavior for muscle was relatively less represented by the strain energy potential.
It was found that for the tested soft tissues, the Polynomial (N= 2)and Ogden (N=1) gave the best fitted results with R2 higher than 0.99. However, since the fitting results were for limited amount of tissue samples, the selection of material models for the proposed study should not be limited to these 2 options.
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