Mechanical characterization of PVA hydrogels' rate-dependent response using multi-axial loading

Area of Science:

• Materials Science and Engineering
• Polymer Physics
• Biomaterials Science

Background:

• Time-dependent properties of rubber-like materials are critical for various applications.
• Current measurement methods (tensile, compression, indentation) are limited, especially for multi-axial loading.
• Few studies explore multi-axial loading for characterizing time-dependent material behavior.

Purpose of the Study:

• To investigate the viscoelastic response of rubber-like materials under multi-axial loading.
• To evaluate the efficacy of the cavity expansion and relaxation test technique for this purpose.
• To characterize PVA hydrogel viscoelasticity using advanced modeling.

Main Methods:

• Performed cavity expansion and relaxation tests on PVA hydrogel specimens.
• Utilized three hyperelastic models and a Prony series to characterize viscoelasticity.
• Employed Finite Element (FE) simulations to validate experimental and analytical results.

Main Results:

• Successfully characterized the viscoelastic response of PVA hydrogels under multi-axial loading.
• Calibrated material coefficients showed excellent agreement between experimental, analytical, and FE simulation data.
• Demonstrated the capability of the cavity expansion technique for measuring time-dependent behavior.

Conclusions:

• The cavity expansion technique is a viable and accurate method for measuring time-dependent behavior in viscoelastic materials.
• This study validates the use of multi-axial loading for comprehensive material characterization.
• The findings support the application of this technique for a broader range of rubber-like and biological materials.