Determining Multiaxial Properties of Porous Viscoelastic Membrane using Bubble-inflation Test

摘要

This paper presents an integrated bubble-inflation and digital image correlation (DIC) technique to investigate the multiaxial viscoelastic creep response of a porous scaffold membrane. The scaffold membrane is a highly fluid-saturated fibrous matrix and when subjected to a uniaxial tension, the fibrillar network reorients itself to align with the axis of the principal stretch. As such the uniaxial stretch response might be due to network reorientation or fibrillar deformation or a combination of both. In compression test, the resistance to fluid flow inside the matrix superimposes the poroelastic response into the viscoelastic response and decoupling of the two is nontrivial. An inflation of a circular membrane into a spherical shape would induce a state of stress where no one direction is a dominant direction and hence no significant network restructuring would result. In the inflation test, interstitial flow is not restricted and the fluid is free to escape therefore poroelasticity is not an issue. Bubble inflation test closely mimics the in-service loading condition of these materials therefore has a practical advantage. The paper presents the complete integrated test-setup, its merits, and drawbacks. A nonlinear viscoelastic creep model that uses the bubble inflation test data is also presented.