Strain measurement in biaxially loaded inhomogeneous, anisotropic elastic membranes

Abstract

 This paper considers the problem of measuring the strain field in biaxially loaded elastic membranes, such as soft biological tissue. Cross-correlation of intrinsic or applied speckle patterns were used to calculate the 2D displacements of small regions on the surface of a deforming membrane. This method was able to resolve 2D displacements to within a twentieth of a pixel. A finite-element model with bicubic-Hermite interpolation was used to represent the geometry of the membrane in the undeformed state. This model was fitted to the measured displacements to obtain the geometry of the membrane in the deformed state, and the strain field was calculated from the change in geometry. The strain fields were measured in both an inhomogeneous isotropic rubber membrane and a section of sheep diaphragm.