Fig. 1: Imaging and analysing elastic waves in a stretched rubber membrane.
From: Non-destructive mapping of stress and strain in soft thin films through sound waves
a Photograph of our rubber sheet. b Optical Coherence Tomography (OCT) cross-sectional image. c, d Wave profiles measured by OCT when the film is c stress-free and d subject to uniaxial stress σ1 ≃ 200 kPa, see Supplementary Movies 1 and 2. The wavefronts become elliptical when stretched. e Corresponding 3D wavefronts, obtained by measuring the vertical displacement from the phase change in the interference signal of the OCT; N indicates the number of weights (each with mass 20 g). f Dispersion relations of the A0 mode obtained at different levels of stress. Each curve is an average over six measurements (for clarity the error bar is not shown here but can be found in Supplementary Fig. 11). g Comparison between measured and applied stress values (σ1, σ2: stress components along, and perpendicular to, the direction of tension, respectively). For reference, the dashed lines show where the measured stresses are equal to the applied stresses. h Comparison between the measured and applied stretch values (λ1, λ2: stretch ratios along, and perpendicular to, the direction of tension, respectively). Dashed lines, expected 1 and -1/2 power laws of the stretches for reference. i Stress-strain curve from the measured data compared to that measured by a standard tensile test. Error bars are the standard deviations from six measurements.
