Abstract:
Existing methods of dynamic viscoelastic properties measurements have some limitation with respect to softness of material, its spatial anisotropy, and frequency range. Specifically, there are very limited capabilities to measure dynamic shear moduli of very soft (real shear modulus value is below 10[sup 4] Pa) and anisotropic materials such as biological tissue and some polymers. The proposed technique is intended to fill this niche. The method utilizes the resonance approach, in which the specimen with certain orientation is treated as a massless spring attached to a massive rigid plate. The plate is excited with a one-dimensional forced vibration in such a way that the specimen has only shear deformation. The resonance oscillation of the plate is analyzed with an impedance head and a spectral analyzer. Once the resonance frequency and the quality factor of the resonance are obtained, the complex shear modulus of the specimen can be calculated. An experimental setup utilizing the proposed approach was built and the complex shear moduli of soft biological tissue with respect to different orientations of the fibers were measured.