Abstract
It is shown that, among anisotropic elastic materials, certain orthotropic and hexagonal materials can have a sphere as a slowness surface branch that is associated with purely longitudinal or transverse waves. If it is associated with a longitudinal wave, it is the inner slowness sheet which is disjoint from the two outer slowness sheets. The two outer slowness sheets touch each other at certain points so that there are acoustic axes of double degeneracy. The waves associated with the two outer slowness sheets are necessarily transverse waves. Therefore any plane wave in these materials is either longitudinal or transverse. If the spherical slowness surface is associated with a transverse wave, it is the medial slowness sheet. The acoustic axes are at the crystallographic axes where the spherical slowness sheet touches the inner and/or outer sheets. All three sheets can touch each other so that the acoustic axis can be of triple degeneracy. In the case of special hexagonal materials with the x 3-axis being the axis of symmetry, the x 3-axis is an acoustic axis of double or triple degeneracy while any line on the x 3 = 0 plane is an acoustic axis of double degeneracy. We also consider anisotropic elastic materials for which a cross-section of a slowness sheet is a circle. Anisotropic elastic materials that possess a circular cross-section in the slowness surface are not restricted to hexagonal or orthotropic materials.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
