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Quadratic invariants of elastic moduli

Andrew N. Norris
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Abstract

A quadratic invariant is defined as a quadratic form in the elements of a tensor that remains invariant under a group of coordinate transformations. It is proved that there are 7 quadratic invariants of the 21-element elastic modulus tensor under SO(3) and 35 under SO(2). This answers some open questions raised by Ting (1987) and Ahmad (2002).

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Andrew N. Norris. 2007-03-09. Quadratic invariants of elastic moduli. https://doi.org/10.1093/qjmam%2Fhbm007

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