ABSTRACT
The present author (Nakaza), introduced a new elastic theory in 2005. According to this theory, the internal stress of an isotropic elastic material consists of an elastic stress governed by Hooke‘s law and an internal pressure governed by the state equation. In conventional theory, the internal stress consists of the two elastic stresses corresponding to the two elastic moduli and thus the force causes the Poisson effect cannot be explained, even if we observe the occurrence of the lateral strains under a uniaxial loading. According to Nakaza’s elastic theory, Hooke‘s law has only one elastic modulus and in this sense, the new theory is consistent with the assertion of Navier who used only one elastic constant to derive his fundamental elastic theory. The new elastic theory may change the stress evaluation from the existing theory.
