Approximate Theories of Elastic Rods with Applications

摘要

In this dissertation, approximate theories involving combinations of small andmoderate strains and rotations for elastic rods are developed. Their usefulness is illustrated with several applications. The rod theory used to construct these theories is the directed (or Cosserat) rod theory developed by Green, Naghdi and several of their co-workers. The approximate theories which are developed in this dissertation are rendered properly invariant under arbitrary superposed rigid body motions by extending some recent work of Casey and Naghdi, and of O'Reilly. These extensions were developed to render the properly invariant theories more amenable to applications. The approximate theory that is the primary focus of this work is one involving small strain and moderate rotation. A parallel development for a directed surface was performed earlier by Naghdi and Vongsarnpigoon. Specifically, it is shown that there are considerable simplifications in the balance and constitutive laws as well as in the strain-displacement relations because of the assumptions made in this theory. p5.