KINKING ANALYSIS BY HYPER-ELASTIC FINITE-ELEMENT METHOD

'Kinking' is known as an unstable behavior of a twisted slender rod, w hich occurs after torsional buckling. It is simulated by a hyper-elast ic finite element code developed by the authors, with hexahedral solid elements. The mechanical characteristics and criterion of kinking are successfully discussed. An incompressible constraint to model a rubbe r-like material is introduced in the simulation by the Lagrange multip lier method and the penalty method. It is found that the former method is, computationally more efficient in the case of large deformation s uch as kinking.