Elastic property ratios of a triple-stranded stainless steel arch wire.

The general elastic property ratio equations for nth-stranded wires are derived and then specified for the case of a triple-stranded arch wire. Several parameters are defined, including the modulus of elasticity (E) and the helical spring (kappa) and bending plane (lambda) shape factors. Thereafter, the elastic property ratios of a wide range of compositional/configurational combinations are determined, using a representative triple-stranded 0.0175 inch (3 X 0.008 inch) stainless steel wire as the base line. These results show that the particular 3 X 0.008 inch wire studied possesses the stiffness of an 0.010 inch stainless steel wire but has at least 20% more strength and range. Furthermore, the stiffness of the 3 X 0.008 inch multistranded wire is similar to an 0.016 inch nickel-titanium wire but only 40% that of an 0.016 inch beta titanium wire. When these elastic property ratios are compared with the previous results reported by Thurow, Burstone, and Kusy, differences are noted which can be explained on the basis of the mechanical property values and/or the geometric modeling assumed.