The wire spiral loops were first modeled using 3-D structural beam elements with two nodes and six degrees of freedom (translation in the x, y, and z, and rotation about x, y, and z axes) per node. The results from these models were used as baseline data or data to compare sequential models. A one-quarter symmetric model was made of the round and flattened spiral wire loops and is shown in Fig. 7. Symmetric boundary conditions were applied at both ends of the spiral and a 3.33-pound point load (one-half of 6.67 full loop load) was applied to the top of the spiral.

This model series consists of three-dimensional, structural solid models meshed with brick-type elements of round and flattened wire mesh furnace belt spirals. These models were used as a stepping stone between the structural beam element models with a point load and the solid model using contact elements nonlinear material properties. The eight-node elements were hexagonal shape solids with three degrees of freedom (translation in the x, y, and z) per node utilizing the quarter symmetry as shown in Fig. 7. Figs. 8a and 8b show the models for this series. Symmetric boundary conditions were applied at both ends of the spiral portion of the model. These models were loaded by applying pressure to one face of an element located at the end of the curve portion of the spiral. The pressure produced a net force of 1.67 pounds.

This series modeled the contact surface interaction between the round and flattened spiral with a round connecting rod. Solid models were created of the top portion of the spiral for both wire types. The models for this series (shown in Figs. 9a and 9b) were constructed using the same three-dimensional structural solids elements used in Series 2. The continuity between the connecting and spiral wires was modeled using surface contact elements. Symmetric boundary conditions were applied at both ends of the spiral portion of the model. These models were loaded by applying 3.33 pounds of force divided among the nodes on each end of the connecting rod. This produced a net force of 6.67 pounds of tension on the spiral. The nonlinear material properties for 310 stainless steel at 2000 degrees F and the cross-sectional properties (Table I) were used for this series.