Date of this Version
Wire rope is a versatile, flexible, high-strength member that is used in many mechanical systems. However, due to the complexity of wire rope, analytical investigations have been relatively limited. Previous attempts to create simplified models of wire rope were not validated with physical testing and used a cumbersome beam-and-shell or beam-and-solid method for simulating the wire rope.
An improved LS-DYNA model of 19-mm diameter 3x7 wire rope commonly used in roadside cable guardrail installations has been developed. A Belytschko-Schwer beam element was selected along with material *MAT_166. Since wire rope displays internal damping due to friction of strands and wires, low-frequency bending modes of wire rope were damped in the model using the LS-DYNA frequency range command, and high-frequency noise was reducing using the part stiffness damping. The optimum element length based on timestep, accuracy, and computational cost was determined to be between 0.4 and 0.8 in. (10-20 mm).
Dynamic component tests were conducted on wire rope to determine material properties, and consisted of high-speed jerk tests of wire rope constrained at one end, and perpendicular impact of wire ropes constrained at both ends. These tests were simulated and the results compared to the physical tests. The new proposed wire rope model more accurately simulated the wire rope tension and bogie vehicle motion than previously-developed wire rope models.
The wire rope was also modeled in full-scale crash test models using a Chevrolet C2500 pickup model, consistent with NCHRP Report No. 350 TL-3 impact conditions. Results of the crash test and simulation were compared, the wire rope response was determined to be accurate, though the wire ropes released from the hook bolts prematurely. Nonetheless, wire rope response, vehicle motion and trajectory were accurate. Therefore the new wire rope model was determined to be an improvement over existing models of wire rope and is recommended for use in cable guardrail simulations.
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