Comparison of white metal and resin socket terminations for wire ropes

Abstract

Previously the authors have presented both theoretical and experimental work discussing the operating mechanism of a wire rope held in a tapered socket by means of a cast resin cone. The work reported here extends the investigation to address the question of whether the same socket fabricated with white metal operates in the same manner. To date, previous investigations have compared the operational efficiency of resin and white metal in terms of both strength and/or fatigue endurance. Some other work has analysed the operation of resin sockets or specific cast metal terminations. This paper seeks to draw the results from this work together, and, in addition to a theoretical analysis, presents experimental data obtained from a direct comparison of the operation mechanism for the same sockets filled with resin or white metal. Results show that white metal terminations have a very different distribution of stresses along the length of the socket basket from resin terminations, and a smaller but still significant amount of socket draw. For both types of termination the socket draw develops high frictional gripping forces which can transfer the load from the rope to the socket. The different stress distributions mean that the consequences of termination fabrication defects may not be the same for resin and white metal terminations.

Mechanism of bonding between Zn–Al-coated wires and Zn–Cu alloy casting medium in hot casting socket terminations for large bridge cables

“…3, the test results were significantly scattered and without a general trend. Similar results were obtained for small ropes by Brandon and Ridge [2] who considered different wires and different casting mediums. This may primarily be attributed to the wires not being fully embedded in the casting medium due to poor casting, although the apparent embedded lengths were determined to sufficiently withstand the breaking force of the wire.…”

“…However, almost all the CA7 specimens could withstand the ultimate tensile force owing to the simple addition of the small cavity angle to the casting medium. This indicates that another bonding mechanism, the so-called wedging effect [1,2,18] produced by friction between the surface of the wire and the conical casting medium, significantly increased the bonding resistance of the socket terminations. The casting temperatures of the Zn-Cu alloy in the CT510 and CT560 specimens were 510°C and 560°C, respectively, which were higher than that of the BAS specimens (460°C).…”

“…The bonding strength of the embedded wire and the casting medium is considered to range between 21 and 28 MPa [8]. However, as noted by Brandon and Ridge [2] and the Japanese Standard Association [8], it is difficult to achieve consistency in the conditions of the embedment of the wires in the casting medium, and the conditions are also affected by very complex load transfer mechanisms, which include chemical adhesion and mechanical friction. Hence, the required bonding strength used for the design purpose is reduced to 8 MPa, which is obtained by considering a safety factor of 2.5 [8].…”