System for Dragline Rope Condition Monitoring

As a successor to the encouraging results of an earlier project (C13039), the purpose of this project was to confirm and formalise the possibility of producing and measuring vibrations in large wire ropes in order to form an assessment of the condition of the wires within that rope, near its socket. The earlier project indicated that vibrations generated in the rope by striking it, exhibited differing signatures in broken and unbroken wires. This project aimed to develop a repeatable and reliable method of generating and measuring that vibration, such that the vibration signatures could be collected and analysed to search for robust indications of rope condition.

Considerable research led us to develop a vibration generation method that relied on a magnetostrictive transducer. After conducting some full scale experiments, we confirmed that the transducer was capable of generating reliable vibration pulses sufficiently powerful to travel the necessary distance along the rope and through the socket, for  detection within the socket. The experiments also revealed some design  was in other parts of the system, which we overcame in subsequent experiments. In the end, we created a system that was able to produce clear, repeatable and individual vibration signatures from the wires within the rope. We manually introduced artificial degradation to the rope to simulate service defects, and collected a great deal of data for later analysis.

Despite many promising indications, the thorough analysis procedure failed to uncover a universally applicable indication of individual wire condition within the data. There were indications that the defect features within the rope did indeed influence the data, but this did not lead to the formulation of a method for absolutely determining the condition of the rope from the data. While we remain confident that the data collected is a sound representation of vibration energy travelling through the rope and being influenced by the rope's internal environment, we are now also confident that the complex nature of the vibration propagation involved makes individual wire condition assessment fundamentally unreliable.