Prediction of fatigue fractures diffusion on the cableway haul rope

• Determination of residual life by prediction of break development on the rope
• Development of the fractures was in progress under the bathtub fatigue curve.
• The increase in the number of breaks has an exponential course.
• Increasing the life of the cableway rope by 117% by means of break development prediction
• The plausibility indicator MAPE does not exceed 10%; it indicates a successful prediction.

Monitoring of the rope condition and lengthening its lifetime - it is a requirement of each user. The operator can get information about the current condition of the rope by using the method of non-destructive rope testing (NDT). Parameters (information) gained from non-destructive testing, such as the number and distribution of the fractures, the rope diameter and the winding height, determinate the further operation of the rope. However, it is possible to observe the trends in monitored parameters, if the NDT inspections are performed regularly. We made an attempt to employ these trends to create the prediction model of monitored parameters changes development and to determine a rope lifetime as well. The rope of the aerial cableway is a subject of monitoring. During the regular checks the condition of the rope was evaluated as well as monitoring of the trend in the ruptures increase was carried out. It was found that the rope was showing practically the regular growth of fractures from the particular period of the operation. The course of the trend was generated gradually; its shape was quite a lot resembled to the bathtub curve known from the maintenance practise. The arm of this general curve is having exponential course. This assumption created the base of the model of monitoring the fractures development in subsequent periods. Besides the record of the course of the fracture growth the prediction of development for the next two years was created after every new NDT measurement. The gradual comparison of real fracture growth development with the prediction supported (confirmed) the prognosis of the exponential course; it enabled setting in advance the date of the rope deployment. The regular NDT checks of the rope and creating the fracture growth development prognosis was very important because of the rope utilization in terms of the safe operation of the cableway. The operator in the past to track cableway regularly coordinated its six years of operation. In the past the rope operating on the monitored cableway was regularly changed after six years or working by the operator. The gradual establishment of the prognosis model based on the regular NDT inspections prolonged the safe operation of the monitored rope up to 13 years.

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