CONDITION BASED MAINTENANCE: IMPROVING THE RAMS PERFORMANCE OF MOVABLE BRIDGES
Lambert Forkink - Witteveen + Bos (June 2022)
SUMMARY
The increasing average age of movable bridges in the Netherlands, in combination with heavier traffic loads, and higher availability demands from society, provides a maintenance challenge for bridge owners. Condition based maintenance can improve the allocation of funds and maintenance capacity to where it is best used. Based on literature, prerequisites for the implementation of condition based maintenance are elaborated. A framework of measurement options is presented, which provides various strategies to extract information from the system. A FMECA, among other requirements, is used to select the hydraulic cylinder for further research. The maintenance interval of the hydraulic cylinder is generally governed by the wear of the rod seal.
A condition based maintenance implementation is presented on the basis of a case study. The case study considers the rod seal wear of the Nauernasche Brug. The wear process is modelled by Archard’s law, which requires a wear coefficient, a normal force, and a sliding distance, and gives a worn volume. The wear coefficient is established from literature. The normal force follows from a mechanical model of the seal, while sliding distance is based on use data. The model is validated by the worn volume measurements of the seal. The seal wear progression can be considered a linear process in movable bridge operation. Further investigation in the primary variables of the degradation model identify the wear coefficient and use data as primary areas for improvement. The sliding speed of the seal in movable bridge operations is an order of magnitude lower than typical sliding speeds used in wear testing. leading to a significantly lower wear coefficient in movable bridges. Improving the quality, quantity, and accessibility of use data increases the predictive power of wear modelling, and thus the usability of the model to improve the availability and maintainability performance of a movable bridge.