Tycho Braams - Degradation of physical systems

author:Tycho Braams
title:Degradation of physical systems
keywords:Fault trees, reliability modeling
topics:Dependability, security and performance
supervisor(s):E.J.J. Ruijters MSc
dr. M.I.A. Stoelinga

Bachelor project


RAMS (Reliability, Availability, Maintenance, Safety) requirements are of utmost importance for safety-critical systems like self-driving cars, drones, and railroad infrastructure. All these systems wear out over time, and require maintenance to keep them in proper condition and ensure their reliability.

A widely used standard for RAMS analysis is fault tree analysis (FTA), which we have extended to include maintenance through fault maintenance trees (FMTs). One challenge in this method is that degradation over time of components must be modelled, while many traditional approaches only distinguish whether a components is 'failed' or 'not failed'. Our current method describes components in several distinct stages of degradation (e.g. 'Good', 'Degraded', 'Almost failed', and 'Failed'), which is clearly not how physical components behave.

In this project you will extend fault trees or fault maintenance trees with a model of degrading components that can describe their physical condition more accurately. For example, wear on a railroad track can be mostly described by how many millimetres of steel have been worn from its surface.

Your tasks will include:

  • Study the degradation of physical systems to determine how to mathematically characterize this.
  • Model this characterization as part of a fault (maintenance) tree.
  • Compare the behaviour of this model against existing models.


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