This course is about why, how and when failures occur. In this course the physical mechanisms leading to failure of components or systems will be treated and applied. In the first part of the course, the principles of mechanisms like fatigue, wear and lubrication, corrosion and electrical failures will be explained. Moreover, quantitative methods to assess the time to failure at a specific loading will be discussed. In the second part of the course, the basic knowledge will be applied to analyze failures of real components and systems, like bearings, gear sets or gas turbines. Also the development of predictive maintenance strategies will be discussed, as well as the application in design processes.