


Politecnico di Torino  
Academic Year 2017/18  
01QYTMN, 01QYTJM, 01QYTLI, 01QYTLM, 01QYTLN, 01QYTLP, 01QYTLS, 01QYTLX, 01QYTLZ, 01QYTMA, 01QYTMB, 01QYTMC, 01QYTMH, 01QYTMK, 01QYTMO, 01QYTMQ, 01QYTNX, 01QYTOA, 01QYTOD, 01QYTPC, 01QYTPI, 01QYTPL Reliability, safety and maintenance 

1st degree and Bachelorlevel of the Bologna process in Mechanical Engineering  Torino 1st degree and Bachelorlevel of the Bologna process in Automotive Engineering  Torino Espandi... 





Subject fundamentals
Reliability and maintenance are issues that meet the need, more than ever, to reduce the risks associated with possible failures of products and processes, improving the quality perceived. Understanding models of reliability, maintenance strategies and the ability to apply these methods to the products/processes can reduce the number of failures, ensure an adequate level of safety, increase the operating time between successive failures and minimize maintenance costs, the main goals of the issues addressed.
This course develops the two issues in order to articulate appropriately them with the aim of transferring to the students the knowledge on reliability and maintenance of components and systems and the appropriate skills for their practical implementation to products and processes. 
Expected learning outcomes
To the student will be transmitted the skills of an analyst of reliability and maintenance, able to calculate the reliability of components/systems, both nonrepairable that repairable, and to define the implementation of the more appropriate maintenance strategy in terms of timing, control parameters and related costs.
In the part relating to reliability, where is developed the study of failure and repair processes both of production lines and its subsystems but also of general products, will be given tools to evaluate the component/system reliability and techniques to improve the socomputed reliability both by analytical methods and engineering techniques such as the Failure Mode Effects and Criticality Analysis (FMECA) and the Fault Tree Analysis (FTA). The study of the repair process will also provide the capability to evaluate the machine down time and the component/system availability at a given instant of time. In the part relating to maintenance, where it is developed the study of the different maintenance strategies (by fault, preventive, inspective) or what actions are necessary to prevent the failure or to solve it when it is present, will be given tools to evaluate their cost functions that are based on the component/system reliability variables under investigation. Skills for the correct choice of the optimal maintenance strategy in the light of application methods based on the evaluation of standard parameters, safety, technical and economic criteria will be provided. The systemic aspect of the productive maintenance and its evolution in the Total Productive Maintenance (TPM) will be finally presented. 
Prerequisites / Assumed knowledge
It is advisable to have learned and assimilated knowledge and basic methods of mathematical analysis, statistics and fundamentals of structural mechanics but it is not required to have passed the exams of these courses. Useful is also knowledge of machine applied mechanics and science, technology of materials/technology of metallic materials for engineering and computer science.

Contents
Failure process: Time To Failure, reliability and failure probability, density of failure probability, reliability of interval, Mean Time To Failure, failure rate, general integral law between reliability variables.
Mathematical reliability models: exponential model, Weibull model, Gaussian model. Nonrepairable systems: series, parallel with independent failures, standby (cold and hot, ideal and real), general model with 3operating states. Repair process: Time To Repair, maintainability, density of repair probability, Mean Time To Repair, repair rate. Repairable systems: states of the system and graph of the states, random variables and related distributions, Fundamental System of integral equations of reliability and its solution, Up Time and Down Time, Mean Time To kth Failure, Mean Time Between (k1)th e kth failures, reliability extended variables, average number of expected failures, instantaneous intensity of failures, availability associated to the upstates of the system, availability and unavailability of renewable components/systems. Engineering methods for complex system analysis: Failure Mode Effects and Criticality Analysis (FMECA), determination of the Risk Priority Number (coefficient of risk priorities, RPN), criticality matrix, Fault Tree Analysis (FTA), reduction to the equivalent fault tree (qualitative analysis) and subsequent evaluation of reliability variables of interest (quantitative analysis). Design Of Experiments (DOE) plan on two factors: concept of interaction, statistical model, analysis of variance (ANOVA) with two factors. Factorial Plan on two levels and two factors: Yates notation for indicating combinations of treatments. Calculation of main effects and interaction: graphical approach and scores table. Fractional factorial plane. The Taguchi method: introduction and general information. Maintenance introduction: origins and definitions, activities and professional figures involved, maintenance organization charts, maintenance role. Maintenance strategies: classification of maintenance types, failure maintenance, preventive maintenance, inspective maintenance, cost functions and optimal time cadence of interventions, methodologies for the selection of the maintenance strategy, productive maintenance and its evolution in the Total Productive Maintenance. 
Delivery modes
The course includes 40 hours of lecture and 20 hours of practice and case studies that consist in exercises and practical problems analysed and solved in application of the concepts covered in the lectures. Aim of the practices is to improve understanding of theory and to provide students with the order of magnitude of the main parameters; to this end, students are advised to prepare short reports on the analysed case studies.

Texts, readings, handouts and other learning resources
On the Course website the lectures handouts as well as texts, datasheets and didactic materials for exercises are available.
Recommended other learning readings for more details are:  G. Belingardi, Strumenti statistici per la meccanica sperimentale e l’affidabilità, Levrotto & Bella  S. Beretta, Affidabilità delle costruzioni meccaniche, Springer, ISBN: 9788847010789  Berger P.D., Maurer R.E., Experimental design with applications in management, engineering and the sciences, ISBN: 0534358225  R. Manzini, A. Regattieri, Manutenzione dei Sistemi di Produzione, Esculapio, Bologna  L. Furlanetto, Manuale di Manutenzione degli Impianti Industriali e Servizi, Franco Angeli, Milano  V. D’Incognito, Progettare il Sistema Manutenzione, Franco Angeli, Milano 
Assessment and grading criteria
The exam consists of a written examination both on exercises and theory questions; the theoretical questions are answered in an "openended form" (not as quiz answers). Please note that the written examination shall cover all the lecture and practice topics of the current academic year.
The written test is composed of one practical problem and two questions related to the theory. During the written test is not possible to consult notes or other didactic material; for the exercise part students can consult notes or other didactic material. The written test duration is 2 hours. The written test is passed with a minimum mark of 18/30. The definition of the final mark of the exam, with maximum mark 30L, is subjected to the student vision of the corrected tests on the date scheduled for each examination session. 
