Showing papers on "Preventive maintenance published in 1976"
47 citations
TL;DR: In this article, the optimum preventive maintenance of systems, if two kinds of system failures are to arise, is investigated, and special cases of the investigated model are the age replacement policy and the minimal repair policy.
Abstract: The paper deals with the optimum preventive maintenance of systems, if two kinds of system failures mag arise. Special cases of the investigated model are the age replacement policy and the minimal repair policy.
35 citations
TL;DR: In this paper, a decision model, valid for all types of life to failure distribution is given and demonstrated by a graph for the Weibull distribution, and an easily calculated approximate optimal maintenance schedule is derived and shown to be within predictable limits of the true optima.
Abstract: The usual criterion of choice between preventive and contingency maintenance, availability, is restrictive in the sense that improvement is, even in ideal circumstances, at most of the order of 10%. Economic criteria are shown to obtain optima at values that do not maximize availability but show better percentage increases in net revenue rate or percentage decreases in maintenance cost. A decision model, valid for all types of life to failure distribution is given and demonstrated by a graph for the Weibull distribution. Finally, if life to failure has the Weibull distribution an easily calculated approximate optimal maintenance schedule is derived and shown to be within predictable limits of the true optima.
30 citations
Journal Article•
TL;DR: In this paper, a two-unit standby redundant system is reviewed under the assumption that all distributions are arbitrary, the first-passage time distributions, the transition probabilities, and the expected number of visits to a certain state are derived.
Abstract: Optimum preventive maintenance policies for a two-unit standby redundant system are reviewed. Under the assumptions that all distributions are arbitrary, the first-passage time distributions, the transition probabilities, and the expected numbers of visits to a certain state are derived. Using the probabilistic quantities above, we discuss the optimum preventive maintenance policies maximizing or minimizing some criteria. We show that under suitable conditions there exist the optimum preventive maintenance policies which are given by the unique solutions of the equations. This paper concludes with numerical examples of such optimum preventive maintenance policies.
18 citations
01 Oct 1976
TL;DR: In this article, a two-unit standby redundant system is reviewed under the assumption that all distributions are arbitrary, the first-passage time distributions, the transition probabilities, and the expected number of visits to a certain state are derived.
Abstract: Optimum preventive maintenance policies for a two-unit standby redundant system are reviewed. Under the assumptions that all distributions are arbitrary, the first-passage time distributions, the transition probabilities, and the expected numbers of visits to a certain state are derived. Using the probabilistic quantities above, we discuss the optimum preventive maintenance policies maximizing or minimizing some criteria. We show that under suitable conditions there exist the optimum preventive maintenance policies which are given by the unique solutions of the equations. This paper concludes with numerical examples of such optimum preventive maintenance policies.
17 citations
TL;DR: In this article, three models for a 2-unit standby system with and without preventive maintenance (PM) to standby unit are presented, and an income structure has been superimposed on the semi-Markov processes generated by the systems to obtain s-expected profit.
Abstract: Three models are presented for a 2-unit standby system, Models 1 and 2 deal with a 2-unit warm-standby system with and without preventive maintenance (pm) to standby unit Model 3 is a 2-unit cold-standby system with pm to operative unit An income structure has been superimposed on the semi-Markov processes generated by the systems to obtain s-expected profit For models 2 and 3, s-expected profit is suggested as the measure of maintenance effectiveness Numerical examples are included to illustrate the results
17 citations
TL;DR: Two reliability models for a 2-unit cold-standby intermittently available system, whose units are subject to repair and preventive maintenance, have been studied in this paper, where the Laplace Transform of the pdf of ''disappointment time'' and in Model II, the LTA of ''interference time'' are derived.
Abstract: Two reliability models for a 2-unit cold-standby intermittently available system, whose units are subject to repair and preventive maintenance, have been studied. In Model I, the Laplace Transform of the pdf of `Disappointment time' and in Model II, the Laplace Transform of the `Interference time' are derived. Disappointment time and the interference time definitions include the demand pattern.
10 citations
TL;DR: In this paper, the authors considered a 1-unit repairable system which operates at discrete times, and discussed optimum preventive maintenance policies which minimize the s-expected cost, after introducing costs.
Abstract: This tutorial paper considers a 1-unit repairable system which operates at discrete times. Some appropriate results for the system are rewritten as discrete time processes. After introducing costs this paper discusses optimum preventive maintenance policies which minimize the s-expected cost.
6 citations
TL;DR: In this paper, the authors present a model of the feedback processes and communication required to control a maintenance system and present a comprehensive costing system is necessary to direct effort to those areas offering the greatest potential benefit.
Abstract: The objective of an industrial maintenance system is to minimise the ‘total’ costs of both production downtime and direct maintenance expenditure. The paper presents a model of the feedback processes and communication required to control a maintenance system. A comprehensive costing system is necessary to direct effort to those areas offering the greatest potential benefit. The extensive variety of equipment and the irregular occurrence of breakdown makes statistical analysis of problem areas both lengthy and expensive. Maintenance policy can be improved either in the form of changes to the effectiveness of the maintenance effort by adoption and subsequent control of a preventive maintenance scheme, or by establishment of procedures to enable the maintenance work load to be completed efficiently and hence improve productivity.
4 citations
Abstract: Optimal preventive maintenance and repairmen policies for a system of machines subject to degradation with age and intermittent breakdowns and repairs are derived using optimal control theory. When this system of machines forms part of a dynamic process control system, a method of obtaining optimal closed-loop control law is indicated.
4 citations
TL;DR: In this article, the problem of determing the optimal set of states at which the unit is replaced with a new one (marginal set) is discussed by using Markov-renewal programming with modified policy iteration cycle.
Abstract: Marginal checking of a Markovian degradation unit is treated when time interval to the next checking is not fixed but obeys a certain general distri bution. The problem of determing the optimal set of the states at which the unit is replaced with a new one (marginal set) is discussed. It is solved by using Markov-renewal programming with modified policy iteration cycle. It is showed that control limit rule holds for the optimal policy. The expected cost associated with preventive maintenance and corrective maintenance when the unit is operated in an infinite time span (cost rate) is derived. The unimodality of the cost rate with respect to the control limit is discussed, and a necessary and sufficient condition for preventive replacement to be effective is given.
01 May 1976
TL;DR: Vibrational analysis can accurately identify such operating problems as permanent and temporary unbalance, impacting, bearing and spindle instability, partial-admission bearing reaction, and double moment of inertia as mentioned in this paper.
Abstract: Vibrational analysis is sufficiently advanced to provide accurate data for planning preventive maintenance programs to improve unit reliability and availability. Vibration analyses can accurately identify such operating problems as permanent and temporary unbalance, impacting, bearing and spindle instability, partial-admission bearing reaction, and double moment of inertia. Details are given on how vibration analysis is applied and on the instruments that are used to gather the necessary data. (MCW)
TL;DR: In this paper, the relationship between dependability, downtime for preventive maintenance, proportion of failures repairable at sea, and equipment failure rate is discussed using a simple diesel generator arrangement as an example.
Abstract: Preventive maintenance and repair during a mission have an important effect on the dependability of ships' systems. Space and weight limitations mean that not all repairs can be carried out during the mission and this limits the dependability which can be achieved. Using a simple diesel generator arrangement as an example, this paper discusses the relationships between dependability, downtime for preventive maintenance, proportion of failures repairable at sea, and equipment failure rate.
01 Sep 1976
TL;DR: In this paper, a consolidated corrosion control facility would seem to offer dollar savings in the form of reduced man-hours required to perform corrosion control and prevention maintenance on vehicles and aerospace ground equipment maintained by a Transportation Squadron Vehicle Maintenance Branch, a Field Maintenance Squadron Aerospace Ground Equipment Branch, and an Organizational Maintenance Squadron Non-Powered Aerospace ground equipment Section on an 'average' Air Force base.
Abstract: : Results of this research were inconclusive. A consolidated corrosion control facility would seem to offer dollar savings in the form of reduced man-hours required to perform corrosion control and prevention maintenance on vehicles and aerospace ground equipment maintained by a Transportation Squadron Vehicle Maintenance Branch, a Field Maintenance Squadron Aerospace Ground Equipment Branch, and an Organizational Maintenance Squadron Non-Powered Aerospace Ground Equipment Section on an 'average' Air Force base. Imperfections in the data and the number of assumptions found necessary, however, make any such finding tenuous at best. Additional study is clearly indicated.
TL;DR: In this paper, the Laplace transform has been used to characterize the probability of a system being in the up or down state of a regenerative stochastic process, and these equations have been solved by employing the LTA technique.
Abstract: p.d.f.'s of the times to failure of the units are assumed to be arbitrary while the rates of preventive maintenance and repair are constants. Initially, one unit is switched on and the remaining (n 1) units are kept as cold standbys. The system breaks down when the last standby fails but it starts functioning again as soon as a unit is made available for operation. It is assumed that the time at which a unit is taken up for preventive maintenance is arbitrarily distributed. In this paper, the system has been characterised by the probability of its being in the up or the down state. Integral equations for these probabilities have been set up by identifying suitable regenerative stochastic processes and these equations have been solved by employing the Laplace transform technique. Explicit expressions for the Laplace transform of the mean down-time of the system during (0, t) and for the mean time to system failure have been obtained. The cases when n = 2 and n = 3 have been discussed.