A maintenance strategy for systems subject to competing failure modes due to multiple internal defects and external shocks

2011 ◽  
pp. 770-775
Author(s):  
I Castro
Keyword(s):  
Failure Modes ◽  
Maintenance Strategy ◽  
External Shocks ◽  
Internal Defects

AN AGE-BASED MAINTENANCE STRATEGY FOR A DEGRADATION-THRESHOLD-SHOCK-MODEL FOR A SYSTEM SUBJECTED TO MULTIPLE DEFECTS

2013 ◽  
Vol 30 (05) ◽  
pp. 1350016 ◽  
Author(s):  
I. T. CASTRO
Keyword(s):  
Poisson Process ◽  
Shock Model ◽  
Maintenance Strategy ◽  
External Shocks ◽  
Internal Defects ◽  
Expected Cost ◽  
Numerical Examples ◽  
Cost Rate ◽  
Gamma Processes ◽  
Theoretical Results

A system subject to internal defects and external shocks is analyzed in this paper. Internal defects initiate following a nonhomogeneous Poisson process (NHPP) and they grow according to deterioration processes modeled as gamma processes. A corrective replacement is performed when the deterioration of a defect exceeds a failure threshold. The system is subject to external shocks. After an external shock, the system is replaced with probability 1 – p and is minimally repaired with probability p. The system is preventively replaced at the age of T. Costs are associated with the maintenance actions. The value of T that minimizes the expected cost rate is obtained analytically. Numerical examples are showed to illustrate the theoretical results.

scholarly journals Risk-Cost Optimized Maintenance Strategy for Steel Bridge Subjected to Deterioration

2021 ◽  
Vol 14 (1) ◽  
pp. 436
Author(s):  
Le Li ◽  
Mojtaba Mahmoodian ◽  
Alireza Khaloo ◽  
Zhiyan Sun
Keyword(s):  
Failure Modes ◽  
Cost Optimization ◽  
Steel Structures ◽  
Steel Bridge ◽  
Maintenance Strategy ◽  
Total Risk ◽  
Chloride Attack ◽  
Risk Cost ◽  
Structural Engineers ◽  
Asset Managers

This paper aims to develop a deteriorated bridge maintenance strategy that ensures the safe operation of steel structures and minimizes the total risk. Five common failure modes are considered for the deteriorated bridge: flexure, shear, deflection, fatigue failure for girder, and chloride attack for the concrete deck. Time-dependent and system reliability analyses are carried out to find the probability of failure under these failure modes. Risk-cost optimization is then used to determine the maintenance strategy. This method was applied to a working example. It was found that the developed maintenance strategy can predict when, where, and what to maintain for a bridge to ensure its safe and serviceable operation during its lifespan. The proposed methodology can help structural engineers and asset managers repair and maintain bridges under deterioration.

scholarly journals Maintenance strategy selection for multi-component systems using a combined analytic network process and cost-risk criticality model

2019 ◽  
Vol 233 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Mahmood Shafiee ◽  
Ashraf Labib ◽  
Jhareswar Maiti ◽  
Andrew Starr
Keyword(s):  
Process Model ◽  
Failure Modes ◽  
Analytic Network Process ◽  
Design Stage ◽  
Maintenance Strategy ◽  
Analysis Model ◽  
Component Systems ◽  
Network Process ◽  
Criticality Analysis ◽  
Cost Risk

Selection of an appropriate maintenance strategy for multi-component systems is a very complex task due to diversity of components and their different failure modes, existence of various dependencies among components and a large number of competing criteria that need to be taken into consideration. This study presents a combined analytic network process and cost-risk criticality analysis model to select a cost-effective, low-risk maintenance strategy for different sets of components of a complex system. The proposed model consists of four maintenance alternatives (i.e. failure-based, time-based, risk-based and condition-based), among which the most appropriate strategy, on the basis of two criteria of maintenance implementation costs and failure criticality, is to be chosen. The former criterion includes the annual maintenance expenditure required for hardware, software and personnel training, while the latter criterion focuses on the capability of maintenance in reducing the failure vulnerability and enhancing the reliability and resilience. The possible dependencies among selection criteria as well as the failure interactions between components are taken into account to evaluate the maintenance alternatives. Finally, the model is applied to determine a suitable maintenance strategy for a new wind turbine configuration consisting of several mechanical, electrical and auxiliary components at the design stage. The results are compared with practices of maintenance over the first year of system operation as well as with the results obtained from an analytic hierarchy process model.

scholarly journals Reliability-Based Preventive Maintenance Strategy of Truck Unloading Systems

2020 ◽  
Vol 10 (19) ◽  
pp. 6957
Author(s):  
Awsan Mohammed ◽  
Ahmed Ghaithan ◽  
Mashel Al-Saleh ◽  
Khalaf Al-Ofi
Keyword(s):  
System Reliability ◽  
Preventive Maintenance ◽  
Failure Modes ◽  
Reliability Function ◽  
Petroleum Products ◽  
Maintenance Strategy ◽  
Mean Time Between Failures ◽  
Time Period ◽  
Critical Components ◽  
One Year

The unloading of petroleum products is a complex and potentially dangerous operation since the unloading system contains complex interdependency components. Any failures in one of its components lead to a cut in the petroleum supply chain. Therefore, it is important to assess and evaluate the reliability of the unloading system in order to improve its availability. In this context, this paper presents the operation philosophy of the truck unloading system, failure modes of the components within the system, and a bottom-up approach to analyze the reliability of the system. In addition, it provides reliability data, such as failure rates, and mean time between failures of the system components. Furthermore, the reliability of the whole system was calculated and is presented for different time periods. The critical components, which are major contributors towards the system reliability, were identified. To enhance the system reliability, a reliability-based preventive maintenance strategy for the critical components was implemented. In addition, the preventive maintenance scheduling was identified based on the reliability plots of the unloading system. The best schedule for preventive maintenance of the system was determined based on the reliability function to be every 45 days for maintaining the system reliability above 0.9. Findings reveal that the reliability of the unloading system was significantly improved. For instance, the system reliability at one year improved by 80%, and this ratio increased dramatically as the time period increased.

scholarly journals Influence of internal imperfections on the fatigue resistance of cast steel – testing methodology

2019 ◽  
Vol 300 ◽  
pp. 09001
Author(s):  
Sven Nagel ◽  
Christof Rauber ◽  
Ines Veile ◽  
Peter Knödel ◽  
Thomas Ummenhofer
Keyword(s):  
Fatigue Resistance ◽  
Failure Modes ◽  
Cast Steel ◽  
Internal Defects ◽  
Destructive Testing ◽  
Tensile Fatigue ◽  
Damage Process ◽  
Individual Specimen ◽  
Stress States ◽  
Propagation Properties

Tensile fatigue specimen of G20Mn5 and G22NiMoCr5-6 were tested to quantify the influence of internal defects on the fatigue resistance of cast steel components. Defects with varying sizes, geometric shapes and distribution were enforced by influencing the solidification and recorded by computer tomography (CT). Besides the characteristics of the detected cavities, the surrounding fungoid microstructure is classified and evaluated. Later the specimens were tested under cyclic tension and S/N-curves are derived. These data form the basis for extensive numerical simulations of the damage process and the crack growth of every individual specimen. Both processes are affected by the local multiaxial stress states and have their origin in the inside of the specimen. For validation, knowledge of the crack initiation time and propagation properties are essential. Therefore, all specimens respectively the properties of the internal defects are monitored during testing with three different state-of-the-art non-destructive testing (NDT) methods. Background and application of these NDT techniques are described within this paper. Finally, fracture surface analyses show different failure modes and provide further information for model validation.

scholarly journals Optimal maintenance strategy for systems with two failure modes

2019 ◽  
Vol 188 ◽  
pp. 624-632 ◽  
Author(s):  
Rui Peng ◽  
Bin Liu ◽  
Qingqing Zhai ◽  
Wenbin Wang
Keyword(s):  
Failure Modes ◽  
Maintenance Strategy ◽  
Optimal Maintenance

Reliability analysis for systems subject to mutually dependent degradation and shock processes

2021 ◽  
pp. 1748006X2110114
Author(s):  
Lina Bian ◽  
Guanjun Wang ◽  
Fengjun Duan
Keyword(s):  
Failure Modes ◽  
Failure Process ◽  
Analytical Techniques ◽  
Reliability Function ◽  
External Shocks ◽  
Reliability Indices ◽  
Soft Failure ◽  
Proposed Model ◽  
Mean Lifetime ◽  
Hard Failure

This paper studies the reliability problem for systems subject to two types of dependent competing failure processes, that is, soft failure and hard failure processes. A soft failure happens when the total degradation of the system exceeds a given critical level, while a hard failure occurs when the accumulative shock load caused by shocks surpasses the hard failure threshold. These two failure processes are mutually dependent due to the fact that external shocks will bring sudden increments in the degradation of the system, and the total amount of degradation will decrease the hard failure threshold of the system. The system fails whenever either of these two failure modes happens. Assuming that the arrival of shocks follows a Poisson process, the reliability function of the system under cumulative shock model is derived by using some analytical techniques. Some important reliability indices, including the mean lifetime of the system, the expected number of shocks until system failure, the probabilities of soft and hard failures, are calculated explicitly. Moreover, a special case that the hard failure process and soft failure process are mutually independent is also discussed. Monte Carlo method is employed to calculate the multiple integrals existing in the expressions of reliability function and reliability indices. A numerical example of the Reinforced Concrete pier columns on sea bridge is presented to illustrate the proposed model.

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