Reliability evaluation based on a dependent two-stage failure process with competing failures

Function dependence takes place in systems where the malfunction of certain trigger component(s) causes other system components (referred to as dependent components) to become unusable or inaccessible. Systems undergoing function dependence often exhibit diverse statuses due to competitions in the time domain between propagated failure from a dependent component and local failure of the corresponding trigger component. If the former wins (ie, occurring first), a failure propagation effect is induced, crashing the entire system. If the latter wins, a failure isolation effect may be induced quarantining the damage from the propagated failure (the isolation effect can occur in a deterministic or probabilistic manner depending on applications). Existing models addressing such competitions have restrictive assumptions such as uncorrelated competitions from multiple function dependence groups, zero or negligible failure propagation time, and deterministic failure isolation effect. This paper advances the state of the art by proposing a combinatorial reliability model for systems undergoing correlated, probabilistic competitions and random failure propagation time for dependent components. A case study of a wireless body area network system for patient monitoring is performed to illustrate the proposed methodology and effects of different model parameters on the system reliability.

Section: Step 5: Integrate For Final System Unreliabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reliability modeling of correlated competitions and dependent components with random failure propagation time

Xing

Zhao

Wang

et al. 2020

“…More precisely, once an external shock occurs, the hazard rate of the hard failure has a random jump. This is known as shot‐noise process, (see, eg, Lemoine and Wenocur and Cha), which is observed in many systems such as electronic actuators or load sharing systems. Here, we denote by Y i the hazard rate increment caused by the i th, ( i = 1, 2, …) shock.…”

Section: Problem Statementmentioning

confidence: 99%

Preventive maintenance policy of single‐unit systems based on shot‐noise process

Qiu

Cui

Dong

2018

Self Cite

This paper develops reliability and maintenance models for a single‐unit system subject to hard failures under random environment of external shocks. Motivated by the observations of shot‐noise process in practice, the impact of shock damage on system failure behavior is characterized by random hazard rate increments. To remove such negative impact, imperfect preventive repair is performed periodically, and preventive replacement is performed after several repairs. Considering the joint effects of both random shocks and imperfect repair on the system hazard rate, we derive recursive equations for the system reliability function. Furthermore, we investigate the optimal maintenance policy that minimizes the expected cost per unit time of the system. The applicability of the reliability and maintenance model is validated by a case study on a wind turbine system.

“…The durations of normal and defective states are, respectively, denoted by random variables X and Y with corresponding baseline hazard rate functions λ X ( t ) and λ Y ( t ). Based on the definition of shot‐noise process, eg, Cha and Mi, Levitin and Finkelstein, and Qiu and Cui, the random hazard rate of X in the presence of external shocks, h X ( t ), is expressed as

h_{X} ((), t) = λ_{X} ((), t) + \sum_{i = 1}^{N ((),, 0, t)} U_{i}

where U i , i = 1, 2, … are the hazard rate increments due to the i th external shock in normal state which are independent and identically distributed, and N ( s , t ) is the number of shocks occurring in time interval ( s , t ).…”

Section: Problem Descriptionmentioning

confidence: 99%

“…The durations of normal and defective states are, respectively, denoted by random variables X and Y with corresponding baseline hazard rate functions λ X (t) and λ Y (t). Based on the definition of shot-noise process, eg, Cha and Mi, Levitin and Finkelstein, and Qiu and Cui, 17,19,38 the random hazard rate of X in the presence of external shocks, h X (t), is expressed as…”

Section: System Failure Behaviormentioning

confidence: 99%

Reliability evaluation and opportunistic maintenance policy based on a novel delay time model

Zhang

2018

The delay time concept is widely adopted in literature to model the two‐stage failure process of most industrial systems which can be divided into normal stage (from new to an initial point of a defect) and defective stage (from defect arrival point to failure). Most existing delay time models assume that the normal and defective stages are independent. A generalized delay time model is proposed in this paper by considering the dependence between the normal and defective stages which is reflected in the fact that they share the same external shock process. According to the definition of shot‐noise process, external shocks will incur random hazard rate increments in the two stages. The failure state is self‐announcing, whereas the defective state can only be detected by block‐based inspection or opportunistic inspection offered by unexpected shutdown due to unavoidable external factors. The system is correctively replaced upon the occurrence of a system failure or preventively replaced at the detection of a defective state. Based on the stochastic failure model and maintenance policy, this paper evaluates system reliability performance and average long‐run cost rate via a Markov‐chain based approach. Finally, a case study on a steel convertor plant is given to demonstrate the applicability of the proposed model.