Condition Monitoring Devices Research Articles

Prognostics Health Monitoring (PHM) for Prior Damage Assessment in Electronics Equipment Under Thermo-Mechanical Loads

Methodologies for prognostication and health monitoring (HM) can significantly impact electronic reliability for applications in which even minimal risk of failure may be unbearable. Presently, HM approaches such as the built-in self-test are based on reactive failure diagnostics and unable to determine residual-life (RL) or estimate residual-reliability. Prognostics health-monitoring (PHM) approach presented in this paper is different from state-of-art diagnostics and resides in the prefailure-space of the electronic system, in which no macro-indicators such as cracks or delamination exist. Applications for the presented PHM framework include, consumer and defense applications such as automotive safety systems including front and rear impact protection systems, chassis-control systems, x-by-wire systems, and defense applications such as avionics systems, naval electronic warfare systems. The presented PHM methodologies enable the estimation of prior damage in deployed electronics by the interrogation of the system state for systems in which the prior stress-history may be unknown or unavailable. The primary focus is on thermo-mechanical stresses. The presented methodologies will trigger repair or replacement, significantly prior to failure. The approach involves the use of condition monitoring devices which can be interrogated for damage proxies at finite time-intervals. The system's residual life is computed based on residual-life computation algorithms. Previously, we have developed several leading indicators of failure. In this paper, a mathematical approach has been presented to calculate the prior damage in electronics subjected to cyclic and isothermal thermo-mechanical loads. Electronic components operating in a harsh environment may be subjected to both temperature variations in addition to thermal aging during use-life. Data have been collected for leading indicators of failure for 95.5Sn4Ag0.5Cu first-level interconnects under both single and sequential applications of cyclic and isothermal thermo-mechanical loads. Methodology for the determination of prior damage history has been presented using non-linear least-squares method based on interrogation techniques. The methodology presented used the Levenberg-Marquardt Algorithm. The test vehicle includes various area-array packaging architectures soldered on immersion Ag finish, subjected to thermal cycling in the range of -40 οC to 125 οC and isothermal aging at 125 οC.

Prognostication of Residual Life and Latent Damage Assessment in Lead-Free Electronics Under Thermomechanical Loads

Requirements for system availability for ultrahigh reliability electronic systems such as airborne and space electronic systems are driving the need for advanced health monitoring techniques for the early detection of the onset of damage. Aerospace electronic systems usually face a very harsh environment, requiring them to survive the high strain rates, e.g., during launch and reentry, and thermal environments, including extremely low and high temperatures. Traditional health monitoring methodologies have relied on reactive methods of failure detection often providing little or no insight into the remaining useful life of the system. In this paper, a mathematical approach for the interrogation of the system state under cyclic thermomechanical stresses has been developed for six different lead-free solder alloy systems. Data have been collected for leading indicators of failure for alloy systems, including Sn3Ag0.5Cu, Sn0.3Ag0.7Cu, Sn1Ag0.5Cu, Sn0.3Ag0.5Cu0.1Bi, Sn0.2Ag0.5Cu0.1Bi0.1Ni, and 96.5 Sn3.5Ag second-level interconnects under the application of cyclic thermomechanical loads. The methodology presented resides in the prefailure space of the system in which no macroindicators such as cracks or delamination exist. Systems subjected to thermomechanical damage have been interrogated for the system state and the computed damage state correlated with the known imposed damage. The approach involves the use of condition monitoring devices which can be interrogated for damage proxies at finite time intervals. The interrogation techniques are based on the derivation of damage proxies and system prior-damage-based nonlinear least square methods, including the Levenberg-Marquardt algorithm. The system's residual life is computed based on residual-life computation algorithms.

A periodic inspection and replacement policy for systems subject to competing failure modes due to degradation and traumatic events

This paper deals with the condition-based maintenance of single-unit systems which are subject to the competing and dependent failures due deterioration and traumatic shock events. The main aim is to provide a model to assess the value of condition monitoring information for the maintenance decision-making. A condition-based periodic inspection/replacement policy is developed and compared with a benchmark time-based block replacement policy. Numerical results show that it is indeed useful to follow closely the actual evolution of the system to adapt the maintenance decisions to the true system state to improve the performance of maintenance policies. The analysis of the maintenance costs savings can be used to justify or not the choice to implement a policy based on condition monitoring information and to invest in condition monitoring devices.

Prognostication of system-state in lead-free electronics equipment under cyclic and steady-state thermo-mechanical loads

In this paper, a mathematical approach for interrogation of system-state under cyclic thermo-mechanical stresses has been developed for three-different lead-free solder alloy systems. Data have been collected for leading indicators-of-failure for alloy systems including, Sn1Ag0.5Cu, Sn3Ag0.5Cu, Sn4Ag0.5Cu second-level interconnects under the application of cyclic thermo-mechanical loads. Methodology presented resides in the pre-failure space of the system in which no macro-indicators such as cracks or delamination exist. Systems subjected to thermo-mechanical damage have been interrogated for system state and the computed damage state correlated with known imposed damage. The approach involves the use of condition monitoring devices which can be interrogated for damage proxies at finite time-intervals. Interrogation techniques are based on non-linear least-squares methods. Various techniques including the Levenberg–Marquardt Algorithm have been investigated. The system’s residual life is computed based on residual-life computation algorithms. Detection of system-state significantly prior to catastrophic failure can significantly impact the reliability and availability of electronic systems. Requirements for system availability for ultra-high reliability electronic systems are driving the need for advanced heath monitoring techniques for early detection of onset of damage. Traditional health monitoring methodologies have relied on reactive methods of failure detection often providing little on no insight into the remaining useful life of the system.

NEWSDESK: MISTRAS receives significant award for US infrastructure research; Fair Access to Engineering; Engineering Council Registrants; Hand-held condition monitoring device detects imbalance in critical tanker exhaust fans

NEWSDESK: MISTRAS receives significant award for US infrastructure research; Fair Access to Engineering; Engineering Council Registrants; Hand-held condition monitoring device detects imbalance in critical tanker exhaust fans

Asset managing the power dilemma

An agent-based asset management platform (AAMP) is a novel asset management platform involving agent technology, advanced modelling methods and probability-based reasoning approaches. It allows for real-time device condition monitoring and intelligent information aggregation for power system asset management. The use of AAMP can improve system reliability, automation maintenance, condition monitoring, information management and risk assessment through advanced transformer thermal dynamics monitoring, more accurate information querying and simple human machine interaction.

Online condition monitoring of engine oil

PurposeEngine oil degrades in quality during its use and after certain period of time the oil needs to be changed depending upon its condition. The purpose of this paper is to design and develop an online condition monitoring device for engine oil.Design/methodology/approachBased on the previous works in this line and some testing of used oils in the laboratory, the correlation of change in colour with other properties were identified. An optical colour sensor was then designed and developed which can transform the darkness of oil colour into electrical resistance. A series of tests were undertaken to calibrate the system for its correctness.FindingsThis type of sensor provides the information about the condition of the oil and also can inform about the probable time for drain‐off of the oil.Practical implicationsEngine oil changes are normally done by schedules which are highly conservative and cost the user as the oil is changed when it could be still used for some time. Use of an online sensor will minimize the cost on lubricants to some extent.Originality/valueThe device is of great value to the users of IC engines as it not only reduces the cost on lubricants but also informs the user about the present condition of the oil.

Artificial neural networks as intelligent condition monitoring devices : Condition Monitoring and Diagnostic Technology, Vol. 2, No. 1, pp. 17–20 (Jul. 1991)

Artificial neural networks as intelligent condition monitoring devices : Condition Monitoring and Diagnostic Technology, Vol. 2, No. 1, pp. 17–20 (Jul. 1991)

Helicopter Avionics

AT a recent symposium at the Royal Aeronautical Society, the Civil Aviation Authority (CAA) made specific references to HARP Report recommendations 1 and 11. These laid emphasis on the CAA initiating a special study into the detail causes of the significant number of helicopter accidents attributable to ‘human error’ to see where technology might contribute to useful improvement, and, that the CAA should set up a working party between experts in the Airworthiness Division of the Ministry of Defence and selected specialists from universities and industry. They would draw up proposals or requirements for parameters to be measured and for new or improved condition monitoring devices or systems, to be widely publicised.