Life Consumption Monitoring

Objectives

Background

Approach

Objectives

• Obtain and implement a prototype device capable of monitoring real and accelerated environment and usage data of equipment in a form that can be made compatible with the input requirements of existing CALCE physics-of-failure (PoF) models.
• Produce a strategy that supports the incorporation of groups of these devices in a process that enables the effective management of critical lifed items in a through life context.

Background

Life consumption monitoring is defined as a method of quantifying a system's deviation from its normal operating state (or system degradation) by monitoring parameters related to the system's environment, and using physics-based equations to convert the measured data into life consumption. Project C00-50 focused on health and life consumption analysis obtained from the assessment of the environment and operational conditions of equipment. There now remains a requirement for CALCE to demonstrate the benefits of data collection systems that can promulgate the use of PoF to predict the onset of failure in real time.

A better understanding of failure mechanisms through the PoF approach allows more proactive and cost effective decisions to be made on critical lifed items during equipment use. Replacement of the monitored items could then be linked to individual equipment usage patterns, thus extending their life to a maximum without adding undue risk of system failure. Eventually, maintenance would occur at the time and place of the users' choosing. In terms of one-shot devices, items that are known to have sufficient life remaining to complete their required mission could be identified. Life consumption monitoring also provides important information for in-service managers.

Data collection devices must be versatile, robust, small, light, have low power requirement, be cheap to install and preferably automatic. The device(s) must be capable of collecting the life consumption data necessary to monitor damage accumulation metrics in a form compatible with all the CALCE PoF models, and ideally should be remotely accessible by the maintenance engineer.

Approach

• Using the output from C99-43, C00-50, and the input requirements of all CALCE PoF models, obtain a prototype device that is capable of monitoring the daily use of say "a vehicle engine management unit," the output of which can be used to monitor real and accelerated equipment usage.
• Install the above device in a vehicle and gather information about the usage and environmental conditions. The initial parameters of interest will be temperature, humidity, and vibration (rates of change, cycles, etc.).
• Show how the usage and environmental information collected from these items can be used to predict the life consumption of the item. The strategy will include data reduction methods for large volumes of data, data translation between time and frequency domains, cycle counting methods for evaluation of fatigue damage, and the use of physics-of-failure and damage accumulation models to determine the life consumption.
• Use the strategy developed to determine the life consumption of a sample item at the end of the data collection period.