The prediction module enables you to predict failure rates for a set of components under given conditions.
The data may be drawn from a selection of industry standard handbooks such as MIl-HDBK-217, 217 Plus, Telecordia, IEC TR 62380 and NSWC.
What's in the Prediction Module?
The failure rate prediction methods all have the same general form. The prediction module provides you with a powerful visual interface through which you can select components, define the conditions in which they operate such as the temperature or environmental conditions.
The prediction software automatically carries out the failure rate calculation as defined by the standard and provides you with the results.
What Industry Standards are Included?
Reliability Workbench™ Prediction includes the following standards:
- Telcordia (Bellcore). This predicts the failure rates for mainly electronic components and is based on research on telecommunications applications.
- MIL-HDBK-217. This predicts failure rates for electronic equipment based on work carried out for the US DoD.
- 217 Plus. This is an updated version of the MIL-HDBK-217. It takes into account new components and better production methods
- IEC TR 62380. This replaced the RDF 2000 standard and predicts failure rates for electronic equipment based on the reliability data handbook published by UTE (Union Technique de l'Electricite). (Both Standards are available to use in RWB.)
- NSWC handbook. This deals with mechanical components and is based on research carried out for the United States Navy.
- GJB/z 299B. This is a Chinese standard for the reliability prediction of electronic components.
The screen shot below shows a sample MIL-217 project with a failure rate vs temperature graph :
How do I use RWB Prediction?
The components that make up a system can be defined in a tree structure. The tree may be composed entirely of components or it could be subdivided into blocks each of which could hold other blocks or components. In this way you can easily represent your system and sub-systems.
The failure rate model for each component is made up of a base failure rate for that particular type of component and multiplying factors known as pi-factors. These factors depend on the operating conditions experienced by the component.
You can input these conditions through simple dialogs and life is made even easier by providing default values for the parameters. If the default parameters don not suit your operating environment, then they can be easily changed.
The failure rates of components are calculated immediately and displayed on the tree diagram. The contributions of components failure rates to blocks and systems failure rates is also displayed. You can examine the effects of stresses caused by the various environmental conditions by displaying the base failure rates and pi-factors for each component.
What else can Prediction do?
The prediction module provides a graphing facility which allows the user to display the variation of predicted failure rates with ambient temperature, stress and environment settings. Variations may be displayed for an entire system or for individual blocks and components. Graphs may also be displayed showing the variation of failure rate over different mission phases.
There are many features designed into the prediction methods that reduce the time it takes for the analysis to be completed. You can cut, copy and paste in the diagram to make rapid changes. Commonly used components can be entered once in a library and then pulled into the project tree each time that the component is used.
Information can be imported from sources such as CAD packages. You can globally edit the project to carry out what if? studies. The powerful reporting and graphing features allow you to create professional standard reports at the click of a button.
Defining Maintenance and Predicting Mean Time to Repair
The prediction module also allows users to define maintenance tasks and assign these tasks to replaceable items in the prediction hierarchy. The program predicts Mean Time to Repair values for sub-system and system levels in support of standards such as MIL-HDBK-472. Tasks are categorized into the following elements :
- Fault Isolation
- Start Up
The screen shot below shows a MIL-217 project with maintenance tasks. The task library is shown in the right hand pane:
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