PRISM Forum - Message Replies
Topic: PRISM Questions and Answers
Topic Posted by: SRC
Date Posted: Wed Jan 12 8:33:33 US/Eastern 2000
Topic Description: Welcome to the PRISM forum! Please feel free to post your questions and comments about the PRISM assessment software here.
Posted by: Super Wong
Date posted: Tue Jun 6 5:00:42 US/Eastern 2006
Subject: About MTBF calculation
1)When we get the result of failure rate,how can we get MTBF(Meantime between failures)? Which expression should we use,MTBF=10e6 /failure rate or MTBF=10e9 /failure rate ?
2)Which code does PRISM follow,MIL-HDBK-217 or Bellcore?As I know,MIL-HDBK-217 MTBF calculation bases on 10e6,Bellcore MTBF calculation bases on 10e9.
Subject: MTBF Calculation
Reply Posted by: David Dylis
Organization: System Reliability Center (SRC)
Date Posted: Tue Jun 6 8:50:57 US/Eastern 2006
1. PRISM outputs failure rates in failures per million calendar hours. The MTBF (in calendar hours) is the inverse of the failure rate.
2. PRISM is a new prediction methodology developed by the Alion System Reliability Center (SRC) and is viewed as the replacement for MIL-HDBK-217 and 217-type modeling methodologies. PRISM deviates from traditional reliability prediction methodologies by allowing a user to factor in test data and address system level design and manufacturing processes to refine a system prediction. These factors known to impact field reliability have been previously ignored by other methodologies. In addition, the PRISM component and system assessment models address not only operational aspects but also non-operational and/or dormant aspects of a part or system. These models based on SRC's most current reliability data (e.g. SPIDR- System and Part Integrated Data Resource) and is updated as new data is collected whereby keeping the models and the PRISM approach current with the state-of-the-art. The best testimonial to PRISMís acceptance in the user community are the systems that are currently being analyzed using PRISM. We are aware that the following types of systems are being assessed: satellite systems, airborne systems, automotive systems, radars, computers, transmitter/receivers, fuel cell electronics and down-hole oil drilling electronics to name a few. PRISM has also been specified as the recommended prediction methodology in a multitude of DoD system procurements.
If you have additional questions, feel free to contact me.