Critical products (systems) should be safe, reliable, and easy to maintain. Indeed, RAMS (Reliability, Availability, Maintainability and Safety) related standards state the RAMS analyses that should be conducted in each stage of the system engineering design process (V model), starting from reliability allocation in the initial design stage, and up to detailed failure modes and effects analysis of the complete design, and safety analysis.
For example, MIL-STD-1629A states: ”The failure mode, effects, and criticality analysis (FMECA) is an essential function in design, from concept through development”, and: “Timeliness is perhaps the most important factor in differentiating between effective and ineffective implementation of the FMECA”.
Furthermore, RAMS analyses are required in most tenders for mission and safety critical systems.
While RAMS analyses are mandatory, they are often put off to late design stages when their effectiveness on the system design is greatly reduced. This bad habit can be understood since program managers and system engineers have enough on their hands without having to deal with RAMS.
This attitude is fine until a critical RAMS issue arises late in the design or leading to failures in the field.
Here are a few examples we encountered during many years in the business:
- A critical electronic board was found to be inadequately designed – high power was applied to a component, causing the board to fail in the field. This could have been prevented by component derating analysis.
- A system was designed to have cold standby backup, but the bring-up time of the backup unit was too long. As a result, the system design was unable to provide the required availability, and deep re-design was required.
- System testability was not in-line with the maintainability concept: certain parts were supposed to be replaceable on-site, but the built-in test was unable to identify which part needs replacing.
BQR’s software minimizes the effort needed to conduct RAMS analyses early in the design stage, and to update the analyses as the design progresses. This is achieved using:
- Plug-In for ECADs (collect design data for RAMS analysis):
- Quick BOM verification and export
- Stress assignment (power, voltage, current)
- Functions and failure modes assignment
- Netlist standard name generator
- Libraries for data reuse:
- Failure Modes
- Centralized project RAMS database
- Integrated software for:
- Component derating analysis
- MTBF allocation and prediction
- FMEA / FMECA
- FMEDA / Analisi di testabilità
- RBD allocation and prediction
- Maintainability and Logistic Support Analysis