Expeditious Component-Level FMECA Modeling for Design Optimization

The Failure Modes Effects Analyses (FMEA) provides a number of benefits to the reliability and design engineer; ultimately improving life cycle cost. These benefits range from identifying potential failures having catastrophic or hazardous impact on personnel or equipment to providing the designer and manufacturer with opportunities to eliminate, or at least minimize, the impact of these failures. The FMEA is the basis for a Fault Tree Analysis (FTA) of safety and mission critical defects. The Failure Modes Effects and Criticality Analysis (FMECA) provides analysis of unanticipated failure modes and quantifiable probability of critical failure modes. Finally, it is a tool for Suitability and Design for Reliability (DfR). FMECA results are ideally suited for design decisions early in the development process in order to minimize program life-cycle cost impact. The current issue is that the time it takes for detailed, part-level, analysis does not allow for results to impact system design. An improved methodology is necessary to provide effective analysis once initial schematics are developed. Robust FMECA for Design provides the capability to perform a FMECA with very little input to identify design weaknesses early in the system design process. Below are abbreviated steps involved: 1. Perform Reliability Analysis on all system or CCA components 2. Export each components inputs and outputs using the schematic tool 3. Using a library of failure modes and next effects (developed as a part of this effort) each component is assigned a next effect based on its inputs and outputs 4. Resulting probability of specific signal impact are then consolidated and easily determined based on mission and system-level impact 5. The Fuzzy Measure Theory, using trapezoidal fuzzy numbers, and Choquet Integral are used to establish a risk priority for each failure mode so the FMECA can be used to affect design change as quickly and efficiently as possible The resulting approach reduces the time to perform a component-level FMECA by 97% based on a typical board/circuit card with 6 functions and 350 parts. Additionally and most importantly, rapid FMECA results allow design recommendations to be made early in the design process. Critical system failures can be avoided early through testability parameters and capability assessment for the greatest impact to life-cycle cost. Assigning risk priority focuses design improvements into target areas. This novel approach improves overall efficiency in the reliability realm and allows reliability to be built into the product design early in the product life cycle.