The Impact of Model-Based Systems Engineering on Reliability Growth

Reliability growth is the improvement in the reliability of a product based on changes in the product’s design and the manufacturing processes of the design. Product and process changes are the result of taking an action to resolve an identified issue. Image 1 shows how issues are identified two ways; “seen” failure modes as a result of testing and product usage and “unseen” failure modes as a result of engineering calculations and technical discussion. All design changes will have issues (“seen” and “unseen”) in the product design, manufacturing and assembly, and service. Reliability growth has been dependent on subjecting a product to physical testing to identify product deficiencies over the product development lifecycle. R&M in a Model-based System Engineering Environment will significantly reduce the amount of physical testing and should increase the number of discovered (seen) failure modes much sooner in the design cycle. However, that will not eliminate the need to conduct technical risk analysis to identify the unseen failure modes. Product launches are getting shorter and customers are requiring higher quality and reliability. That is why the latest SAE J1739 FMEA Standard recommends conducting a preliminary risk assessment to prioritize which areas of the product design require DFMEA and which areas of the manufacturing and assembly process require PFMEA. Conducting FMEA on the critical areas of the design and process will support the identification of unseen failure modes. However, there is a methodology to enhance the ability to identify unseen failure modes as a result of conducting a focused review of tested products. The methodology is called Design Review Based on Test Results (DRBTR). The mindset of DRBTR is to look for buds of problems (“unseen” failure modes) by studying tested products in a formal review. DRBTR takes advantage of running limited test samples by documenting observations that will address concerns for both the product and process.