A Fast First-Order Method for Filtering Limit States

System reliability calculation for large-scale structural systems is complex due to the large number of potential failure locations and failure modes unless a priori knowledge can be used to significantly reduce the number of failure locations and modes. However, a priori knowledge may not be available for future aircraft systems that operate in new environments ‐ such as hypersonic ‐ or consist of unconventional designs with limited production runs. As a result, a fast first-order reliability based filtering method has been developed to numerically quantify the error incurred by filtering a limit state. A “filtering error” is calculated based on a certain limit state’s contribution to the system probability of failure. This is compared to a chosen error tolerance to determine if a limit state is a critical location or should be filtered. The method is fast and scalable to large models. Three examples show the accuracy and efficiency of the new algorithm.