Improving system reliability by failure-mode avoidance including four concept design strategies

To be reliable, a system must be robust—it must avoid failure modes even in the presence of a broad range of conditions including harsh environments, changing operational demands, and internal deterioration. This paper discusses and codifies techniques for robust system design that operate by expanding the range of conditions under which the system functions. A distinction is introduced between one-sided and two-sided failure modes, and four strategies are presented for creating larger windows between sets of one-sided failure modes. Each strategy is illustrated through two examples from industrial practice. For each strategy, one example is from paper handling and another is from jet engines. By showing that every strategy has been successfully applied to each system, we seek to illustrate that the strategies are widely applicable and highly effective. © 2005 Wiley Periodicals, Inc. Syst Eng 8: 245–261, 2005