Advanced Dynamic Fault Tree Analysis Techniques for Complex Systems Dependability Analysis

Through this Phase I Small Business Innovation Research (SBIR) effort, Quality Research Associates, Inc. (QRA) developed and determined the feasibility of an enhanced dynamic fault tree analysis methodology for safety and risk assessment of critical computer-based systems (CBS). CBS are being used in many critical applications where failures can lead to loss of life or severe economic or environmental consequences. These systems must be designed to high standards for dependability. One of the means to do dependability assessment is fault tree analysis. Currently available fault tree analysis tools are not adequate or effective when the system to be evaluated is large, complex, dynamic, or includes non-hardware influences. Feasibility of the methodology was determined by using the methodology to evaluate three diverse and complex systems. This new methodology will help users more effectively model and analyze critical system dependability, yielding the potential for more dependable and safe systems. This new methodology and resulting tool can be applied to many types of CBS. Features of the methodology (which we call SHADETree(TM)) include the ability to perform system dependability evaluation, evaluate large systems, evaluate dynamic systems, provide ease of use, include all significant influencing factors in the evaluation, and perform supporting and complementary analyses. [SHADETree is a trademark of Quality Research Associates, Inc.]