Equivalent Signal Method for Fatigue Analysis and Repair Assessment

ATA Engineering proposes a Phase I project to develop and demonstrate a novel equivalent signal method for assessing structural fatigue under combined frequency domain definitions of random, sinusoidal, shock, and quasi-static loads. To document improvements in accuracy and reduction in analysis uncertainty, the project will first compare the novel approach to classical methods for uni-axial random and sine loading. With confirmation of the approachs validity, it will be extended to studies of multi-axial and combined sine and random environments. ATA will also develop a workflow for post-repair assessment utilizing the approach and use it to determine the durability of an example repair on a notional rotocraft component. In the Option period, ATA will encapsulate the method and associated guidelines into a prototype software toolset based upon commercial finite element analysis and forced response analysis software codes. In Phase II, the analytic methodology and software will continue to be matured, integrated with advanced fatigue codes, and validated through correlation with experimental data to achieve a tool that provides efficient assessment of remaining structural life based on repair conditions and operating environment.