A system for performing fatigue evaluation of a fatigue-prone location in an engineering structure in a product of a manufacturing process, the system comprising a controller and a display, wherein the controller is programmed to input a multi-axial load locus representing a fatigue prone location of a tangible structure under loading and convert the multi-axial loading data of the fatigue prone location to a set of equivalent constant amplitude loading data for the structure by: generating a multi-axial load locus by mapping load parameters of the loading data into an equivalent space of dimension n, where n represents the number of independent stress or strain components and the loading data is produced by subjecting the fatigue prone location of the structure to a one-time or repeated loading event such that the multi-axial load locus represents the structure; identifying a maximum range between two points on the load locus to define a loading path (A, B, C, D, E) along at least a portion of the load locus, the loading path extending from a point of origin P to a point of termination Q; identifying any time-dependent interior turning points R and any corresponding projected turning points R* along the loading path from the point of origin P to the point of termination Q; counting half cycles in the loading path by referring to the interior and projected turning points R, R* along the loading path and to the point of origin P and the point of termination Q on the load locus; determining a stress range Δσ e, loading path length L, and virtual path length for each of the counted half cycles; determining additional stress ranges Δσ e, loading path lengths L, and virtual path length recursively for half cycles counted in additional loading paths on the load locus; transforming data representing the counted half cycles, the stress ranges Δσ e, the loading path lengths L, and the virtual path lengths or combinations thereof, to a tangible set of equivalent constant amplitude loading data representing the structure; and displaying the tangible set of equivalent constant amplitude loading data on the display as a representation of the fatigue prone location of the tangible structure; wherein the data can be used to modify or validate the design of the structure, or to modify or validate the structure itself. generating a multi-axial load locus by mapping load parameters of the loading data into an equivalent space of dimension n, where n represents the number of independent stress or strain components and the loading data is produced by subjecting the fatigue prone location of the structure to a one-time or repeated loading event such that the multi-axial load locus represents the structure; identifying a maximum range between two points on the load locus to define a loading path (A, B, C, D, E) along at least a portion of the load locus, the loading path extending from a point of origin P to a point of termination Q; identifying any time-dependent interior turning points R and any corresponding projected turning points R* along the loading path from the point of origin P to the point of termination Q; counting half cycles in the loading path by referring to the interior and projected turning points R, R* along the loading path and to the point of origin P and the point of termination Q on the load locus; determining a stress range Δσ e, loading path length L, and virtual path length for each of the counted half cycles; determining additional stress ranges Δσ e, loading path lengths L, and virtual path length recursively for half cycles counted in additional loading paths on the load locus; transforming data representing the counted half cycles, the stress ranges Δσ e, the loading path lengths L, and the virtual path lengths or combinations thereof, to a tangible set of equivalent constant amplitude loading data representing the structure; and displaying the tangible set of equivalent constant amplitude loading data on the display as a representation of the fatigue prone location of the tangible structure; wherein the data can be used to modify or validate the design of the structure, or to modify or validate the structure itself.