A new quality index for characterizing aluminum cast alloys with regard to aircraft structure design requirements

A new quality index QD for characterizing aluminum cast alloys with regard to their suitability for use in damage-tolerant aircraft structures is introduced. The proposed quality index involves the material properties yield strength Rp and strain energy density W. The yield strength accounts for the region of allowable service stresses and strain energy density accounts for tensile ductility and fracture toughness. Both properties, Rp and W, are evaluated from the tensile test. The index QD was used to evaluate the quality of the cast aluminum alloys A357, A224, and 7475 and rank them accordingly. The evaluation results were compared against the results obtained by using the classical quality index currently involved by the industry to characterize the quality of aluminum cast alloys.