Daniel_C._Drucker--William_K._Estes

Daniel Charles Drucker (June 3, 1918 – September 1, 2001) was American civil and mechanical engineer and academic, who served as president of the Society for Experimental Stress Analysis (now Society for Experimental Mechanics) in 1960–1961, as president of the American Society of Mechanical Engineers in the year 1973–74, and as president of the American Academy of Mechanics in 1981–82.Drucker was known as an authority on the theory of plasticity in the field of applied mechanics. His key contributions to the field of plasticity include the concept of material stability described by the Drucker stability postulates and the Drucker–Prager yield criterion.