Short biography 
Georg Duffing was born on 11 April 1861 in Waldshut in Baden. He was the eldest of six children of Christian Duffing and his wife Julie, nee Spies. Duffing enrolled in 1878/79 in the Polytechnische Schule at Karlsruhe. Duffing had a heart valve defect that freed him from military service by the way. After completing his studies Duffing went to Cologne to the Deutz Gas Engine Works and worked on the development of a gas engine that ran successfully in 1905. He published a book on determining the form of changes in offset crankshaft .
In 1910 Duffing joint the Westinghouse Electric company which pioneered long-distance power transmission and high-voltage transmission. Westinghouse Electric received the rights for the first patent for alternating-current transmission from Nikola Tesla and unveiled the technology for lighting in Great Barrington, Massachusetts. Duffing remained there for several months before returning to Germany as an inventor and freelance researcher. In 1913 the family moved to Berlin, especially because he was there listening to lectures on quantum theory of Max Planck, a characteristic behavior of Duffing thirst for knowledge ! During the First World War, Duffing worked on vibration, brakes, gears, fuel injection engines. The week-end, he went regularly to experiment at the Technical University of Berlin (Berlin-Charlottenburg), where Eugen Meyer had given him the opportunity to take advantage of the local apparatus. During this period, Duffing worked on vibrations and differential equations and published the equation which was named after him .
In 1921, Duffing moved to Hamburg for working for the oil company, Stern-Sonneborn AG. For instance, in June 1922, he gave a talk entitled Über Reibungsversuche und Messung derselben unter Bezugnahme auf die Verwendung von Schmierölen  at the Annual General Meeting of the Association of German Chemists. He went back to Berlin in 1931. He died on 5 April 1944 at the age of almost 83 years.
Some works by G. Duffing
Some of the early german patents by G. Duffing
 From F. P. J. Rimrott, Georg Duffing (1861 - 1944), Technische Mechanik, 14, 1994. There is a forthcoming book on Duffing here
 G. Duffing, Beitrag zur bestimmung der formveränderung gekröpfter kurbelwellen, Springer (Berlin), 1906.
 G. Duffing, Erzwungene Schwingungen bei veranderlicher Eigenfrequenz und ihre technische Bedeutung, 1918.
 About friction experiments and measurement of the same with reference to the use of lubricating oils.