Georg Duffing : from engineering to nonlinear dynamics

Georg Duffing (1861-1944)

 Short biography [1]
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 [2].

The Duffing equation (1918)

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 [3].

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 [4] 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

• G. Duffing, Beitrag zur bestimmung der formveränderung gekröpfter kurbelwellen, Springer (Berlin), 1906.

• G. Duffing, Erzwungene Schwingungen bei veränderlicher Eigenfrequenz (Forced vibration with variable natural frequency). F. Vieweg, Braunschweig, 41/42, 1918.

• G. Duffing, Zur Theorie der Flüssigkeitsbewegungen zwischen Zapfen und Lager (On the theory of fluid movements between shaft and bearing, Zeitschrift für Angewandte Mathematik und Mechanik, 4, 296-314, 1924.

• G. Duffing, Reibungsversuch am Gleitlager (Friction test on the plain), Verein Deutscher Ingenieure -Zeitschrift, 72 (15), 495-499, 1928.

• G. Duffing, Elastizität und Reibung beim Riementrieb (Elasticity and friction of the belt drive), Forschung auf dem Gebiete des Ingenieurwesens, 2 (3), 99-104, 1931.

• G. Duffing, Messung der Zähigkeit durch gleichförmige koaxiale Bewegung einer Kugel in einem Kreiszylinder (Measurement of toughness by uniform coaxial movement of a ball in a circular cylinder), Zeitschrift für Angewandte Mathematik und Mechanik, 13, 366-373, 1933.

• G. Duffing, A new form of absolute viscometer, First World Petroleum Congress (London, UK), July 18-24, 1933.

 Some of the early german patents by G. Duffing

• 1908 DE 210 927 : gears with teeth across the width direction of the split sprocket

• 1909 DE 219 285 : Fluid control inhibitions.

• 1909 DE 227 724 : Apparatus for exercise of a variable pressure on the linkage of a control device for combustion engines.

• 1908 DE 231 179 : reservoir for closed control inhibitions with blocking parts of opposite lock and the same meaning in a passage

• 1910 DE 231 627 : Isodrom control device for combustion engines.

• etc.