Ernst Lehr

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Ernst Lehr (born July 4, 1896 in Groß-Eichen ; † March 24, 1945 in Berlin ) was a German materials scientist and mechanical engineer.

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Ernst Lehr was born on July 4, 1896 in Groß-Eichen in Upper Hesse. After graduating from high school in Friedberg, he studied mechanical engineering and electrical engineering at the Technical University of Darmstadt with Viktor Blaess and Enno Heidebroek, among others , and did not take his diploma until 1922 due to the First World War, which he experienced as an artillery officer. He then joined the Darmstadt-based machine factory Carl Schenck AG as a development engineer , where he specialized in the development of high-frequency traction machines based on the resonance principle, fatigue bending machines and torsional vibration machines for fatigue testing. Lehr received his doctorate in 1925 based on the knowledge he gained in the field of strength theory.

In 1935, Lehr moved to the State Prussian Materials Testing Office in Berlin-Dahlem as the head of the mechanical engineering and mechanical technology departments , where he shifted his research focus to the practical determination of the stress distribution in difficultly shaped machine parts and the force curve in rapidly moving machine parts. In addition, he received a teaching position as a private lecturer at the TH Berlin , where he also completed his habilitation in 1936.

At the instigation of the High Command of the Navy , Lehr was appointed to MAN in Augsburg in 1938, where he set up and headed the Research Institute for Mechanics and Design for the German ship machine manufacturers . In addition, he took over the management of the Research Institute for Tracked Vehicles at the MAN plant in Nuremberg . On a business trip to Berlin to the Army Weapons Office , Lehr was killed in a bomb attack in 1945.

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Lehr's work can be seen as a continuation of the research carried out by his role models Johann Bauschinger , August Wöhler , Adolf Martens and Carl von Bach and mainly includes vibration problems, which strength theory also helped to clarify . Lehr redefined the term "fatigue strength" as a limit value for changing stresses, discovered common principles of mechanical and electrical vibrations, modernized Otto Dietrich's lacquer process, dealt with vehicle suspension and the load-bearing capacity of press material bearings and invented the first torsion bar suspension with the largest spring deflection for heavy vehicles . In one of his last papers from 1943, for example, he deals with the question of the durability of crankshafts in large diesel engines. According to him, this is also Lehr's damping named.

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personal data
SURNAME Lehr, Ernst
BRIEF DESCRIPTION German physicist, materials researcher and mechanical engineer
DATE OF BIRTH 4th July 1896
PLACE OF BIRTH Large oaks
DATE OF DEATH March 24, 1945
Place of death Berlin