András Reuss (engineer)

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András Reuss (also: Endre Reuss ; * July 1, 1900 in Budapest ; † May 10, 1968 in Budapest) was a Hungarian engineer for mechanical engineering . His research area was mechanics, in particular the theory of plasticity.

Life

As an 18-year-old high school student, Reuss took first place in a nationwide mathematics school competition, which was endowed with the Loránd Eötvös Prize of the Hungarian Mathematical and Physical Society. In 1922 Reuss received the engineering diploma for mechanical engineering at the Technical University of Budapest and worked at the faculty there as an assistant until 1924. From then until 1950 Reuss was an operations engineer at the municipal gas works in Budapest. With his work Influence of cold deformation on the yield point of iron and steel , submitted in 1931 , Reuss obtained his doctorate the following year, he completed his habilitation in 1942, after which he became a private lecturer at the Technical University of Budapest. In 1950 he came to the planning center of the chemical industry in Hungary. In 1953 Reuss was appointed professor to the chair for technical mechanics at the TU Budapest, where he worked until his retirement in 1965, including 1955-57 as dean of the faculty.

plant

Elastic properties of polycrystals

If one wants to calculate the elastic properties of the associated isotropic polycrystals from the components of the elasticity tensor (English: stiffness tensor)) of anisotropic single crystals , all spatial orientations have to be statistically averaged (see also Polycrystal # elastic properties ). After Voigt (1887) had carried out such averaging assuming a uniform deformation of all grains of a polycrystal, Reuss calculated an averaging in 1929 assuming a uniform stress in the polycrystal. The arithmetic mean of the two mean values ​​(referred to as the Voigt-Reuss-Hill approximation) is now the standard approximation for converting single-crystal to poly-crystal related elastic modules.

Prandtl-Reuss equations

Although the formulation of Hooke's law (1678) on the proportionality of stress and elastic deformation was known for a long time, de Saint-Venant (plane problem) and Levy (spatial problem) 1870's approaches to proportionality between shape-changing stress and shape-changing deformation rate were purely rigid- formulated plastically, i.e. without elastic components. After Prandtl (1924) had included elastic deformations in a flat plastic problem, Reuss (1930) did so in a spatial problem, but in ignorance of Prandtl's 1924 contribution. Reuss now added elastic deformation rates in the approach of de Saint-Venant / Levy (of the type like the deformations in Hooke's law) additive to the plastic, in order to obtain a total deformation rate for the mixed elasto-plastic behavior. For the insertion of the plastic behavior in the loading history of a workpiece Reuss has the comparison voltage according to von Mises used. The evaluation of the total deformation rates shows that the volume change is purely elastic, while the change in shape has both an elastic and a plastic component. The equations for the deformation rates are now called Prandtl-Reuss equations and are the basic equations of the (time-independent) plasticity theory.

literature

Individual evidence

  1. ↑ A. Reuss: Calculation of the yield point of mixed crystals based on the plasticity condition for single crystals . In: Z. angew. Math. Mech . tape 9 (1) , 1929, pp. 49-58 , doi : 10.1002 / zamm . 19290090104 .
  2. ↑ L. Prandtl: Stress distribution in plastic bodies . In: Proc. First Int. Congr. Appl. Mech. Delft . 1924, p. 43-54 .
  3. ^ A. Reuss: Consideration of the elastic deformation in the plasticity theory . In: Z. angew. Math. Mech . tape 10 (3) , 1930, pp. 266-274 , doi : 10.1002 / zamm.19300100308 .
personal data
SURNAME Reuss, András
BRIEF DESCRIPTION Hungarian mechanical engineer
DATE OF BIRTH July 1, 1900
PLACE OF BIRTH Budapest
DATE OF DEATH May 10, 1968
Place of death Budapest