Franz Grashof

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Franz Grashof

Franz Grashof (born July 11, 1826 in Düsseldorf , † October 26, 1893 in Karlsruhe ) was a German mechanical engineer and university professor . He was professor of theoretical mechanical engineering at the Technical University of Karlsruhe .

biography

As the son of Elisabeth Brüggemann and Karl Grashof, who taught "Life and Culture of the Greeks and Romans" at the Royal High School in Düsseldorf, Franz Grashof attended elementary and secondary school in Düsseldorf and, in 1843, the trade school in Hagen . Motivated by the boom in steamships and the railroad, he began his practical work in a locksmith's shop. In October 1844, Franz Grashof left school without having passed a final exam in order to begin studying metallurgy at the Königlichen Gewerbeinstitut Berlin , an industrial and trade school. For this purpose, he studied mathematics, physics and mechanical engineering. From 1847 to 1848 he interrupted his studies to do his one year military service as a volunteer with the 7th Jäger Battalion in Düsseldorf. Encouraged by the desire to serve the fatherland as a naval officer, Franz Grashof hired as a simple seaman on the Hamburg sailing ship "Esmeralda". On the sea voyage, which lasted from March 1849 to December 1851, he realized that he was not fit to be a seaman and that instead of a practical activity he should take up an apprenticeship in technical subjects. That is why he continued his studies in Berlin in 1852, with the help of Nikolaus Druckermüller, a friend of the Grashof family, who was director of the Royal Industrial Institute and lecturer at the Ministry of Commerce in Berlin, he achieved a rapid rise. As early as 1853, while Franz Grashof was attending the top class, he was commissioned to hold a lecture on applied mechanics and to work out the lecture content in a "General Encyclopedia of Physics". In 1856 the first chapters appeared on "Elasticity and strength of building and machine materials" and "Applications of statics in testing the stability and resistance of building structures", which were also Grashof's first works. In April 1854 he completed his studies with the state examination for teachers at the Prussian provincial trade schools in order to then take up his teaching post in the subjects of mathematics and mechanics at the Royal Industrial Institute in Berlin . For this purpose the lectures “Analytical Mechanics”, “Elasticity and Strength”, “Hydraulics” and “Machine Mechanics” were created. On December 28, 1854, he married Henriette Nottebohm, before he was awarded the management of the Royal Weights Office in Berlin on January 1, 1855 as a secondary position. In May 1856, Franz Grashof helped found the Association of German Engineers and became its director. In addition, he was entrusted with the management, editing and administration of the archive of the association's newly created magazine. His extensive influence on this association and its magazine was recognized by the appointment of Franz Grashof as an honorary member in 1887, before he was retired as director of the Association of German Engineers on December 14, 1890 . He contributed over 42 papers in 29 years of the journal. In 1860 Franz Grashof received an honorary doctorate from the Philosophical Faculty of the University of Rostock.

Franz Grashof was from September 15, 1863 to 1891, as the successor to Ferdinand Redtenbacher, professor of general and theoretical mechanical engineering at the Polytechnic, later at the Technical University of Karlsruhe . He taught the subjects of strength theory , hydraulics , heat theory and general mechanical engineering , whereby he limited himself to teaching theory and relinquished the practical part to Josef Hart. Franz Grashof was appointed director of the Karlsruhe University in 1867/68, 1868/69, 1872/73, 1882/83 and 1885/86 and was therefore represented in the first chamber of the Baden state estates from 1877 to 1889. In addition, he occupied the chairmanship of the Natural Science Association in Karlsruhe, which appointed him honorary president after his departure. In 1877 he was appointed to the “Commission for the determination of abbreviated designations of the measures and weights introduced uniformly for the whole empire”. He increasingly campaigned for technical universities to be placed on an equal footing with the humanities universities. After he had resigned from the main and editorial management of the journal of the Association of German Engineers in 1881, Franz Grashof suffered a first stroke on December 28, 1882, from which he recovered well and was largely able to continue his activities. From 1882 to 1892 he was a permanent member of the Imperial Standard Calibration Commission, and in 1887 he was also a member of the Board of Trustees of the Physikalisch-Technische Reichsanstalt. Weakened by another stroke, Franz Grashof died on October 26, 1893.

Grashof's rule

Grashof discovered Grashof's rule, named after him, in the transmission theory, which states that in a flat quadrangle, a continuous relative movement between two links is only possible if the sum of the lengths of the shortest link (s) and the longest link (l) is less is than the sum of the lengths of the other two terms (p + q). According to Grashof's rule, the shortest link can rotate continuously if:

s + l ≤ p + q.

This inequality must be satisfied in order for one of the links to rotate completely relative to the other.

Grashof's rule does not determine which of the links is fixed or in which order the links are connected, but there are some changes of position ( kinematic inversion ) if one selects a fixed link and arranges the interplay of the links according to their length.

Honors

Monument in Karlsruhe
The name of Grashof on the column of the monument that was erected to mark the 75th anniversary of the VDI
  • From 1877 to 1882 and from 1887 to 1890, Grashof was a member of the First Chamber of the Baden Estates Assembly appointed by the Grand Duke .
  • In 1866 he was given the honorary title of councilor .
  • In 1867 he received the Knight's Cross 1st Class of the Grand Ducal Baden Order of the Zähringer Lion .
  • In 1874 he was given the honorary title of Privy Councilor .
  • In 1877 he was awarded the title of Secret Council, Second Class.
  • In 1885 he was awarded the Commander's Cross 2nd Class of the Order of the Zähringer Löwen.
  • In 1892 he was awarded the Royal Prussian Crown Order 2nd Class with a Star.
  • He was an extraordinary honorary member of the Berlin Academic Association Hut .
  • The highest honor of the Association of German Engineers, the Grashof Memorial Coin , is named after Franz Grashof . It was first awarded to Carl von Bach on August 28, 1894 . It is recognized as an award for engineers who have achieved outstanding scientific or professional achievements in the technical field. Engineers such as Ferdinand von Zeppelin , Wilhelm Maybach , Carl Bosch and Ferdinand Porsche are early owners of the commemorative coin. One of the sponsors in the recent past is Rudolf Schulten .
  • The Franz Grashof monument in Karlsruhe, inaugurated on October 26, 1896, is located in the south-west of the city on Beiertheimer Allee. The bronze bust created by the sculptor Karl Friedrich Moest was melted down in 1943 for armament purposes and only replaced in 1960 by a new bust by Carl Egler (1896–1982).
  • A dimensionless number in fluid mechanics , the Grashof number , is named after Grashof .
  • A pre-diploma award at the Technical University of Karlsruhe (Karlsruhe Institute of Technology since 2009) is named after Grashof. The prize is awarded for the four best grades in the intermediate diploma in mechanical engineering. The prize is donated by the LuK Group in Bühl.
  • The Franz-Grashof-Strasse in Bremen - Neustadt , in Karlsruhe- Weststadt and in Mannheim were named after him, as was Grashofstrasse in his home town of Düsseldorf.
  • The Grashof lecture hall in the Karlsruhe Institute of Technology got his name.
  • The Grashof house at the Beuth University of Applied Sciences in Berlin was named after him.

Fonts

Grashof was the author of basic textbooks on mechanical engineering and numerous scientific essays on the topics of strength theory, hydraulics, pneumatics, heat theory and the theory of mechanical engineering.

  • On the principles to be laid at the foundation of the organization of polytechnic schools . In: VDI magazine . tape 8 , 1864, p. 592-616 .

literature

Web links

Commons : Franz Grashof  - Collection of images, videos and audio files
Wikisource: Franz Grashof  - Sources and full texts

Supporting documents and comments

  1. ↑ Ahmed A. Shabana: Introduction to multi-body simulation . John Wiley & Sons, 2017, ISBN 978-3-527-67809-9 , pp. 130 ( google.de [accessed on January 12, 2019]).
  2. ↑ Ludwig Bauer, Bernhard Gißler: The members of the first chamber of the Baden Estates Assembly from 1819 - 1912. Fidelitas, Karlsruhe 1913, p. 94
  3. ^ House Grashof (C): Beuth University of Technology Berlin. Retrieved November 11, 2017 .
personal data
SURNAME Grashof, Franz
BRIEF DESCRIPTION German engineer
DATE OF BIRTH July 11, 1826
PLACE OF BIRTH Dusseldorf
DATE OF DEATH October 26, 1893
Place of death Karlsruhe