Grashof, Franz

(b Düsseldorf, Germany, 11 July 1826; d. Karlsruhe, Germany, 26 October 1893)

applied mechanics, thermodynamics, machine design.

Son of a teacher of the humanities, Grashof had a strong practical bent, interrupting his early schooling to work for a locksmith. He went to Berlin in 1844 and spent the following three years at the Gewerbe-Institut, studying mathematics, physics, and machine design as preparation for a career in metallurgy.

After a year as an army volunteer, a career as naval officer seemed attractive; Grashof shipped out as apprentice seaman on a sailing vessel, returning in 1851. Having found himself during this voyage, Grashof realized that he was not suited to a life of physical activity (in part because of myopia) and that his real inclination was to teach engineering sciences.

In 1852 Grashof resumed his studies at Berlin, where he was entrusted with lectures on applied mathematics. Elevated in 1854 to staff membership of the Gewerbe-Institut as teacher of mathematics and mechanics, he was also director of the Office of Weights and Measures.

On 12 May 1856, Grashof was among the twentythree founders of the Verein Deutscher Ingenieure (VDI). Although no unified Germany then existed, this society was to include the engineers of the twenty-five German states and Grashof was to implement its organization; because of his scientific reputation he was made director of the society and editor of its Zeitschrift. The University of Rostock conferred an honorary doctorate in 1860.

Following Ferdinand Redtenbacher’s death in 1863, Grashof was named his successor as professor of applied mechanics and the theory of machines at the Polytechnikum in Karlsruhe. He lectured on strength of materials, hydraulics, thermodynamics, and machine design with clarity and precision. He remained in Karlsruhe, rejecting an offer from Aachen and two from Munich.

Although he resigned the editorship of the Zeitschrift, Grashof remained director of the VDI and turned much of his attention to technical writing, He was the first to present the fundamental equations of the theory of elasticity, in a text on strength of materials in which he treated flexure, torsion, buckling, plates, and shells. His three-volume Theoretische Maschinenlehre (1871–1886) was characterized by sharp insight and critical observation with respect to the limits of accuracy and the admissibility of assumptions; no contemporary English or French work was its equal.

During his lifetime Grashof was recognized as an authority on mechanical engineering in its broadest sense. As teacher and engineer, and as founding member, editor, and long-time director of the VDI, he influenced a generation of engineers by bringing mathematical and scientific considerations to the burgeoning problems of the steam-engine age. Grashof used analysis, supporting and exploiting it with all available experimental work; he shunned the graphical approach of his contemporary Karl Culmann, who founded graphic statics.

Grasho’s name is perpetuated in several ways. There is the dimensionless Grashof number of heat transfer in free-convection flow systems (a criterion similar to Reynolds’ number of forced convection) for the transition from laminar to turbulent flow. Another Grashof criterion is used in kinematics for establishing whether one link of a four-bar chain can rotate completely. The VDI honored his memory by erecting the Grashof Monument in Karlsruhe and by establishing the annually awarded Grashof Medal, its highest honor for achievements in technology.

Grashof suffered a stroke in 1883 that restricted his activity. In that year he became a member of the Standards Commission; in 1887, he was named a trustee of the Bureau of Standards and received honorary membership in the VDI. A second stroke in 1891 disabled him and he, died two years later, survived by his wife and two children.

BIBLIOGRAPHY

I. Original Works Grashof published forty-two articles in Zeitschrift des Vereins deutscher Ingenieure (1857-1885). His books include Angewandte Mechanik, vol. V of Gustave Karsten’s Allgemeine Encyklopädie der Physik (Leipzig, 1856–1862): Festigkeitslehre mit Rücksi’cht auf den Maschinenbau (Berlin, 1866), 2nd ed., under the title Theorie del Elastizität und Festigkeit (Berlin, 1878); Resultate der mechanischen Wämetheorie (Heidelberg, 1870); and Theoretisch Mascllinenlehre, 3 vols; (Leipzig. 1871-1886). Other works are listed in Poggendorfl, III, 543.

II. Secondary Literature. On Grashof or his work, see H. Lorenz “Die wissenschaftlichen Leistungen F. Grashofs,” in Beitrläge zur Gesechite del Industrie und Technik, 16 (1926), 1–12; C. Matschoss, Männer der Technik (Düsseldorf. 1925), p. 94; K. Nesselmann, in Neue deutsche Biographic, VI (Berlin, 1964), 746; R. Plank. “Franz Grashof als Lehrer und Forscher:” in Zeitschrift des Vereins deutscher Ingenieure, 70 (1926). 28. and, S. Timoshenko, History of the Strength, of Materials (New York, 1953), p. 133.

Obituaries are, in Zeifschrift des vereins deutscer Ingenieure, 37 (1893), 48; and Transactions of the American Society of Mechanical Engineers, 15 (1894).

R. S. Hartenberg