Yield Criterion— Henri Tresca
Henri Édouard Tresca applied the tools of science to test materials and evaluate the performance of mechanical devices. Arthur Morin recruited Tresca, in 1853, to join the Conservatoire des arts et métiers in the new role of engineer on staff. Tresca’s first assignment was to convert the abandoned church of the priory of Saint-Martin-des-Champs into a machine hall where visitors could see full-sized machines — steam engines, pumps, and machine tools — in operation.
The Conservatoire had its origins during the French Revolution as a repository for valuable instruments, tools, drawings, and machines acquired by the national government. The intent was to safeguard and disseminate knowledge that could advance the development of industry, in the spirit of Diderot’s Encyclopedia project. In time, the Conservatoire assumed the function of a three-dimensional encyclopedia, a place where craftsmen could come to upgrade their knowledge and skills by seeing how new things were done.
With the advance of the industrial revolution, expanding the breadth and scope of technological innovation, the Conservatoire’s collection grew in size and importance. Beginning around the middle of the 19th century, the Conservatoire took on an important new role. Under Morin’s leadership as Director, the Conservatoire added testing and evaluating new materials and new technologies to its existing roles educating France’s craftsmen and workers and as a national archive.
For this purpose, Tresca established the Mechanical Trials Laboratory (Laboratoire d’essais mécaniques). Tresca’s laboratory became a model for the establishment of testing laboratories around the world, and it continues to function today as the Laboratoire national de métrologie et d’essais.
Tresca is remembered for his research to characterize the behavior of ductile materials, such as steel and aluminum. This work led to the development of the Tresca yield criterion, which is still widely used to evaluate the strength of ductile materials. Tresca had a role in the international adoption of the metric system; he designed the platinum alloy rods adopted as the international standard of length for the metre in 1875. (Originally, in 1793, the metre was defined as the distance between the north pole and the equator divided by 10 million. Currently, the metre is defined as the distance traveled by light in a vacuum in 1/299,792,458 seconds.)
Henri Tresca is one of the 72 engineers and scientists named on the Eiffel Tower. Tresca’s machine hall is now part of the Musée des Arts et Métiers.
