COSSERAT, Théorie des Corps Déformables, 1909

First edition.
The brothers, Eugène Cosserat (1866-1931), mathematician and astronomer, professor at the Faculty of Sciences and director of the Toulouse Observatory, and François Cosserat (1852-1914), chief engineer of the Ponts et Chaussées, are famous for their pioneering work in continuum mechanics. They developed a theory of deformable bodies that generalizes the classical theory of elasticity by introducing additional degrees of freedom (rotations and deformations of micro-elements). This work is their major contribution, laying the foundations for what is today known as Cosserat's theory of elasticity or Cosserat media. It is a fundamental text for applied mathematics, physics, and engineering, marking a significant advance in the understanding of the behavior of materials.