The quantum mechanics, in the infinitesimal world, is the reign of the quantification of energies, and of the probability of presence of particles with the famous wave function ψ associated at the Schrodinger equation. The General relativity, is for it, reserved at the infinitely large world where the mater, the energy density influence the curvature of the space time at 4 dimensions and reciprocally. Finally, the strength of materials is the mechanic of objects at the human scale (beams, columns, plates, shells) used for the design of structures, without common measures with this two pillars of the of the physics cited earlier. We are going to show in first part of this paper that the results of the quantum mechanics (quantification of energy, shape of the wave function) are similar at the eigen frequencies and eigen modes of a beam. In second part, we will show on simples cases, that the concepts of curvature linked with energy density present in general relativity are equally at the bases of the fundamental equations of the elasticity and of the strength of material. We will demonstrate finally that the stress energy tensor written for small speeds non relativistic is an extension in 4 dimensions of stress tensor of the elasticity theory.