STRENGTH THEORIES 2> Theories of strength: Some assumptions about the cause of the strength failure of materials 3 Types of failure of materials: (1)yield; ( 2)rupture 1) Galileo planted the seed of the first strength theory 2) Mariotto's statement about the rupture of material due to excessive deformation is the flush of the second strength theory 3) C Duguet proposed the theory of the maximum shearing stress 4) Maxwell brought forward the theory of the maximum distortional energy theory early, which was known after his letters were published2、Theories of strength：Some assumptions about the cause of the strength failure of materials . 3、Types of failure of materials：⑴ yield； ⑵ rupture 1)、Galileo planted the seed of the first strength theory； 2)、Mariotto’s statement about the rupture of material due to excessive deformation is the flush of the second strength theory； 3)、C.Duguet proposed the theory of the maximum shearing stress； 4)、Maxwell brought forward the theory of the maximum distortional energy theory early, which was known after his letters were published. 7