# The Main

Theme 4. Fundamentals of the theory of stress and strain state of stress state at the point of the deformed body. The main site and principal stresses. Types of stress of the material (linear, planar and spatial). Linear stress. Determination of stresses on the inclined plane. Plane stress.

Definition stresses on the inclined plane (direct problem). Dependence between the stresses on two mutually perpendicular sites. Law sum of normal stresses. Act pairing shear stresses. Graphical method determine the stresses on the inclined plane (circle Mora). Plane stress.

Determination of principal stresses and principal planes of the known stresses on two mutually perpendicular areas (Inverse problem). Volumetric stress. The stresses on planes parallel to one of the principal stresses. Pie chart Mora. Maximum normal and shear stresses, the site of their action. Deformation under complex stress state. Identify the main linear deformations (the generalized Hooke's law). Volume strain. Hooke's law for volumetric strain. Specific strain energy, and its separation into parts corresponding to the volume change and change in shape. Hypotheses and destruction of plastic deformation (the theory of strength). The need for and purpose of the hypotheses of strength. The equivalent stress. The hypothesis of maximum normal stress. The hypothesis of the largest linear deformations. The hypothesis of the greatest shear stress. The distortion energy hypothesis. Recommendations for the use of different hypotheses. The concept of Moore's conjecture for materials with different characteristics in tension and compression. Topic 5. Determination of the stress shift in the shear plane. The state of stress in shear.