Fracture initiation sequence of double-layer beam layers under three-point loading

The article deals with brittle failure of a two-layer beam under three-point loading conditions depending on the parameters under consideration — different proportions of thicknesses, Young's moduli and strengths of both layers. Based on the equations of force and moment equilibrium, the dependences of the position of the beam neutral axis and its curvature are derived and the regions of parameters are determined, at which the failure begins earlier in the layer to which the load is applied than in the outer opposite layer to the load.