Equations of Equilibrium. F 0 M O 0 Fx 0 Fy 0 Fz 0 M x 0 M y 0 M z 0 Fx 0 Fy 0 M O 0 Example Determine the resultant internal loadings acting on the cross section at C of the machine shaft. The shaft is supported by bearings at A and B, which exert only vertical force on the shaft. ESFUERZO DISTRIBUCIÓN DEL ESFUERZO NORMAL PROMEDIO +↑ FRz = Fz; dF dA A P A P A EJEMPLO La lámpara de 800 N está sostenida por dos barras AB y BC. Si AB tiene un diámetro de 10 mm y BC tiene un diámetro de 8 mm, determine el esfuerzo normal medio en cada barra. ESFUERZO CORTANTE PROMEDIO prom V A Cortante simple Cortante doble EJEMPLO The wooden strut is suspended froma10mm diameter steel rod, which is fastened to the wall. If the strut supports a vertical load of 5kN, compute the average shear stress in the rod at the wall and along the two shaded planes of the strut, one of which is indicated as abcd. SOLUCIÓN Esfuerzo cortante promedio V 5000 N 63.7 MPa 2 A 0.005m Para la barra, prom Para el puntal, prom V 2500 N 3.12 MPa A 0.04m 0.02m Ans.... Ans.... The average-shear-stress distribution on the sectioned rod and strut segment as shown in figs. (d) and (e), respectively. Also shown with these figures is a typical volume element of the material taken at a point located on the surface of each section. Note carefully how the shear stress must act on each shaded face of these elements and then on the adjacent faces of the elements.