Internal Forces in Beams. Axial Force \(\rightarrow\) Tension/Compression. Shear Force \(\rightarrow\) Sliding/Shear Stress. Bending Moment \(\rightarrow\) Bending/Normal Stress (Tension/Compression).
Shear force is an internal force acting parallel or tangential to the cross-section of a structural member like a beam. It arises from external transverse loads. This internal shear force represents the tendency of one part of the beam to slide vertically relative to the adjacent part. This tendency to slide causes shear stresses within the material. Compression and tension are associated with normal forces (perpendicular to the cross-section), typically caused by axial loads or bending. Bending is caused by bending moments. Therefore, shearing force tends to cause sliding of one section relative to another.