In solid mechanics, shearing forces are unaligned

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...

s acting on one part of a body in a specific direction, and another part of the body in the opposite direction. When the forces are collinear (aligned with each other), they are called tension forces and

compression forces In mechanics, compression is the application of balanced inward ("pushing") forces to different points on a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions.Ferdinand P ...

. William A. Nash defines shear force in terms of

planes Plane(s) most often refers to: * Aero- or airplane, a powered, fixed-wing aircraft * Plane (geometry), a flat, 2-dimensional surface Plane or planes may also refer to: Biology * Plane (tree) or ''Platanus'', wetland native plant * ''Planes' ...

: "If a plane is passed through a body, a force acting along this plane is called a ''shear force'' or ''shearing force''."

Force required to shear steel

This section calculates the force required to cut a piece of material with a shearing action. The relevant information is the area of the material being sheared, ie the area across which the shearing action takes place, and the shear strength of the material. A round bar of steel is used as an example. The shear strength is calculated from the tensile strength using a factor which relates the two strengths. In this case 0.6 applies to the example steel, known as EN8 bright, although it can vary from 0.58–0.62 depending on application. EN8 bright has a tensile strength of 800MPa and mild steel, for comparison, has a tensile strength of 400MPa. To calculate the force to shear a 25 mm diameter bar of EN8 bright steel; : area of the bar in mm² = (12.5²)(π) ≈ 490.8mm² : 0.8kN/mm² × 490.8mm² = 392.64kN ≈ 40tonne-force : 40tonne-force × 0.6 (to change force from tensile to shear) = 24tonne-force When working with a

rivet A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched ...

ed or tensioned bolted joint, the strength comes from friction between the materials bolted together. Bolts are correctly torqued to maintain the friction. The shear force only becomes relevant when the bolts are not torqued. A bolt with property class 12.9 has a tensile strength of 1200MPa (1MPa = 1N/mm²) or 1.2kN/mm² and the yield strength is 0.90 times tensile strength, 1080MPa in this case. A bolt with property class 4.6 has a tensile strength of 400MPa (1MPa = 1N/mm²) or 0.4 kN/mm² and yield strength is 0.60 times tensile strength, 240MPa in this case.

References

{{reflist Force Civil engineering

Force required to shear steel

See also

References