Bolted Joint Force
Bolted Joint Force is the force exerted by the bolts on the assembled parts in a clamped bolted joint. Figure 1 shows the cross section of an assembled flange, which is a joint of this type. The forces exerted by the bolts must compensate for: internal hydrostatic pressure, the forces to compress the gasket and spring washers, an allowance for bolt fatigue, a safety factor, and other mechanical forces acting upon the joint.
Fig 1: Assembled Flange Cross Section
When the bolts are tightened, they stretch, acting like springs pressing upon the assembly. The resulting spring force holds the joint together. Assembly procedures routinely specify torque values for tightening the bolts. Such values are commonly determined by trial and error because it is difficult to measure the force exerted by the bolts directly. However, Fujifilm Prescale® pressure indication film is frequently used to show the pressure effects of the bolt force.
Simply place Fujifilm Prescale® pressure indicating sensor film between any two surfaces that touch, mate or impact. Apply pressure, remove it and immediately the film reveals the pressure distribution profile that occurred between the two surfaces. Conceptually similar to Litmus paper, the color intensity of Fujifilm Prescale® is directly related to the amount of pressure applied to it. The color intensity is directly proportional to the applied pressure. This is illustrated by Figure 2.
Fig 2: Quickly Developed, Fujifilm Prescale® Dramatically Reveals a Complete Pressure Map