Preloading Force: Turning the bolt causes the threads to engage and stretch, which produces the preload force that keeps the threads in place. Shear Force: The shear force is the transverse pressure working against the bolt in a perpendicular direction. It can be present alone or in combination with tension force.
Consequently, what is pretension in bolts?
Manual Pretensioning of Preloaded Bolts. Preload is the tension load developed in a fastener while tightening. The tensile force thus induced in bolt, creates a compressive force in the bolted joint this is called clamp force. The clamp force in an unloaded bolted is assumed to be equal and opposite of the preload.
What is a clamp load?
The clamp load, also called preload of a fastener, is created when a torque is applied, and so develops a tensile preload that is generally a substantial percentage of the fastener's proof strength. Fasteners are manufactured to various standards that define, among other things, their strength.
Why is bolt preload important?
However, when applied correctly, preloading can reduce or overcome the causes of bearing vibration, heat build-up, noise and fatigue. This is important because the degree of internal clearance within a bearing can influence a variety of factors, including noise, vibration, heat build-up and fatigue life.