Search results
Results from the WOW.Com Content Network
A major part of the torque is due to friction, so the differences in friction can cause large variations of the preload with the same torque setting; [3] angle-controlled tightening (also known as turn-of-the-nut method) is a technique where the bolt joint is rotated to some angle that ensures the stress beyond the yield limit of the parts.
Preload in such cases is important for several reasons. First, a tightened bolt experiences only a small fraction of any external load that will be applied later, so that a fully tightened bolt can (depending on the exact application) sustain a much greater load than a loosely tightened bolt.
The applied torque causes the bolt to "climb" the thread causing a tensioning of the bolt and an equivalent compression in the components being fastened by the bolt. The preload developed in a bolt is due to the applied torque and is a function of the bolt diameter, the geometry of the threads, and the coefficients of friction that exist in the ...
The torque applied to the fastener must be determined such that it does not contribute to a service condition where the fastener enters a low-cycle fatigue regime. In general, the use of torque-to-yield fasteners is deprecated except in cases where the materials and structures comprising the entire assembly are certified to be within tolerances ...
In critical fastener joints, embedment can mean loss of preload. Flattening of a surface allows the strain of a screw to relax, which in turn correlates with a loss in tension and thus preload. In bolted joints with particularly short grip lengths, the loss of preload due to embedment can be especially significant, causing complete loss of preload.
ISO 898 is an international standard that defines mechanical and physical properties for metric fasteners.This standard is the origin for other standards that define properties for similar metric fasteners, such as SAE J1199 and ASTM F568M. [1]
The bolt was qualified to a preload (F p*) of 19,300 lbf (85,900 N), actuated by torque (τ) from an actuator (3) having a maximum sustained output of 1,600 lb⋅in (180,000 mN⋅m). [105] The effective preload can change (F cte ) after berthing by the difference between coefficients of thermal expansion of bolts and flanges.
A click torque wrench. A torque wrench is a tool used to apply a specific torque to a fastener such as a nut, bolt, or lag screw.It is usually in the form of a socket wrench with an indicating scale, or an internal mechanism which will indicate (as by 'clicking', a specific movement of the tool handle in relation to the tool head) when a specified (adjustable) torque value has been reached ...