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Multi-jackbolt tensioners (MJTs), registered under the trademark Superbolt or Supernut, are designed to decrease the torque required to tighten large bolted joints. One of the major problems associated with traditional bolt tightening methods is as the diameter of the bolt increases, the amount of torque required to tighten it increases in the third power of the diameter. [1]
The curve representing a clamped parts-to-bolt stiffness ratio of 0.01 shows that when the relative stiffness of the clamped parts is very low, almost all of the load is transferred to the bolt, down to the point where a compressive load equals the preload, and separation at the bolt head occurs, reducing the force in the bolt to zero.
The actual thread heights on both the internal (nut) and external (bolt) threads differ from P / 2 by allowances (or clearances): A minimum root-crest clearance of 0.01 in (0.25 mm) (diametral) between opposing threads with 10 tpi (threads-per-inch) or fewer, and 0.005 in (0.13 mm) for finer pitches.
The mechanical advantage MA of a screw is defined as the ratio of axial output force F out applied by the shaft on a load to the rotational force F in applied to the rim of the shaft to turn it. For a screw with no friction (also called an ideal screw ), from conservation of energy the work done on the screw by the input force turning it is ...
Rd 30° [5]DIN 405 / DIN 20400 Acme thread [6]: 29° ASME/ANSI B1.5-1988 [7]: Metric trapezoidal threads [1]: Tr 30° DIN 103 Buttress threads [6]: S 45° DIN 2781 German buttress threads [6]
The Perry–Robertson formula is a mathematical formula which is able to produce a good approximation of buckling loads in long slender columns or struts, and is the basis for the buckling formulation adopted in EN 1993.
A full (100%) UTS or ISO thread has a height of around 0.65p. Threads can be (and often are) truncated a bit more, yielding thread depths of 60% to 75% of the 0.65p value. For example, a 75% thread sacrifices only a small amount of strength in exchange for a significant reduction in the force required to cut the thread.
If an impeller has only a few blades (i.e a large pitch), it will result in less lift force and in a similar manner for more blades (i.e. very low pitch), there will be high drag force. Blade solidity should not be confused with rotor solidity, which is the ratio of the total area of the rotor blades to the swept area of the rotor.