By
George T. Hahn
George T. Hahn
Mechanical Engineering,
Vanderbilt University
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Kaushik A. Iyer
Kaushik A. Iyer
U.S. Army Research Laboratory
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Carol A. Rubin
Carol A. Rubin
Mechanical Engineering,
Vanderbilt University
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ISBN-10:
0791802388
No. of Pages:
280
Publisher:
ASME Press
Publication date:
2005
Defining the Clamping Force (Bolt Tension). The stress concentrations in a shear joint in the clamping mode depend on both friction and the clamping force or bolt tension, QC, (Equation (1.2), Chapter 1.4). Clamping is obtained when the pre-assembly shank height1, H0, is less than 2t0, the combined initial thickness of the two (or three) panels. The shank must then stretch during assembly to accommodate the misfit. The clamping force, QC, is the elastic restoring force, which is related to ε, the elastic strain of the shank after assembly:
$QC=εEAS$
Where ε = (H − H0)/H0, H is the shank length after assembly, E is the Young's Modulus, and AS is the cross sectional area of the shank. The average shank tensile stress is2:
$σS=εE=QC/AS$
While the key variable for clamping is the shank strain, ε, it is convenient to use the nominal clamping, %CL, which is easy to evaluate, as a measure of ε:
$%CL=100(2t0−H0)∕H0$
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