3/24/2021 0 Comments Lifting Lug Design Calculation Pdf
The value of K n is determined by interpolating between the following plots.Lugs are used in combination with clevis pins to transmit load between different mechanical components.
These failure modes are associated with different areas of the lug, as illustrated in the figure below ( Note: Figure not to scale ). The numbers correspond with the labeled sections from the above figure. This has the advantage of being relatively easy, but it only gives an approximate determination of the adequacy of the lug. This method allows for lugs under axial loading, transverse loading, or oblique loading. This method also accounts for the interaction between the lug and the pin. This method is simpler than the Air Force Method, but it only allows for lugs under axial loading and does not account for the interaction between the lug and the pin. While it is relatively easy to perform, it only gives an approximate determination of the adequacy of the lug and should not be employed for critical structure. The equation above assumes a uniform tensile stress over the cross-section. In reality there will be a stress concentration due to the flow of stress around the hole. A simple and conservative approach is to calculate the length of a single shear plane as. If it is desired to account for a slightly longer shear plane, it is common practice to consider a 40 degree line extending from the center of the shear pin. At the point where that 40 degree line intersects the pin hole, extend the shear plane horizontally to the outer edge of the lug. The ultimate bearing strength can be approximated as 1.5 S tu. This method follows closely with the methods presented in Melcon Hoblit and Bruhn, and it relies heavily on curves generated by empirical data. Although this method is somewhat more complex than other lug analysis methods, it is incredibly useful because it allows for lugs under axial loading, transverse loading, or oblique loading, and because it accounts for the interaction between the lug and the pin. These sections disregard the effect of the pin on the lug strength. A discussion of the pin and lug interaction is given at the end. Three of the failure modes are actually combined into a single failure mode -- the bearing strength accounts for bearing, shear-out, and hoop tension. For larger values of eD, the hole is spaced farther from the edge and so bearing is likely to be the critical failure mode. The value of K is read off of one of the following two plots. The first plot is used for Dt 5, which is the most common case. If Dt 5 then the lug is thin, and in that case the value of K is read off of the second plot below. Note 2).
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