strength calculation of lifting eye
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![Page 1: Strength Calculation of Lifting Eye](https://reader035.vdocuments.site/reader035/viewer/2022071702/563db97e550346aa9a9dda24/html5/thumbnails/1.jpg)
Strength calculation of Lifting eye
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All ships have lifting eye provided for lifting motors, their parts, and other
equipments. The following procedure describes how to verify the strength of the
lifting eye
Design load (P) = Safe Working Load (SWL) x Dynamic coefficient (Dynamic
coefficient is taken as 1.3. recommended by Classification society rules)
Allowable stress
Tensile stress, σa = Yield limit / (1.5 k) = 235 ƒ1 / (1.5 k)
Shear stress, τa = σa / √3 = 235 ƒ1 / (1.5 k x √3 )
where k = 0.85 (mild steel) and 1.0 for high tensile steel, and ƒ1 = 1.0 (mild steel),
1.08 (AH27), 1.28 (AH32), 1.35 (AH34), 1.39 (AH36), 1.43 (AH40)
![Page 2: Strength Calculation of Lifting Eye](https://reader035.vdocuments.site/reader035/viewer/2022071702/563db97e550346aa9a9dda24/html5/thumbnails/2.jpg)
Required section area for shear stress, Ars
For shear stress the area shown by the hatch on the righ section is applicable.
Ars = P / τa = 1.3 x SWL / (235 ƒ1 / (1.5 k x √3 )) = (3.38 x k x SWL) / 235 ƒ1
Actual section area for shear stress, Aas
Aas = b x t (as shown in the shaded area on the right section)
Required section for tensile stress, Art
For tensile stress, the area is shown by two shaded hatch on the lower part is
applicable.
Art = P / σa = 1.3 x SWL / ( 235 ƒ1 / (1.5 k)) = (1.95 x k x SWL) / 235 ƒ1
Actual section area for tensile stress, Aat
Aat = 2 x b x t (as shown by two shaded hatch on the lower drawing)
Evaluation
Aas ≥ Ars (satisfies shear stress requirement )and
Aat ≥ Art (satisfies tensile stress requirement)