Tension in Lifting Slings
This spreadsheet calculates the tension in each leg of a four leg, single point lifting sling set. User inputs the weight of the object that is being lifted and the locations of the lifting points on the body of the object relative to the apex of the sling set. Excel solver is used to find the sling tensions necessary for equilibrium. All the user needs to do is open (or activate and open) solver and press "solve". The lift points are assumed to lie in a horizontal plane.
Enter weight of object in the blue box labeled "weight".
Enter the lift point locations in their blue boxes.
The vertex of the sling set is considered to be the origin point.
Lift point locations are measured relative to the origin.
Lift points are assumed to lie in a horizontal plane.
All the user needs to do is open the solver and hit run!
Sling tension results are displayed in the "solver results" box.
The solver routine finds the sling tensions necessary for equilibrium.
Target cell is the "total summation" of all force and moment sums.
Goal is for total sum to equal zero.
Variable cells are the sling tension cells.
Extra constraints added that all force and moment summations must equal zero.
Evolutionary solver tends to work best.
Be patient as the solver frequently runs several thousand subproblems.
Sling Tension Calculation
Safe Working Load
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