Physics Help Forum Capstan Equation

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Aug 24th 2019, 04:34 PM #1 Junior Member   Join Date: Aug 2019 Posts: 3 Capstan Equation I need help please, as this math is beyond me For capstan , bollard frictions. I even have trusted document that has let me make sense and understand many things of knots and bollard frictions. . Jrre.org/att_frict.pdf gives .25 coefficient for nylon rope on aluminum pipe for brake force. . I have made this chart, the paper shows brake force same on larger pipe, friction by degrees of contact. . I am seeking to mostly fill in 180° on to table assuming same coefficient to show pattern. But , would also like to show 90°, 360°, 720° please. Wouldn't mind knowing how to calc or some tool even. This would help immensely to define more about working knots and rigging, thank-you! . __________________ "Nature, to be commanded, must be obeyed" -Sir Francis Beacon
 Aug 28th 2019, 05:51 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 998 If you have Microsoft Excel available to you, try placing the data into a graph and fitting an exponential trend-line through the data. This will give you an equation fitting the data. However I doubt that, in practice, the actual friction is as precisely matched to the theoretical friction, as this table suggests. For a practical estimate of the friction, I would suggest that a simple linear interpolation (straight line between the adjacent points in the table) will suffice. Having said that, the gap between 5pi and 7pi is a bit large, which will result in a simple linear estimate being less than ideally accurate. If data in this region is vital, then the more accurate exponential fit is indicated. __________________ ~\o/~

 Tags brake force, capstan, equation, friction

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