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UID:0-297@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20191225T163000

DTEND;TZID=Asia/Jerusalem:20191225T173000

DTSTAMP:20230527T131159Z

URL:https://aerospace.technion.ac.il/events/influence-of-the-slings-on-the
 -dynamics-of-slung-load/

SUMMARY:Influence of the Slings on the Dynamics of Slung Load
DESCRIPTION:Lecturer:Matan Steiner\n Faculty:Department of Aerospace Engine
 ering\n Institute:Technion – Israel Institute of Technology\n Location:C
 lassroom 165\, ground floor\, Library\, Aerospace Eng.\n Zoom: \n Abstract
 : \n Details: \n Transportation of external loads by helicopters is very c
 ommon and is used for a fast transfer of large loads to places that are ha
 rdly accessible by other means. In these cases\, the load is connected to 
 the bottom of the helicopter by slings. During flight\, the load is subjec
 ted to aerodynamic forces and moments that cause it to oscillate and to ro
 tate about its vertical axis.\nDue to the rotation\, the slings twist and 
 wind together to form a helical ply structure. The winding of the slings c
 reates a torque that opposes the rotation\; as a result\, the rotation slo
 ws down\, stops and then a rotation in the opposite direction develops (un
 winding). This periodic motion is difficult to model\, not only because of
  the complex aerodynamics of the torsional moment (autorotation)\, but als
 o because of the difficulty in modeling the cables periodic winding and un
 winding and predicting the torque that the slings apply on the rotating lo
 ad. The present research deals with the latter torque\, which is a superpo
 sition of the torque induced by the torsional rigidity of each of the slin
 gs\, and the torque induced by changes of the slings spatial geometry as a
  result of the rotation of the load.\nRopes are complex structures and the
 ir mechanical properties are affected by many factors. An empirical model 
 for the torsional rigidity of the ropes is presented. This model includes 
 the influence of tension\, number of rotations in each direction\, and hys
 teresis. The empirical model is used to describe four different kinds of r
 opes and is verified by various tests that include different combinations 
 of tensions and torsion histories.\nThe model of the torque induced by cha
 nges of the slings spatial geometry as a result of the rotation of the loa
 d is derived using energy methods. The solution includes two different reg
 ions: cases where the ropes are not in contact with each other and cases w
 here the ropes are in contact and wind together to form a ply structure.\n
 The coupled model is verified by comparisons of its results to detailed te
 sts that include  different magnitudes of the load rotation angle and dif
 ferent load weights. The verified model is used for parametric studies. Fi
 nally\, the dynamic rotation of the load is modeled and solved. The deriva
 tion includes the effects of friction between the ropes and damping caused
  by each rope. The solution is verified for the four types of ropes and fo
 r different load weights and moments of inertia.
CATEGORIES:Seminars
LOCATION:Classroom 165\, ground floor\, Library\, Aerospace Eng.

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DTSTART:20191027T010000

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