Question

Predict pullout force for cancellous screw insertion test in lateral femoral neck. Assume ultimate tensile strength 83MPA, screw outer diamerter= 6.5mm, average uncortical wall tickness3D4mm, screw thread pitch=2.75mm, thread lenght is 40mm and steel bone bone friction factor is 0.35.

Answer 1

pullout formula is given by chapman:

punout = S shear XILOox ( - 2 + 1 - 3 a 6 ) whene Sshear = 83MPA, = thread length = 40mm Do = Outer diameter = 6.5mm Pa pitch = 2.75 mm d = thickness 3D = 4 mm substitute it in formula, F pullout - 83 x 22 x 40 x 6.5 ( 12 4 3 2 1 43) = 11-6x22 x 40x6.5 (5 tonzsver ut = 11.8x22x 40 +6.5 (0.5 +0.5 x 1.45) - 64,380.8(1:45) E pull out = 93, 352.16. Scanned with CamScanner

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