Notch Effect in Four Different Designs

Screwdriver is an instrument to use for screwing (installing or removing) cortical, spinal, or locking screws in the medical sector. These screwdrivers, working in the medical sector, operate in relatively difficult conditions. It is used with a torque handle while screw insert to human bone and these types of instruments are sterilized many times under the dry steam with an autoclave. We are going to examine the notch effect on the four different designs in this article with the aid of finite element analysis.
Four different designs were made in the same shape except for the notch section. AISI1020 was used for four different designs and they are fixed in the same region(Six hexagon face). 10Nm torque was applied to parts. Each part of mesh size was applied 1mm and mesh control was applied 0.08mm on Hexagon surfaces and notch surfaces.

Screwdriver

Surface of Applying Torque

Fixture for the Parts

Screwdriver Bit Designs

Part 1

Part 2

Part 3

Part 4

Results

Designs	Min	Max
Part 1	0	11.055,07
Part 2	0	9.972,53
Part 3	0	10.646,66
Part 4	0	10.119,90

Von Mises Stress(MPa)

Designs	URES
Part1	0,422
Part2	0,463
Part3	0,436
Part4	0,427

Displacement(mm)

Designs	Min	Max
Part1	-3.542,57	3.820,14
Part2	-4.505,51	4.500,71
Part3	-5.042,64	5.045,13
Part4	-4.816,49	5.085,81

Shear Stress(TXZ: Shear in Z Dir. On YZ Plane)

Designs	Min	Max
Part1	-3.925,31	4.990,82
Part2	-2.504,68	4.714,16
Part3	-3.220,74	4.722,68
Part4	-2.895,93	2.802,05

Shear Stress(TYZ: Shear in Z Dir. On XZ Plane)

Designs	Min	Max
Part1	-4.228,01	5.325,54
Part2	-4.122,09	4.020,45
Part3	-5.031,32	4.888,66
Part4	-5.261,00	5.360,00

Shear Stress(TXY: Shear in Y Dir. On YZ Plane)

Shear Stress TXZ for Part 2

Conclusion

When you look at the finite element analysis, You will see the von mises stress in part 2 lower than the others. Also displacement of part 2 is higher than the others. When the Shear stresses were examined, Part 2 exhibited good performance against the other except TXZ. It was clearly found to be the most effective part 2 than the other designs in preventing notch damage. İt is obvious that the notch effect will occur in part 1. The results are showing that except TXZ.