Bolts in Tension pt 2 Andrei Lozzi

1. Bolts in Tension pt 2 Andrei Lozzi Toshiba high pressure turbine casing for 600 MW power station, showing unusually long clamping bolts with very narrow flanges

2. Another apparently good connection rod bolts – note narrow flange & non standard threads

4. β α Modeling frustums of rectangular section that allows for different expansion angles of the sides β to the front α

7. Apparently good connection rod bolts – note narrow flange

8. One more even better connection rod bolts – note short external threads

9. The connecting rod from an Australian manufactured top fuel drag car, without the above features

10. Engine block of GM V16 ‘uniflows’ engine used in locomotives and other high power industrial application. Note block is not a casting but a weldment of rolled plates that have been punched and formed, together with steel castings such as main bearing supports

11. Main bearings of GM V16 ‘uniflows’ engine used in locomotives and other high power industrial application. Note 4 clamping bolts, cast steel construction, castellated nuts, serrated interface. The light is to check alignment of bearings at overhaul

13. This V16 crankshaft is two V8s shafts bolted together at a coupling. The spot welds placed to stop the heads of the clamping bolts from turning gave raise to a surface concentration factor which led to fatigue failures

14. 747 RR engine

15. Middle section of RR engine showing a number of flanges where this engine may be split into functionally separable sections. This is useful for appropriate maintenance, overhaul and replacements.

16. Gear case showing lightweight and low volume bolted joints, that house high capacity power trains

17. 747 upper mounting bolt (one) built into a Hookes joint and having a predictable and very important fatigue failure mode

18. This Wright R3350 turbo cyclone is held in place to the wing by two 10 mm and two 12 mm bolts, at the far left of this image. This engine weighs about 2500 kg

19. The Turn of angle method of determining bolt pretension. The pitch of the thread by the angle of turn, determines how much the bolt will be elongated by, but the members will also be compressed, therefore one needs to know the relative stiffness of kb and km to predict the angle of turn in each situation. In the main it appears to be a significantly better method than the use of torque wrenches, We may estimate that it results in half the uncertainty than is associated with the use of torque wrenches.

21. a) b) Fn F c) d) Sheet steel and cast or forged Al wheels a) Spherical screw seat can relieve bending moment from screw thread. Both screws and bolts can be used to attach wheels but a circular shoulder b) should be used to center the wheel. Spherical and conical seats c) increases contact force Fn and with friction resists turning or loosening of screws. Both conical and spherical seats induce greater stresses in the wheel center than flat seats. Large flat steel washers also improve fatigue stresses in bolts, but requires some additional care in their application (USYD can do it), 1). Sheet steel wheel at centre and cast or forged BMW Al wheel above.

22. Getting around to the wheel attachments used for a multimillion $ crane, newly arrived from Germany.

23. The wheels on the crane uses 10 relatively small bolts. If this could be simply scale down to FSAE size, it would seem to suggest that about 10 2 mm dia screws would do the job. Note that there are 10 holes in the disks spaced neatly between bolts. Germans are noted for this sort of thinking.