Load on bolts due to eccentric loading

[Bharathsf]

I have a flange on which a motor weighing 175 kgs is mounted. The CG of the motor is 155 mm from the flange. The flange is fitted to a shell using 12 bolts circumferentially. What would be the load on each of the boltts due to the eccentric load of the motor. The load is perpendicular to the axis of the bolt. I know there is going to be a moment and a vertical shear load. What would be the secondary shear due to the moment and which bolts would be in tension and which would be in compression?

 

[msquared48]

Are there more rabbits in the mountains or in the winter?

Post a picture. You have not given enough information to answer the question.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ishvaaag]

I would say that is more a question for fabricators of dynamic parts than structural designers. Typically these are provided with the maximum reactions (or a representative set of concurrent reactions) to be applied to the support; some specs on tolerances and permissible deformations may complete the purveyot's data. This may be necessary (apart from usual practice for installation of machines) because the structural designer may not have enough data to derive the proper forces applied to the support, or is to stay ignorant of the particulars of the dynamics effects in the normal and extraordinary events' functioning of the machine; in more than many times being less than prepared to deal with all the dynamic force effects of the machines, just as machine designers use not to be versed in the particulars of structural design.

 

[rb1957]

you need to read up on "bolt group" analysis ... this is a simple problem with a simple analysis.

there are also many inputs missing for a complete answer ...
req'd load factor ?
engine failure torque ?
suport structure ? (is the assumption of plane sections remaining plane valid ?)
oh, and of course PCD of bolts !!

 

[Bharathsf]

Sorry, I couldnt give more information, I was in a hurry. PCD of bolts is 432mm. I just wanted to know in what direction the primary shear and secondary shear forces act in a general way due to the eccentric load

 

[rb1957]

draw yourself a free body. ask your self what loads need to be reacted by the bolts; start with the the case you're posted (there are others to consider) ... there'll be a (shear) force reaction and a moment reaction. then ask yourself how'll these reactions be divided amongst the bolts, go with the simplest ...

sorry, but this is a vey simple bolt group problem

 

[rb1957]

draw yourself a free body. ask yourself what loads need to be reacted by the bolts; start with the the case you've posted (there are others to consider) ... there'll be a (shear) force reaction and a moment reaction. then ask yourself how'll these reactions be divided amongst the bolts, go with the simplest (don't over think it) ...

sorry, but this is a vey simple bolt group problem.

tell us what you think and we'll give more suggestions.

if you ae stuck, and have no to ask (or don't want to ask) then google "bolt group analysis" or get hold of a practical textbook (bruhn, niu, etc) that'll describe the solution approach.