Recent content by ghobbs

There is a lower bearing, but at this stage it's not assembled. I'm not sure what detail I've missed out. I guess the idea of a free body diagram is to keep it simple. The pivot at the top is fixed, so the shaft is only able to pivot about the pivot. There is a magnetic bearing which I've...

Hi I have a problem in understanding the attached free body diagram problem. I have a shaft that is pivoted at the top. Below the pivot is a magnetic bearing with a radial stiffness of 2600N/mm. I've modeled this as a springs in parallel. Below the bearing is a motor with a radial stiffness of...

Thanks Simon I've not used matweb much before, but looking at it now it does seem a very good resource. The Wiley's book is not really what I'm after. I've got plenty of general engineering handbooks. They only ever give a very general listing of material properties. What I'm after is a book...

Hi. I'm looking for a recommendation for a book (or website) that has detailed information on properties of materials. Specifically on mechanical properties. A book that covers all grades of materials, not just a general guide. I'm forever to-ing and fro-ing between websites, datasheets and my...

Ah yes, I understand now. Thanks for the clarification.

Hi. I have a door mounted on 2 hinges, aligned on a vertical axis. The hinge shafts run in flanged plain bushes. I'm trying to work out what forces the flanged bushes will see. The door weighs 100Kg, with the centre of mass at the centre of the door. The door is 2m wide and 2m vertically...

It's essentially a rack of equipment, but to all intents and purposes it's a heavy door. There are 2 hinges in line vertically. My concern is that due to the large inertia, once the door starts moving it won't easily stop.

Hi. I'm designing what effectively is a large door on hinges. The door has the following properties Mass = 336 kg Width = 1.8m The door rotates from closed position through 45deg to open position. In order to 'control' or damp the rotation of the door, I'm fitting a 3Nm friction clutch on...

thanks doc al, that's further clarified things. I'm now fully convinced the springs act in parallel. Thanks again to everyone.

Ah yes, brilliant. That makes sense. Thank you.

Thanks for everyone's response, but unfortunately I still haven't got my head around this. I can't understand how the left spring can be adding to the overall stiffness when it is effectively assisting the motion to the right. If the springs are the same, then we are saying that the overall...

Sophiecentaur, thanks for your reply, but you statement 'k1-k2' doesn't make sense. If the 2 springs have the same spring constant k, then you are saying that the overall spring constant is zero! This is exactly what I'm struggling with. My feeling is that the springs should 'cancel...

Thanks for your replies. If the springs were not precompressed, then yes, I can completely see that the left hand spring would be opposing the motion. Moving the mass to the right would compress the right hand spring and extend the left hand spring, both opposing the motion. But with...

Hi. I have a mass between 2 springs. See attachment. Both springs are compressed. I'm trying to convince myself that the springs act in parallel. I've done the calculations and it checks out ok, but I'm struggling to visualise this. In my mind, if an external force is applied to the mass to...