Skr*w set to carry shear just won't

[ptc-1847855]

This is a problem that I encounter in ProE WF3 Mechanica. Model: A cylinder tube with plates skr*wed on to seal the ends. The load is an internal pressure in the structure. I am using simple fasteners/scr*ws made of steel, set to carry shear. Problem: When simulated, the tube walls move outwards (radially) without affecting the end plates at all. This means the fastener holes of the plates are in a fix radial position, while those in the tube move radially. So it would seem the scr*ws do not carry shear load. However, it seems the fasteners do carry _tensile load, because the end plates follow in that direction (along cylinder axis). Any hints on what is the problem are appreciated. / Adam
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[ptc-758976]

HI, I think the problem is with modelization. I mean, when you assemble the plates to the tube, you must establish a RIGID connection between the plate outer surface and the inner surface of the tube (where they are in contact). With this the load will be transmitted to the fasteners. If this doesn't help you, please let me know about the constraints you have used, so that we can improve the modelization. Shekar

[ptc-1847855]

Thank you for your reply. I have tried setting some different kinds of rigid constraints between the cylinder and the end plate, but nothing seems natural, nor does the model produce reasonable results. Also, I wonder why this rigid constraint should be necessary - the fastener should itself be the constrainer! I fail to see how the fastener could be a realistic model if extra constraints are needed. / Adam

[ptc-758976]

Hi, I have no clue exactly what constraints you have provided. as per your posting, I understand that, a cylinder tube is assembled with a plate , by means of screws. I had requested to establich a rigid connection, because, when an internal pressure is applied on the surface, then when a rigid connection is established between two surfaces, then load will be transmitted from the cylinder surface to the plate, and in turn to the fasteners. With this we can achieve good results. In order to find out the stresses then we have to have a measure (in mechanica) option given to the screw surface, then when you check the RPT file, you will be able to see realistic results. If you can let me know you mail ID, I can send you the suggested technique to use fastener connections. I don't know where to upload in this forum. Shekar[/url]

[ptc-1847855]

I tried sending you pictures of my model to your mail, but it bounced. Guess you have an old adress linked..? However, if you would write me at - I will reply shortly. / Adam

[ptc-758976]

Hi , I have sent you to your given mail ID, a suggested technique to use fastener connections, please go through it and it might help you out. IF you still have problem, please send models to shekar_kandukuri@rediffmail.com, I might help you out. Shekar