Metal screw contact surface with Wood and Steel Angles

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sam.fares@newmill.com posted this 1 weeks ago

Hi All,

i have got 1/4" diameter metal un-threaded screws that will positioned inside predrilled holes in steel (5/16" diameter holes). The screw will drill thru the wood. So under load, the wood block will try to slide at the screws will try to resist the sliding motion. In doing so, the screw shank will be bearing against the wood block and the interior surface of the pre-drilled hole in steel angles. 

1. What type of contact surface shall i use between screw and steel angle in Ansys Mechanical? 

2. 1. What type of contact surface shall i use between screw and wood in Ansys Mechanical? 

 

Regards,

Sam

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peteroznewman posted this 6 days ago

Hi Sam,

Geometry

Screw: a head and a shank the length of the screw. Don't model the screw threads, don't model the pointed tip, just a flat end instead of a pointed end to make it easier to mesh. Split the face of the shank at the depth of the pre-drilled hole in the wood.

Wood: a 5/16" hole the length of the predrilled hole and a 1/4" hole at the bottom of that hole that is  equal to the depth of thread engagement. In other words, subtract the screw from the wood to make a hole. There will be a small flat between the pre-drilled 5/16" hole and the 1/4" screw hole in the wood. That is okay.

Steel: you already have that hole.

Contacts

  • Bonded contact between the bottom half of the screw and the screw hole in the wood.
  • Frictional contact between the top half of the screw and the pre-drilled hole in the wood.
  • Frictional contact between the top half of the screw and the hole in the steel.
  • Note: the above two can be in a single contact definition, make the screw the Target and the two holes the Contact side.
  • Frictional contact between the underside of the screw head and the steel flange face.
  • Frictional contact between steel flange faces and the wood face.

Best regards,
Peter

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sam.fares@newmill.com posted this 6 days ago

i already removed the threads. I just need to remove the tip.

Thanks a lot for your detailed answer  Peter!

sam.fares@newmill.com posted this 6 days ago

Hi Peter,

1. Is there a way  in spaceclaim to  select all the screws in the model by clicking on one screw and then all other solids of the same shape? There are many screws  in the model and i don't want to select all screws individually?

 

2. Is there a simple way to remove the screw tip on one screw and apply this operation to all other screws?

3. i created  a hole in the wood at each screw. The hole shape in the wood matches up the screw shape. So if i remove the screw tip, do i need to use the "combine" tool again. i am trying to save time because it took me a lot of time to do it.

Regards,

Sam

peteroznewman posted this 6 days ago

Hi Sam,

1. If you used Assemblies and Components, then there is only one screw used many times. If you change that one screw, they will all update.

2. See #1.

3. Removing the screw tip is only a minor improvement to the mesh and not worth a great deal of effort. Leave the tip in place for now.

What is important is to split the face of the screw to separate the part of the screw that is bonded to the wood in the 1/4" hole and the part of the screw that has frictional contact in the 5/16" hole.

Regards,
Peter

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  • sam.fares@newmill.com
sam.fares@newmill.com posted this 6 days ago

Thank you Peter!

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