What about if the bolt is a revolute feature and the shank is made up of 2, coaxial surfaces?? Ansys will not allow you to pick those 2 surfaces to apply the pretension, which is extremely aggravating.
What about for blind holes in assemblies? if I have a fully threaded bolt inserted into a blind hole connecting 2 parts, would the whole shaft of the bolt be the body i apply in pretension?
Hello Jack, First question I have for you is what is important? Are you studying the failure of the threads? Or is this clamping a gasket you're studying? In other words, is the failure of the hardware itself important or what it is fastening? If you are interested in seeing if the hardware is going to fail, you're going to have to model the threads in and do a small scale analysis and I'll explain why. When a screw and threaded hole engage, the bottoming of the screw will cause the screw to deform and the bottom area will get wider. This will cause the last 2-3 threads to be the only threads truly engaging. If you are not interested in the hardware, I recommend just bonding the surfaces in the blind hole to the shaft. Sincerely, John Dao
@@johndao8592 Hello John, Thank you for the reply and recommendation. Sorry i did not specify what I'm trying to simulate. The model is simply a table and its legs screwed in from the top. So in total i have 4 pretension bolts, in blind holes and im looking to see if the table and legs remained fastened together when subjected to a large load in the y direction. Around 100lbs for the load. I modeled the screws without any threads and separated the faces with their respective contact (leg and table). Thank you, Jack
Hello Cylex96, I usually try to insert a "method" and apply a "multizone" to get a a nice hex mesh. There are many meshing capabilities of Ansys, I hope to walk you through some in more tech-tip videos or our live AVA webinars. Please subscribe if you haven't! Sincerely, John Dao
There is no sense to make bolts so long. You set all contacts as Bonded, and this is real issue. Keep in mind that Petension tool splits bolt's mesh on bolt centroid plane, and here it happens inside bonded contact surface area (looks like bonded contact between bolt and washer? =) ). Contacts must be bonded only bolt-nut (and maybe bolt-upper plate). All others are Frictional. No contact (or set Frictionless) must be along cylindrical face of bolt except bonded bolt-nut.
@@KETIVTechnologies describe the contact used between the surfaces of interest. I mean between the nut and the washer. Between the washer and the plate ...
Ohhhh, you´re amazing! you save my university project jaja. Greetings from Argentina! and thank you!!
Happy to hear that!
Very useful tip. Thanks, mate.
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It was really helpful
Glad you found it helpful!
excellent video.
What type of contact do you use between the components?
Greetings from Peru
What about if the bolt is a revolute feature and the shank is made up of 2, coaxial surfaces?? Ansys will not allow you to pick those 2 surfaces to apply the pretension, which is extremely aggravating.
Thanks!
sir could u please explain how u setup contact in this analysis
What about for blind holes in assemblies? if I have a fully threaded bolt inserted into a blind hole connecting 2 parts, would the whole shaft of the bolt be the body i apply in pretension?
Hello Jack,
First question I have for you is what is important? Are you studying the failure of the threads? Or is this clamping a gasket you're studying? In other words, is the failure of the hardware itself important or what it is fastening?
If you are interested in seeing if the hardware is going to fail, you're going to have to model the threads in and do a small scale analysis and I'll explain why. When a screw and threaded hole engage, the bottoming of the screw will cause the screw to deform and the bottom area will get wider. This will cause the last 2-3 threads to be the only threads truly engaging.
If you are not interested in the hardware, I recommend just bonding the surfaces in the blind hole to the shaft.
Sincerely,
John Dao
@@johndao8592 Hello John,
Thank you for the reply and recommendation. Sorry i did not specify what I'm trying to simulate. The model is simply a table and its legs screwed in from the top. So in total i have 4 pretension bolts, in blind holes and im looking to see if the table and legs remained fastened together when subjected to a large load in the y direction. Around 100lbs for the load. I modeled the screws without any threads and separated the faces with their respective contact (leg and table).
Thank you,
Jack
Why I got more faces in threading place and got more mesh time how to avoid that
What are your mesh settings for the bolts?
Hello Cylex96,
I usually try to insert a "method" and apply a "multizone" to get a a nice hex mesh. There are many meshing capabilities of Ansys, I hope to walk you through some in more tech-tip videos or our live AVA webinars. Please subscribe if you haven't!
Sincerely,
John Dao
Thanks John!
There is no sense to make bolts so long. You set all contacts as Bonded, and this is real issue. Keep in mind that Petension tool splits bolt's mesh on bolt centroid plane, and here it happens inside bonded contact surface area (looks like bonded contact between bolt and washer? =) ). Contacts must be bonded only bolt-nut (and maybe bolt-upper plate). All others are Frictional. No contact (or set Frictionless) must be along cylindrical face of bolt except bonded bolt-nut.
Hi, and which contacts you user?
Hello can you clarify the question please? KETIV | Nicole Morris
@@KETIVTechnologies describe the contact used between the surfaces of interest. I mean between the nut and the washer. Between the washer and the plate ...