{"id":215870,"date":"2022-06-09T18:34:05","date_gmt":"2022-06-09T18:34:05","guid":{"rendered":"\/forum\/forums\/topic\/how-to-model-bearing-with-springs-on-a-shaft\/"},"modified":"2022-06-09T18:34:05","modified_gmt":"2022-06-09T18:34:05","slug":"how-to-model-bearing-with-springs-on-a-shaft","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-to-model-bearing-with-springs-on-a-shaft\/","title":{"rendered":"How to model bearing with springs on a shaft"},"content":{"rendered":"
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Hello ANSYS experts,<\/span> <\/span><\/p>\n<\/div>\n

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I am working on a project regarding the deflection calculation of a shaft supported by two tapered roller bearings, and I am just trying a simple test model to figure out how to set up bearing configuration and boundary conditions in Workbench.<\/span> <\/span><\/p>\n<\/div>\n

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I have the following questions that I am struggling with for months, and I sincerely look for your inputs to guide me through the problems. <\/span> <\/span><\/p>\n<\/div>\n

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Problem Description:<\/span> <\/span><\/p>\n<\/div>\n

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Material Property of Test Shaft<\/span> <\/span><\/p>\n<\/div>\n

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Bearing Properties:<\/span> <\/span><\/p>\n<\/div>\n

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Bearing <\/span>stiffess<\/span>: K11=K22=5E5 N\/mm<\/span><\/span> <\/span><\/p>\n<\/div>\n

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Bearing Preload: 200 <\/span>lbf<\/span><\/span> <\/span><\/p>\n<\/div>\n

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Question 1:<\/span> <\/span><\/p>\n<\/div>\n

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How to set up boundary conditions for longitudinal springs if I use them to represent bearings in Workbench? How to setup the six DOFs in remote displacement for the spring mobile end connected to the vertex on shaft?<\/span> <\/span><\/p>\n<\/div>\n

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<\/span>PS: My shaft was created in a line body in Design Modular and these two bearing locations are just represented by two vertices. I want to set up each bearing in the way of ANSYS bearing connection but with preload and just two 90-degree spacing springs.<\/span> <\/span><\/p>\n<\/div>\n

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I created each spring with one end grounded and another end to the same remote point <\/span>scoped<\/span> to the vertex which represents the bearing location on this shaft.  <\/span><\/span> <\/span><\/p>\n<\/div>\n

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Question 2: Can you explain how overall the six DOFs of the shaft rigid body are constrained in the scenario considering bearing stiffness?<\/span> <\/span><\/p>\n<\/div>\n

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PS: The bearing stiffness effect on shaft deflection is my study of interest. I don’t want to just fix both UY and UZ at the two bearing locations (plus fixing UX at one shaft end and fixing ROTX at one bearing location for static solver). <\/span> <\/span><\/p>\n<\/div>\n

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I’ve tried to set the Y direction spring’s mobile end only movable along Y axis (Only UY is free, all other DOFs are fixed and I believe that is how a longitudinal spring is supposed to work- only moves along one axis). The same applies to Z direction spring. However, the solver still says my model has been set to fully constraint rigid body motion and can’t give proper computing result for deflection.<\/span> <\/span><\/p>\n<\/div>\n

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Question 3: I wonder if ANSYS Workbench allows people to configure bearing support in the way I used?<\/span> <\/span><\/p>\n<\/div>\n

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PS: As I am interested in seeing the shaft deflection at its hangover tip and these two bearing locations, I setup a Y direction and a Z direction spring to represent a bearing’s stiffness along Y and Z axis. In this test model, the shaft is just subjected to a Y direction 1000 N force. So, I am thinking only using a Y direction spring at both of the two bearing locations is sufficient.<\/span> <\/span><\/p>\n<\/div>\n

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However, in my real project, the shaft hangover tip is also subjected to Z direction force. I don’t want to setup the model separately (Y axis spring one time and Z axis spring one time) for analyzing the Y and Z deflection impact of the forces from different direction. Can you guide me to setup my model to do both tasks at once?  <\/span> <\/span><\/p>\n<\/div>\n

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Question 5: If I model the bearing supports with springs which constraint bearing’s deflection along UY and UZ instead of directly set UY=UZ=0, will the solver essentially give me warning said “you model has not enough constraints and might cause rigid body motion”?<\/span> <\/span><\/p>\n<\/div>\n

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PS: Does this warning pop-up always mean the model is not set properly and results are wrong? <\/span> <\/span><\/p>\n<\/div>\n

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Question 6: What is the length of the spring I should set? Is the length equal to 0.5*(Bearing housing bore Diameter- Shaft Diameter)?<\/span> <\/span><\/p>\n<\/div>\n

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I have read all Peter’s comments on this forum and still have no clue on my project. I also attached a link below of my ANSYS workbench project file for people to help me edit bearing setup and boundary conditions. <\/span><\/span><\/p>\n

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PLEASE CLICK HERE TO<\/strong> <\/span><\/span>Download Workbench Model from Google Drive<\/a> (I use ANSYS Student 2021 R2 and save my project in .<\/span>wbpz<\/span> format on google drive). <\/p>\n

Thanks a lot, in advance.<\/span><\/span> <\/span><\/p>\n<\/div>\n

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Best Regards,<\/span> <\/span><\/p>\n<\/div>\n

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Mito<\/span> <\/span><\/span><\/span><\/p>\n<\/div>\n","protected":false},"template":"","class_list":["post-215870","topic","type-topic","status-closed","hentry","topic-tag-ansys-structural","topic-tag-ansys-workbench"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["58821","196745","240","268142"],"_bbp_likes_count":["0"],"_btv_view_count":["3167"]," _bbp_likes_count":["0"]," _bbp_last_reply_id":["0"],"_bbp_author_ip":["104.119.188.15"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["215870"],"_bbp_forum_id":["27791"],"_bbp_engagement":["240","58821","196745","268142"],"_bbp_voice_count":["4"],"_bbp_reply_count":["6"],"_bbp_last_reply_id":["241317"],"_bbp_last_active_id":["241317"],"_bbp_last_active_time":["2022-11-18 09:59:50"]},"test":"luanhanminggmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/215870","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/215870\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=215870"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}