{"id":440151,"date":"2025-08-27T08:04:56","date_gmt":"2025-08-27T08:04:56","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/thermomechanical-analysis\/"},"modified":"2025-08-28T13:04:21","modified_gmt":"2025-08-28T13:04:21","slug":"thermomechanical-analysis","status":"answered","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/thermomechanical-analysis\/","title":{"rendered":"Thermomechanical Analysis"},"content":{"rendered":"

<p><p><p class=”my-0″>Hi,<\/p><p class=”my-0″>I am working on a 3D thermomechanical analysis using ANSYS APDL. I have completed the transient thermal analysis and am now coupling the thermal results with the mechanical model using load-teansfer coupling method, where the temperature distribution from the thermal analysis acts as a thermal load in the structural model. The body starts at an initial temperature above 2000°C and cools down to below 1800°C.<\/p><p class=”my-0″>I have two questions regarding the structural analysis setup:<\/p><\/p><\/p><\/p>\n

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  1. <p class=”my-0″>What should be used as the reference temperature for thermal strain calculations? Should it be 20°C, representing a no-thermal-strain baseline, or the initial temperature of 2000°C, given that the body contracts during cooling?<\/p><\/li>\n
  2. <p class=”my-0″>Should the structural analysis be run as a transient or a static analysis? Considering that the thermal analysis is transient, is it necessary for the structural solution to also be transient to capture thermal stresses accurately?<\/p><\/li>\n<\/ol>\n

    <p><p><p class=”my-0″>Additionally, does the structural solution need transient time steps to properly capture the effects of the cooling rate on thermal stresses?<\/p><p class=”my-0″>Any guidance on best practices or examples for modeling this type of thermomechanical cooling scenario in APDL would be highly appreciated.<\/p><\/p><p> <\/p><p>Here is the first version of the code I am using, but it does not work (only the first step’s temperature profile is read through out the time):<\/p><div>fini<\/div><div>\/clear<\/div><div> <\/div><div>! Lire le resultat de la thermique<\/div><div>!———————————————————————————————————–<\/div><div>RESUME,’Thermal_Analysis’,’db’,,0,0<\/div><div>\/reset<\/div><div> <\/div><div>!——————————————————————————————————–<\/div><div>\/filname,Mechanical_Analysis,1<\/div><div>save<\/div><div>!——————————————————————————————————–<\/div><div> <\/div><div>! Delete unused elements et nodes<\/div><div>!———————————————-<\/div><div>\/prep7                                                ! Enters the model creation preprocessor.<\/div><div> <\/div><div>allsel<\/div><div>esel,s,type,,10,110,1                          ! Selects a subset of elements.<\/div><div>nsle,s,1                                              ! Selects those nodes attached to the selected elements.<\/div><div>edele,all                                             ! Deletes selected elements from the model.<\/div><div>ndele,all                                             ! Deletes selected nodes from the model.<\/div><div>etdele,10,110,1                                  ! Deletes element types.<\/div><div> <\/div><div>allsel<\/div><div>cmsel,u,vol_b1                               ! Unselect vol 1<\/div><div>vclear,all                                         ! Deletes nodes and volume elements associated with selected volumes.<\/div><div>aslv,s                                              ! Selects those areas contained in the selected volumes<\/div><div>lsla,s                                               ! Selects those lines contained in the selected areas<\/div><div>ksll,s                                               ! Selects those keypoints contained in the selected lines<\/div><div>vdele,all                                          ! Deletes unmeshed volumes.<\/div><div>adele,all                                          ! Deletes unmeshed areas.<\/div><div>ldele,all                                           ! Deletes unmeshed lines.<\/div><div>kdele,all                                          ! Deletes unmeshed keypoints.<\/div><div> <\/div><div>esel,s,type,,2                                  ! Selects a subset of elements<\/div><div>edele,all                                          ! Deletes selected elements from the model<\/div><div>etdele,2                                           ! Deletes element types<\/div><div>allsel<\/div><div> <\/div><div>! Suppression des conditions aux limites thermiques<\/div><div>!———————————————————————<\/div><div>lsclear,all                                             ! Clears loads and load step options from the database<\/div><div> <\/div><div>! Switch Element type<\/div><div>!—————————-<\/div><div>ETCHG,TTS                                        ! Converts the Thermal elements to Structural elements (70 > 185)<\/div><div> <\/div><div>! Proprietes des materiaux<\/div><div>!———————————–<\/div><div>\/input,Material_Properties,inp<\/div><div> <\/div><div>! Components definition<\/div><div>!——————————<\/div><div>…<\/div><div> <\/div><div>!———————————————————————————————————–<\/div><div>! Boundary Conditions<\/div><div>!———————<\/div><div>FINISH<\/div><div>\/SOLU<\/div><div>! Zero displacement defined at some surfaces<\/div><div>!————————————————————-<\/div><div>cmsel,s,nsurf_1               ! Selects a subset of components and assemblies<\/div><div>cmsel,a,nsurf_2               ! Selects a subset of components and assemblies<\/div><div> <\/div><div>D,all,ux,0                          ! Zero displacements in the x-axis<\/div><div>D,all,uy,0                          ! Zero displacements in the y-axis<\/div><div>D,all,uz,0                          ! Zero displacements in the z-axis<\/div><div>allsel<\/div><div>save<\/div><div> <\/div><div>!———————————————————————————————————–<\/div><div>! Solution of thermal-stress problem<\/div><div>!————————————<\/div><div>\/solu<\/div><div>ANTYPE,trans,new                              ! Specifies the analysis type and restart status<\/div><div>rescontrol,define,all,last                       ! creation des restart files pour tous les loadstep et dernier substep Dispose d’un menu contextuel<\/div><div>TREF,2000                                           ! Defines the reference temperature for thermal strain calculations<\/div><div>allsel<\/div><div> <\/div><div>! Initial condition<\/div><div>!——————<\/div><div>ldread,temp,1,,,2,”Thermal_Analysis”,rth<\/div><div>time,time_array(1,1)<\/div><div>kbc,1<\/div><div>autots,on<\/div><div>solve<\/div><div> <\/div><div>! *do,i,1,n_time_step,1<\/div><div>*do,i,2,10,1<\/div><div>\/solu<\/div><div>time,time_array(i,1)<\/div><div>autots,on                                      ! Specifies whether to use automatic time stepping or load stepping<\/div><div>lnsrch,on                                      ! Activates a line search to be used with Newton-Raphson<\/div><div>outres,all,all                                 ! Controls the solution-result data written to the database<\/div><div>ldread,temp,i,,,1,”Thermal_Analysis”,rth<\/div><div>solve<\/div><div>save<\/div><div>*enddo<\/div><p><br> <\/p><\/p><\/p>\n","protected":false},"template":"","class_list":["post-440151","topic","type-topic","status-answered","hentry","topic-tag-ansys-mapdl-1","topic-tag-ansys-structural","topic-tag-apdl","topic-tag-coupled-simulation","topic-tag-thermomechancial"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27791"],"_bbp_topic_id":["440151"],"_bbp_subscription":["478016","9935","589822"],"_bbp_author_ip":["147.161.153.18"],"_bbp_last_reply_id":["440453"],"_bbp_last_active_id":["440453"],"_bbp_last_active_time":["2025-09-01 07:46:02"],"_bbp_reply_count":["4"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["478016","9935"],"_btv_view_count":["525"],"_bbp_topic_status":["answered"],"_bbp_likes_count":["1"],"_edit_last":["478016"],"_bbp_revision_log":["a:2:{i:440196;a:2:{s:6:\"author\";i:478016;s:6:\"reason\";s:16:\"Adding APDL code\";}i:440249;a:2:{s:6:\"author\";i:478016;s:6:\"reason\";s:26:\"correcting coupling method\";}}"],"_edit_lock":["1756470177:478016"]},"test":"ad03686f05bc30ed78712674d85add55df38955f"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/440151","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":2,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/440151\/revisions"}],"predecessor-version":[{"id":440249,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/440151\/revisions\/440249"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=440151"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}