OptiStruct: Can I use buckling constraints on a topology or free-size optimization?<\/p>\n
There are several barriers for buckling constraints in topology optimization:
\nBuckling constraints are conditional, similar to stress constraints (see Can I use stress constraints with topology or free-size optimization?). Structural instability does not exist when structural parts vanish. This results in the phenomenon of singular topology, where sudden changes of the feasible design domain occur when the density of a design element approaches zero. Gradient based optimization algorithms cannot overcome this barrier. For example, structural stability might be most critical around an opening in a panel. Instead of removing material from the boundary to improve the shape of the opening, the optimization process usually tends to try to add material to the boundary to improve the stability. This prevents the finding of more meaningful topology and shape.
\nAlthough low density material might have very little impact to structural stiffness, it can significantly impact the buckling load limits; often times a small amount of lateral support can significantly improve structural stability.
\nBuckling modes in vanishing areas (low density zones) have no implication to the structural integrity. How to effectively filter out these buckling modes remains another challenging task for buckling constraints.
\nBecause of the above reasons, for the time being, reasonable success can only be expected for one class of design problems — shell structures with non-zero base thickness.<\/p>\n","protected":false},"excerpt":{"rendered":"
OptiStruct: Can I use buckling constraints on a topology or free-size optimization? There are several barriers for buckling constraints in topology optimization: Buckling constraints are conditional, similar to stress constraints (see Can I use stress constraints with topology or free-size optimization?). Structural instability does not exist when structural parts vanish. This results in the phenomenon […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","_lmt_disableupdate":"yes","_lmt_disable":"","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[24,28],"tags":[],"class_list":["post-539","post","type-post","status-publish","format-standard","hentry","category-hypermesh","category-optistruct"],"modified_by":"gantovnik","jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8bH0k-8H","jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":536,"url":"https:\/\/gantovnik.com\/bio-tips\/2020\/05\/optistruct-during-topology-optimization-can-i-use-stress-constraints-through-dresp1-in-the-design-space\/","url_meta":{"origin":539,"position":0},"title":"OptiStruct: During topology optimization, can I use stress constraints through DRESP1 in the design space?","author":"gantovnik","date":"2020-05-09","format":false,"excerpt":"OptiStruct: During topology optimization, can I use stress constraints through DRESP1 in the design space? Defining local stress constraints through DRESP1 in the design region for Topology Optimization is allowed. The Stress-Norm method is used to aggregate stress responses.","rel":"","context":"In "HyperMesh"","block_context":{"text":"HyperMesh","link":"https:\/\/gantovnik.com\/bio-tips\/category\/hypermesh\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1538,"url":"https:\/\/gantovnik.com\/bio-tips\/2022\/08\/210-parametric-curve-in-3d-2-2-2-2-2-2-2-2-2-2-2-2-2-3-2-2-2-2-2-2-2-2-2-3-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2-2\/","url_meta":{"origin":539,"position":1},"title":"#295 DOPTPRM, OPTMETH","author":"gantovnik","date":"2022-08-18","format":false,"excerpt":"","rel":"","context":"In "OptiStruct"","block_context":{"text":"OptiStruct","link":"https:\/\/gantovnik.com\/bio-tips\/category\/optistruct\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1095,"url":"https:\/\/gantovnik.com\/bio-tips\/2021\/11\/190-run-options-for-optistruct\/","url_meta":{"origin":539,"position":2},"title":"#190 Run options for OptiStruct","author":"gantovnik","date":"2021-11-13","format":false,"excerpt":"List of possible run options for OptiStrut -analysis | submit an analysis run. Check the optimization data. -optskip | submit an analysis run without optimization. -check | submit a check job through the command line. -nt X | number of threads\/cores (X) to be used for multiprocessor (SMP) run. -np\u2026","rel":"","context":"In "OptiStruct"","block_context":{"text":"OptiStruct","link":"https:\/\/gantovnik.com\/bio-tips\/category\/optistruct\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":541,"url":"https:\/\/gantovnik.com\/bio-tips\/2020\/05\/doptprm-discrete\/","url_meta":{"origin":539,"position":3},"title":"DOPTPRM, DISCRETE","author":"gantovnik","date":"2020-05-11","format":false,"excerpt":"DOPTPRM, DISCRETE Bulk Data Entry Discreteness parameter. Influences the tendency for elements in a topology optimization to converge to a material density of 0 or 1. Default DISCRETE=1. Recommended bounds are 0.0 and 2.0 for shells, or 3.0 for solids. Improving Discreteness. There are numerous ways to improve the discreteness\u2026","rel":"","context":"In "HyperMesh"","block_context":{"text":"HyperMesh","link":"https:\/\/gantovnik.com\/bio-tips\/category\/hypermesh\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2146,"url":"https:\/\/gantovnik.com\/bio-tips\/2024\/04\/418-some-comments-about-exclude-command-in-linear-buckling-analysis-using-optistruct\/","url_meta":{"origin":539,"position":4},"title":"#418 Some comments about EXCLUDE command in Linear Buckling Analysis using OptiStruct","author":"gantovnik","date":"2024-04-10","format":false,"excerpt":"The EXCLUDE command can be used to select a set of elements to be excluded from a Linear Buckling Analysis. EXCLUDE = ESID (ESID is Set identification number of an element set) The excluded elements are only removed from the geometric stiffness matrix, resulting in a Buckling Analysis with elastic\u2026","rel":"","context":"In "HyperMesh"","block_context":{"text":"HyperMesh","link":"https:\/\/gantovnik.com\/bio-tips\/category\/hypermesh\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1827,"url":"https:\/\/gantovnik.com\/bio-tips\/2023\/04\/344-failsafe-topology-optimization\/","url_meta":{"origin":539,"position":5},"title":"#344 Failsafe topology optimization","author":"gantovnik","date":"2023-04-20","format":false,"excerpt":"Failsafe topology optimization: FSO divides the structure into damage zones and generates multiple models (equal to the number of failure zones). Each model is the same as the original model minus one failure zone. In this process, the FSO method is applied by running Topology Optimization simultaneously for all such\u2026","rel":"","context":"In "HyperMesh"","block_context":{"text":"HyperMesh","link":"https:\/\/gantovnik.com\/bio-tips\/category\/hypermesh\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"_links":{"self":[{"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/posts\/539","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/comments?post=539"}],"version-history":[{"count":0,"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/posts\/539\/revisions"}],"wp:attachment":[{"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/media?parent=539"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/categories?post=539"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gantovnik.com\/bio-tips\/wp-json\/wp\/v2\/tags?post=539"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}