{"id":457479,"date":"2026-04-30T18:16:22","date_gmt":"2026-04-30T18:16:22","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/runtime\/"},"modified":"2026-04-30T18:16:22","modified_gmt":"2026-04-30T18:16:22","slug":"runtime","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/runtime\/","title":{"rendered":"Runtime"},"content":{"rendered":"<p>&lt;p class=&#8221;isSelectedEnd&#8221;&gt;Hi there,&nbsp;&lt;\/p&gt;&lt;p class=&#8221;isSelectedEnd&#8221;&gt;I have an explicit simulation that is running very slowly. One of the parts in the simulation is rigid, and according to the messag file, this part has the lowest timestep.&nbsp;Based on the LS-DYNA documentation, I decreased the young&rsquo;s modulus of the rigid part (by assigning different material properties) in order to increase the timestep and reduce the overall runtime. I then ran the simulation again; however, it is now running even slower.&nbsp;Could anyone help me understand why reducing the young&rsquo;s modulus of the rigid part would make the simulation slower instead of faster (although the document says it should make it faster)?&lt;\/p&gt;&lt;p class=&#8221;isSelectedEnd&#8221;&gt;I also have another question. The other components of the simulation consist of uniformly distributed SPH particles. I checked the d3hsp file for the &#8220;smallest&#8221; timestep entries, and indicate a few SPH nodes. My question is: if the SPH particles are distributed uniformly, why are only a few of them controlling the smallest timestep? What could be causing this? How can I correct the issue??&lt;\/p&gt;&lt;p&gt;I would appreciate any help with these issues.&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-457479","topic","type-topic","status-publish","hentry","topic-tag-ls-dyna-run-time-1","topic-tag-timestep","topic-tag-timestepsize"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27814"],"_bbp_topic_id":["457479"],"_bbp_author_ip":["142.104.85.82"],"_bbp_last_reply_id":["457663"],"_bbp_last_active_id":["457663"],"_bbp_last_active_time":["2026-05-06 09:18:42"],"_bbp_reply_count":["3"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["682300","13640"],"_btv_view_count":["90"],"_bbp_topic_status":["unanswered"],"_bbp_subscription":["13640","682300"]},"test":"lsdyna928gmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/457479","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\/457479\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=457479"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}