https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10595158#M13318 <P>Attached is the staircase shell model I created for design. It pop's up multiple warnings when I run the analysis and I don't know how to fix it.</P><P>&nbsp;</P><P>Please help.</P><P>&nbsp;</P><P>&nbsp;</P> Fri, 03 Sep 2021 00:07:57 GMT Anonymous 2021-09-03T00:07:57Z https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10595158#M13318 <P>Attached is the staircase shell model I created for design. It pop's up multiple warnings when I run the analysis and I don't know how to fix it.</P><P>&nbsp;</P><P>Please help.</P><P>&nbsp;</P><P>&nbsp;</P> Fri, 03 Sep 2021 00:07:57 GMT https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10595158#M13318 Anonymous 2021-09-03T00:07:57Z https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10595161#M13319 <P>Model file attached&nbsp;<A href="https://we.tl/t-plJNokAt8e" target="_blank">https://we.tl/t-plJNokAt8e</A></P> Fri, 03 Sep 2021 00:10:52 GMT https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10595161#M13319 Anonymous 2021-09-03T00:10:52Z https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10596452#M13320 <P>Hi @Anonymous&nbsp;</P> <P>Reduce thickness of panel</P> <P>Why do you have Kz in vertical panel, it's not a problem to run the model, but is it necessary?</P> <P>&nbsp;</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="thickness and kz.png" style="width: 244px;"><img src="https://forums.autodesk.com/t5/image/serverpage/image-id/960780i963C859DBF9E860D/image-dimensions/244x417?v=v2" width="244" height="417" role="button" title="thickness and kz.png" alt="thickness and kz.png" /></span></P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="thickness.png" style="width: 273px;"><img src="https://forums.autodesk.com/t5/image/serverpage/image-id/960782i179DD59E82A4C4BA/image-dimensions/273x478?v=v2" width="273" height="478" role="button" title="thickness.png" alt="thickness.png" /></span></P> <P>&nbsp;</P> <P>You don't need to tick Z direction</P> <P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="modal.png" style="width: 255px;"><img src="https://forums.autodesk.com/t5/image/serverpage/image-id/960783i31400B4D0469A1F6/image-dimensions/255x423?v=v2" width="255" height="423" role="button" title="modal.png" alt="modal.png" /></span></P> Fri, 03 Sep 2021 12:02:09 GMT https://forums.autodesk.com/t5/robot-structural-analysis-forum/instability-type-3-matrix-not-defined-and-problem-902/m-p/10596452#M13320 Simau 2021-09-03T12:02:09Z