<p class=”MsoNormal”>It is not clear to me from your description, and the pictures, if the convergence failure is indicative of a numerical instability or a physical instability.<\/p><p class=”MsoNormal”>What is your expectation for this application?<\/p><p class=”MsoNormal”>Sometimes it is helpful to post process reaction force vs displacement to ascertain the state of structural stiffness at the point of non-convergence.<\/p><p class=”MsoNormal”>If the structure is going completely plastic thru an entire cross section and CZM is beginning, perhaps the structure lacks sufficient stiffness to resist further loading and the non-convergence is indicative of a physical failure.<\/p><p class=”MsoNormal”>If there is plenty of stiffness in the structure and the convergence failure is exclusively a numerical instability, you could try a number of different things in addition to what you already mentioned about contact stiffness factor:<\/p><ul class=”topic-with-bgcolor” type=”disc”><li class=”MsoListParagraph hassub”>Use many more substeps<\/li>\n
<li class=”MsoListParagraph hassub”>Add stabilization damping<\/li>\n
<li class=”MsoListParagraph hassub”>Try dropping midside nodes (in the first pictures you shared, there appeared to be some local hour glassing in a few of the elements at the corner)<\/li>\n
<li class=”MsoListParagraph hassub”>Sometimes, it helps to add a frictional contact pair on top of the bonded pair to help stabilize the elements at the CZM surface after debonding begins.<\/li>\n
<li class=”MsoListParagraph hassub”>Force Full Unsymmetric solver (for enhanced solver robustness after debonding)<\/li>\n
<li class=”MsoListParagraph hassub”>Consider adding local damping to the CZM material model (refer to Section 4.20.5 on ‘Viscous Regulation’ of CZM in the Material Reference Guide.<\/li>\n<\/ul>\n","protected":false},"template":"","class_list":["post-288590","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t