Element instability leads to the unexpected element erosion. Observed symptoms indicative of instabilty are wild distortions of the element seen right before failure. I was able to get stable behavior using the attached input deck. Here, the element remains stable until failure, yield occurs at an x-stress of XT, and failure occurs at an x-strain of DFAILT=0.06. Notable changes made to the model are: - time step scale factor is set to 0.7, and - hourglass control is set to type 6 (with an hourglass coefficient of 0.1), and - for the sake of simplicity, some of the more esoteric variables for the material are left blank. You'll notice that history variable #1, which represents the failure flag for tensile fiber mode, goes from 1 to 0 when the tensile fiber stress (x-stress) reaches XT. It may be of interest to know that extra history variables for mat 54 solids are: 1 failure flag tensile fiber mode 2 failure flag compr. fiber mode 3 failure flag tensile matrix mode 4 failure flag compr. matrix mode 5 total failure 6 damage parameter (SOFT) 15 local fiber strain 16 local matrix strain 17 local shear strain jd Ticket#2019111810000133 ___________________________________________________________ Author: Stefan Hartman Date: 2017-04-03 01:30:21 -0700 (Mon, 03 Apr 2017) New Revision: 8278 Modified: trunk/Vol_II_Materials/MAT_054__MAT_ENHANCED_COMPOSITE_DAMAGE.docx Log: Add parameter TI for transversal isotropic behavior for solids ______________________________________________________ Author: Stefan Hartman Date: 2014-06-18 03:12:09 -0700 (Wed, 18 Jun 2014) New Revision: 5496 Modified: branches/R7.1/Vol_II_Materials/MAT_054__MAT_ENHANCED_COMPOSITE_DAMAGE.docx trunk/Vol_II_Materials/MAT_054__MAT_ENHANCED_COMPOSITE_DAMAGE.docx Log: Corrected some enhancements to MAT_054 for thick shells type 3 & 5 __________________________________________________________ TSHELLS: We've become aware that contrary to what the manual currently states, MAT_54 does (since 2016) support the TSHELLS that use the thin shell material routines (i.e. types 1, 2 and 6). Ticket#2019101510000141 and offline email between Jim, Lee, and Alex. trunk Manual updated on 1/15/20 by jd. ---------------------- I don't think there is any reason for lack of support by forms 1 and 2 other than the work was not done to enable them. With some effort, I think a number of materials could be enabled for thick shells. Lee 9/12/12 I confirmed with the attached test case that tshell forms 1 and 2 don't accept mat_054 whereas tshell forms 3 and 5 are OK with it. Jim 9/12/12 ________________________________________ In any case, here's what I can gather from my reading of the code - The fiber and matrix failure criteria are applied only to the local x-y plane of the element, and the out-of-plane constitutive relation is not affected. In essence, for the purpose of calculating the damage, the x-y plane of the solid element is considered as a shell surface. Some of the history variables are as follows: 1 failure flag tensile fiber mode 2 failure flag compr. fiber mode 3 failure flag tensile matrix mode 4 failure flag compr. matrix mode 5 total failure 6 damage parameter (SOFT) 15 local fiber strain 16 local matrix strain 17 local shear strain Ushnish 9/17/12 Ushnish or I will dissect f3dm54 as necessary to resolve any questions about mat54 solids. From your earlier comments, you indicated that Dynamore was not involved in development of f3dm54 so I shouldn't have been bothering you and Stefan in the first place. Jim yes, these materials were developed by Dynamore for shells a long time ago. I think the extension to solid elements (f3dm54) was done later by John, but I am not sure. And I saw that for mte.eq.54 and mte.eq.55 the same subroutine f3dm54 is called. For me, it seems that only material 54 will work correctly. History variables of shell mat 54 and solid mat54 should be the same for numbers 1 to 6. Best regards, Tobias 9/5/12 ___________________________________________________________ From http://www.dynasupport.com/howtos/material/history-variables, 1 failure flag tensile fiber mode 2 failure flag compr. fiber mode 3 failure flag tensile matrix mode 4 failure flag compr. matrix mode 5 total failure 6 damage parameter (SOFT) common/aux14loc/ ccc 19.6.89 ma 18.07.89 c neue felder: ec,qq1,qq2,d,ec2, dt cge...reihenfolge vertauscht 23.11.90 &sig1(nlq),sig2(nlq),sig3(nlq),sig4(nlq), &sig5(nlq),sig6(nlq),sig7(nlq), &ef(nlq),ec(nlq),em(nlq),ed(nlq), &efail(nlq),dam(nlq),dtfail(nlq), &q1(nlq), &q11(nlq),q12(nlq),q13(nlq),q31(nlq), &q32(nlq),q33(nlq), & eps1(nlq),eps2(nlq),eps4(nlq), &qq1(nlq),qq2(nlq), &ef2(nlq),ec2(nlq),em2(nlq),ed2(nlq),c11(nlq),