Composite Failure UMAT in Plane Stress - Constitutive Models
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/
PolymerFEM.com Discussion Boarden-USTue, 05 Dec 2023 09:30:33 +0000wpForo60
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/paged/2/#post-11495
Thu, 19 Feb 2015 10:51:06 +0000Constitutive Modelsatrahttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/paged/2/#post-11495
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11245
Mon, 30 Jun 2014 07:24:41 +0000Im currently facing exactly the same problem like yours. When I tried to simulate progressive damage of a laminate structure with USDFLD, it wil meet convergence difficulty upon reaching the failure stress. Can you please tell me how youve solved this? Thanks a lotXinyao]]>Constitutive Modelsrocketzjuerhttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11245Mr
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11244
Mon, 30 Jun 2014 07:18:58 +0000Hello there,Im now facing exactly the same convergence problem when trying to simulate progress damage with USDFLD. When reaching the failure criterion, it will suffer with convergence difficulty with little increment. Can you please tell me how you finally solve it? ThanksXinyaoMy end goal is to develop an Abaqus UMAT that can be used for progressive failure of laminated composites in plane stress. Im working from the ground up here, but Ive reached a sticking point. I implemented and validated isotropic elasticity and then orthotropic elasticity for a single composite (8-ply) shell. Now Im working with a 4x16 mesh of shell elements, and the problem Im having is that Abaqus seems to be having a convergence problem right at the point of failure. Ive got solution-dependent variables to flag failure, and if I disable the degradation, I can see that the failure stress is being reached in one of the plys, and the appropriate solution-dependent variable gets set. However, if I enable the degradation portion of my UMAT, then Abaqus gets stuck iterating right where failure first occurs. The last step printed to the odb file is the one where all stresses are within allowables.Im wondering if it might have something to do with my degradation approach. Right now, Im using the simplest possible method: if the stress is above allowable, then reduce all elastic moduli by a factor of 1e5. Im confused as to why this causes convergence issues, though. Even if I use a degradation factor smaller than 1e5 Abaqus crashes. In other words, it seems that once any material point undergoes softening, Abaqus cant get the solution to convergence. My expectation here is that the other plys should continue to carry the load once failure occurs in the first ply, but this does not seem to be occurring. Does anyone have any thoughts or suggestions? They would be much appreciated. Thank you!]]>Constitutive Modelsrocketzjuerhttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11244
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11241
Mon, 23 Jun 2014 05:53:03 +0000Constitutive ModelsJorgenhttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11241
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11237
Wed, 18 Jun 2014 03:44:56 +0000Constitutive Modelsmahbodhttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-11237
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-10963
Sun, 09 Jun 2013 08:05:29 +0000Constitutive ModelsFrankMonkeyhttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-10963
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-10962
Sat, 08 Jun 2013 07:48:50 +0000Constitutive Modelsbw_compositehttps://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-10962Composite Failure UMAT in Plane Stress
https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-28718
Tue, 26 Mar 2013 15:19:42 +0000Now Im working with a 4x16 mesh of shell elements, and the problem Im having is that Abaqus seems to be having a convergence problem right at the point of failure. Ive got solution-dependent variables to flag failure, and if I disable the degradation, I can see that the failure stress is being reached in one of the plys, and the appropriate solution-dependent variable gets set. However, if I enable the degradation portion of my UMAT, then Abaqus gets stuck iterating right where failure first occurs. The last step printed to the odb file is the one where all stresses are within allowables.Im wondering if it might have something to do with my degradation approach. Right now, Im using the simplest possible method: if the stress is above allowable, then reduce all elastic moduli by a factor of 1e5. Im confused as to why this causes convergence issues, though. Even if I use a degradation factor smaller than 1e5 Abaqus crashes. In other words, it seems that once any material point undergoes softening, Abaqus cant get the solution to convergence. My expectation here is that the other plys should continue to carry the load once failure occurs in the first ply, but this does not seem to be occurring. Does anyone have any thoughts or suggestions? They would be much appreciated. Thank you!]]>Constitutive Modelseric01https://polymerfem.com/community/constitutive-models/composite-failure-umat-in-plane-stress/#post-28718