nexusiv
Aerospace
- Feb 20, 2013
- 2
Hi everyone!
I am trying to model crack closure in a PMMA beam. I want to model active repair so I need to have both opening and closure of the crack. I modeled the beam with a sharp edge crack, using wedge element on crack tip and brick 20-node element for the rest of the domain. No errors or warning for the mesh validation. Both surface of the crack has the same mesh. The crack was modeled with Contour Integral and the contact interaction with General Contact on Initial step. Properties of the contact are Hard Contact and frctionless tangential behaviour. My problem is that the solution won't converge. The beam is encastred on left side and has a symmetry condition on back side. Here is the error statement:
"Too many attempts made for this increment. Abaqus/Standard Analysis exited with an error - Please see the message file for possible error messages if the file exists."
Message file on last iteration:
***WARNING: THE SYSTEM MATRIX HAS 1 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.
7 SEVERE DISCONTINUITIES OCCURRED DURING THIS ITERATION.
7 POINTS CHANGED FROM OPEN TO CLOSED
CONVERGENCE CHECKS FOR SEVERE DISCONTINUITY ITERATION 6
MAX. PENETRATION ERROR -2.32894E-06 AT NODE BEAM-1.2250 OF CONTACT PAIR
(GENERAL_CONTACT_FACES_1,GENERAL_CONTACT_FACES_1)
MAX. CONTACT FORCE ERROR -2.97514 AT NODE BEAM-1.16992 OF CONTACT PAIR
(GENERAL_CONTACT_FACES_1,GENERAL_CONTACT_FACES_1)
PENETRATION ERROR TOO LARGE COMPARED TO DISPLACEMENT INCREMENT.
AVERAGE FORCE 6.96 TIME AVG. FORCE 5.72
LARGEST RESIDUAL FORCE 1.60 AT NODE 16992 DOF 1
INSTANCE: BEAM-1
LARGEST INCREMENT OF DISP. 2.410E-05 AT NODE 2249 DOF 2
INSTANCE: BEAM-1
LARGEST CORRECTION TO DISP. 4.153E-05 AT NODE 2249 DOF 2
INSTANCE: BEAM-1
FORCE EQUILIBRIUM NOT ACHIEVED WITHIN TOLERANCE.
***NOTE: THE SOLUTION APPEARS TO BE DIVERGING. CONVERGENCE IS JUDGED UNLIKELY.
Any help would be appreciated.
I am trying to model crack closure in a PMMA beam. I want to model active repair so I need to have both opening and closure of the crack. I modeled the beam with a sharp edge crack, using wedge element on crack tip and brick 20-node element for the rest of the domain. No errors or warning for the mesh validation. Both surface of the crack has the same mesh. The crack was modeled with Contour Integral and the contact interaction with General Contact on Initial step. Properties of the contact are Hard Contact and frctionless tangential behaviour. My problem is that the solution won't converge. The beam is encastred on left side and has a symmetry condition on back side. Here is the error statement:
"Too many attempts made for this increment. Abaqus/Standard Analysis exited with an error - Please see the message file for possible error messages if the file exists."
Message file on last iteration:
***WARNING: THE SYSTEM MATRIX HAS 1 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.
7 SEVERE DISCONTINUITIES OCCURRED DURING THIS ITERATION.
7 POINTS CHANGED FROM OPEN TO CLOSED
CONVERGENCE CHECKS FOR SEVERE DISCONTINUITY ITERATION 6
MAX. PENETRATION ERROR -2.32894E-06 AT NODE BEAM-1.2250 OF CONTACT PAIR
(GENERAL_CONTACT_FACES_1,GENERAL_CONTACT_FACES_1)
MAX. CONTACT FORCE ERROR -2.97514 AT NODE BEAM-1.16992 OF CONTACT PAIR
(GENERAL_CONTACT_FACES_1,GENERAL_CONTACT_FACES_1)
PENETRATION ERROR TOO LARGE COMPARED TO DISPLACEMENT INCREMENT.
AVERAGE FORCE 6.96 TIME AVG. FORCE 5.72
LARGEST RESIDUAL FORCE 1.60 AT NODE 16992 DOF 1
INSTANCE: BEAM-1
LARGEST INCREMENT OF DISP. 2.410E-05 AT NODE 2249 DOF 2
INSTANCE: BEAM-1
LARGEST CORRECTION TO DISP. 4.153E-05 AT NODE 2249 DOF 2
INSTANCE: BEAM-1
FORCE EQUILIBRIUM NOT ACHIEVED WITHIN TOLERANCE.
***NOTE: THE SOLUTION APPEARS TO BE DIVERGING. CONVERGENCE IS JUDGED UNLIKELY.
Any help would be appreciated.