fehrich
New member
- Feb 18, 2010
- 7
Hi everyone,
Since a couple of days I try to model (Abaqus 6.8 Explicit) an impact on a composite plate which includes a cohesive layer for delamination. Since I use a VUMAT for shell elements, I want the layers be modelled in conventionell shell elements.
However, I could not get it working. Here is what I did:
1) model one 3D solid and apply cohesive element section. Mesh as cohesive element
2) model two 3D planar shell elements and add composite layup. mesh with shell elements
3) define for each part a surface
4) tie the buttom surface of the upper laminate to the top=sied of the cohesive layer and vice-versa for bottom plies
5) add one interaction face-to-face for each of the contact sides with frictionless tagential behaviour
6) apply BC arround the edges of the plate
Although it runs, it produces a whole lot of warning messages I cant solve.
So could you please explain, if the general procedure is correct? I attached the inp file.
Many thanks
Fabian
-----------------------------------------------
PS: The warnings are
Node set assembly_plate-1-1_plate-1-refpt_ has no members and will be ignored. Nodes defined in this set may have been deleted because they were not connected to any elements.
The option *boundary,type=displacement has been used; check status file between steps for warnings on any jumps prescribed across the steps in displacement values of translational dof. For rotational dof make sure that there are no such jumps. All jumps in displacements across steps are ignored
THE SECOND SHEAR NOMINAL STRAIN IS NOT SPECIFIED OR THE SPECIFIED VALUE IS EQUAL TO OR SMALLER THAN ZERO. THIS IS NOT ALLOWED IN Abaqus. THE SAME VALUE OF FIRST SHEAR NOMINAL STRAIN WILL BE ASSIGNED TO IT IN THIS CASE
There are 4 warning messages in the data (.dat) file. Please check the data file for possible errors in the input file.
The elements in element set WarnElemFailElemInContact are part of a deformable surface that is referenced by a *CONTACT PAIR option in addition to having material properties that allow the element to fail. For elements that can fail, contact should be defined using the *CONTACT option.
The thickness used in the general contact algorithm for elements in element set WarnElemGContThickReduce has been reduced. See the status file for further details.
Boundary conditions are defined at the the nodes contained in node set WarnNodeBcIntersectKinCon. In addition the nodes are also part of a surface involved in kinematic contact. The kinematic contact constraint will be overridden by the boundary conditions in case of a conflict. Penalty contact may be used instead.
For a self contact surface, the facets of the elements in element set WarnElemFacetThickPt63d-Step1 are thicker than 0.6 times an edge or diagonal length of the facets. Use the MAXRATIO parameter on *SURFACE DEFINITION to allow automatic rescaling of the contact thicknesses where necessary for this surface. Refer to the status file for further details.
The slave surface nodes in node set WarnNodeMassRatio3fix-Step1 have much larger masses than the nodes on the master surface. Significant contact noise may result. Suggested workarounds include setting the WEIGHT parameter so that what was the master surface becomes a pure slave surface in the contact pair, using mass-scaling to adjust the ratio of nodal masses, or using the penalty contact algorithm. See the status file for further details.
The option *BOUNDARY,TYPE=DISPLACEMENT has been used with a jump in displacements at the nodes in node set WarnNodeWithJump-Step1 at the beginning of the next step; all jumps in displacement across steps are ignored. See the status file for further details.
Since a couple of days I try to model (Abaqus 6.8 Explicit) an impact on a composite plate which includes a cohesive layer for delamination. Since I use a VUMAT for shell elements, I want the layers be modelled in conventionell shell elements.
However, I could not get it working. Here is what I did:
1) model one 3D solid and apply cohesive element section. Mesh as cohesive element
2) model two 3D planar shell elements and add composite layup. mesh with shell elements
3) define for each part a surface
4) tie the buttom surface of the upper laminate to the top=sied of the cohesive layer and vice-versa for bottom plies
5) add one interaction face-to-face for each of the contact sides with frictionless tagential behaviour
6) apply BC arround the edges of the plate
Although it runs, it produces a whole lot of warning messages I cant solve.
So could you please explain, if the general procedure is correct? I attached the inp file.
Many thanks
Fabian
-----------------------------------------------
PS: The warnings are
Node set assembly_plate-1-1_plate-1-refpt_ has no members and will be ignored. Nodes defined in this set may have been deleted because they were not connected to any elements.
The option *boundary,type=displacement has been used; check status file between steps for warnings on any jumps prescribed across the steps in displacement values of translational dof. For rotational dof make sure that there are no such jumps. All jumps in displacements across steps are ignored
THE SECOND SHEAR NOMINAL STRAIN IS NOT SPECIFIED OR THE SPECIFIED VALUE IS EQUAL TO OR SMALLER THAN ZERO. THIS IS NOT ALLOWED IN Abaqus. THE SAME VALUE OF FIRST SHEAR NOMINAL STRAIN WILL BE ASSIGNED TO IT IN THIS CASE
There are 4 warning messages in the data (.dat) file. Please check the data file for possible errors in the input file.
The elements in element set WarnElemFailElemInContact are part of a deformable surface that is referenced by a *CONTACT PAIR option in addition to having material properties that allow the element to fail. For elements that can fail, contact should be defined using the *CONTACT option.
The thickness used in the general contact algorithm for elements in element set WarnElemGContThickReduce has been reduced. See the status file for further details.
Boundary conditions are defined at the the nodes contained in node set WarnNodeBcIntersectKinCon. In addition the nodes are also part of a surface involved in kinematic contact. The kinematic contact constraint will be overridden by the boundary conditions in case of a conflict. Penalty contact may be used instead.
For a self contact surface, the facets of the elements in element set WarnElemFacetThickPt63d-Step1 are thicker than 0.6 times an edge or diagonal length of the facets. Use the MAXRATIO parameter on *SURFACE DEFINITION to allow automatic rescaling of the contact thicknesses where necessary for this surface. Refer to the status file for further details.
The slave surface nodes in node set WarnNodeMassRatio3fix-Step1 have much larger masses than the nodes on the master surface. Significant contact noise may result. Suggested workarounds include setting the WEIGHT parameter so that what was the master surface becomes a pure slave surface in the contact pair, using mass-scaling to adjust the ratio of nodal masses, or using the penalty contact algorithm. See the status file for further details.
The option *BOUNDARY,TYPE=DISPLACEMENT has been used with a jump in displacements at the nodes in node set WarnNodeWithJump-Step1 at the beginning of the next step; all jumps in displacement across steps are ignored. See the status file for further details.