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Dear all:

  I want to simulate the  inclusion-matrix debonding under tensile load with abaqus cohesive element.But when I added the cohesive element around the inclusion, the stress filed was totally changed. I think it is because the stiffness of the cohesive element (K/G1/G2)was not right. Do you know how to choose it so it will not affect the stress field of the oringinal structrure? or can you give me an example? Thanks very much.

I am simulating a cube of sides 10 units. I have applied the
load as pressure of 16 units at top. The cube is meshed by usign a
global seed size of 5. It means, there are 9 elements and 27 nodes
(using C3D8R). I have used the material property of steel for instance.
The base of the cube is fixed and the sides are allowed to move
vertically.  Now i want to calculate the nodal force at the centre of
the cube i.e. at the centroid of the cube (not in the centre of any of
the exterior sides). 

The element is added displacement load in one direction, at the steptime=0, the nodal displacement is zero, and so as the integrated points' strain and stress. However, the internal force NFORC is nonzero. When we calculate internal force by ourselves, it is obtained by the integral for BT*stress. But the stress is zero, how Abaqus calculates the nonzero initial internal force?

The details can be found  in the attachment.

Hello,

I am having issues running an Eigen value simulation on a bridge model that I have developed. The model consists of a bridge super-structure supported by pinned connections on the ends of the bridge length and a roller support in the middle.

The model runs without errors when I do not request an Eigen value analysis, but aborts when I request an Eigen analysis. The message file sites the cause as a factorization error. Warnings also appear stating a zero pivot when releasing the 1st dof of the nodes associated with the roller connection.

This subroutine using VUSDFLD is to
determine position of damage and provide evolution of damage surface, when some
elements failed. The “outer” damage status will transfer to “inner” damage
status.

Now the problem is that when I read the
coordinates of material points, using coordMp（k,1),coordMp（k,1),coordMp（k,1), it returns wrong locations. Then I
tried a very simple loop:

Do
k=1,nblock

        stateNew(k,7)=nblock

end Do

As we know, the extended finite element method has been well used to simulate the localization band propagation and crack propagation without remeshing. It can deal with both strong discontinuity problems (displacement discontinuity) and weak discontinuity problems (strain or acceleration discontinuity). Now, I have always a question: when is strong and when is weak discontinuity using XFEM? In other words, what is the difference for the interpolation function and level set function or other function between strong and weak discontinuity? Thanks.

Liu pengfei