balakrishnan's blog

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Sandwich plates using Higher order theories

Hi,

While modeling laminated composites we use their material properties (stiffness matrix) to compute the ABD matrix. When E_z of the core is much higher than E_x and E_y, how can we model such a plate using 2D FEM?

How to find normals stresses in the global x y z direction in ABAQUS?

I am trying to find normal stresses (in the global x-y-z direction) of individual layups (plies) in ABAQUS. While post processing I only find S11 S22 S12. Do I always have to use a transformation matrix to find my Sxx Syy and Sxy? Is there a GUI/ Command way to extract the stresses in each ply in xyz directions?

shear stresses in abaqus : Is S13 same as sigma_xz?

Hi,

I have a 0/90/0 rectangular laminate (all 3 D solid elements) . When I plot a through thickness shear stress S13, I want to know if the results are in the local coordinate system or the global coordinate system x-y-z.

ABAQUS: Thermal stresses in a rectangular composite plate

Trying to model a crossply square plate with a sinusoidal temperature loading (uniform along the thickness). I am trying to match the results by Kant et al 2008 and Rohwer et al 2001. I am modeling the compoosite as a 3-D solid elements (making a part and dividing into 4 layers). I always obtain transverse shear stress on the 90 degree layer at 0,b/2,z to be zero.  My results match with that of the paper when I have a single layer of orthotropic material but they dont match when I have 4 layers of equal thickness and an aspect ratio of 5 (length/thickness).

Finding Nx Ny and Nxy in ABAQUS

I am performing a thermal stress analysis of composites. I need to verfiy the results with an existing paper. The variation of the thermal force resultants, Nx, Ny, and Nxy, of the plate along the y direction . I would like to know how to obtain the same with abaqus.

Load Displacement curve for XFEM in ABAQUS

I am using Maxps Damage criteria for an XFEM crack for a three point bending case. I am using displacement loading on the specimen and wish to plot reaction load v/s mouth opening displacement. I would like to know how to obtain the crack tip opening displacement in ABAQUS. All the journal papers I read show a slump in reaction force after the crack starts to propagate. I plot the results and contour plots show me clearly that the crack has started to propagate. Please help.

How to use abaqus input files from abaqus example problems guide

I am new to abaqus and am going through this tutorial on "Damage and failure of a laminated composite plate".  I find lot of input files at the bottom of this example. I tried "importing" them by going to file->import but I find that there is no geometry or mesh associated with it. Does one create the geometry oneself? How do we use the sample ".inp" and ".f" files to learn about abaqus sample problems.

Imperfection in a Riks Analysis (ABAQUS)

I am performing a nonlinear post buckling using Riks method. I went through different tutorials for the same. I happen to see that an *IMPERFECTION is introduced while performing the non linear buckling analysis.Why is it done? How does/will the model react differently if the Imperfection is no introduced?

I wish to plot the graph of load v/s displacement for 1,2,3,4...10 times the critical buckling load during the post buckling analysis (Riks method). How do I do that?

wave propogation in with non local deformation

I have a one dimensional bar with a triangular pulse given at one end for 2 microseconds. The boundary conditions are free-free.I am having two cases. One in which the deformation is local (Hooke's law) and other in which the deformation is dependent on a kernel of radius r (say 5* element length).I find that the wave speed is higher when the deformation is non-local as compared to local deformation case. Is this correct? Is there a way to verify the solution?