Does fiber orientation in a polymer matrix composite had any impact on moisture diffusivity? how fibre orientation effect hygrothermal aging/ageing?

I am using following code in python script in abaqus to get the stress data at nodes. How to get it according to global node number so it is easier to plot.

All_points = odb.steps['Step1'].frames[-1].fieldOutputs['S'].getSubset(region=sett,position=ELEMENT_NODAL).values

This gives output according to local node number.

Thank you!

Hi everyone,

I want to extract the global mass and stiffness matrices of an Abaqus modal analysis, so as to post-processing it with Matlab.

I have already read many comments on RG regarding this question and added the following lines at the end of my Input file to get the mass and stiffness matrix.

*STEP

*MATRIX GENERATE, STIFFNESS, MASS

*MATRIX OUTPUT, STIFFNESS,MASS,FORMAT=MATRIX INPUT

*END STEP

So far, everything is fine.

I have also written Matlab code that works perfectly for 3D solids or shell elements, but not when both solid and shell elements are together.

In my model, I had to use both solid and shell elements in Abaqus. Looking at the mass and stiffness matrices, I saw that there are 3DOF per node for solid elements and 6 DOF for shell elements, so I cannot use the attached Matlab code as the model has 3DOF for solid elements and 6DOF for shell elements.

My mass matrix looks like this:

1,1, 1,1, 5.115770202111807e-10

1,2, 1,1, 4.923414202110917e-12

1,3, 1,1, -5.733085750203833e-15

2,1, 1,1, 1.453330463639921e-11

2,2, 1,1, -2.461707101055460e-12

2,3, 1,1, 2.866542875101822e-15

1,4, 1,4, 4.295511112920469e-14

1,5, 1,4, -4.054846090561977e-14

1,6, 1,4, -8.889774326370160e-16

2,4, 1,4, 1.225209356335630e-14

2,5, 1,4, -1.103358818158063e-14

2,6, 1,4, -4.552490123962178e-16

...

131010,1, 131010,1, 6.793914400596321e-08

131010,2, 131010,2, 6.793914400596321e-08

131010,3, 131010,3, 6.793914400596321e-08

131011,1, 131011,1, 7.423556175182037e-08

131011,2, 131011,2, 7.423556175182037e-08

131011,3, 131011,3, 7.423556175182037e-08

As you see here, some parts have 3DOF and some parts have 6DOF. Some parts are like a lumped and some parts are like a consistent mass matrix.

In this case, how can one use Matlab in order to get a global stiffness and mass matrices from this?

I've been struggling with this problem for a long time and still haven't been able to solve it.

Here, I am attaching both the mass.mtx file and the Matlab code.

Any help would be appreciated.

function [matlab_matrix] = import_matrix(mtx_file)

%============== Import Stiffness Matrix ==============%

abaqus_stiffness_matrix = dlmread(mtx_file);

% merge node number info from column 1 and DOF info from column 2 and

% store in the 1st column of a new matrix

%If number of DOF are 2,multiply by 2.

matlab_nodes(:,1) = 2*(abaqus_stiffness_matrix(:,1)-1)+ ...

abaqus_stiffness_matrix(:,2);

% merge node number info from column 3 and DOF info from column 4 and

% store in the 2nd column of a new matrix

matlab_nodes(:,2) = 2*(abaqus_stiffness_matrix(:,3)-1)+ ...

abaqus_stiffness_matrix(:,4);

% extract the stiffness values from the .mtx file, and store in a double

% length vector

stiffness_values = [abaqus_stiffness_matrix(:,5); ...

abaqus_stiffness_matrix(:,5)];

% create a matrix of the new matlab node numbers, and a vector of indices

% of their position in the abaqus stiffness matrix

[matlab_matrix_indices, abaqus_stiffness_value_index] = unique( ...

[matlab_nodes; matlab_nodes(:,2) matlab_nodes(:,1)], 'rows');

% compile the stiffness matrix using the new node numbering convention

matlab_matrix = accumarray( matlab_matrix_indices, ...

stiffness_values(abaqus_stiffness_value_index), [], @max, [], true);

so currently im trying to model a masonry structure (clay brick) on ABAQUS and i want to know the compression and tension that is happening on my model. how do i know how to define this material, can i use the von misses stress to know this?

After analysis of a model in ABAQUS CAE, in the results of Pore water pressure am getting white color (in spectrum) as shown in the attached picture. What does it mean..?

Hope someone will help me in this. Thanks in advance..

I want to do a parameter study of a aixsymmetric cylinder in Abaqus. I want to create several jobs where I get the stresses for 3 different points in my model. These points are defined. I wrote a python programm who does exactly that. But as I have not found a way to define nodes/elements with coordinates, my points where I want the stresses of are at the wrong places when the dimensions change. Does anyone have an idea how I could change that?

Hi all ,

I have the following command for accessing the constraint contact pair in abaqus explicit model.

How do i get the master surface name as the output?

I have the following script so far...

>>>>>print((mdb.models[ModelName].constraints['CP-X-1-Lamella-De-Di-27z-1-lin-1-2-Lam']))

({'adjust': ON, 'constraintEnforcement': SURFACE_TO_SURFACE, 'constraintRatio': 0.0, 'constraintRatioMethod': DEFAULT, 'master': ('CP-X-1-Lamella-De-Di-27z-1-lin-1-2', 'Assembly', 1, 9, 0), 'name': 'CP-X-1-Lamella-De-Di-27z-1-lin-1-2-Lam', 'positionTolerance': 0.0, 'positionToleranceMethod': COMPUTED, 'slave': ('CP-X-1-Lamella-De-Di-27z-1', 'Assembly', 1, 9, 0), 'suppressed': False, 'thickness': ON, 'tieRotations': ON})

Hello there,

I am currently working on a python script for abaqus to extract the strain on section points (centroid) of a composite laminate. What worries me is that even for a small amount of data (1250 x 2 in my special case) this takes atleast two minutes. I need to do this for models several times for not only one but atleast 7 section points which seems to take forever.

I will attach my python file down below, maybe there is a faster way to extract the data. Maybe there is even a way to adress the section points of element sets directly, because right now I am adressing them by the element labels, which works in a really weird way.

Thanks alot for all replies

Best regards

I am currently modelling a load being applied in the joint zone of a hemipelvis, which correspond to a person while one leg standing.

Previously, I validated my model with an already existent one from the literature by focusing on the contact area and contact pressure parameters. Nevertheless, when it comes to comparing Von Mises stress between both models, the result variance has increased.

I have asked myself this variance question without yet confirming which is the cause.

Both models have the same boundary conditions and the same magnitude of load. Additionally, they also use the same elements and order of elements(C3D4).

After comparing displacement between them, it seems to be a slight difference (higher in the literature validated model) between them. I attribute this difference to the fact that the already validated model has a smaller thickness than mine in the zone of interest where the load is being transmitted..

Since von Mises stress is calculated from displacement in nodes, it seems plausible to me that the differences in stress between my constructed and the already validated model is due to thickness difference ergo displacement and stress.

Can somebody aid me on this matter?