Question
Asked 22nd Oct, 2020

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

will the moisture diffusivity of a unidirectional and quasi-isotropic laminate same?
If yes, why?
If no, why?

All Answers (3)

23rd Oct, 2020
Orestis Triantopoulos
Vrije Universiteit Brussel
25th Oct, 2020
Vigneshwaran Shanmugam
Luleå University of Technology
Yes, fibre orientation affects the moisture diffusion considerably due to the variation in fibre dispersion as well as edge defects at fibre in the composites....
These investigations are helpful, go through these,
1) The effect of fiber orientation angle in composite materials on moisture absorption and material degradation after hygrothermal ageing
2) Effect of geometric dimensions and fibre orientation on 3D moisture diffusion in flax fibre reinforced thermoplastic and thermosetting composites
2 Recommendations
26th Oct, 2020
Hakim S. sultan Aljibori
University of Warith Al-anbiyaa
Highlights
With increase in temperature, diffusion coefficient and absorbed moisture increased.
The diffusion coefficient and weight gain are higher in water than sea water.
Mechanical degradation caused decrease in failure force and maximum displacement.
The fiber–matrix interface at higher temperature is weaker than lower temperature.
ABAQUS can properly predict the saturation time of aged specimens.

Similar questions and discussions

How to extract global stiffness matrices with Abaqus for post-processing with Matlab?
Question
5 answers
  • Zafer Gokay TetikZafer Gokay Tetik
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);

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