Dear Mechanicians,

time and again the question of modeling moving heat sources pops up, often in the context of laser heating.

One can achieve this using the subroutine DFLUX in ABAQUS.

I decided to post some links here to avoid responding with a longer explanation to every individual seeking assistance.

Please note that I have never worked with any one of these codes and have no access to ABAQUS at present.

No warranty is given by me.

"ELEMENT DELETION" is available in Abaqus Explicit:
User's Manual 23.8.1 User-defined mechanical material behavior

For welding you can also use the Abaqus Welding Interface
http://www.3ds.com/products/simulia/portfolio/abaqus/abaqus-portfolio/ab...

For an introduction to subroutine coding get the file
http://imechanica.org/files/Writing User Subroutines with ABAQUS.pdf

For any ABAQUS-related question: seek advice from the Abaqus mailing list
https://groups.yahoo.com/neo/groups/Abaqus/info
This is a moderated list. Search the archive of this mailing list for the terms "laser", "welding" and "(moving) heat source" in combination with "DFLUX". It has been discussed several times. Two of the links below are taken from the archive of that list.

Try to verify your model with analytical solutions provided in these books:
Carslaw and Jaeger: "Conduction of Heat in Solids"
Duley, Walter W.: "Laser processing and analysis of materials"

Good luck

Frank

----------------------------------------------------------------------------------

http://abaqus-users.1086179.n5.nabble.com/Gaussian-beam-incident-on-cyli...
Gaussian beam incident on cylinder

Moving laser load around the cylinder
http://abaqus-users.1086179.n5.nabble.com/Moving-laser-load-around-the-c...

 
http://www.dtic.mil/dtic/tr/fulltext/u2/a403503.pdf
DEPARTMENT OF THE ARMY
U.S. Army Corps of Engineers
Publication Number:  ETL 1110-2-365
Title: Engineering and Design - Nonlinear, Incremental Structural Analysis of Massive Concrete Structures
Proponent: CECW-ED
Publication Date: 31 August 1994

Rodrigo Andrade:
Pipe circularity reformation via line heating
Massachusetts Institute of Technology
http://dspace.mit.edu/handle/1721.1/16795

with implementation of a laser :
A THERMAL AND MECHANICAL MODEL OF LASER CLADDING
BY AUGUSTO MOITA DE DEUS
www.demat.ist.utl.pt/~augusto/papers/thesisAMD.pdf

CONCURRENT FIRE DYNAMICS MODELS AND THERMOMECHANICAL
ANALYSIS OF STEEL AND CONCRETE STRUCTURES
PhD thesis by Joonho Choi
Georgia Institute of Technology
December 2008

A Thermal and Mechanical Model of Laser Cladding
PhD thesis
Augusto Moita de Deus
University of Illinois at Urbana-Champaign, 2004

Hi my Friends,

I am doing abaqus run for a copper specimen under hydrostatic pressure. The magnetude of pressure is in order of several Giga Pascals. In my material definition, I have defined stress-strain flow up to strain of 0.4. But as you can see in attached photo, some elements show very large deformation (considerably larger than 0.4). Knowing that I have not defined stress strain behaviour for srain greater than 0.4, how this can be occure? Unfortunately, niether adaptive meshing nor element deletation were not eliminate this issue!!

Best Thanks

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For more information and to apply for the position, see the link below.
https://jobs.bd.com/job/durham/cae-senior-engineer/159/404781

Attached paper supplies detailed procedure and necessary scipt for applying PBC.

Hi all,

I have a  20 node hexahedral "Thermomechanical" element in our inhouse software which i am trying to validate against Abaqus .

The problem is, the displacements, nodal forces match exactly ( Just compared the max min values in the legends! and checked a few random nodes).

The Abaqus input file is attached:

The problem is as follows:

One single element is chosen with a linear elastic material model (Some parameters are chosen in an unphysical manner but here the idea is

to just validate the implementation):

In Z direction, the bc used in abaqus is encastre.  Then there are two prescribed temperature fields:

Initial step = 0 on the entire element (all nodes)

step 1 0.005 on all nodes 

YOungs modulus E = 2.1e11, Poissions ratio nu = 0.31

and heat expansion coefficient alpha = 1.0 (unphysical) No heat conduction!

Essentially a thermal expansion problem.

The element type is the quadratic 20 node with full integration! 

As mentioned earlier, the results of my code and abaqus match exactly on the nodal displacements and reaction forces. But I am trying

to compare the stresses at Nodes (Least square fit). What appears is that the normal stresses at the corner nodes seem to match well but the

mid-side nodes, differ by a factor of atleast 1.5! (Any).The Shear stresses are exactly the same!!!

In order to get to the source of the problem, i first compared a simple uniaxial tensile test against abaqus. There everything matched very well. All stresses and strains, displacements, Reaction forces.

Therefore there seems to be no problem with the implementation of the shape functions or any of its derivatives. 

We use the same quadratic shape functions for the temperature field as for the displacement field. Now since the thermal strains only affect the diagonal stress components,

the matching of shear stresses is no surprise. But the difference in normal stresses suggests that Abaqus is doing something else. 

I am not sure why because the displacements and reaction forces are the same? Any help is appreciated. 

One educated guess would be that abaqus uses linear shape functions to interpolate temperature distribution. But then the question is which is correct
and why? With such large difference in stresses, which one is more reliable?

Thanks,

MS

We performed a comprehensive study of a large class of Implicit and Explicit integration algorithms for Elastic-Plastic behaviors in Finite Element Analysis (FEA) developed in UMAT and VUMAT for ABAQUS and presented various unique results. We also showed detailed integration algorithms for both Associated and Non-Associated Flow Rules with mixed isotropic and kimenatic hardening with expandable number of internal variables (damage and etc).

Full bibliographic details:

Safaei, M., Lee, M.-G., & De Waele, W. (2015). Evaluation of stress integration algorithms for elastic–plastic constitutive models based on associated and non-associated flow rules. Computer Methods in Applied Mechanics and Engineering, 295, 414-445. doi: http://dx.doi.org/10.1016/j.cma.2015.07.014

Link: http://www.sciencedirect.com/science/article/pii/S0045782515002261

Hi friends, I'm new here and also new using abaqus.

I need to do my final project about bird strike analysis using abaqus. But for now, I try to follow the tutorial from youtube about impact bullet first. For some trial sometimes i found errors and never succeed to solve it. Included the impact bullet trial. This is what i've got:

errors:

Degree of freedom 11 and at least one of degrees of freedom 1 thru 6 must be active in the model for *dynamic temp-disp. Check the procedure and element types used in this model.

warnings:

Both the transition and melting temperatures are zero. Temperature dependencies are suppressed

Both the transition and melting temperatures are zero. Temperature dependencies are suppressed

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

Degree of freedom 4 is not active in this model and can not be restrained

Degree of freedom 5 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 5 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 5 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 4 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 4 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Can you guys help me out? Thx before.

Hi friends, I'm new here and also new using abaqus.

I need to do my final project about bird strike analysis using abaqus. But for now, I try to follow the tutorial from youtube about impact bullet first. For some trial sometimes i found errors and never succeed to solve it. Included the impact bullet trial. This is what i've got:

errors:

Degree of freedom 11 and at least one of degrees of freedom 1 thru 6 must be active in the model for *dynamic temp-disp. Check the procedure and element types used in this model.

warnings:

Both the transition and melting temperatures are zero. Temperature dependencies are suppressed

Both the transition and melting temperatures are zero. Temperature dependencies are suppressed

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

Degree of freedom 4 is not active in this model and can not be restrained

Degree of freedom 5 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 5 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 5 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 4 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Degree of freedom 4 is not active in this model and can not be restrained

Degree of freedom 6 is not active in this model and can not be restrained

Can you guys help me out? Thx before.

Hi,

I am now using ABAQUS subroutine FRIC to define some solution-dependent state variables, and I am currently able to check these values throung writing them into a TXT file in the subroutine. However, I cannot find these SDVs displayed in the ABAQUS visualization module although I have already specify them in the Field/History output manager.

I will be appreciate if anyone could give me some advice on this.

Thanks a lot,

Yi 

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  The ideal candidate will have a background in solid mechanics with expertise in finite element simulations, in particular numerical implementation of non-linear material models. This individual will have the opportunity to be directly involved in complimentary experimental investigations in the medical school at UPenn and our collaborators elsewhere. 

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  If you have any question regarding this position and/or about Prof. Shenoy's group activities, please feel free to contact me at : dibakar_datta [AT] alumni.brown.edu 

Dear Mechanicians,

ABAQUS has a number of little-known built-in material models that are not documented in the manuals.

They are accessible from https://www.3ds.com, follow the path "Support", "Knowledge Base" and search for "Built-in user material models for Abaqus/Standard and Abaqus/Explicit". Below is a text version of the output.

It may be that you need special rights on the site; these can be requested from your regional SIMULIA HQ.

See also http://imechanica.org/node/18476 for the shape memory alloy model.

Good luck

Frank

-----------------------------------------------------------------------------------------------------------------------

Built-in user material models for Abaqus/Standard and Abaqus/Explicit
Portfolio / Domain:     SIMULIA Abaqus Unified FEA / SIMULIA Abaqus Unified FEA
Product:     n/a

Question    
What Abaqus material models are available as built-in user subroutines?

Answer    
The following table lists Knowledge Base Articles that document the currently available built-in user material models.

Routine
   

Abstract
 

VUMAT
Bergstrom-Boyce polymer hysteresis model
 

VUMAT
Johnson-Holmquist & Johnson-Holmquist-Beissel for ceramics and brittle materials
 

VUMAT
Holmquist-Johnson-Cook for concrete
 

VUMAT
Mechanical response and failure of molded plastics
 

CREEP
Tertiary creep analysis using the Omega method
 

VUMAT
Continuum damage model for fabric reinforced composites
 

UMAT
Isotropic porous viscoplasticity for metals 
 

VUMAT
Damage and failure in unidirectional fiber composite materials
 

UMAT
Multilinear kinematic hardening for cyclic plasticity
 

CREEP
Lead-free solder: Modified Anand, Double-Power, Hyperbolic Sine
 

VUMAT
Orthotropic honeycomb
 

VUMAT
Foam models: Viscous, Rate sensitive, Fu-Chang anisotropic, Fu-Chang isotropic
 

CREEP
Solder creep: Anand, Darveaux, Temperature dependent hyperbolic sine
 

UMAT, VUMAT
Elastic-plastic behavior of shape memory alloy (Nitinol)

 
Keywords     UMAT, VUMAT, umat, vumat, usub, usermaterial, usermat, user, usersub, 4565

Hello,

I would like to calculate the area and volume of the solid of revolution obtained by revolving a sketch. I have used the query tool (mass properties) to get such values. The volume is OK but the area is equal to zero. How can this be possible? This is the warning I get from abaqus:

"Warnings: Some mass properties could not be computed due to the following issues detected while querying the selected region(s) - zero thickness, zero material density, missing section definition."

Is there any other method/work-around to calculate the area of the Solid of revolution?

I add the code in case someone finds it clarifying somehow. 

Thank you!

from abaqus import *
from abaqusConstants import *

#Definitions
model=mdb.models['Model-1']
assy=model.rootAssembly
assy.DatumCsysByDefault(CARTESIAN)

#Sketch
s0 = model.ConstrainedSketch(name='__poly0__',sheetSize=2000.0)
s0.Line(point1=(914.1, 554.1), point2=(914.1, 579.2))
s0.Line(point1=(914.1, 579.2), point2=(928.8, 579.2))
s0.Line(point1=(928.8, 579.2), point2=(928.8, 554.1))
s0.Line(point1=(928.8, 554.1), point2=(914.1, 554.1))

#Solid of revolution
s0.ConstructionLine(point1=(0.0,0.0), point2=(1.0, 0.0))
pr0 = model.Part(name='Part-0-r', dimensionality=THREE_D,type=DEFORMABLE_BODY)
pr0 = model.parts['Part-0-r']
pr0.BaseSolidRevolve(angle=360.0, flipRevolveDirection=ON, sketch=s0)
del model.sketches['__poly0__']
assy.Instance(dependent=ON, name='Part-0-r-1', part=pr0)

#How can a solid of revolution have volume but not area (?)
volumeRing0= assy.getMassProperties()['volume']
print volumeRing0
areaRing0= assy.getMassProperties()['area']
print areaRing0

Hi all,

I would like to know if someone has a trick to deform a mesh generated in Abaqus thanks to Computer Tomography measurements ? 

The file I received from CT is a .stl.

Do you know an open source software that can compute deviations between point clouds?

Thanks in advance for your support :-D

Hi,

I have modeling a ground in abaqus and simulated earthquake. will i need allow infinite elements in the laterals model (left and right). In other examples i see in the features (module part) created  "shell planar" en the places to create the infinite element (edge, no plane)... so .. how its made ?

thanks. 

PD: Me english is terrible, sorry.

hi

im making a 3d model of a tunnel excavation and its subsequent settlement using abaqus.

i have made a model in which the tunnel is excavated to a certain section. but my problem is that i cant simulate the progress of excavation. for example a model in which the tunnel gets excavated in 2-meter steps. and in each step 2 meter of soil gets excavated.

i have searched the internet and i think there are plug-ins which can help doing this. can anyone tell me how i can download such plug-ins? or introduce me another way to model the progress of the tunnel excavation?

thanx

Hi,

I am trying to generate an element based surface in Abaqus using python scripts. I need to create this surface in order to create an offset layer of solid elements using the offset mesh method in the edit mesh dialogue. It is not possible to use this feature using geometry based surfaces. The surface that I would like to generate is not all in one plane, I think this may add to my difficulty (see image, part). If I were able to generate an element based surface from a geometry based surface this would also work for me as I can easily generate a geometry based surface.

The main difference I can see between surfaces defined based on geometry versus those based on based elements are the sides defined per:
mdb.models['Model-1'].parts['Part-1'].allSurfaces['Surf-1'].sides
For geometry based surfaces, geometric surfaces are defined here; for element based surfaces, element faces are defined. However, these sides have no further properties, i.e.
mdb.models['Model-1'].parts['Part-1'].allSurfaces['Surf-1'].sides[0] = SIDE1 #(geometry based surface)
mdb.models['Model-1'].parts['Part-1'].allSurfaces['Surf-2'].sides[0] = FACE1 #(mesh based surface)

Element based surfaces are defined using the following commands:
p = mdb.models['Model-1'].parts['Part-1']
f = p.elements
face1Elements = f[140:160]+f[172:192]+f[212:232]+...
face2Elements = f[0:20]+f[60:80]+f[736:756]+...
face4Elements = f[163:164]+...
face5Elements = f[15:20]+f[35:40]+f[55:60]+...
face6Elements = f[1176:1177]+f[1180:1181]+...
p.Surface(face1Elements=face1Elements, face2Elements=face2Elements,
face4Elements=face4Elements, face5Elements=face5Elements,
face6Elements=face6Elements, name='Surf-2')
#: The surface 'Surf-2' has been created (1272 mesh faces).

I am able to identify the elements relevant to the surface; however, I do not know how to identify which of the element faces lies on the desired surface in order to define the surface correctly.

Can anyone tell me how define a surface based on elements as described using python?? Maybe I'm going about this in completely the wrong way. It would be of massive help. Images of the relevent surface attached. Thanks.

Wednesday October 28th, 2015

9.30am-5pm

Hayes Mansion, San Jose, CA

Organisers: SIMULIA West Region

This full-day seminar will be held the day before the SIMULIA West Regional User Meeting. This seminar will showcase the seamless integration between Simpleware ScanIP and SIMULIA Abaqus. The morning will consist of technical presentations from leaders in the biomedical engineering field followed by an afternoon of hands-on training. The afternoon training will feature a heart model workflow from start to finish using both ScanIP and Abaqus. The goal of this seminar is to highlight the exciting new opportunities now possible in the biomedical engineering field and provide detailed instruction on how to use realistic simulation to move us closer personalized health care products and services.

Advances in medical imaging have opened up a new era of multiphysics simulation of human and other natural forms. With this non-CAD simulation market beginning to explode, SIMULIA and Simpleware want to educate those in the medical or related industries on the benefits of our integrated solutions. At a high level, Simpleware’s software is tuned to take image data to create 3D meshes directly, which easily import into Abaqus.

Fee: free-to-attend

Agenda:

9:30 – 12:30   Technical Presentations

12:30 – 1:30   Lunch

1:30 – 5:00   Hands-on Workshop

Registration:

The seminar is free but pre-registration is required as places are limited.

Register here: http://www.3ds.com/events/simulia-regional-user-meetings/west-regional-user-meeting/registration/

Hi,
Can someone comment on using libraries in Abaqus subroutines?

I would like to use pressure load on a element based surface, in Abaqus. This surface is a combination of small surface elements (in an orphan mesh). But to apply pressure load you need to have a geometic surface.

How can I do this? Is it possible to make a geometric surface using this element-based surface?

Regards,

Omid

 I want to simulate a dynamic motion of a pipe under periodic displacement loads.

The whole periodic displacement loads was decomposed into 2 halves. The first half was from 0 at initial configuration to a middle configuration to final configuration, then the second half goes back from final configuration to middle configuration, to initial configuration (Fig.1). The displacement loads of these 4 configurations was given. Using Abaqus Explicit, the whole dynamic motion was simulated.

But, I find a problem as follow.

1.     The Kinetic energy was discontinuity at the middle configuration. In other words, the Kinetic energy at the middle configuration shouldn’t be 0 (Fig.2).

The attachment is the .inp file for solve, just only running “T4Solve3_CompPrd-ok.inp” file under the Abaqus work directory.

(The inp file can't upload the web. ) 

Can anyone suggest a reason as to why this would happen?

Thanks in advance for any advice.