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How to solve the issue of Time vs Acceleration result issue?

 

Dear friends,

I have run a dynamic explicit analysis towards my model with acceleration input data in AMP>tabular, and it is applied on a single node. The tabular amplitude input data is ranging from 0-10s with time increment of 0.01 ( 0, 0.01, 0.02 , 0.03, 0.05 ........10). 


My objective is to develop time vs acceleration curve and export the xy data so that it can be used in MATLAB program .


However, after i plotted the time vs acc curve on the loaded node, the result is seems illogical.The curve is in linear shape, which supposely to be in sinusoidal shape. 


For information, i've activated the ma ss scaling in dynamic explicit (to overcome the excessive distortion error). Does this can be the reason of this issue ? or is there any mistake on the analysis parameter? Can anyone guide me on this matter ?


*new user,Helps needed


hereby i attached the link of curve figures:


https://drive.google.com/folderview?id=0Bx70tzXndz85fmdaaXhYZnlQSjNYWEQ1M3JuVS1FUURmMnd0REp3M2NGUWc1S3RCdTlvMlE&usp=sharing




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Posted by: raimy.haidar <at> yahoo.com
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Contact Pressure vs Stress at specific point on the contact surface

 

Hello,

I'm wondering what is the difference between the contact pressure (CPRESS) output at a specific node on the contact surface and the stress component (e.g. S22 or S33) at the same point?
What is the physical meaning of both and why CPRESS value always less than the stress value?

In other words, I'm modeling a contact pressure on pipe while what I expect is the weight of the soil above that pipe. The stress values at the contact surface gives me the right pressure which is the weight of the soil column however the contact pressure on the pipe (CPRESS) is less.

Any explanation will be greatly appreciated.

M. Hussein

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Posted by: "Mahmoud Gad-El Rab" <mahmoud_gadelrab <at> yahoo.com>
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how to write fieldoutput report using a script without opening the GUI?

 

Hi everyone,
Is it possible to write a fieldoutput report without a viewport in display?
Or is there a function that I can use to extrapolate integration point value to nodal value?
I have some variables only available on integration point, but I want the nodal value, I found abaqus will extrapolate the result when writing a fieldoutput report.
Thank you for your help.
Qiang
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Posted by: Qiang Fang <godblessfq <at> gmail.com>
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Select codes on the cylindrical surface excluding edge nodes using Script

 

Hi all,

I am trying to get the nodes on the circumferential surface of a circullar rod using python script. Also, I shouldnt select the nodes on the edges of the circumferential surface.

To achieve the objective, I found that getbyboundingbox/cylinder/sphere is not of much help.

Like in CAE, is there any option in scripting: nodes outside the bounding box.

Appreciate your inputs. Thanks in advance.


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Posted by: a.rajaneesh <at> gmail.com
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ctp chruss@gmx.de [Abaqus] | 24 Apr 13:54 2015
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Boundary conditions for CEL interaction (e.g. tie contact interfaces)

 

I read through the Abaqus documentation looking for different boundary conditions supported for an eulerian mesh within a Coupled Eulerian Lagrangian simulation setup. I initially found information about inflow/outflow conditions and mesh boundaries in regards to the eulerian domain movement (e.g. the mesh can follow the surface). These are NOT the BCs I am looking for. Instead I want to create boundary conditions connecting some parts of the lagrangian model to the euler material/nodes. I am aware that there are many restrictions for this, but I thing this it should generally be possible. In the Abaqus documentation section "14.1.1 Eulerian Analysis" in the paragraph about "Limitations" it states: (1) Boundary conditions: You cannot apply prescribed nonzero di splacement boundary conditions to Eulerian nodes. (2) Lagrangian attachments: You cannot attach Lagrangian elements to Eulerian nodes. *Use tied contact interfaces instead*. (3) Constraints: You cannot apply Lagrangian constraints (MPCs, etc.) to Eulerian nodes. *Use tied contact interfaces instead*. Essentially, I want to accomplish (2), but I have no idea how to do use these *tied contact interfaces* for CEL and any help, guidance or example would very much be appreciated if you know how to setup such an example. For my use case, imagine I have a circular lagrangian surface and would like to attach a half-spherical (eulerian) object in its center. I would like this object to stay attached to the base when it deforms (see screenshot). In lagrangian space I could simply tie them together with some constraints, but how do you do that within CEL? PS: attached a basic lagrangian example of what I am imagining

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Posted by: ctp <chruss <at> gmx.de>
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[XFEM] SIF calculations

 

Welcome everyone,


I am a student who is writing thesis involved with crack propagation. In order to understand model behaviour I try to simulate crack propagation in specimens. I am confused because I read couple of articles about calculations of Stress Intensity Factor and the materials properties are not defined clearly. My question is what properties should I input to get Stress Intensity Factor in specimen with cracked domain. I know that if I define Elastic modulus, Poisson's ratio, MAXPS and damage evolution it could be done, but I am curious about different options.


Thank you in advance :)

Slawomir

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Posted by: slawomir.polanski <at> yahoo.com
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chruss@gmx.de [Abaqus] | 24 Apr 13:59 2015
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Boundary conditions for CEL interaction (e.g. tie contact interfaces)

 

I read through the Abaqus documentation looking for different boundary conditions supported for an eulerian mesh within a Coupled Eulerian Lagrangian simulation setup. I initially found information about inflow/outflow conditions and mesh boundaries in regards to the eulerian domain movement (e.g. the mesh can follow the surface). These are NOT the BCs I am looking for. Instead I want to create boundary conditions connecting some parts of the lagrangian model to the euler material/nodes. I am aware that there are many restrictions for this, but I thing this it should generally be possible. In the Abaqus documentation section "14.1.1 Eulerian Analysis" in the paragraph about "Limitation s" it states: 

(1) Boundary conditions: You cannot apply prescribed nonzero displacement boundary conditions to Eulerian nodes. 
(2) Lagrangian attachments: You cannot attach Lagrangian elements to Eulerian nodes. Use tied contact interfaces instead.&nb sp;
(3) Constraints: You cannot apply Lagrangian constraints (MPCs, etc.) to Eulerian nodes. Use tied contact interfaces instead

Essentially, I want to accomplish (2), but I have no idea how to do use these tied contact interfaces for CEL and any help, guidance or example would very much be appreciated if you know how to setup such an example. 

For my use case, imagine I have a circular lagrangian surface and would like to attach a half-spherical (eulerian) object in its center. I would like this object to stay attached to the base when i t deforms. In lagrangian space I could simply tie them together with some constraints, but how do you do that within CEL


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Posted by: chruss <at> gmx.de
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Brake disc modelling

 

Hello,

I need some help to model a brake disc rotor. Can anyone help out with this, perhaps a previous model I can use to get some understanding of the modelling. I am new to FEM and Abaqus.

Thanks
Ebi
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Posted by: ebi ebi <kkrabbi <at> yahoo.com>
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Brake disc analysis

 


Hello,

I intend to model the thermo-mechanical stress in a brake disc. Please can anyone advise which of the two approaches, fully coupled or the sequentially coupled would be the correct approach.

Regards,
 Ebi


Sent from my HTC

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Posted by: "=?utf-8?B?a2tyYWJiaUB5YWhvby5jb20=?=" <kkrabbi <at> yahoo.com>
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BRAİN MATERİALS

 

Hİ ALL


I have a 3D brain model.ı want to enter value of  viscoelastic material...how do ı entered tis value in abaqus


G0=0.528 MPa, (short term shear moduls)

Ginf=0.168MPa,(long term shear moduls)

b = 35 (Decay contant)


thanks


fehmi



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Posted by: bilgefehmi <at> yahoo.com.tr
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rigid bodies constrain error- kindly help me

 

i am doing forming analysis of thin sheet. i used die and punch as analytically rigid bodies. but during analysis the following error occurs.kindly help me to rectify the error.
The rigid bodies with the reference nodes contained in node set ErrNodeRefNodeNoRotInert have no rotary inertia associated with them and the rotational degree of freedom of the reference nodes is not restrained. Either rotary inertia must be defined at the reference node or the rotational degree of freedom of the reference nodes must be constrained. See the stat us file for further details. The rigid bodies with the reference nodes contained in node set ErrNodeRefNodeNoMass have no mass associated with them and some degrees of freedom of the reference node are not restrained. Either mass must be defined or all of the translational degrees of freedom must be constrained. See the status file for further details.

***WARNING:  Rotary Inertia for the ROTARYI element 181 about the local-3 axis
            is given as zero


***WARNING:  Rotary Inertia for the ROTARYI element 182 about the local-3 axis
            is given as zero


Abaqus/Explicit 6.10-1 DATE 21-Apr-2015 TIME 10:47:49 ------------------------------------------------------------------------------- PREPROCESSOR WARNING MESSAGES ------------------------------------------------------------------------------- status file: ***WARNING: There are 1 warning messages in the data (.dat) file. Please check the data file for possible errors in the input file. ***WARNING: Rotary Inertia for the ROTARYI element 181 about the local-3 axis is given as zero ***WARNING: Rotary Inertia for the ROTARYI element 182 about the local-3 axis is given as zero ------------------------------------------------------------------------------- MODEL INFORMATION (IN GLOBAL X-Y COORDINATES) ------------------------------------------------------------------------------- Total mass in model = 17645. Center of mass of model = ( 1.000000E+00, 1.500425E-01) Moments of Inertia : About Center of Mass About Origin I(XX) 1.618125E+02 5.590501E+02 I(YY) 5.294940E+04 7.059440E+04 I(XY) 3.616512E-05 -2.647500E+03 I(ZZ) 5.311291E+04 7.115515E+04 ------------------------------------------------------------------------------- STABLE TIME INCREMENT INFORMATION ------------------------------------------------------------------------------- The stable time increment estimate for each element is based on linearization about the initial state. Initial time increment = 5.29052E-05 Statistics for all elements: Mean = 5.29053E-05 Standard deviation = 0.0000 Most critical elements: Element number Rank Time increment Increment ratio (Instance name) ---------------------------------------------------------- 61 1 5.290525E-05 1.000000E+00 SHEET METAL-1 63 2 5.290525E-05 1.000000E+00 SHEET METAL-1 65 3 5.290525E-05 1.000000E+00 SHEET METAL-1 66 4 5.290525E-05 1.000000E+00 SHEET METAL-1 67 5 5.290525E-05 1.000000E+00 SHEET METAL-1 70 6 5.290525E-05 1.000000E+00 SHEET METAL-1 71 7 5.290525E-05 1.000000E+00 SHEET METAL-1 73 8 5.290525E-05 1.000000E+00 SHEET METAL-1 75 9 5.290525E-05 1.000000E+00 SHEET METAL-1 78 10 5.290525E-05 1.000000E+00 SHEET METAL-1 Instance name for the most critical element will be printed if the critical element changes or at the beginning of a new page. ***NOTE: Contact output has been requested for at least one contact pair involving an analytical rigid surface. For each of these pairs, contact output will not be provided for the analytical surface, but will be provided for the opposing surface. ***ERROR: Rotary inertia is not defined for the rigid bodies with the reference nodes listed below, but not all rotational degrees of freedom are constrained at the reference node. Abaqus/Explicit now requires rigid bodies to have a positive definite rotary inertia unless rotational constraints are applied with the *BOUNDARY option (see the Abaqus Analysis Users Manual). Nodes that are part of a rigid body do not require mass and inertia individually, but the rigid body as a whole must possess mass and inertia unless constraints are used. To remedy this error, either add rotational constraints to the reference nodes with the *BOUNDARY option or add inertia using the *ROTARY INERTIA option, whichever is appropriate to obtain the desired response. A node set named "ErrNodeRefNodeNoRotInert" containing the problematic reference nodes is also created for use in Abaqus/Viewer to help locate the error and modify the input definition. Reference Nodes: node: 1 instance: PART-2-1 ***ERROR: Mass is not defined for the rigid bodies with the reference nodes listed below, but not all translational degrees of freedom are constrained at the reference node. Abaqus/Explicit now requires rigid bodies to have a non-zero mass unless translational constraints are applied with the *BOUNDARY option (see the Abaqus Analysis Users Manual). Nodes that are part of a rigid body do not require mass individually but the rigid body as a whole must possess mass unless constraints are used. To remedy this error, either add translational constraints to the reference nodes with the *BOUNDARY option or add mass using the *MASS option, whichever is appropriate to obtain the desired response. A node set named "ErrNodeRefNodeNoMass" containing the problematic reference nodes is also created for use in Abaqus/Viewer to help locate the error and modify the input definition.


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Posted by: karthiv91 <at> yahoo.com
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Gmane