Contact problem with SPH Metal cutting in Abaqus

[azerty001]

I have worked since a while in the ‘’Abaqus’’ FEM model developed in ‘’ Prediction of Residual Stresses after Laser-assisted Machining of Inconel 718 Using SPH ’’.
Although model description seems to be clearly simple, the model steel not working. I try to sum à rise a brief description of the model
[highlight #FCE94F]Inconel-718[/highlight]
Conductivity 44
Density 1.28E-8
Elastic (Shear Modulus ) 80769
Specific Heat 435000000
Plastic A=1241 ; B=622 C=0.0134 n=0.6522 m=1.3 RefplasticStrain=1 MeltingTemp=1600 Transition Temp=293
Mie-Gruneisen EOS type Us-Up C0=4578 s=1.33 Gamma0=1.67
[highlight #FCE94F]Substrat_WCCo[/highlight]
Conductivity 80
Density 1.5E-008
Elastic Young=800000 Poisson=0.23
Expansion 4.5E-6
Specific Heat 203000000

2- Step procedure : Dynamic,Temp-dip,Explicit (step time=0.001)

3- The contact between the workpiece and tool was defined using general contact not with node-to-surface contact algorithm
-Tangential Behavior (Penalty)
Friction coef =0.2
-Thermal conductance
Conductance / Clrearance line1 : 10000000/0 line 2: 0/0.001
-Heat Gneration
Fraction of dissipated energy caused by friction : Default
Fraction of converted heat distributed to slave surface : 61%
4- The tool is modeled with Coupled temperature-displacement Tet C3D4T elementsand the workpiece with 3D stress Hex (conversion To particles , coteron : time , Threshold : 0. ,PPD :1 , Kernel : Cubic , )

As you can see from Fig 1, the change in mass scaling can affect the chip forming process, but none of these 3 cases can be accepted as a solution

also with a mass scaling 10E-7 and C0=4578E3 Mie-Gruneisen EOS parameter fig2 (This change is not justified a problem of unit) but the chip is generated (even in this case the model diverges).

I would be highly grateful if any one can help me to detect the problem with this model and to present a much more accurated and detailed description in node-to-surface contact algorithm considered in this work

 

[swimfar]

Is your time step really 0.001? That's huge! Remember that the time step is a function of the square of density. So if you want to increase your time step by a factor of "only" ten (that would actually be a huge increase), you need to increase your density 100x. If you look at the mass added to your simulation to achieve the time step you want I be it's enormous. Mass scaling isn't just some option that you use to adjust how quickly your simulation runs, otherwise it would be turned on by default (everyone wants their simulation to run faster). You need to be able to justify why you are able to use it without affecting your results. So the first thing I would do is to turn that off. A large time step can also cause contact problems.

Also, none of the numbers you included have any units. As an engineer you should always properly communicate the units that you're using/assuming, especially if you're asking for help about what is wrong with your analysis.

 

[azerty001]

I changed the step time and the mass scaling but no with no result
for the unit SI(mm) only the strain rate reference had to be change from 1 to 1000 but with no effect
I try to model it with a inp file change

Bowth the tool and the workpiece were modeled with Coupled temperature-displacement elements with a node-to-surface contact algorithm. I had to define a node set for the workpiece and to assign it a dammy mass.

I fixed the bottom and left-hand face of the workpiece ( pic 2) and I fixed all node under the tool (pic1) but wiht the same results

http://files.engineering.com/getfile.aspx?folder=f6d5a353-ffb1-42b1-ad25-36d57f8f9a7d&file=Pic_1.png

http://files.engineering.com/getfile.aspx?folder=d0f1efaf-86b8-4320-8b19-0f670136edfc&file=Pic_2.png

http://files.engineering.com/getfil...-4d4a-8f6e-d2ae2d6510d4&file=Abaqus+units.png

http://files.engineering.com/getfile.aspx?folder=6e781585-e364-48c8-a9a3-e43d6c8e2d43&file=Us-Up.jpg

I can't send you the CAE file for bowth model