Learning Forum

[Sami Farag]

Hello,

I am trying to model an orthotropic material using shell elements, but I have noticed that the elements have different directions. Aren't they all supposed to have the same direction? Won't this be a problem with an orthotropic material?

I would really appreciate if you could clarify this to me.

 

[peteroznewman]

Insert Element Orientation under the Geometry branch in the Outline.

Here is an example for solids, but it works with shell elements also.

[Sami Farag]

But I am working on LS PrePost. Is there a way to fix this on prepost?

[peteroznewman]

I am sure there is. I have no idea how to do that. Try looking in the documentation.

[Andreas Koutras]

Hello Sami,

The shell element N1-to-N2 direction can be modified as:

 

The orthotropic material axes are displayed as:

[Sami Farag]

 

 

 

Thank you so much for your reply,

 

In my case, all elements have the same direction only when I use the mesher of the prepost but, when I use prepost to mesh a STEP file made on Solidworks, they tend to have different directions. Do you maybe know what causes this problem?

And if I am working on an orthotropic material, does that mean that I indeed have to modify all elements so that they all have the same direction?

Also, the material direction doesn’t appear to show for me like your second picture even when I define a coordinate system and refer to it in AOPT in the material keyword. I have read somewhere that I have to load an input deck first in order to show the material direction. Is that correct? What is an input deck and how can I load it?

 

 

 

[Andreas Koutras]

Hello, please check for LSPP warning messages at the the bottom right side of the GUI. The "input deck" is the LS-DYNA input file. The element local coordinate system can be modified as shown in the my first picture above. For example, try with the Vector or Orient options. If the material coordinate system in the shell through-thickness layers is correct (and independent from the element local system), the element local coordinate system won't affect the result. However, if you need to output shell stresses or shell resultants in the element local coordinate system, it will help to have well oriented element axes. Also see the definition of AOPT under the section of MAT_002 in the LS-DYNA manual vol II.

[Sami Farag]

Hello Andreas,

Thanks you so much! I really appreciate your help.

I have noticed that the material direction only shows when I use MAT_002, but I doesn't show however when I use MAT_274_PAPER which is the material I am working on and it is also an orthotropic material. I have added screenshots of both cases and of the last few lines of the LSPP messages exactly after selecting the elements. I have tried to read the MAT_274 but I couldn't find why the material direction doesn't show.

Is this a problem with the MAT_274 itself? If so, how do I make sure in my case that the material has the direction I specified on AOPT?

Also, how do I make the material coordinate system independent from the element local system like you said?

 

[Sami Farag]

Hello Andreas,

 

Thank you so much! I really appreciate your help.

When I define a local coordinate system and use it in AOPT, I noticed that the material directions show only for the MAT_002, and It doesn't show however when I use MAT_274_PAPER which is the material I am working on and it is also an orthotropic material. I have read the part of MAT_002 and MAT_274 in the manual, but I still don't know why the material directions don't show for me. I have added screenshots of both when I tried MAT_002 and MAT_274, and also a screenshot of the last few lines of the LSPP messages exactly after selecting elements to show the material directions for when using MAT_274.

Is that a problem with the material model of the MAT_274 itself? If so, how do I make sure that the material gets the same directions I specified in AOPT?

Also, how do I make the material coordinate system independent from the element local coordinate system like you said?

 

[Andreas Koutras]

Hello Sami,

It works for me. I'm using LSPP v4.11. See the pictures below and let me know what you are doing differently. Thanks.

 

[Sami Farag]

Hi Andreas,

 

It was indeed the version, I had V4.7 and It only worked when I downloaded V4.10. Thank you so much! 

Would you please do me one last favour, I need the curves S01,S02,S03,S04, and S05 if possible. I am currently learning to work with this paper model but I still don't have paper material properties that I can use. I would really appreciate if you could send them to me or guide me where to find them.

[Andreas Koutras]

Hello Sami,

Note that we cannot provide recommendations on specific material stress-strain data. I cannot share the data of the MAT_PAPER above.

Here is another example.

*MAT_PAPER_TITLE
Lower 00
$#     mid        ro        E1        E2        E3      pr21      pr32      pr31
         1 1.0000E-9 7122.3200 2948.3900 14.000000      0.46        0.        0.
$      G12       G23       G13       E3C        CC      TWOK
 1685.6900 30.000000 30.000000      0.47     24.46        4.
$      S01       A01       B01       C01       S02       A02       B02       C02
     -101.        0.        0.        0.     -102.        0.        0.        0.
$      S03       A03       B03       C03       S04       A04       B04       C04
$ A4=B4=C4=0 ger idealplastiskt i tryck sig=S04 i MD
     24.64      5.82    117.25    865.05     39.13        0.        0.        0.
$      S05       A05       B05       C05      PRP1      PRP2      PRP4      PRP5
$ A5=B5=C5=0 ger idealplastiskt i tryck sig=S05 i CD
     17.23        0.        0.        0.        0.        0.     1.E-4     1.E-4
$     ASIG      BSIG      CSIG      TAU0      ATAU      BTAU
    -16.45    16.550     -3.16       2.1        9.        2.
$#    aopt      mafc        xp        yp        zp        a1        a2        a3
  2.000000  1.000000     0.000     0.000     0.000  1.000000     0.000     0.000
$#      v1        v2        v3        d1        d2        d3      beta
     0.000     0.000     0.000     0.000     0.000  1.000000     0.000
*MAT_PAPER_TITLE
Mid 00
$#     mid        ro        E1        E2        E3      pr21      pr32      pr31
         2 1.0000E-9 4029.2000 1823.5500 13.000000      0.44        0.        0.
$      G12       G23       G13       E3C        CC      TWOK
 1023.0200 35.000000 35.000000      0.38     16.33        4.
$      S01       A01       B01       C01       S02       A02       B02       C02
     -201.        0.        0.        0.     -202.        0.        0.        0. 
$      S03       A03       B03       C03       S04       A04       B04       C04
$ A4=B4=C4=0 ger idealplastiskt i tryck sig=S04 i MD
     16.48     11.66     37.68    253.82     25.58        0.        0.        0.
$      S05       A05       B05       C05      PRP1      PRP2      PRP4      PRP5
$ A5=B5=C5=0 ger idealplastiskt i tryck sig=S05 i CD
     10.93        0.        0.        0.        0.        0.     1.E-4     1.E-4
$     ASIG      BSIG      CSIG      TAU0      ATAU      BTAU
    -11.78    11.880     -1.92      0.95        9.        2.
$#    aopt      mafc        xp        yp        zp        a1        a2        a3
  2.000000  1.000000     0.000     0.000     0.000  1.000000     0.000     0.000
$#      v1        v2        v3        d1        d2        d3      beta
     0.000     0.000     0.000     0.000     0.000  1.000000     0.000
*MAT_PAPER_TITLE
Upper 00
$#     mid        ro        E1        E2        E3      pr21      pr32      pr31
         3 1.0000E-9 7361.5298 2788.4900 20.000000      0.48        0.        0.
$      G12       G23       G13       E3C        CC      TWOK
 1764.0699 84.000000 84.000000      0.47     24.46        4.
$      S01       A01       B01       C01       S02       A02       B02       C02
     -301.        0.        0.        0.     -302.        0.        0.        0.
$      S03       A03       B03       C03       S04       A04       B04       C04
$ A4=B4=C4=0 ger idealplastiskt i tryck sig=S04 i MD
     24.54      6.38    144.25    552.02     41.57        0.        0.        0.
$      S05       A05       B05       C05      PRP1      PRP2      PRP4      PRP5
$ A5=B5=C5=0 ger idealplastiskt i tryck sig=S05 i CD
     17.41        0.        0.        0.        0.        0.   1.00E-4    1.0E-4
$     ASIG      BSIG      CSIG      TAU0      ATAU      BTAU
    -16.45    16.550     -3.16       2.7        9.        2.
$#    aopt      mafc        xp        yp        zp        a1        a2        a3
  2.000000  1.000000     0.000     0.000     0.000  1.000000     0.000     0.000
$#      v1        v2        v3        d1        d2        d3      beta
     0.000     0.000     0.000     0.000     0.000  1.000000     0.000
*MAT_COHESIVE_GENERAL
$#     mid        ro     roflg   intfall       tes      tslc       gic      giic
         5 1.0000E-9         1  1.000000     2.000         2  0.083800  0.174700
$#     xmu         t         s     stfsf
  1.000000  0.240000  1.125000   2.00000
*DEFINE_CURVE_TITLE
 TSLC
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
         2         0  1.000000  1.000000     0.000     0.000         0
$#                a1                  o1
               0.000               0.000
            0.003460            1.000000
            0.400000               0.300
            1.000000               0.000
*DEFINE_CURVE_TITLE
MD Tension Bottom
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
       101
$#                a1                  o1
                 0.0               39.13
               5.E-3              60.169
               1.E-2              72.490
               1.E-1              72.490
*DEFINE_CURVE_TITLE
CD Tension Bottom
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
       102
$#                a1                  o1
                 0.0              17.230
               5.E-3              23.761
               1.E-2              27.890
              1.5E-2              30.727
              2.0E-2              33.200
              2.5E-2              35.600
              2.7E-2              36.540
               1.E-1              36.540
*DEFINE_CURVE_TITLE
MD Tension Mid
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
       201
$#                a1                  o1
                 0.0               25.58
               5.E-3              35.000
               6.E-3              36.277
               1.E-1              36.277
*DEFINE_CURVE_TITLE
CD Tension Mid
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
       202
$#                a1                  o1
                 0.0              10.930
               5.E-3              14.410
               1.E-2              16.590
              1.5E-2              17.980
              2.0E-2              19.110
              2.5E-2              20.186
              2.9E-2              21.000
               1.E-1              21.000
*DEFINE_CURVE_TITLE
MD Tension Top
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
       301
$#                a1                  o1
                 0.0               42.57
               5.E-3              57.470
               1.E-2              67.500
               1.E-1              67.500
*DEFINE_CURVE_TITLE
CD Tension Top
$#    lcid      sidr       sfa       sfo      offa      offo    dattyp
       302
$#                a1                  o1
                 0.0              17.410
               5.E-3              23.430
               1.E-2              27.355
              1.5E-2              29.634
              2.0E-2              31.200
              2.5E-2              32.533
              2.8E-2              33.287
               1.E-1              33.287