ABAQUS Unit Conversion for nanometer.

[wanbot]

Hi all,

I ran a pre-buckling analysis using ABAQUS. However, I found the eigenvalue (in nN range) is not as what I expected (uN range). My initial guess for this problem is due to the unit conversion. I choose nanometer as my unit length. For Young's modulus value, I wrote 0.0000001 for 100 GPa.

Is my conversion for Young's modulus is correct? Thank you very much for your response.


Wanbot

 

[xerf]

After a quick check, it seems ok...

 

[wanbot]

Thanks for the reply.

So I guess the problem must be something else. My sample is a bar with a rectangular cross section (170 nm * 150 nm). Material's Young's modulus and Poisson ratio is 100GPa and 0.3 respectively.

If you find any mistake on my input file below, please kindly inform me. Thanks in advance.

Below is the ABAQUS input file:

*Buckle
6, , 12, 30
**
** BOUNDARY CONDITIONS
**
** Name: Fixed Type: Displacement/Rotation
*Boundary, op=NEW, load case=1
_PickedSet4, 1, 1
_PickedSet4, 2, 2
_PickedSet4, 3, 3
_PickedSet4, 4, 4
_PickedSet4, 5, 5
_PickedSet4, 6, 6
*Boundary, op=NEW, load case=2
_PickedSet4, 1, 1
_PickedSet4, 2, 2
_PickedSet4, 3, 3
_PickedSet4, 4, 4
_PickedSet4, 5, 5
_PickedSet4, 6, 6
** Name: Pinned Type: Displacement/Rotation
*Boundary, op=NEW, load case=1
_PickedSet5, 1, 1
_PickedSet5, 2, 2
*Boundary, op=NEW, load case=2
_PickedSet5, 1, 1
_PickedSet5, 2, 2
**
** LOADS
**
** Name: Force Type: Concentrated force
*Cload
_PickedSet6, 3, -1.
**
** OUTPUT REQUESTS
**
*Restart, write, frequency=0
**
** FIELD OUTPUT: F-Output-1
**
*Output, field, variable=PRESELECT
*End Step

 

[wanbot]

I didn't paste all the input file. Below is the complete input file:

*Heading
Axial load
** Job name: Force Model name: Model-1
*Preprint, echo=NO, model=NO, history=NO, contact=NO
**
** PARTS
**
*Part, name="Soft nanoneedle"
*Node
1, -500., 350., 10000.
2, -500., 500., 10000.
3, -500., 350., 9500.
4, -500., 500., 9500.
5, -500., 350., 9000.
6, -500., 500., 9000.
7, -500., 350., 8500.
8, -500., 500., 8500.
9, -500., 350., 8000.
10, -500., 500., 8000.
11, -500., 350., 7500.
12, -500., 500., 7500.
13, -500., 350., 7000.
14, -500., 500., 7000.
15, -500., 350., 6500.
16, -500., 500., 6500.
17, -500., 350., 6000.
18, -500., 500., 6000.
19, -500., 350., 5500.
20, -500., 500., 5500.
21, -500., 350., 5000.
22, -500., 500., 5000.
23, -500., 350., 4500.
24, -500., 500., 4500.
25, -500., 350., 4000.
26, -500., 500., 4000.
27, -500., 350., 3500.
28, -500., 500., 3500.
29, -500., 350., 3000.
30, -500., 500., 3000.
31, -500., 350., 2500.
32, -500., 500., 2500.
33, -500., 350., 2000.
34, -500., 500., 2000.
35, -500., 350., 1500.
36, -500., 500., 1500.
37, -500., 350., 1000.
38, -500., 500., 1000.
39, -500., 350., 500.
40, -500., 500., 500.
41, -500., 350., 0.
42, -500., 500., 0.
43, -330., 350., 10000.
44, -330., 500., 10000.
45, -330., 350., 9500.
46, -330., 500., 9500.
47, -330., 350., 9000.
48, -330., 500., 9000.
49, -330., 350., 8500.
50, -330., 500., 8500.
51, -330., 350., 8000.
52, -330., 500., 8000.
53, -330., 350., 7500.
54, -330., 500., 7500.
55, -330., 350., 7000.
56, -330., 500., 7000.
57, -330., 350., 6500.
58, -330., 500., 6500.
59, -330., 350., 6000.
60, -330., 500., 6000.
61, -330., 350., 5500.
62, -330., 500., 5500.
63, -330., 350., 5000.
64, -330., 500., 5000.
65, -330., 350., 4500.
66, -330., 500., 4500.
67, -330., 350., 4000.
68, -330., 500., 4000.
69, -330., 350., 3500.
70, -330., 500., 3500.
71, -330., 350., 3000.
72, -330., 500., 3000.
73, -330., 350., 2500.
74, -330., 500., 2500.
75, -330., 350., 2000.
76, -330., 500., 2000.
77, -330., 350., 1500.
78, -330., 500., 1500.
79, -330., 350., 1000.
80, -330., 500., 1000.
81, -330., 350., 500.
82, -330., 500., 500.
83, -330., 350., 0.
84, -330., 500., 0.
*Element, type=C3D8R
1, 43, 44, 46, 45, 1, 2, 4, 3
2, 45, 46, 48, 47, 3, 4, 6, 5
3, 47, 48, 50, 49, 5, 6, 8, 7
4, 49, 50, 52, 51, 7, 8, 10, 9
5, 51, 52, 54, 53, 9, 10, 12, 11
6, 53, 54, 56, 55, 11, 12, 14, 13
7, 55, 56, 58, 57, 13, 14, 16, 15
8, 57, 58, 60, 59, 15, 16, 18, 17
9, 59, 60, 62, 61, 17, 18, 20, 19
10, 61, 62, 64, 63, 19, 20, 22, 21
11, 63, 64, 66, 65, 21, 22, 24, 23
12, 65, 66, 68, 67, 23, 24, 26, 25
13, 67, 68, 70, 69, 25, 26, 28, 27
14, 69, 70, 72, 71, 27, 28, 30, 29
15, 71, 72, 74, 73, 29, 30, 32, 31
16, 73, 74, 76, 75, 31, 32, 34, 33
17, 75, 76, 78, 77, 33, 34, 36, 35
18, 77, 78, 80, 79, 35, 36, 38, 37
19, 79, 80, 82, 81, 37, 38, 40, 39
20, 81, 82, 84, 83, 39, 40, 42, 41
*Nset, nset=_PickedSet2, internal, generate
1, 84, 1
*Elset, elset=_PickedSet2, internal, generate
1, 20, 1
** Region: (NeedleSectionicked)
*Elset, elset=_PickedSet2, internal, generate
1, 20, 1
** Section: NeedleSection
*Solid Section, elset=_PickedSet2, material=Silicon
1.,
*End Part
**
**
** ASSEMBLY
**
*Assembly, name=Assembly
**
*Instance, name="Soft nanoneedle-1", part="Soft nanoneedle"
*End Instance
**
*Nset, nset=_PickedSet4, internal, instance="Soft nanoneedle-1"
41, 42, 83, 84
*Elset, elset=_PickedSet4, internal, instance="Soft nanoneedle-1"
20,
*Nset, nset=_PickedSet5, internal, instance="Soft nanoneedle-1"
1, 2, 43, 44
*Elset, elset=_PickedSet5, internal, instance="Soft nanoneedle-1"
1,
*Nset, nset=_PickedSet6, internal, instance="Soft nanoneedle-1"
1, 2, 43, 44
*End Assembly
**
** MATERIALS
**
*Material, name=Silicon
*Elastic
1e-07, 0.3
**
** BOUNDARY CONDITIONS
**
** Name: Fixed Type: Displacement/Rotation
*Boundary
_PickedSet4, 1, 1
_PickedSet4, 2, 2
_PickedSet4, 3, 3
_PickedSet4, 4, 4
_PickedSet4, 5, 5
_PickedSet4, 6, 6
** Name: Pinned Type: Displacement/Rotation
*Boundary
_PickedSet5, 1, 1
_PickedSet5, 2, 2
** ----------------------------------------------------------------
**
** STEP: Apply load
**
*Step, name="Apply load", perturbation
Axial load
*Buckle
6, , 12, 30
**
** BOUNDARY CONDITIONS
**
** Name: Fixed Type: Displacement/Rotation
*Boundary, op=NEW, load case=1
_PickedSet4, 1, 1
_PickedSet4, 2, 2
_PickedSet4, 3, 3
_PickedSet4, 4, 4
_PickedSet4, 5, 5
_PickedSet4, 6, 6
*Boundary, op=NEW, load case=2
_PickedSet4, 1, 1
_PickedSet4, 2, 2
_PickedSet4, 3, 3
_PickedSet4, 4, 4
_PickedSet4, 5, 5
_PickedSet4, 6, 6
** Name: Pinned Type: Displacement/Rotation
*Boundary, op=NEW, load case=1
_PickedSet5, 1, 1
_PickedSet5, 2, 2
*Boundary, op=NEW, load case=2
_PickedSet5, 1, 1
_PickedSet5, 2, 2
**
** LOADS
**
** Name: Force Type: Concentrated force
*Cload
_PickedSet6, 3, -1.
**
** OUTPUT REQUESTS
**
*Restart, write, frequency=0
**
** FIELD OUTPUT: F-Output-1
**
*Output, field, variable=PRESELECT
*End Step