Thanks Xerf,
I realized that my mesh quality was poor for the continuum plate (only one-element thick! or 2 nodes to define thickness), which gave much lower Mises stress result than predicted.
I made the thickness of the continuum plate 5 elements thick, and now it is giving reasonable...
Hi Xerf,
Thanks for the tip.
I must use "Shell" type and prefer "Dynamic, Explicit" step for my analysis, because the flat sheet is just a reference case for a more complicated "sheet" composed of many thin structures.
I tried to compare the shell (Explicit element library, Shell family...
Hi,
With ABAQUS/Explicit, I'm modeling the mechanical bending behavior of a 100mm x 100mm x 0.5mm flat sheet of Silicon. I apply the force in the center and see where it breaks (when Mises stress = yield stress).
Since the plate is sufficiently thin relative to other dimensions, I decided to...
Hi,
With ABAQUS/Explicit, I'm performing a force vs displacement measurement of a 100mm x 100mm x 0.5mm Silicon wafer (applying BC of velocity in the center, wafer sitting on frictionless "square ring", wafer slips down through if displacement is too high).
Use the following to extract the...
Hi,
I'm simulating the bending of a sheet of (amorphous, poly)silicon of ~300um in thickness.
Currently, I have the following material properties
density
young's modulus
poisson's ratio
I consider 2% strain the breaking point (my definition of "damage"), which can be obtained from LE...
Hi bfillery,
Thanks for the suggestion.
However, I forgot to mention the fact that I am to use ABAQUS/Explicit. The step I use is "Dynamic, Explicit" and nlgeom is turned on.
The reason why I'm sticking with Explicit is due to a more complex structure (the plain sheet of silicon is a...
Hi,
I am trying to model the force vs. displacement behavior of a thin sheet of silicon.
The four corners of the square sheet are fixed using a boundary condition (U1=U2=U3=0). I am to apply a point load in the center.
I would like to obtain a graph of this load force vs. downward...
...my structure would not only take a long time to do but it would also slow down my computation.
So I tried using "General Contact (Explicit)" All* with Self, but it gave me an error:
*CONTACT cannot be defined on 2D element facets. If the model contains 2D or axisymmetric elements, then...
It looks like rather than /Explicit, /Standard is recommended.
However, I have no experience with using /Standard, because the biggest reason why I considered /Explicit was its automatic stability.
I tried using /Standard (Dynamic, Implicit), but to my horror, the structure failed to...
...force"? This should be pointing the other direction, because the more the spirals unroll, the greater the spring/reaction force becomes...
*I got "Section Integrated Output" to find out the total amount of force on a surface, but unfortunately it only gives you the values of the load, not...
Hi brep,
Yes, I've tried the above, but it still gives me flat zero lines.
I noticed that if I fix a boundary condition (ENCASTRE) to one end of the spiral and pull the other one, the reaction force (of the encastred region) magically spits out nonzero data.
So I am wondering why Reaction...
Hi xerf,
Every time I try to plot "RF" reaction force from history output, I get a flat zero line (meaning no useful data).
Since I'd like to measure the spirng reaction force, I request history output (RF) on the surface that I also apply the force to pull the spiral.
Is there something...
Hi israelkk,
Thanks for replying.
I actually keep the silicon from breaking by coating the structure with a layer of ductile substance.
My interest is in extracting force vs. displacement data, and you suggested this book (which is quite expensive).
Is there another (free) online source...
Real silicon ceramic (stiff)
Young's Moduls : 112.4 GPa
Poisson's Ratio : 0.28
Thanks.
PS. The stress/strain data is of no interest to me for now, despite the obvious immminent fracture upon unrolling.
Hi,
I'm running a simulation of unrolling a flat spring made of silicon to obtain the system's reaction force (spring force) vs. displacement graph.
See the picture at :
http://i102.photobucket.com/albums/m97/jongyonkim/flatspring.jpg...
Hi,
I'm running a simulation of unrolling a flat spring made of silicon to obtain the system's reaction force (spring force) vs. displacement graph.
See the picture at :
http://i102.photobucket.com/albums/m97/jongyonkim/flatspring.jpg...
...density becomes 2.329E-6 kg/mm^3. However, for Young's Modulus, don't you have to take into account the N in Pa = N/mm^2? With the mm scale, N = kg*mm/s^2 , so Pa = N/mm^2 = kg*mm/s^2/mm^2 = kg/(mm*s^2). One of the mm in the denominator cancels out. So it should be 1.124E8 (kPa)?
2) I had...
Hi xerf, I didn't quite understand what you mean by "convert all the lengths in (mm)" for 200um.
Do you mean,
a) 200um -> 200mm, so use a "factor of 1E-3", which applies to other variables.
b) 200um -> 200mm, just use mm instead of um.
If you were me, how would you scale density and Young's...
...Density = 2.329E3 kg/m^3 = 2.329E3 x (1E-6)^3 = 2.329E-15
Young's Modulus = 1.124E11 = 1.124E11 x 1E-6 = 1.124E5
where YM's unit Pa has been broken down to N/m^2 = kg*m/(s^2*m^2) = kg/(m*s^2)
Please tell me if I've made any mistakes, or if there is a better scaling standard than this.
Thanks.
...= 2.329E3 x (1E-6)^3 = 2.329E-15
Young's Modulus = 1.124E11 = 1.124E11 x 1E-6 = 1.124E5
where YM's unit Pa has been broken down to N/m^2 = kg*m/(s^2*m^2) = kg/(m*s^2)
I think the orders E-15 and E5 are throwing me off...Time/LPF Inc is around 1E-10...
Please tell me if I've made any...
