I'm trying to help a friend with your master's degree. He needs to compare a experimental data with a FEA data. We have a Uniaxial Tension data of a hyperelastic material. Usually I work with cfd, It's my first simulation with this materials.

So, I searched some videos, forums, papers, but I feel losting yet.

I input the data on ansys: strain (this is simple strain (Δl/lo) or I have to use Stretch ratio (λ) ?) and stress (F/A)

and I choose the method (Yeoh 1st order), solve the curve fit and copy the calculated values:

And I have to compare the exp data with 12 methods [Mooney-Rivlin (3, 5 e 9 parameters); Ogden (1a, 2a e 3a order; Yeoh (1a, 2a e 3a order); Polinomial (1a, 2a e 3a order).]

Then I put this material on my project (Static structural).

I set the mesh:

Then, my boundary conditions: (dispacement = 195mm (like the max displacement on experimental test))

Set my Analysis settings: (most are set as default)

When I run my simulations I have the follow results:

But I don't know if is a correct, because when I compare to experimental data is so different:

I have no idea where the error is, if it exists. Or if it is problems in my engineering interpretations, I am still studying this type of material and its behavior and applications in FEA. Can someone help me? Tips, useful links, things like that?

Sorry for the long post and thanks for any help.

André Moura

]]>I'm modelling a layered cube with SOLID186 in Mechanical APDL. Each layer has controlled gaps (1mm voids) in specific positions. Because of that, my geometry model ends up with coincident lines with different length, not being able to use NUMMRG,ALL to merge them before meshing. If I didn't have those gaps, I would just use NUMMRG,ALL command to merge coincident KP,lines, etc. and my mapped meshing would work great.

I'm creating geometry with volumes using BLOC4 command. Each layer is composed of two blocs. Here are some pictures:

The regions like the one marked in red have 3 coincident lines, each of different length. Is there an "easy" way or command to be able to merge or reppair this problem, instead of having to do a more complicate geometry modelling?

Thanks in advance.

-Rodrigo

]]>My name is André Moura, i'm try running a hyperelastic simulation. I have the uniaxial test data from experimental test. After some troubles and changes we reach some "good" results.

This is my geometry, 2D.

I got a result of the force close to the experimental by selecting faces A+B (on left) with fixed suport, but when I select only face A, the results are so different (like a half).

On right side I set displacement. After this, Can I simplify my geometry to area left outside those squares?

My main question at the moment is whether this simplification of using only the reduced section is valid.

Do you know if it is possible to access the equations that ansys uses for the simulations?

And, Is it possible to obtain the data of this graph?

thanks a lot.

]]>Note that in previous runs I used either all solid bodies, or all shell bodies. Here I have both solids and a shell body.

Please correct me if I am wrong, doesnt applying symmetry constrain the object in the corresponding directions? If so, why would this node be unconstrained in those directions (X and Y)? Furthermore, if I were to constrain the Z displacement of the sample, wouldn't it be unable to deform under the load?

May I know how should I constrain the model to solve these warnings? Or could it be a result of other ill-defined parts of the model? Hope someone can shed light on this, thanks in advance!

]]>I'm doing some calculations in POST26 and get them output with the *VGET and *VWRITE command:

NSOL,4,nodeID,VOLT,voltage

*GET,size,VARI,NSETS

*dim,u,array,size

VGET,u(1),4

*CFOPEN,%f_sim%Hz_u_LS_%current_load_step%,txt

*VWRITE,u(1)

(E)

But how do I get the time from the post26 so that I can write the time vector in an identical form?

Thanks a lot in advance!

]]>figure-1

figure-2

I will be glad if you give an idea!

Regards

]]>Could somebody, please, help me with an tutorial or some suggestions about modelling the butt weld of polyetilene pipes. I need to make a burst pressure test with explycit dynamics for the welded pipe. I think that firstly i must do a transient thermal analysis where to introduce the temperature at the ends that are welded, but I don t know how to do that. After, i think that i should do the explycit dynamic analysis where to introduce the internal pressure acting on the pipe walls. I really need some help. Thank you very much.

]]>I am modeling a nonlinear material using bilinear.

It is a plastic material where stress is dropping after yield point and modulus given in the specification is secant modulus NOT tangent modulus (initial best straight line).

I wanted to know for the ANSYS bilinear input below:

Modulus: Should I use tangent modulus or secant modulus (usually use this for linear properties)

Yield Strength: Should I use the stress point at the end of best straight line or yield point (usually use it for linear properties)

Tangent modulus: Should the tangent modulus be calculated based on engineering stress/strain or true stress/strain?

]]>I am running a static nonlinear of pulling a rob with large displacement and bilinear properties but it cannot converge as below... I am not sure what are missing...

Eigenvalue multiplier is 20,306 for 0,001 mpa . So my critical buckling have to be lower 0,0203. Finally ı wanted to see my model behavior for overall buckling and collapse buckling.

Can you help?

Model - R(radius)=500 mm h=1250 mm t(thickness)=1 mm

Top and Bottom simply supported (displacement x=y=z=0)

1-ansys model

2-eigenvalue multiplier

3-newton raphson -stabilization energy constant 0,001 (initial 200 min 100 max 2000 substeps) result

4-arclength commond

5-my arclength result(finished 0,63 sn and not converged)

6-true arc length grafic (wanted)

how to fix this problem?

thanks

Talking about a compression test on a sample with an hydraulic press: what's the real difference between using 4 LVDTs to measure displacement (like the one of the photo below) compared to using only the actuator's internal displacement transducer? Would it cause a higher displacement measure to use the second method, and hence, a loss in stiffness?

I'm wondering about this, because I carried this same compression test, but measuring the displacement by the second method, and I'm thinking it might be the cause of the big nonlinear-elastic part of my experimental curves:

The black lines are FEM modelling. I would really appreciate if you know any literature/article discussion this.

Thanks in advance

]]>So I have been using Ansys for a while and I feel I am able to understand and use It fluently.

But I always have a doubt regarding discretization and Interpolation .

I would like to clear that off before I start working on something big.

Lets Say Structures for example - Whats ansys does is :

We choose the mathematical model and it's respective governing equations

Then we apply the weighted function for piece wise polynomial approximation- to make it simple

(Differential equations to linear)

Then define a equation for a node- Which is discretization.

Then we obtain the equations for the other nodes using interpolation.

Then set the boundary conditions

After which we obtain a system of linear equations and solve them.

After which any other variable can be found .

If non-linear

We apply guess values , imbalance reduction and so on.

I know this is a bit lengthy ,

But please correct me , please ,

If I made a mistake while stating the solving steps of ANSYS.

Thank You Very Much !

]]>How to obtain the deformed area or the displacements of the points to draw the deformed area by action of the forces on the element shown, try to take an image and take it to autocad to draw the deformed area but the resolution is very low? (blue area).

I can do it manually by selecting node by node and evaluating the maximum displacement but it is a cumbersome procedure

What exactly is a remote point and remote displacement ?

What is the benefit of using these two options ?

]]>Here is my doubt. I did an example just to learn how combin14 beams work. Now I'm trying to define the torsional stiffness as a parameter in order to change it in the design points table in workbench.

Thank you all for your answers, regards,

Óscar

]]>Background: I am currently running a simulation that exports a temperature profile from Fluent to transient structural because I want to analyze how the temperature in the fluid causes thermal stress in the solid.

Do I want to use the static temperature result from Fluent, or should I use the total temperature results?

What temperature does the solid really 'see' when thermal stress is created?

Thank you!

]]>Initially I had tried to give the initial velocity and then found out the radial distance between the point of contact and then entered the angular velocity. I did this to reduce the time it takes for the wheel to reach the stable non slip rolling velocity.

But, is there a way to make the wheel rotate without slipping from the get go. This is an issue for me as I have to analyse the impact force for different velocities of the wheel.

]]>I was trying to model a bonded connection between to shell edges but I keep having this Error pop up "The normal of target element 46002 is not consistent with the normal of target element 46029 in real set 99. Please use the ENORM command to correct it." every time I tried Running it. Can Anyone help me solve this issue? I am trying to limit number of elements that's why I have two different mesh size. Shared topology would increase my number of elements or reduce/increase the standard mesh metrics. The bonded contact is at the boundary of the differing mesh sizes. When I use MPC in the formulation the Model solves but I get a weird stress at the boundary it doesn't have continuity.

Thanks.

I am trying to solve a simple fixed beam with udl and reinforced bars at the bottom. I did not get a way to connect the bars with the concrete beam. Can you please help me get the connection as I get the solver pivot error and I'm unable to resolve it.

Is it possible to calculate radiation efficiency factor (often denoted as sigma) of a structure (e.g. cylindrical shell from steel) in harmonic acoustic analysis in ANSYS 2020R1? Let the inner surface of shell be excited by some sinusoidal harmonic force. Let the boundary conditions to be free-free. i can model air enclosure and tell ansys to calculate Radiated Sound Power, Far field sound power level, ... as a function of frequency.

Is it possible somehow to display radiation efficiency factor as function of frequency as well?

In the picture i present formula that should be used by Ansys to calculate sound power level:

However this equation does not contain radiation factor sigma:

On the internet i found this:

but i dont know how to extract radiation ratio efficiency from the results ansys can provide me in harmonic acoustic analysis

]]>I am trying to model the gap in my timber floor-board as shown in the figure 1. Please advise me how I am able to achieve that. Figure 2 is my FEM of floor-board.

Figure 1: Gap between adjacent floor-boards

Figure 2: Finite element model of floor-board

Thank you in advance.

Regards,

Dheeraj

]]>Per the solution, the tympanic seems to resonate right around the frequencies these bats send out, which is good news; however, to be honest, I'm not sure if I am doing any of this correctly. Surely, I must be doing something wrong. Is this the correct analysis to test something like this? Also, there are phase angles in the solution - what are they and are they important for my analysis? I have attached a photo of the model for now - only modeling half of the apparatus (they are symmetrical). I can post an actual file and/or results in a bit, but I figured this would be a good start for now.

I know the values of a and b but I don't know how to create the crack and obtain the value of the stress intensity facor with this configuration

Thank you very much

]]>**Сalculation of the bearing capacity of a pile for a pile field** (for example, 4 piles with a square arrangement) small for permafrost soil, taking into account the probability of its seasonal thawing (with the possibility of thermal stabilization of the near-pile zone).

**The following pile parameters are known:**

Diameter - 219 mm (wall thickness 11 mm)

Immersion depth in the ground - 25 m

Load on one pile up to 50 kN

Corrosion activity on carbon steel - moderately aggressive

On concrete structures - non-aggressive

Arrangement of piles in a square with a distance between them 3000 mm

**The following soil parameters are known:**

values of natural moisture and density of wet soil 0.47 and 1.74 g / cm3

porosity coefficient - 1.288

specific adhesion value 9 kPa

angle of internal friction 5.7 °

Compression modulus 0.4 MPa

Guideline value of adhesion according to triaxial tests 14 kPa

Plasticity 0.21

Frozen ground temperature minus 0.1 minus 3 °С

Frozen soils are in a frozen state

The temperature of thawed soils reaches a maximum value of 0.5 °С

]]>