Average Stress

Rahul_P1

We installed some strain gauges on a suspension part of a trailer which I need to simulate in Hyperworks.
These strain gauges have a typical size of 6x6mm. I want to represent these strain gauges in my FE-model and compare analysis results with the measurements.

First of all I defined my surface that represents the strain gauge by Geometry > Create > etc. .
After that I used 2D-Automesh to create a fine mesh and created a tetra mesh on all geometry with the option 'match existing mesh'.

Now to my problem:
I need the average strain of all nodes on my 'strain gauge-surface'. I want to use this information to compare this average strain with the measurement results. I have seven node sets which i have to evaluate, so a manual procedure is to time-consuming.
Do you know a tool or an script that is able to do that?

Rahul_P1

Dennis,

I mainly want to introduce to the expression builder or the result math module of HyperView where you can do such calculations easily.

Your explanation is very clear however I still need some more clarifications

you say - I need the average strain of all nodes on my 'strain gauge-surface'

strains will be output to the elements so you are actually looking at two step averaging,
first you will need to average the strains of the elements to the nodes
and then the average of all the nodal values in the set. is this right?

why not use the element strain value and average of the elemental strain values to compare with the real life results?

Here is a simple procedure

Why not create components of all these different strain gauge surfaces ? because then you can easily use the bcelemtopart in the result math > model (And why sets for these different surfaces? if it has to be sets then we have to use bcelemtoset)

just go to results > create > derived results > use the model library > and doubleclick bcelemtopart

(please uncheck hide default arguments as a new user)(you can give a name for htis experession which will then be populated int he result type table of the contour panel)

your syntax should be BCElemToPart(src,aggregate,elems) src will be element strains which you can select under table and just insert it other arguments will be taken by default so for example your syntax will read BCElemToPart(T1, avg, LC0F1.elements) this will average all the element stresses to the part i.e. component and place it as a new result type in your contour panel result types section, so when you contour this result type you will get one value for the component which is the average of the strain values of all the elements in this part.

Altair Forum User

Altair Forum User said:

 

just go to results > create > derived results > use the model library > and doubleclick bcelemtopart
 

Hi Rahul, 

I am interested in your solution but I can't seem to find the 'Model Library'. I am only able to choose between the 'Math Library' and the 'Expressions Library'. 

I am working with HyperWorks 12.0,  if that's helpful.

Regards, 

Marion

Altair Forum User

Hi Marino,

 

Make sure you have selected the Advanced Result Math Template when you load the model at the bottom right corner as shown in the image below:

 

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Thank you Prakash, I missed that part indeed. 

I want to use the bcelemtoset function but I don't know how to fill the 'Set table' argument. There is no Sets in the Table selector while they are defined entities in my model (as shown below). How should I proceed ? 

Regards, 

Marion
 

 

 

Altair Forum User

Hi,

 

Under table you should see Sets. Can you scroll down the table and see if sets are available in the list?

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi, 

Sets is not available in the scroll-down list. 
If I type LC0F1.Sets as argument, I get the warning : 'Unsupported binding type (Sets). Please use an appropriate binding change operator. '

Thanks for your help, 

Marion

Altair Forum User

Hi @marion.fournely

 

Can you create a set in HV and check if you can include the same in expression?

pohan

Hello

I can create the average stress and strain for BCset but I can not edit the expressions that I created. Could you please show me how?

Mario_21478

Hello,

 

Search for your expression in the browser, e.g. Results->Scalar->YourExpression (if Scalar), right click and pick 'Edit'.

 

Best Regards,

Mario

 

pohan

Hello.

Could we export the average to Tfile for plotting?