HOW TO SET A DYNAMIC ANALYSIS (TRANSIENT DIRECT)

Altair Forum User

Hello guys,

I would like to know if the application of a pressure in case of dynamic analysis(Transient direct) has to be done in this way.

I have to apply a pressure on my component,  to divide on 4 different areas of the component (the areas has the same value). This pressure is time variable, in particular is equal to 0 MPa at the time t=0 s and is equal to -3.648 MPa at the time t=2s.

I created a load collector (named “Pressure”), I highlighted the elements on which to apply the pressure (and so I defined the 4 areas on which to apply the pressure), I choose a load type PLOAD4 and I defined the magnitude of the pressure (to the value -3.648/4= -0.912).

 I created a load collector(named “Interval”) with Card Image TSTEP, and since that I would like to divide my time interval of 2 seconds in 5 steps of 0,4s I set N=5 and DT=0,4s.

I created a load collector (named “transient') with Card Image TABLED1, I set Data:

 

0 s            0 MPa

0.4 s         -0.1824 MPa

0.8 s         -0.3648 MPa

1.2 s         -0.5472 MPa

1.6 s        -0.7296 MPa

2 s            -0.912 MPa

 

I created a load collector (named “Study”)with Card Image TLOAD1 setting EXCITEID=Pressure and TID=transient

 

I created a loadstep with Analysis type=Transient(direct). I set Dload=Study and TSTEP=Interval

 

I have a first question, since that I have 4 areas to load, the magnitude of “Pressure” to set has to be equal to - 0.912 MPa or to (-0.912*4= -3.648) MPa?

Moreover I would know if also the values of the pressure in the Data have to be multiplied for 4 or to be left as written previously.

The second question is the following, is this the right way to set the problem in Hypermesh?

Thank you for your support!

Altair Forum User

Hi Mil,

 

Calculate the number of elements and divide the pressure with elements. This will apply result on each element. 

Altair Forum User

So, my pressure at t=2s  is equal to -3.648 MPa, I must divide this value with the number of elements because select the elements on which I want to apply the load isn't enough, it's right?

Moreover, the pressure to insert in the field Exciteid of TLOAD1 has to be equal to the value of pressure at the time 2 s (that is the final instant of my time interval), it's right?

Thank you for your support

Altair Forum User

Mil,

 

If your interest is to apply on total area then Yes, For example if you want to appy 100Mpa on an area which covers 5 elements then you need to divide pressure for each element.

Instead provide a load factor. For example for same 5 elements at t=0 pressure is 5Mpa and at t=2 pressre is 100Mpa

So I create a pressure load collector of 1Mpa per element which makes 5Mpa for t=0 and in tabled1 I provide Y=20 scaling the pressure to 100Mpa

Altair Forum User

So, if I understand, suppose that I must apply a pressure of:
0 MPa at t=0s 
5 MPA at t=0.4s
10 MPa at t=0.8 s
20 MPa at t=1.2 s
30 MPa at t=1.6 s
50 MPa at t=2s
The elements on which I want to apply it are 5. 
First, I create a load collector 'pressure' (loadtype PLOAD4) and it is equal to 1 MPa.
Then I create al loadcollector Tabled1 and I set
X=0 Y=0
X=0.4 Y=1
X=0.8 Y=2
X=1.2 Y=4
X=1.6 Y=6
X=2 Y=10.

It's right?
Thank your very much!!!

Altair Forum User

@mil

 

Yes, but my case is different. So you need to decide how you want to apply pressure.

 

For example, If you want to apply a pressure of 25Mpa on a tail surface, you need pressure on each and every element with a magnitude of 25Mpa