Fatigue Analysis

SIVAPRAKASH V
SIVAPRAKASH V Altair Community Member
edited June 10 in Community Q&A

Hi,

I am using to Altair Hypermesh(optistruct) solver to perform Fatigue Analysis. I am a Beginner in fatigue Analysis.

I want to define the Load Time History under TABFAT card. Now I am stuck in the Load Time history creating process.

 Actually software identifies what values in X column and Y column. ?

As per My knowledge, X is Time in seconds and what is Y , it is a scale factor of load or Actual. what we put in y column.

I assume two cases : Assume my actual Load is 500 N

Case 1: X (TIME in seconds)      Y(LOAD in N or KN)

                    0                      0
                    1                      1
                    2                      2
                    .                       3
                    .                       4
                    5                      5
                    6                      0
 
Here I am used to created a load time history by using  scale Factor of the Load in the Y(Load) column.

For Example : If I Given the force value as 500 N in the Working Model, then I enter the Scale factor of the Load as 1, 2, 3....respectively.

Case 1: X (TIME )      Y(LOAD)
                    0                      0
                    1                      500
                    2                      1000
                    .                       1500
                    .                       2000
                    5                      2500
                    6                         0
  
Here I am used to created a load time history by using Actual Load Y(Load) column. 

For Example : If I Given the force value as 500 N in the Working Model, then I enter the actual load in the upcoming Time (seconds).

Based on the Two assumptions which one is correct or Correct me if I am Wrong.



Thanks & Regards,

Sivaprakash V,
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Answers

  • Adriano A. Koga
    Adriano A. Koga
    Altair Employee
    edited June 10

    you should take a look at FATLOAD and TABFAT help sections.

    https://help.altair.com/hwsolvers/os/topics/solvers/os/tabfat_bulk_r.htm

    TABFAT contains only the Y values of your load history. FATLOAD has a multiplier, scale factor, that could be used to multiply your load history.

    Additionally, this is related to your reference load case used into FATLOAD, so the actual final load, is a combination of all these.

  • SIVAPRAKASH V
    SIVAPRAKASH V Altair Community Member
    edited June 10

    Thankyou for your reply. I understood the FATLOAD, In fatload we define the Load steps and enter the scale if we want.

    My doubt is Load time History.

    How software consider the values what we enter in the Y column of load time History.

    If we enter 1 in Y column, it takes as scale factor or actual load?

    The below Image contains one load time history, the actual load is 500 N(For Example)

    If I created a Load Time History likes this, How software consider this like  what is X and Y i
    image

     I request to please clarify my doubt in Creating Load Time History .


    Thanks & Regards,

    Sivaprakash V

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