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HOW TO APPLY CYCLIC LOADS IN ABAQUS

Submitted by Bharadwaj on

I've performed a experiment in fatigue.I need to now perform analysis in ABAQUS and validate the results.

MY QUESTION IS - HOW TO APPLY CYCLIC LOADINGS IN ABAQUS,SAY FOR INSTANCE I'VE RUN 60000 CYCLES AT 10 HZ AT A MAXIMUM-MINIMUM LOAD OF 18 KN - 2KN

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Akumar

T = 1/10 = 0.1s.

 So for 60000 cycles define an amplitude function (better in terms of total time) of duration 60000*0.2 = 12000 s. It will be a series of triangular loading cycles where in 0.1 , peak load is reached and then in next 0.1s unloading is done. So a total of 30000 triangular units each of 0.2 s duration. Recommendation will be to load in one step and unloading in another step (that's why amplitude definition in total time). Use restart analysis as it will generate massive output file.

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The world started with 0, is progressing with 0, but doesn't want 0.

Wed, 01/30/2013 - 14:27 Permalink
seyed mehdi raoufi

hi.

i am modelling a composite plate subjected to a cyclic loading

i wnat to model a 1000 cycle with 10 hz frequency.

 i have some question from you.

is it possible to use static,general as step?

on the other hand , i use  umat subroutine for egradation of properties, i want to have a degraded properties,in each cycle.

is it true that i assme  that every increment is 1 cycle?

and at last, i dont understand what exactly,do you mean in this sentences "Recommendation will be to load in one step and unloading in another step"

can you explain it?

 

thanks 

Wed, 10/22/2014 - 18:15 Permalink
mmalekan

 

When two-step loading being used and based on Abaqus step chronically, Is this type of loading definition (actually, step definition)can be called a Fatigue load?

Wed, 01/30/2013 - 15:17 Permalink
RaphEmm

You have to create a periodic amplitude and apply it on your loading.

create a periodic amplitude which content :

circular frequency : 2*pi*f 

starting point : as you want

initial amplitude : average load 

Write in A & B as :

A*cos(wt)+B*sin (wt)

Tue, 03/05/2013 - 09:07 Permalink
RaphEmm

You have to create a periodic amplitude and apply it on your loading.

create a periodic amplitude which content :

circular frequency : 2*pi*f 

starting point : as you want

initial amplitude : average load 

Write in A & B as :

A*cos(wt)+B*sin (wt)

Tue, 03/05/2013 - 09:08 Permalink
amiraha

Hi Friends, 

I am really stuck in applying cyclic loads to a simple 2-3D beam in Abaqus. The material is defined just as elastic. I want to apply half-sine loads. So I have defined Tabular data in Amplitude curve like this instead of using Periodic option of Amplitude (as it gives the whole sinusoidal load and not the half-sine): 

0 0.00 

0.05 0.31 

0.1 0.59 

0.15 0.81 

0.2 0.95 

0.25 1.00 



On the other hand, I have defined my pressure load equal to 10MPa. The problems are: 

1. I cannot see any displacement stresses after completing the job, seems there is a problem with reading the Tabular data because when I run the program without assigning Amplitude and just the ramp loading, it gives outcomes! 

2. Can I define for example 1000 half-sine cycles in Tabular data in Amplitude curve section? or I need to go through other options. 



Please consider my question as I really need help. Thanks Pals! 



P.S.:I defined a crack with XFEM at the bottom of the beam.

Mon, 06/24/2013 - 14:11 Permalink
Alfred1991

Hello all dear experts, 

I want to run a tension-tension fatigue on my flat specimen. I need and 0.01 mm increase in each cycle. I mean in first step the displacement is equal to 0.01 mm and come back to 0. Then in 2nd cycle the displacement is 0.02 mm and again come back to 0; and so on. Note that, the time of my first cycle is 1 s, the scond cycle is 2 s and third is 3 s; and so on. 
My question is that how can I perform such a methode in ABAQUS? 

Thanks in advance. 

yamimansoorina [at] gmail.com 

Tue, 11/17/2015 - 07:48 Permalink