Example:

if we want to apply 1000 load cycles, the time period of each cycle is 0.25s.

Amplitude, as the term suggests, is just a scaling factor to the amount of load you wish to apply. So, instead of ramping up the load to the final value, if I wanted to have a triangular waveform, I could enter a table in the amplitude definition as follows:

Time | Amplitude

==================

0.0 | 0.0

_______________

0.5 | 0.5

_______________

1.0 | 0.0

So, if my ultimate load value is, say, 100 N, then at time=0.0, load=0.0*100=0.0. At time=0.5, load=0.5*100=50, ..

You can even assign a user defined loading protocol, if that's needed.

Example:

if we want to apply 1000 load cycles, the time period of each cycle is 0.25s.

Amplitude, as the term suggests, is just a scaling factor to the amount of load you wish to apply. So, instead of ramping up the load to the final value, if I wanted to have a triangular waveform, I could enter a table in the amplitude definition as follows:

Time | Amplitude

==================

0.0 | 0.0

_______________

0.5 | 0.5

_______________

1.0 | 0.0

So, if my ultimate load value is, say, 100 N, then at time=0.0, load=0.0*100=0.0. At time=0.5, load=0.5*100=50, ..

You can even assign a user defined loading protocol, if that's needed.

You can apply a waveform as ramps in such way to form a triangular waveform.

Other way is to apply the loading history by introducing constant increments of time, for each value of load, in a given period of time, until you reach the maximum load. Then you do it again, changing the sense of loading. You can enter this loading history by means of a table: time X load

This video tutorial gives good overview of  Direct cyclic analysis in Abaqus.

https://www.youtube.com/watch?v=CDfwV-d4dLQ&index=3&list=PLE4jpqcRJiBrNlnkqCrCLJHKoIEs71mQP

Thanks for your answer.

I have a questions.

How can I apply a number of cycle?

For example, i want to apply the time period of each cycle is 1s and 10000 load cycle.

Hello, may I know..

if Direct Cyclic analysis is applied for Step 2, so what analysis should apply for Step 1?

Thank you

Dear Nazirah,

I'm not expert in the FCG topic, But I think you have to use a "General Static" analysis for step 1, and apply the initial loading in this step. The initial loading could be the minimum load in the fatigue analysis.

Your problem should be belonged to high-cycle, however, ABAQUS deals with low-cycle problem.