If a calculation does not converge, abaqus cuts back the time increment, it does this 5 times, then it throws the too many attempts-error.

Look at the msg-file (or the job diagnostics) for the warning before the "too many attempts". This will tell you why the time increment has to be cut back and where the problem in convergence actually lies.

If this happens at the beginning of the step, reduce the initial time increment.

If you get the minimum time increment-error, reduce this in the step definition.

It is also helpful to use

*controls, analysis=discontinuous

in the inp-file (you can also set this with CAE in the step solver controls somewhere)

I would also recommend to read the Getting-Started manual if you are new to Abaqus, where all these concepts are explained very clearly

The solution in Abaqus solver is iterative. The message is prompted when the number of iterations reach a maximum value. You may try to change the options in the "Incrementation" Tab of the Step Menu.

The non-linear solver appears to be struggling to reach a converged answer and this may be due to the problem that you are giving to it.  In these situations I would suggest checking that a linear analysis of the problem runs correctly and then add the non-linearities in a piecemeal fashion each time ensuring that your answer is sensible.  You might want to try starting with a problem that has a known theoretical solution or a numerical solution of sound provenance...

If a calculation does not converge, abaqus cuts back the time increment, it does this 5 times, then it throws the too many attempts-error.

Look at the msg-file (or the job diagnostics) for the warning before the "too many attempts". This will tell you why the time increment has to be cut back and where the problem in convergence actually lies.

If this happens at the beginning of the step, reduce the initial time increment.

If you get the minimum time increment-error, reduce this in the step definition.

It is also helpful to use

*controls, analysis=discontinuous

in the inp-file (you can also set this with CAE in the step solver controls somewhere)

I would also recommend to read the Getting-Started manual if you are new to Abaqus, where all these concepts are explained very clearly

Thank you to all. Your answers have helped me.

Actually I am new to Abaqus and currently working on concrete damage plasticity model. I want to model axial compression test and flexure test on concrete. for this should I apply displacement or should I apply the prssure(load)? and what should be the value for this displacement or load?

In general, compression tests are performed by imposing a displacement and a displacement rate. The value highly depend on what you are looking for. A low compression rate (e.s. 1 mm / 30 seconds) ensures a static behaviour.

Imposing displacements also has the numerical advantage of being less prone to instabilities, especially if you use a damage model.

Thanks to all for your replies.

I want to simulate the experimental test on concrete and to verify the results from experimental results. In laboratory the load is applied at a constant strain rate. Is it possible to assign a constant strain rate in Abaqus? Up to my knowledge Abaqus allow to apply a displacement but I don't know how to convert this strain rate into displacement. The another question is can Abaqus show the cracking pattern also?

Constant strain rate = linear increment of applied displacement.

I have got this error "DURING THE CONVERSION FROM CRACKING TO PLASTIC STRAIN Abaqus FOUND NEGATIVE AND/OR DECREASING VALUES OF PLASTIC STRAIN". But I don't understand why abaqus is showing error even I have entered plastic strain in increasing order?