Actually they are not different. The problem with load boundary condition is that based upon the component stiffness, even a small amount of load increment may cause large displacement increment at the contact, so that problem does not converge. This problem may occur even if you apply displacement boundary condition and use large time increment. With the load boundary condition, you should always have an idea about how much displacement it may cause. Try to use smaller time increments when such error occurs. Hope this helps. 

Thanks Anshul for your suggestion. I already tried it but still same error pops up. I guess there should be some other way to resolve this error.

Are you applying pressure or concentrated load?

I am applying concentrated load.

have you solved the contact problem?

Yes, In my case issue was due to improper constraints but usually it resolves through displacement boundary conditions only.

hey pankaj, i have also tried with displacement , it works upto small displacements but if i gave more displacement then it is giving the same error as you mentioned. can you please help me with this.

Hi Vijay,

In general, if there is possibility of rigid body motion during your analysis, you can add elastic springs to prevent it and avoid convergence issues.

My problem is bolted lap connection with bolts placed centrally of the hole with a clearance of 1mm. for this type of problem, will you suggest anything more to avoid convergence issues?

How are you trying to impose displacements? Can you make it bit more clear?

i'm imposing displacement at the end of the plate by kinematic coupling of all points on that edge throughout the thickness and applying displacement at the middle point.