strain is always unitless, give 0.01 for1%.

Strain is a unit less parameter. but in ABAQUS while using the SI units, mm/mm in percentage should be used for strains.

unitless

Agree, give as absolute number e.g. 0.01 but make sure that the metric elasticity module E=2.1 x 10^11 N/mm^2.

Abaqus is unitless. You can use any unit. However, you have to stick with same unit in everywhere. Like N and mm. No matter what unit you use but you have to be consistent and same for output.

@all thank you very much

strain is the yield product of but even if it expressed in percent it is unit is in mm as SI