- Select your shape and go to Object > Path > Offset Path…
- Set a negative value for the Offset to put the new path
INSIDE the existing one. You may need to experiment with the other settings to get a result that you like the look of.
- Change the style of your new, inner path to a dashed line. This
option can be found in the Stroke palette. Again, experiment with the settings to taste.
Source : Link , Question Author : ariasaven , Answer Author : Westside