Solaris

this may be done from /etc/shadow
root:.eGLAkNXjAuc.:6445:x :x :x :x :x :x replace each x with appropriate value to do this see man /etc/shadow for available x values

As already stated, this can't be done with /etc/shadow as the smallest expiration period is one day and 30 minutes is smaller than that.

Not recommended, but if you require this functionality you could try to have cron execute a script every 30 minutes to issue a 'passwd -f ${username}' for a list of users. This will prompt the user to change his/her password at next login.
You could also integrate 'last' (/var/adm/wtmpx) output to acquire login timestamps for user(s) so as to reset user(s) account after 30 minutes usage.

SRG

yes..that is the way i know...but i wanted to know if there us any file in which we can edit and make it possible

you could always set a job in crontab to run the passwd -f command on certain users every 30 minutes.

There is no OS setting to do it. You would have to do the "band aid" approach of using passwd -f and cron. The draw back with that method is you would have to remember to add each new user you add to the system to that cron job.

If this is only for testing purposes, you could put the clock into the future to force passwords to expire.