Convert NVARCHAR to MM/DD/YYYY format

hi all,

I need to convert all the dates (in NVARCHAR) to MM/DD/YYYY format. I need to achieve this in calculated columns.i have tried searching, but not getting clear idea.

the client doesn't want to convert in IDT or webi. I tried using date(ERDAT) but  its coming as Aug 14,2015. But I need in MM/DD/YYYY format so that no conversion is required in webi or universe.

Is there any function of to achieve this?

thank you