I am an amateur researcher, Judith, (having only researched family and friends as a hobby) so confirm anything I tell you independently.
There is no database you can access to get details of the circumstances regarding his Purple Heart. There were too many of them awarded to detail them to any significant degree.
If you can get his personnel records you should be able to establish where and when he suffered the wound for which he received the decoration.
To find out any significant details your only hope may be to find men who were serving with him at the time he was wounded. This is a long shot, especially at this late date. Time has now taken many of those who were not killed in the war. In the past, one of the best resources in this regard has been formal veterans groups, such as unit vet associations. Many have contact info you can find online.
Here are some web pages with info that may be useful (and interesting) to you, in the event that you have not already found them. (You will notice the first two are both found at the National Archives website.)