One thing I have noticed when strain is being discussed in bowmaking conversations is that folks with engineering backgrounds understand strain as how much the back or belly is stretched or compressed due to the radius of bend. Of course overcompressing a belly causes set, which all bowyers agree is not desirable. Conversations can become a bit uncertain when folks with differing backgrounds and training use the term strain in a more general fashion or as understood in other disciplines.
A bow with equal strain all along the length of the bow could be understood by some as a circle of arc tiller in something like a bendy handle. Of course other design factors like stiffer handles or tips add to arrow performance in more geometrical ways with out being strained (from an engineering perspective) very much at all. The circle of arc example above only holds true in an engineering sense of strain, if the thickness of the bow remains constant and all tapering is done in width. This is not a bow seen very often.