Join Date: May 2005
Location: Mayenne France
My Motorhome: Carthago
Thanked 229 Times in 206 Posts
The problem with any thin material flat sheet is that it will not have much resistance to being bent, the only way resistance to bending is achieved is by using angles or radius corners and then of course how much resistance will be is determined by the actual thickness and shape.
The most resistant will be carbon fibre, but even with that you'd be limited in how resistant it was by its design and thickness.
Just a thought but on the majority of trousers or jeans the rear pockets are actually higher than the seating area, so the amount of bending moment will not be so severe as perhaps you imagine.
Most likely more of a squash than bend.
Sorry but that doesn't help with your question, perhaps invest in a high end phone made from materials more resistant.