This is a paid asset, but now you can download Mecanim Ragdoll Animation Blender Free.
Detail this asset from Unity Store: Original Link
Mecanim Ragdoll Animation Blender v1.2 (Latest version)
This asset simulates ragdoll physics with the mecanim animation system. Your animated characters will react with to the physics engine while remaining animated. The asset handles blending between animation and physics based on physics collisions on your character. Balance is also simulated allowing animated characters to be knocked down (using ragdoll physics). Once knocked down, the characters can get back up after a set amount of time.
If you have any questions about the asset, contact me at [email protected] You can find help for the asset in the videos / tutorial videos below.
Demonstration Video
Setup Tutorial
Tutorial #2
Tutorial #3