Is there a difference between a tear strap and a doubler? If I get it right, the tear strap reinforce the main structure locally and prevent the propagation of tears, while the doubler, well, it has the same function. Is the difference lying in their geometry?
The difference is the doubler has a broader application, as a general reinforcement of a skin, web, or flange to increase tensile strength, compression strength or stiffness by making the part thicker over an area, generally with multiple load paths to absorb.
A tear strap, being a "strap", is more targeted as a tension-only reinforcement that is applied along a particular load axis to offload some of the tension load on the underlying part along that axis.