Dashes are usually fine. Did you try replacing the _ with -?

I try to avoid _ in filenames, but - works for me.

On Thu, Feb 5, 2015 at 6:42 PM, Timothée Flutre <timflutre@gmail.com> wrote:
In the org file, it would look like this:
#+latex_header: \graphicspath{ {./images/} }
[[file:simul001_a-4_b-0.1.pdf]]



John

-----------------------------------
Professor John Kitchin 
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803