What do you want to achieve from the simulation? Do you want to see the specimen fracture? Do you want to get the force-disp curve before failure? or Do you want even the descending part of the force-disp curve? Can you also insert an image of the model result and setup? Knowing these information can help people give better suggestions.
Regarding the kinetic energy, since it is very large, you are actually modeling an impact problem instead of a quasi-static loading problem. That's why you should make the end time longer. If the two specimen faces are not contacting each other, you can try to adjust the loading velocity. A better way is to adjust their initial positions so that they are in contact at the beginning of the simulation.