Acceleration Loading

I have a weldment which is all steel. I am trying to analyze a crash load condition which induces a 1000 lb crash load which would not be a full 1G crash. Since you still would have gravity loading of 1G down, how do you induce an acceleration load  of say 0.5G in the side direction along with the gravity load of 1G down?????

SolidworksSimulation