To run this simulation inside the browser, a free plugin needs to be installed first. The plugin can be downloaded from the Wolfram research (Mathematica) web site http://www.wolfram.com/cdf-player/
Once the plugin is installed on your PC, then you should be able to interact with this simulation (you might want to refresh this page or restart the browser to make sure the plugin is active).
This is a demonstration written in Mathematica showing finite element solution by Ritz method for a simple axially loaded beam fixed at one end and free to extend on the other end