here is the change you have some mistake with the units of there
http://files.engineering.com/getfile.aspx?folder=8d339c81-d95a-4281-aacb-71f62a7be3ba&file=Collapse.xmcd
The ecuation you are have infinetly solutions and you can work with some parameters I modify you can see my idea .the result for simply is dispalyed but cant be save you will seehttp://files.engineering.com/getfile.aspx?folder=9f411e29-5ed8-4043-80c2-a550f491640f&file=stroh_mcad[1].xmcd