EPTIm having a final exam in structural mechanics on thursday and things are looking quite good. Although I have some problems on the concept with elastic instability , i.e the Euler cases.
For the Euler cases the critical load can be calculated, my problem is to understand what happends when the critical load is applied?
For the other problems in the exam I can visulize what is happening and then begin to solve the problem, however I just can't seem to understand what models to use when applying to problems like: (http://www.am.chalmers.se/~moller/HALLFF/EXAMS/tenta2_06.pdf problem 3 it is in swedish.)
For those of you guys who arent fluent in swedish, it is a set of two ridig bars (representing a roof) and a hinge. Rain water falls on the roof creating a force which is spread over the bars.
I can derive the correct equations from vertical equilibrium and moment around the hinge. I just cant understand why the critical load is given for L = 3*K/(2rho*g). K is a spring constant, rho is the density and g is the gravitational acceration.
I would be grateful if someone could explain it for me or link to an appropriate page.
/Jacob
