 #1
pjotrjanusz
 1
 0
 Homework Statement:

Calculate force, mass, damping and stiffness of horicontally oscillated IPE beam, completely fixed on the one end and free on the other
Length: 5990mm ;Deflection: 1cm, 3cm, 5cm, 7cm
 Relevant Equations:
 I am given data of our project that includes the measurement of the acceleration of the beam after being deflected as named above each and left to swing for 1 minute.
1.) I'd calculate the force needed to deflect the beam by using the method of virtual work for t=0 which is u[L] = FL^3/3EI. From there on I am completely clueless.
2.) Task is to calculate damping, mass and stiffness of the SDOF by using the data sheets which is basicly the u''(t) function of each experiment. I thought the mass of the SDOF can be generalised by putting the mass of the IPE beam (V*p) concentrated in a singular dot which represents the SDOF. Am I wrong by assuming this?
3.) Bendingstiffness in statics is always a combination of young's modulus and moment of inertia, but how do I find out the stiffness the beam has when experiencing dynamic stress? I don't know how to calculate the stiffness.
4.) I'd calculate the damping of the system by solving the differential equation of motion. But how am I supposed to get the inputs for that equations?
> Basically I am confused because we are only given the acceleration graphs of the tip of that beam after being deflected by us. I just need a good tip on how to start. Do I have to select some critical coordinates in those graphs and use them as input for the ODE to or three times as damping and stiffness is going to be constant anyways? each of the 8 graphs contain more than 60k coordinates... You can cleary see how lost I am so I'd be so thankfull for any help or tips!
2.) Task is to calculate damping, mass and stiffness of the SDOF by using the data sheets which is basicly the u''(t) function of each experiment. I thought the mass of the SDOF can be generalised by putting the mass of the IPE beam (V*p) concentrated in a singular dot which represents the SDOF. Am I wrong by assuming this?
3.) Bendingstiffness in statics is always a combination of young's modulus and moment of inertia, but how do I find out the stiffness the beam has when experiencing dynamic stress? I don't know how to calculate the stiffness.
4.) I'd calculate the damping of the system by solving the differential equation of motion. But how am I supposed to get the inputs for that equations?
> Basically I am confused because we are only given the acceleration graphs of the tip of that beam after being deflected by us. I just need a good tip on how to start. Do I have to select some critical coordinates in those graphs and use them as input for the ODE to or three times as damping and stiffness is going to be constant anyways? each of the 8 graphs contain more than 60k coordinates... You can cleary see how lost I am so I'd be so thankfull for any help or tips!
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