I have a simple problem: a cantilever beam with a tip mass of 0.0634 Kilograms has some vibrational response from an impact, and from that data I used a FastFourierTransform to get the natural frequency, which turned about to be 10.5882 Hz. And the beam's dimensions are as follows - L = 0.186 m, B = 0.03 m, H = 0.001 m (a thin beam). So my natural frequency should be sqrt(k/m), where k for a cantilever beam is 3EI/L^3. From the natural frequency obtained from the FFT of the data, we get E as 2.369e11 Pa.
I am supposed to validate this using FEA, but my natural frequency falls way short only when using a 3d solid model. Using a wire model with assigned sections and no mass, and just an inertia at the tip is perfect. But the second I transition to a 3d solid model, it stops working completely.
Here's what I have tried:
1) Assign an arbitrarily low mass density, create a node set, define an inertia > non-structural mass for the nodal set with the tip mass
2) Assign a mass density such that the total mass is the same as the mass of the tip
3) Create a tip mass with an RP and arbitrarily low mass density.
All of them predict my natural frequency to be incredibly low.
Any suggestions as to why this is?
I don't want to create a part on top of the beam with the tipmass, I want the nodes at the end to have some mass, should I look into kinematic coupling?
I am supposed to validate this using FEA, but my natural frequency falls way short only when using a 3d solid model. Using a wire model with assigned sections and no mass, and just an inertia at the tip is perfect. But the second I transition to a 3d solid model, it stops working completely.
Here's what I have tried:
1) Assign an arbitrarily low mass density, create a node set, define an inertia > non-structural mass for the nodal set with the tip mass
2) Assign a mass density such that the total mass is the same as the mass of the tip
3) Create a tip mass with an RP and arbitrarily low mass density.
All of them predict my natural frequency to be incredibly low.
Any suggestions as to why this is?
I don't want to create a part on top of the beam with the tipmass, I want the nodes at the end to have some mass, should I look into kinematic coupling?
