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I am solving the equations numerically but I want to find the mode shapes and natural frequencies analytically (according to the paper attached) to validate my numerical results. Like I said, the thing I am not sure about is the way I have excited the bar. I am not that young to do homework and...

Thank you. Unfortunately, I don't have access to this book. I am not sure what the book suggests but I need to use the methods described in the attachment to arrive at the natural frequencies and mode shapes of a 1D continuos bar governed by the wave equation. The point I am not sure about is...

I am trying to excite the bar using some sinusoidal function at that free boundary. I am not quite sure if what I have done is correct.

Thank you both. I hope I have not insulted anyone by asking if anyone has a good understanding of continuos system, I was not very familiar with the forum. With regards to my question, from your replies I am concluding that an added mass does effect the natural frequencies and mode shapes but...

Thanks Greg, The reason I am confused is that I have seem cases where there was a mass at the end of a 1D bar and that has been taken into account when working out the natural frequencies. For instance case 4 on page 11 of the attached file. Another case I have come across is where you have a...

Hi, Is there anyone who has a good understanding of vibration of continuos systems. I need to calculate the natural frequencies of a 1D bar governed by the wave equations: d^u/dt^2 = sqrt(E/rho)*d^u/dx^2 . I have an idea of how to obtain the natural frequencies using fixed or free boundary...

I just found out that I have not really implemented the boundary condition in the code. Have done that now and results seem more reasonable. Having said that, I would appreciate some guidance on how I can evaluate the results, and how to work out the eigenvectors of a forced system.

Hi All, I am having difficulty understanding a set of results I have obtained by solving the dynamic equations of a 1D bar, fixed on the left hand side, and excited by an external force of F0*sin(w*t)on the right hand side. I have integrated in time using an explicit Euler scheme. I suspect for...

I've ignored radiation and am just looking at condution and convection!! The block is sat on the plate, so I've partitioned the Aluminuim sheet so that I can apply the heat flux coming from the block at that partitioned face. Is that method ok? Cause its not really working? Thanks!

Thanks Corus! I think I've managed to do it. I am getting an error that says: NO VALID RADIATION OUTPUT REQUESTS HAVE BEEN GENERATED. THIS MAY BE DUE TO EARLIER INPUT ERRORS OR SPECIFICATION OF A NONEXISTANT CAVITY OR SURFACE NAME Do you know what it is implying?

I am trying to model the heat trasfer in a square Aliminuim sheet. Heat is applied to the sheat from a heater block that is attatched to the Aliminuim sheet in the middle. The power from the heater is 150 W and the sheet is initially at room temperature.I'm not sure about a few things: 1) When...

When I create a reference point I get the same error as 'sarasvensson'. I was also wondering whether this problem only occurs with ABAQUS 6.8??

Thanks...I am using plain strain as my element type when I create the mesh but when I create my section I don't have an option to choose plain strain. Its either generelised plain strain or homogenous. My model is two dimnesional and deformable and its not rigid. If I use a reference point...

I have exprienced the same problem when I was trying to create a generelized plain strain section. Is there a way of creating a generelized plain strain section without creating a reference point?