# hrbeu221's blog

## rotation spring setting

Dear all, these days I use combin14 to simulate the boundary conditions. I use two types of springs to simulate support. One is linear displacement spring, the other one is rotational spring. When the spring is on the radial edges, the rotation is about radius direction. When the spring is on the circumferential direction, the rotation is about circumferential direction. So i translate all the nodes to local cylndrial coordinate system. When the spring constants are large enough, the simulation results do not meet well with the clamped boundary conditions.

## Vibration analysis with uncertainty properties

Dear all,

These days I am doing some research on vibration analysis with uncertain properties. In traditional, Monte Carlo Simulation is used to do this simulation. But the drawback is time-consuming for the determinstic analysis.

For this, how to solve this problem? Please help me on it. Please give me some suggestion on it.

Thank you for your concern.

## compiler for FORTRAN

Hello, everyone,

These days, I am studying the Fortran. I want to know which complier is good for fortran. My computer system is 64 bit Win7 system. I want to use fortran to do some numerical calculation about the structure dynamics.

Thank you for your sugestion.

## orthotropic plates analysis

Hi, please help me on the simulation on the orthotropic material in ABAQUS. I have the parameters for the material density=1584;
Ex=127.9e9
Ey=10.27e9
muxy=0.22;
muyx=0.0177;
Gxy=7.312e9;How can i use the orthotropic or engineering constant to simulate the material. I want to calculate frequency for orthotropic plates.

Graphite epoxy plates

Graphite/epoxy consisting of 12 plies oriented at 0 and fabricated from Fiberite
Hy-E1034C prepreg

Thank you for your concern.

## Explicit Integral

When use matlab or mathematica integrate this y = int(cos(m*pi*x/a)*cos(n*pi*x/a)/(x+a0)^2,x,0,a); (m,n=0,1,2,3,4,5...)

There is some explicit integral. I try to solve this problem. But the result is complex.

Is there some effective way to solve this problem.

Thanks!

## Circle transform to square

Hi, everyone, Is there some methd for the coordinate transform from circle to square.

Thank you for your suggestion.

## Ask for help for one paper

Ask help for one paper in the inter noise conference 2011

Title: Application of virtual mode synthesis method for ship compartment impact noise

Page: 147-156

Thank you very much.

## draw mode shape with matlab

if M is your mass matrix and K is the stiffness matrix, use
[phi w2]=eig(K,M);
phi contains the eigenvectors (each column is a modeshape)
w2 is a diagonal matrix, each diagonal entry contains wn(i)^2
(i.e. the i'th natural frequency squared).

Then how to draw the mode shape with eigenvectors?

Thank you.