# Mahdi Ebrahimnejad ShalmaniIsfahan University of Technology | IUT · Department of Mechanical Engineering

Master of Science
Doing MSc Project. Research.

Introduction
Skills and Expertise

## Questions

Questions (2)
Question
I have a simulation code for a Horizontal Washing Machine.
The code solves the equations of motions of the system by Matlab ode45 and plots the vibration response of the system at the transient state of performance.
In this code, the frequency (omega) is an exponential function of time, as it's stated below (and its diagram is attached to 'the question'):
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omega= (1-exp((-0.5)*t))*omega_0+(1-exp((-0.5)*heaviside(t-t1).*(t-t1)))*(omega_1-omega_0);
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ode command:
-----------------------------------------------------------------------------
[T,Y]=ode45(@snowa1,tspan1,initial_vector1);
plot(T,Y(:,1)-mean(Y(:,1)))
-----------------------------------------------------------------------------
The resulting displacement response is attached to the question.
It is desired to :
First, increase the frequency to omega_0 by exponential1
Then, increase it to omega_1 by exponential2
But 'the problem' is that:
the displacement response shows an unexpected increase in frequency at the beginning of the second exponential increase (it becomes 20 Hz, which is much larger than the maximum frequency in the simulation- 10 Hz).
Do you know what could be the reason for this response?
Any help would be gratefully appreciated.
Question
Hello dear friends,
To do my MSc project, I've read this paper: 'Stability and dynamic analyses of a horizontal axis washing machine with a ball balancer' - by Chen (2015),
and found these expressions for the equations of motion dimensionally inconsistent. And I need these equations to make progress in my project.
Would you please check the paper and let me know if I'm wrong or how can I deal with it?
Matrices and vectors dimensions:
M (8*8)
k(8*1)
Gama(8*1)

## Projects

Project (1)
Project
The new ball balancer will be effective in reducing the transient vibration of washing machines. It's economically preferred among the other methods of vibration control. Also, the design configuration has less complexity.