Republic of Serbia
College of applied
Vranje
Seminar paper
In
English language
Topic: Applications in system dynamics and vibrations
Professor: Student:
Dr. Maja Stanojevic Gocic Miroslav Toncic 294/ MI
Vranje,2015
Applications in system dynamics and vibrations
2
Contents
Introduction..............................................................................................
3
Vibration measurement ............................................................................6
Forms of vibration......................................................................................8
Generate noise in mechanical systems.......................................................10
Displacement, speed and Acceleration………………………………………...............11
Complex vibration......................................................................................12
Energy and power…………………………………………………………………………...........13
Natural frequencies...................................................................................15
References.................................................................................................16
Applications in system dynamics and vibrations
4
Frequency
vibration is the reciprocal of the value of the period, and indicates
the number of periods per second
f = 1/T [Hz]
The period of vibration
the time it takes for one cycle
f = n/60
Turning speed
also called
angular frequency
, the angle is described in a given
time
ω = 2 π f
Vibration speed
varies in each part of the cycle, but at any moment in time is:
V = dx/dt
Acceleration
is also prom at all times, and its value is calculated as:
a = d
2
x/dt
2
Vibrations in its simplest form can be seen as fluctuations or moving object that
iterates over some equilibrium position.
Equilibrium position is the position in which the object remains outside the
influence of the external force.
This type of vibration is called a '' full-body movement "which means that each
part of the body moves along in the same direction, direction and time.
Vibraciono movements of the entire body can be fully described as a
combination of individual movement through six different types. This is the
translation
in three perpendicular projection of x, y and z, and
Rotate
around
the x, y, and z axes. Each complex movement can be represented as a
combination of these six simple movements. On the basis of this we can say
that the body has
six degrees of freedom
.
Applications in system dynamics and vibrations
5
Figure 3. 119. Defining degrees of freedom of movement
Suppose the object retains one direction. For example, the pendulum clock is
moving in a plane. Hence it is called a system with one degree of freedom.
Another example of a system with one degree of freedom (individual) is an
elevator moving up-down, etc.
Vibration of an object usually causes
force excitation
(excitation).
The object may appear:
-
external force or
-
force that may occur in the facility.
The frequency and size of the vibrations of a given object are fully specified:
-
force excitation,-direction and-frequency.
For this reason the analysis used to determine the vibration force motives
when the machine is in operation.
These forces depend on the State of the machine, knowledge of its
characteristics and interactions which allow us to diagnose engine problems.
The simplest possible vibraciono movement that there is movement in one
direction, controlled one spring-
simple harmonic motion.
y
z
x
y
z
x
