Role of Vibrations in
Structure
The subject of vibration
deals with the oscillatory motion of dynamic systems.
The objective of the designer is to control the vibration when it is objectionable and to enhance
the vibration when it is useful.
Most vibrations are
undesirable in machines and structures because they produce;
ü Increased stresses
ü Energy loses
ü Wearing problems
ü Increasing bearing loads
ü Induce Fatigue
On the other hand, shakers
in foundries and vibrations in testing machines require vibration.
Problem Solving Approach
· Statics - Engineering mechanics course dealt with
rigid-body members especially the force associated with them
·
Kinematics of
Machines - kinematics of machinery
dealt with the displacement, velocity, and acceleration of machines.
·
Study of
Oscillatory Motion (Mechanical
vibrations)- when there is a deformation of the various members of the machine
when the deformation is there or the members are flexible then we cannot
decouple the kinetic analysis and the dynamic analysis of machine or mechanisms
in that case when we are analyzing the motion of that flexible member machines the force also we have to consider simultaneously for the analysis.
The primary objective of our study is to analyze the oscillatory motion
of dynamic systems and the force associated with the motion.
The ultimate goal in the study of vibration is to determine its effect
on the performance and safety of the system.
The study of vibration is concerned with
the oscillatory motions of bodies and the forces associated with them. All
bodies possessing mass and elasticity are capable of vibration.
Classification of Vibrations
System vibrations can be classified into three categories:
· Free Vibrations
· Forced Vibrations
· Self-excited vibrations
Free Vibrations:
Forced Vibration of a system is a vibration that occurs in the absence of
any force, where damping may or may not be present
In the absence of damping, the total mechanical energy due to the initial
conditions are conservative, and the system can vibrate forever because of
the continuous exchange between the kinetic and potential energies.
Forced Vibrations:
An external force that acts on the system causes forced vibrations. In In this case, the exciting force continuously supplies energy to the system to
compensate the energy disputed by damping.
The behavior of the system under forced vibrations is dependent on the
type of excitation. If the excitation is periodic, then vibrations of a linear the system is also periodic.
Linear vibration:
If all the basic components of a vibratory system – the spring the mass
and the damper behave linearly, the resulting vibration is known as linear
vibration. The principle of superposition is valid in this case.
Nonlinear Vibration:
If one or more basic components of a vibratory system are not linear
then the system is nonlinear.
Deterministic:
If the value or magnitude of the excitation (force or motion) acting on
a vibratory system is known at any given time, the excitation is called
deterministic. The resulting vibration is known as deterministic vibration.
Random Vibration:
In the cases where the value of the excitation at any given time can not
be predicted. Ex. Wind velocity, road roughness and ground motion during earth
quake.
Key FEA activities
carried:
· Vibration
analysis on Oil and Gas pump support structure. Modal and Harmonic analysis.
· Vibration
analysis on Automobile mounting brackets carrying artillery systems. Modal,
Harmonic and Random vibration analysis.
· Design optimization
to overcome resonance
· Seismic analysis
on oil and gas skid structures and storage tanks. Shock load analysis.
Design
Validations as per Industrial codes such as
· API
· ISO
· DNV
· ASME section
VIII division 2 & 3
· Eurocode etc
Our FEA
expertise combined with our industry-renowned process will mitigate your risk,
improve the performance of your product, shorten your lead times and reduce
your costs.
Projects
Executed for:
· APSCO USA
· Hydro UK
· Gdyson Pumps
