SECOWND Flashcards
No oscillation, sluggish return
Overdamped
No oscillation, fastest return to equilibrium
Critically Damped
Oscillatory motion with decreasing amplitude
Underdamped
It refers to a periodic oscillation, typically sinusoidal, in a system subjected to a restoring force proportional to its displacement.
Harmonic motion
When the restoring force is directly
proportional to displacement and
directed towards the equilibrium
position.
Simple Harmonic Motion (SHM)
This occurs when a system loses energy due to a resistive force proportional to its velocity. This is
common in many mechanical systems.
Viscous damping
This in vibration analysis involve ensuring that structures and mechanical systems operate safely and efficiently under dynamic loads.
Design considerations
Ensure the system’s
… are away from
operating frequencies to avoid
resonance.
natural frequencies
Incorporate adequate … to reduce vibration amplitudes.
damping
Choose materials with
appropriate stiffness, strength, and
damping characteristics.
Material Properties
Use … to
account for uncertainties in loadings and
material properties
safety factors
It refers to a system’s ability to return to its equilibrium position after a disturbance.
Stability
The system returns to
equilibrium after a disturbance.
Stable Equilibrium
The system moves
away from equilibrium after a
disturbance.
Unstable Equilibrium
The system remains in
its new position after a disturbance.
Neutral Equilibrium
Involves determining the
response of a system to small
perturbations and ensuring that it remains stable under operational conditions.
Stability Analysis
Does damping affect free vibration?
In undamped free vibration, the system oscillates indefinitely, but in damped free vibration, energy is gradually lost, reducing amplitude over time.
What is the difference between free and forced vibration?
Free vibration occurs without continuous external forces, while forced vibration occurs due to an external periodic force.
What is the equation of motion for a simple undamped free vibration system?
mx..+ kx = 0, where 𝑚 is mass,
𝑘 is stiffness, and
𝑥 is displacement.
It occurs when a system oscillates due to an initial disturbance without any external force acting on it after the motion begins.
Free vibration
It is characterized by natural frequency, amplitude, and mode shape, occurring in the absence of external forces.
Free vibration
What determines the natural frequency of a system in free vibration?
The natural frequency is determined by the system’s mass and stiffness.
It refers to the effect that reduces the amplitude of oscillations over time due to resistive forces like friction or air resistance.
Damping
What are the three types of damping in second-order systems?
Underdamped, critically damped, and overdamped.
