ISDA

DAMPED VIBRATION

Type of vibration when vibration of a system is diminished by friction or other external forces.

SIX

How many degrees of freedom does an object have in nature?

VIBRATION

is a continuous cyclic motion of a structure or a component.

ROXBEE COX AND PUGSLEY

the term “aeroelasticity” was proposed by __________ in the early 1930's

ARTHUR RODERICK COLLAR

In 1947, _____________ defined aeroelasticity as "the study of the mutual interaction that takes place within the triangle of the inertial, elastic, and aerodynamic forces acting on structural members exposed to an airstream, and the influence of this study on design".

Underdamped vibration

Undamped vibration

Overdamped vibration

Critically damped vibration

None of the above

A vibratory system in which the amplitude is reduced to the state of rest at very slow rate.

DAMPING COEFFICIENT

Defined as the damping force per unit velocity

Underdamped vibration

Undamped vibration

Overdamped vibration

Critically damped vibration

None of the above

A system that, after an initial disturbance, oscillates with decreasing amplitude before settling to a stationary state

PHASE ANGLE

Angular position of an oscillating object at a specific point in time

DAMPING

The process of energy dissipation within a system, effectively reducing or preventing oscillations by gradually decreasing the amplitude of motion over time, usually caused by friction or resistance forces acting within the system

FORCED VIBRATION

Type of vibration when periodic force from outside feeds the system’s own vibrations.

STIFFNESS

A material's or structure's ability to resist deformation when an external force is applied.

Underdamped vibration

Undamped vibration

Overdamped vibration

Critically damped vibration

None of the above

A system that has the optimal level of damping. It returns to its equilibrium position in the fastest possible time without oscillating.

DEGREES OF FREEDOM

_______ is the number of independent variables that define the possible positions or motions of a mechanical system in space.

PHOTOELASTIC PHENOMENON

Phenomenon that aeroelasticity was coined from.

AMPLITUDE

________ is the displacement of an oscillating object from the equilibrium.

Potential energy is highest at maximum displacement and velocity is at minimum

Kinetic energy is greatest at the equilibrium point

Kinetic energy is lowest at the equilibrium point

Potential energy is lowest at maximum displacement and velocity is at maximum

None of the above

Which of the following statements is correct?

UNDAMPED VIBRATION

A system vibration with a damping ratio of 0. 

12/08/1903

An aeroelastic failure was recorded in 1903 of a powered flight at the Potomac River by Samuel Langley (Secretary of Smithsonian Institution in Washington). It was recovered and repaired a second time 9 days before the Wright‘s historic flight. When was it recovered?

DAMPING RATIO

A dimensionless variable that describes how quickly oscillations decay after disturbance.

AEROELASTICITY

_________ is the study of the interactions between dynamic, inertial and aerodynamic forces that arise when a body is immersed in airflow.

Underdamped vibration

Undamped vibration

Overdamped vibration

Critically damped vibration

None of the above

Oscillatory motion where energy loss due to resistive forces (like friction or air resistance) is negligible, resulting in the vibration continuing indefinitely without any decrease in amplitude

loss and reversal of aileron control

energy loss and aerodynamic inefficiency

nose wheel shimmy

pilot fatigue

None of the above

The following are adverse effects that vibrations cause to aircraft and spacecraft structures except ____?

FREE VIBRATION

Type of vibration when a body vibrates at its own frequency without any external force.

UNDERDAMPED VIBRATION

A system vibration with a damping ratio of less than 1.