Structural Dynamics & Aeroelasticity

Subtopic: Free & Forced Vibrations of Continuous Beams

The response x(t) of a freely vibrating single degree of freedom underdamped system is given below. In the equation, A and $\phi$ are constants. The damping ratio of the system is ________ (rounded off to 3 decimal places). x(t) = Ae-5t sin(10t + $\phi$)

Subtopic: Free & Forced Vibrations of Continuous Beams

A system comprising a bar, spring and mass is shown in the figure below. The bar, having negligible mass, is made of a material having Young's modulus E = 200 GPa, cross-sectional area A = 100 mm2, and length L = 100 mm. The spring stiffness k = 200 kN/mm and the mass M = 100 kg. The natural frequency of free vibration of the system is ________ rad/s (rounded off to the nearest integer).

Subtopic: Free & Forced Vibrations of Continuous Beams

A uniform rigid bar of mass 3 kg is hinged at point F, and supported by a spring of stiffness k=100 N/m, as shown in the figure. The natural frequency of free vibration of the system is ____rad/s (answer in integer).

Subtopic: Free & Forced Vibrations of Continuous Beams

Consider the free vibration responses P, Q, R and S (shown in the figure) of a single degree of freedom spring-mass-damper system with the same initial conditions. For the different damping cases listed below, which one of the following options is correct? 1. Overdamped 2. Underdamped 3. Critically damped 4. Undamped

Subtopic: Free & Forced Vibrations of Continuous Beams

Which of the following statement(s) is/are true about harmonically excited forced vibration of a single degree-of-freedom linear spring-mass-damper system?

Subtopic: Free & Forced Vibrations of Continuous Beams

A single degree of freedom spring-mass-damper system is designed to return to its equilibrium position in the shortest possible time without exhibiting oscillatory overshoot. The damping ratio $\zeta$ of this system must be:

Subtopic: Free & Forced Vibrations of Continuous Beams

A critically damped single degree of freedom spring-mass-damper system used in a door closing mechanism becomes overdamped due to softening of the spring with extended use. If the new damping ratio ($\zeta_{new}$) for the overdamped condition is 1.2, the ratio of the original spring stiffness to the new spring stiffness ($k_{orig} / k_{new}$), assuming that the other parameters remain unchanged, is _________ (round off to two decimal places).

Subtopic: Free & Forced Vibrations of Continuous Beams

In the spring-mass system, shown in the figure, mass $m = 3$ kg and the spring stiffness $k = 20$ kN/m. The natural frequency (in Hz) of the system is _________ (round off to the nearest integer).

Subtopic: Free & Forced Vibrations of Continuous Beams

For a damped spring-mass system, mass $m = 10$ kg, stiffness $k = 10^3$ N/m, and damping coefficient $c = 20$ kg/s. The ratio of the amplitude of oscillation of the first cycle to that of the fifth cycle is _________ (round off to 1 decimal place).

Subtopic: Free & Forced Vibrations of Continuous Beams

For the system of springs and masses shown below, $k = 1250$ N/m and $m = 10$ kg. The highest natural frequency, $\omega$, of the system is _________ radians/s (round off to the nearest integer).

Subtopic: Free & Forced Vibrations of Continuous Beams

For a damped single degree of freedom system w ith damping ratio of 0.1, ratio of two successive peak amplitudes of free vibration is ___________ (accurate to two decimal places).

Subtopic: Free & Forced Vibrations of Continuous Beams

The roots obtained by solving longitudinal characteristic equations of motion for a statically stable aircraft are given below: 21.2 = N^3.4= -2.00=2.50i, where i = V-1 The undamped short-period longitudinal natural frequency (radians/sec) and damping ratio, in that order, are close to

Subtopic: Flutter Phenomenon & Divergence Speed

450 515 550 500 500 475 2 km Which of the following is the steepest path leaving from P?

Subtopic: Free & Forced Vibrations of Continuous Beams

The natural frequency of the system suspended by two identical vertical springs each of stiffness $k = 1000$ N/m carrying a mass $m = 2$ kg in parallel is _________ rad/s (round off to 1 decimal place).

Subtopic: Free & Forced Vibrations of Continuous Beams

The boundary conditions for a rod with circular cross-section, under torsional vibration,are changed from fixed-free to fixed-fixed. The fundamental natural frequency of the fixed-fixed rod is k times that of fixed-free rod. The value of k is

Subtopic: Free & Forced Vibrations of Continuous Beams

1kg mass is hanging from a spring of stiffness 500N/m attached to a massless,symmetric beam of length 0.6m, moment of inertia about the bending axisII = 8.33 × 10-10 mm4 and Young's modulus E=210GPa as shown in the figure. The fundamental natural frequency (in rad/s) of the system is

Subtopic: Free & Forced Vibrations of Continuous Beams

A cantilever beam of negligible mass is 0.6 m long. It has a rectangular cross-section of width 8 mm and thickness 6 mm and carries a tip mass of 1.4 kg. If the natural frequency of this system is 10 rad/s, Young's modulus of the material of the beam in GPa is ________ x M M L b 2m D 1m 1m A B C P y 2013 AEROSPACE ENGINEERING - AE AE 15/19

Subtopic: Free & Forced Vibrations of Continuous Beams

Following table gives data on tourists from different countries visiting India in the year 2011. Country Number of Tourists USA 2000 England 3500 Germany 1200 Italy 1100 Japan 2400 Australia 2300 France 1000 Which two countries contributed to the one third of the total number of tourists who visited India in 2011?

Subtopic: Free & Forced Vibrations of Continuous Beams

The mode shapes of an un-damped two degrees of freedom system are {}10 . 5 T and {}10 . 6 7 5 T - . The corresponding natural frequencies are 0.45 Hz and 1.2471 Hz. The maximum amplitude (in mm) of vibration of the first degree of freedom due to an initial displacement of {}21 T (in mm) and zero initial velocities is ____. 2012 AEROSPACE ENGINEERING - AE AE 5/12 Questions Q.31 to Q.55 are multiple choice type.

Subtopic: Free & Forced Vibrations of Continuous Beams

The boundary condition of a rod under longitudinal vibration is changed from fixed-fixed to fixed- free. The fundamental natural frequency of the rod is now k times the original frequency, where k is

Subtopic: Free & Forced Vibrations of Continuous Beams

If a prime number on division by 4 gives a remainder of 1, then that number can be expressed as:

Subtopic: Free & Forced Vibrations of Continuous Beams

Choose the word that is opposite in meaning to the word 'DORMANT':

Subtopic: Free & Forced Vibrations of Continuous Beams

The natural frequency of bending vibration is highest when

Subtopic: Free & Forced Vibrations of Continuous Beams

In a spring-mass-damper single degree of freedom system, the mass is 2 kg and the undamped natural frequency is 20 Hz. The critical damping constant of the system is

Subtopic: Free & Forced Vibrations of Continuous Beams

What will be the logarithmic decrement if a free vibration test is performed?