Defence Research & Development Organisation Research Intern Interview Questions and Answers

Brittle materials fail as spiral fracture surface under torsion due to their inability to deform plastically.

• Brittle materials lack ductility and are unable to deform plastically under stress

• Under torsion, the material experiences shear stress which leads to the formation of spiral fracture surfaces

• The lack of plastic deformation causes the material to fail catastrophically along these spiral paths

• Examples of brittle m...read more

Entropy is a measure of disorder or randomness in a system.

• Entropy is a thermodynamic property that quantifies the amount of energy in a physical system that is not available to do work.

• It is a measure of the number of possible arrangements of particles in a system.

• Entropy tends to increase in isolated systems over time, leading to a state of maximum disorder or equilibrium.

• An example of entropy is the melting of ice -...read more

Natural frequency can be found practically by conducting modal analysis or using specialized equipment like accelerometers.

• Conduct modal analysis by applying a force or impulse to the structure and measuring the resulting vibrations.

• Use specialized equipment like accelerometers to measure the vibrations of the structure.

• Calculate the natural frequency using the formula: f = 1 / (2π√(k/m)), where f is the natural freque...read more

Fast Fourier Transform (FFT) is an algorithm used to compute the Discrete Fourier Transform (DFT) of a sequence or signal.

• FFT is used to analyze the frequency content of a signal by decomposing it into its constituent frequencies.

• It is commonly used in signal processing, image processing, audio analysis, and many other fields.

• FFT algorithms are much faster than the naive DFT computation, making it practical for real-ti...read more

FFT is a faster algorithm for calculating DFT

• FFT is faster than DFT in terms of computation time

• FFT uses a divide-and-conquer approach to reduce the number of operations

• DFT computes all frequencies while FFT only computes the frequencies of interest

• FFT is commonly used in signal processing applications

Factor of safety is a design parameter that accounts for uncertainties in material properties and loading conditions.

• Factor of safety is the ratio of the maximum stress a material can withstand to the maximum stress it is subjected to in a given application.

• It ensures that the structure or component will not fail under normal operating conditions.

• Higher factor of safety values indicate a more conservative design approa...read more

Tolerance refers to the allowable variation in dimensions or properties of a part or product.

• Tolerance is important in engineering to ensure proper fit and function of components.

• It is typically specified as a range of acceptable values, such as +/- 0.1mm.

• Tolerance can be applied to dimensions, material properties, surface finish, etc.

• For example, a hole may have a tolerance of +/- 0.05mm to allow for proper alignment