Design Engineer Interview Questions And Answers

A mechanism is an assembly of different parts which perform a complete motion and is often part of a machine.

According to the Hess law the energy transfer is simply independent of the way being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.

Pump is a device that is used to transfer fluid from one place to another place which means it develops flow not pressure.

The six stroke engine is based on the concept of four stroke engine but built with an intention of improvising the efficiency in reducing emission. Every cycle of a four stroke engine involves the upward and downward movement of the piston which happens twice in the chamber, resulting in four total strokes and one of which is the power stroke which provides the torque to move the vehicle. A six stroke engine works similarly except that there are two power strokes.

The major difference is that a projectile has no motor or a rocket on it, due to which the momentum is given to it as it is launched. A pen thrown across a room is a classic example of a projectile motion. On the other hand, a rocket or missile has a motor on it which helps in accelerating while moving. This helps in resisting other forces such as gravity. A projectile does not have any specific shape, it is a point mass, whereas rocket has a particular shape having its center of gravity situated at a particular point on its body. Thus rocket motion comes under kinetics and projectile comes under kinematics.

The advantage of reheater is that it significantly increases the thrust; which is a prime reason for its use in gas turbines.

Carbon content is generally 3.5-4.5%.

GD&T is Geometric Dimensioning and Tolerancing .Its a language through which Design Engineers
communicate.Stanley Parker introduced the concept of Geometric Dimensioning and Tolerancing (GD&T) in 1930’s and he was from Scotland.

The strength depends on design, material and thickness of the part. So in order to increase strength of the bottle one can provide the ribs and make the bottom of the bottle concave shaped. You can also increase its strength by using a stronger material and increasing its thickness.

The entropy of the universe increases over time and moves towards a maximum value.

A tin and lead alloy is commonly called solder. Usually solder is a wire with a rosin core used for soldering. The rosin core acts as a flux.

A UDL or uniformly distributed load is a load, which is spread over a beam in such a way that each unit length is loaded to the same extent.

Copper conducts heat faster than steel or brass. Any material that is good for conducting heat is also good for electricity in most cases. Wood terrible for transferring heat thus is also insulator for electric.

Orthographic projections are views of a 3D object, showing 3 faces of it. The 3 drawings are aligned so that if the page were folded, it would create part of the shape. It is also called multiview projections.
The 3 faces of an object consist of its plan view, front view and side view. There are 2 types of orthographic projection, which are 1st angle projection and 3rd angle projection.

A Force applied to an object will cause a displacement. Strain is effectively a measure of this displacement (change in length divided by original length).
Stress is the Force applied divided by the area it is applied. (E.g. pounds per square inch)
Therefore, to answer the question, the applied force produces both “Stress and Strain”. “Stress and Strain” are linked together by various material properties such as Poisson's ratio and Young's Modulus.

Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.

☛ The law of inertia: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
☛ Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Force=Mass times acceleration.
☛ For every action there is an equal and opposite reaction.

Bearing is a device that helps smoother movement with minimal friction which in turn helps enhances efficiency and speed. Considering two types of loading, radial and thrust, there are different types of bearings which help handle these loads. The basic difference in the types of loads is essentially due to their ability to handle weight and different kinds of loads for various applications. Different types of bearings are:

☛ Ball bearing
☛ Roller bearing
☛ Ball Thrust bearing
☛ Roller thrust bearing
☛ Tapered roller bearing
☛ Magnetic bearings
☛ Giant Roller Bearing

Nikolaus Otto invented the four stroke engine. Both, two stroke and four stroke have their own advantages and disadvantages. 4 stroke is more fuel efficient. However, 2 stroke produces more power.

(i) Temperature Sensor- This device collects information about the temperature from a source and converts it to a form which is understandable by another device or person. Glass thermometer is the best example where mercury acts as the temperature sensor.

(ii) IR Sensors- This device detects and/or emits infrared radiation to sense a particular phase in the environment. Mostly thermal radiation is emitted by all the objects in the infrared spectrum. This type of radiation is not visible to the human eye but the infrared sensor detects it.

(iii) UV Sensors- These sensors measure the intensity of the ultraviolet radiation. This form of electromagnetic radiation has wavelengths which are longer than x-rays yet shorter than visible radiation. UV sensors can discover the exposure of environment to ultraviolet radiation.

(iV) Touch Sensor- A touch sensor acts as a variable resistor based on the location where it is sensed. Proximity Sensor- A proximity sensor detects the presence of objects that are placed in close proximity without any point of contact.

☛ McPherson struts
☛ Leaf spring
☛ Coil spring
☛ Torsion beam
☛ Wishbone
☛ Air Suspension

The following types of stresses are prevalent in shafts:
☛ > At the outermost surface of the shaft the max shear stress occurs on the cross-section of the shaft.
☛ > At the surface of the shaft on the longitudinal planes through the axis of the shaft the maximum longitudinal shear stress occurs.
☛ > At 45 degrees to the maximum shearing stress planes at the surface of the shafts the major principal stress occurs. It equals the max shear stress on the cross section of the shaft.
☛ > For certain materials where the tensile and compressive strengths are lower in measure as compared to the shear strength, then the shaft designing should be carried out for the lowest strengths.
☛ > All these stresses are of significance as they play a role in governing the failure of the shaft. All theses stresses get generated simultaneously and hence should be considered for designing purposes

As we all know that its impossible to get a machine which gives you exact physical parts according to the required dimension. There is always some sort of deviation in the part manufactured. The deviations are caused due to following reasons:

☛ 1) Vibration in the machine
☛ 2) Tool Wear and Tear
☛ 3) Friction
☛ 4) Mounting Error
☛ 5) Human Error
☛ 6) Environment conditions.

So to meet the actual condition of machining tolerances and allowances are provided to the dimensions. So we require GD&T.

The metaphor here is to get the applicant to think about ALL of the different aspects in a certain phenomenon. The mindset that you are looking for is one that sees the bigger picture and can understand the various influencers in your product.

a) Working fluid: Pneumatics use air, Hydraulics use Oil
b) Power: Pneumatic power less than hydraulic power
c) Size: P components are smaller than H components
d) Leakage: Leaks in hydraulics cause fluid to be sticking around the components. In pneumatics, air is leaked into the atmosphere.
e) Pneumatics obtain power from an air compressor while hydraulics require a pump
f) Air is compressible, hydraulic oil is not