Atlas Copco Design Engineer Interview Questions and Answers

Synchronous speed of a motor is the speed at which the rotating magnetic field produced by the stator rotates.

• It is determined by the number of poles and frequency of the power supply.

• It is the speed at which the motor would run if there was no load or slip.

• It is expressed in revolutions per minute (RPM).

A spring fails under stress beyond its elastic limit.

• A spring fails when it is subjected to stress beyond its elastic limit.

• The elastic limit is the maximum stress a spring can withstand without permanent deformation.

• Factors affecting the failure of a spring include material properties, design, and operating conditions.

• Examples of spring failure include fracture, fatigue, and creep.

• Fracture occurs when the spring is subjected to stress beyond its ultimate strength.

• Fatigue fai...read more

Sub-type or specific failure stress for springs can include yield stress, ultimate tensile stress, fatigue stress, etc.

• Different types of springs may have different failure stresses

• Yield stress is the point at which a material begins to deform plastically

• Ultimate tensile stress is the maximum stress a material can withstand before failure

• Fatigue stress is the stress level at which a material fails after repeated loading cycles

Types of stresses include tensile, compressive, shear, bending, and torsional.

• Tensile stress: pulling force that stretches material apart (e.g. stretching a rubber band)

• Compressive stress: pushing force that squeezes material together (e.g. pressing on a spring)

• Shear stress: force that causes layers of material to slide past each other (e.g. cutting paper with scissors)

• Bending stress: combination of tensile and compressive stresses on opposite sides of a material (e.g. bendin...read more

Stress is internal resistance to deformation, while pressure is force applied over an area.

• Stress is a measure of the internal resistance of a material to deformation under an applied force.

• Pressure is the force applied perpendicular to the surface of an object per unit area.

• Stress is a tensor quantity, while pressure is a scalar quantity.

• Examples: A rubber band under tension experiences stress, while a balloon filled with air exerts pressure on its walls.

Synchronous speed is the speed at which the magnetic field rotates in a synchronous motor.

• Synchronous speed is determined by the frequency of the power supply and the number of poles in the motor.

• Formula for synchronous speed: Ns = 120f / P, where Ns is synchronous speed in RPM, f is frequency in Hz, and P is number of poles.

• For example, a 4-pole motor connected to a 60 Hz power supply would have a synchronous speed of 1800 RPM.

Units of pressure include pascal, bar, atmosphere, and psi.

• Pascal (Pa) is the SI unit of pressure

• Bar is commonly used in meteorology and scuba diving

• Atmosphere (atm) is the average pressure at sea level on Earth

• Pounds per square inch (psi) is used in engineering and automotive industries