What is the main purpose of a factor of safety in machine design?
A Increase weight
B Prevent failure
C Strengthen material
D Enhance performance
The factor of safety in machine design is a critical design parameter that provides a safety margin to prevent failure. It is the ratio of the material’s ultimate strength to the expected load. A higher factor of safety ensures that the component will not fail under anticipated stresses.
Which type of stress is most commonly analyzed in machine design?
A Shear stress
B Torsional stress
C Tensile stress
D Bending stress
Tensile stress is the most commonly analyzed stress in machine design because it occurs when a material is pulled or stretched. Engineers frequently design components to withstand tensile forces, ensuring the material does not fail under tension.
Which material is most commonly used for shafts in machine design?
A Steel
B Plastic
C Copper
D Aluminum
Steel is widely used for shafts due to its excellent mechanical properties, including high tensile strength, durability, and resistance to wear. It is an ideal material for shafts, which are subjected to significant mechanical loads.
What is the primary function of a bearing in machine design?
A To absorb vibrations
B To provide lubrication
C To reduce friction
D To increase power
Bearings are used to reduce friction between moving parts in machines. They support rotating components and help distribute the load evenly, reducing wear and tear, thus enhancing efficiency and lifespan of the machine.
What does the term ‘fatigue failure’ refer to in machine design?
A Failure due to corrosion
B Failure due to repeated loading
C Failure due to overloading
D Failure due to thermal effects
Fatigue failure occurs when a material fails due to repeated or cyclic loading, even if the loads are below the material’s yield strength. Over time, microscopic cracks form, leading to catastrophic failure after many cycles of loading and unloading.
What is the main purpose of stress analysis in machine design?
A To optimize cost
B To predict failure
C To reduce weight
D To increase strength
Stress analysis is essential for predicting the potential failure points in a design. By calculating the stresses on components, engineers can identify areas at risk and modify the design to avoid failure under expected loads.
Which of these is a common type of joint used in machine design?
A Weld
B Rivet
C Screw
D All of the above
Rivets, screws, and welds are all commonly used joints in machine design. Each type serves different purposes: rivets are used for permanent joins, screws for adjustable joins, and welding for high-strength, permanent connections.
What does CAD software help with in machine design?
A Material selection
B Rapid prototyping
C Visualization of designs
D Stress testing
CAD (Computer-Aided Design) software is crucial for visualizing designs in 3D, allowing engineers to create precise models. It helps identify design flaws early, facilitates simulation, and ensures that the product can be manufactured effectively.
Which of the following is a common failure theory used in machine design?
A Hooke’s law
B Coulomb friction theory
C Bernoulli’s principle
D Fatigue theory
Fatigue theory is one of the most commonly used failure theories in machine design. It helps predict how materials will behave under cyclic loading and when they are likely to fail due to fatigue, even at stresses lower than their tensile strength.
What is the purpose of a clutch in machine design?
A To reduce vibrations
B To connect or disconnect shafts
C To store energy
D To increase speed
A clutch is a mechanical device used to connect or disconnect two rotating shafts in a machine. It is typically used in systems where power needs to be transmitted intermittently, such as in automobiles.
Which component is commonly used to control the rotational speed of machines?
A Gear
B Bearing
C Rivet
D Bolt
Gears are essential components in machine design used to transmit motion and control rotational speed. By varying the size and arrangement of gears, engineers can adjust speed, torque, and direction of rotation in a mechanical system.
What is meant by ‘buckling’ in structural design?
A A failure due to shear stress
B A failure due to torsion
C A failure due to compression
D A failure due to stretching
Buckling occurs when a structural member fails due to compressive forces. It causes the member to deform or collapse, often resulting in the component’s inability to carry the load. It is most common in slender, long components like columns.
In machine design, which factor is critical for material selection?
A Density
B Mechanical properties
C Texture
D Color
The mechanical properties of a material, such as tensile strength, hardness, and fatigue resistance, are critical when selecting materials for machine components. These properties ensure that the material can withstand the forces and conditions it will encounter during operation.
What type of spring is commonly used to store energy in machines?
A Torsion spring
B Compression spring
C Extension spring
D Leaf spring
Torsion springs are commonly used in machines to store mechanical energy. They work by twisting or rotating around an axis and are used in applications such as door hinges and watches, where rotational energy needs to be stored.
Which type of loading is considered dynamic in machine design?
A Static loading
B Thermal loading
C Steady loading
D Impact loading
Dynamic loading refers to loads that vary with time, such as impact loading. These loads can cause more significant stress and wear on components than static loads and need to be carefully considered in design to prevent failure.