Buckling occurs in columns when they are subjected to compressive forces beyond a critical value, causing them to deform laterally. It results in instability, leading to failure without significant material deformation.
What is the strength criterion for ductile materials?
A Von Mises yield criterion
B Maximum shear stress theory
C Maximum normal stress theory
D Mohr’s circle theory
The Von Mises yield criterion is commonly used for ductile materials. It states that yielding begins when the deviatoric stress reaches a critical value, which is a combination of shear and normal stresses.
What is the main purpose of energy methods in structural analysis?
A To calculate internal stresses
B To analyze material toughness
C To calculate shear forces
D To determine deflection and deformation
Energy methods, such as the work-energy principle, are used to calculate deflection, deformation, and internal forces in structures. These methods provide a simplified approach compared to traditional force-based methods.
What is residual stress in materials?
A Stress under constant load
B Stress developed from temperature variations
C Stress after unloading
D Stress caused by external forces
Residual stress is the internal stress remaining in a material after external forces are removed. It can be caused by manufacturing processes like welding or cooling and may affect the material’s strength and stability.
What is the effect of work hardening on materials?
A Decreases strength
B Increases strength
C Increases ductility
D Reduces hardness
Work hardening (also known as strain hardening) increases the strength of a material as it is deformed plastically. The material becomes more resistant to further deformation due to dislocation movements.
What is the main objective of softening in materials?
A To reduce strength and increase ductility
B To increase hardness
C To improve fracture resistance
D To decrease toughness
Softening is the process of reducing a material’s strength while increasing its ductility. It allows the material to deform more easily, which can be useful in certain manufacturing processes like forging.
What is the common testing method used for hardness measurement?
A Torsion test
B Compression test
C Brinell test
D Fatigue test
The Brinell hardness test is commonly used to measure the hardness of materials by pressing a hard spherical indenter into the material’s surface and measuring the size of the indentation.
What is the main goal of strength criteria in materials?
A To measure material toughness
B To determine material cost
C To estimate material deflection
D To predict failure conditions
Strength criteria are used to predict the failure conditions of materials under different loading conditions. They help engineers select appropriate materials and design structures that are safe and reliable.
What happens to a material when it undergoes plastic deformation?
A It remains unaffected
B It undergoes permanent shape change
C It becomes stronger
D It returns to its original shape
Plastic deformation occurs when a material is subjected to stress beyond its yield point, causing permanent changes in shape. Unlike elastic deformation, it does not return to its original form once the stress is removed.
What is the purpose of fatigue testing?
A To measure the material’s response to repeated stress
B To measure the material’s strength
C To measure hardness
D To measure thermal expansion
Fatigue testing is conducted to assess a material’s behavior under cyclic loading. It helps predict the material’s lifespan under repeated stress, which is critical for components subjected to dynamic or fluctuating loads.
What is the effect of residual stress on material performance?
A It increases material hardness
B It improves material ductility
C It can lead to unexpected failure
D It reduces material toughness
Residual stress can lead to premature failure, especially in materials under high external loads. If not properly managed, it can cause crack initiation or distortion, reducing the material’s performance and reliability.
What is the role of shear stress in material failure?
A Causes tensile fracture
B Causes bending of the material
C Causes elastic deformation
D Causes shear deformation and eventual failure
Shear stress leads to deformation by causing layers of the material to slide past each other. If the shear stress exceeds the material’s shear strength, it can cause fractures or material failure.
How does a material respond to axial tensile stress?
A It twists
B It elongates
C It compresses
D It bends
Axial tensile stress causes a material to elongate along the direction of the applied force. The material stretches, and this deformation is proportional to the applied force within the material’s elastic limit.
What is the significance of material toughness?
A Ability to deform without cracking
B Ability to resist fracture
C Ability to return to its original shape
D Ability to resist wear and tear
Material toughness refers to its ability to absorb energy and deform plastically without cracking or fracturing. It is a critical property in materials subjected to impact or dynamic loads.
What is a common cause of failure in materials due to cyclic loading?
A Stress corrosion
B Plastic deformation
C Fatigue failure
D Creep deformation
Fatigue failure occurs when a material is subjected to cyclic loading, even if each individual load is below the material’s ultimate strength. Over time, repeated stresses lead to crack formation and eventual failure.