Strength Of Materials! Trivia Questions Quiz

High carbon steel has higher hardness, ultimate strength and yield strength. But, less ductility

In a compression on mild steel, necking does not occur. Necking is a phenomenon that typically happens in tension, where the material starts to narrow down at a localized point before it eventually fractures. In compression, the material is subjected to forces that push it together, rather than pull it apart, which prevents the occurrence of necking.

The yield stress of a twisted bar is 50% more compared to an ordinary mild steel bar. This means that the twisted bar can withstand 50% more stress before it starts to deform permanently. The twisting process increases the strength and resilience of the bar, making it more resistant to bending or breaking under pressure.

The endurance limit for carbon steel is approximately 0.5. This means that carbon steel can withstand cyclic loading and stress up to a certain level without experiencing fatigue failure. The endurance limit is the maximum stress that a material can endure for an infinite number of cycles without failure. In the case of carbon steel, this limit is around 0.5, indicating its ability to withstand repeated stress without breaking or wearing out.

The correct answer is "The stress dependent part of the plastic deformation is referred to as creep, and the time dependent part which is also influenced by the temperature as slip." This statement is false because the stress dependent part of plastic deformation is referred to as slip, and the time dependent part influenced by temperature is referred to as creep.

The correct answer is that the ultimate strength in compression is generally much larger than the ultimate strength in tension because of flaws such as microscopic cracks or cavities. Brittle materials are more prone to failure in tension due to the presence of these flaws, which act as stress concentrators and reduce the material's ability to withstand tensile forces. In compression, these flaws are less likely to propagate and cause failure, resulting in a higher ultimate strength.

As the carbon content increases in carbon steels, the ductility of the metal decreases. This means that the ability of the metal to deform without breaking or fracturing decreases. Additionally, the percentage elongation of the steel also decreases, indicating that the steel becomes less capable of stretching or elongating before it fractures. Therefore, statements 3 and 4 are correct.

Manganese is primarily responsible for the toughness of steel. Manganese is added to steel as an alloying element to improve its strength, hardness, and toughness. It forms a solid solution with iron, which helps to enhance the grain structure of the steel, making it more resistant to deformation and fracture. Manganese also helps to reduce the formation of brittle phases in the steel, improving its toughness and impact resistance. Therefore, the presence of manganese in steel plays a crucial role in determining its toughness.

An isotropic material is one in which all the properties are the same in all directions at every point. This means that the material has the same mechanical, thermal, and electromagnetic properties regardless of the direction in which they are measured. However, this does not necessarily mean that an isotropic material is always homogeneous. Homogeneous materials have the same composition and structure throughout, while isotropic materials only have the same properties in all directions. Therefore, Statement A is false because isotropic materials can be either homogeneous or non-homogeneous. Statement R is true because it accurately defines what an isotropic material is.

Fatigue failure occurs due to repeated loading cycles and large stress concentrations. Large variations in stress can also contribute to fatigue failure, but it is not a necessary factor. Therefore, the factors associated with fatigue failure are 1 and 3.

Simple working stress design is suitable for metal structures subjected to stress reversals and impact as it considers the working stress and the material's yield strength. Semi-rigid design is also suitable as it allows for some flexibility and redistribution of stresses. Elastic rigid design is suitable as it considers the structure's elastic behavior under stress. Rigid plastic design, on the other hand, is not suitable as it assumes that the material behaves plastically and does not consider the structure's elastic behavior. Therefore, the correct answer is 1, 3, and 4.

A deviator state of stress is characterized by a change in volume without distortion. This means that the stress applied to a material causes a change in volume but does not cause any change in the shape or distortion of the material. This can occur, for example, when a material is subjected to hydrostatic pressure, where the stress is uniformly applied in all directions, causing a change in volume but not in shape.