Tell me about yourself. What is difference between plane stress and plane stress condition? Draw S-N curve (High cycle and low cycle). How fracture is related to high and low cycle fatigue? What technical problem is our product?

Question

Accepted Answer

The interview covered topics on stress and fatigue, including plane stress, S-N curve, and technical problems with a product.

Plane stress refers to a state where stress is only present in two dimensions, while plane stress condition is when stress is present in all three dimensions.
S-N curve is a graph that shows the relationship between stress and the number of cycles to failure.
High cycle fatigue occurs when a material fails due to repeated stress cycles at a high frequency, while low cycle fatigue occurs at a low frequency.
Fracture is related to high and low cycle fatigue because repeated stress cycles can cause cracks to form and grow, eventually leading to failure.
The interviewee was asked about a technical problem with a product, but the specific problem is not mentioned.

Accepted Answer

My name is sanjit Kumar Thakur...

1. Difference between plane stress and plane strain conditions:

In the field of mechanics and materials engineering, plane stress and plane strain refer to different two-dimensional stress and strain conditions.

- Plane Stress: This condition occurs in thin structures or components subjected to loads within their plane. In such cases, the stress in the third dimension (thickness direction) is negligible or very small. It means the stress components acting perpendicular to the plane are close to zero. Examples include thin plates and shells.

- Plane Strain: This condition occurs in thick structures or components where deformation in the thickness direction is constrained. In plane strain, the strain in the third dimension (thickness direction) is negligible or small. It means the strain components in the thickness direction are close to zero. Examples include thick plates and large structural members.

2. S-N Curve (High cycle and low cycle fatigue):

An S-N curve, also known as a Wöhler curve, is a graphical representation that shows the relationship between cyclic stress amplitude (S) and the number of cycles to failure (N) for a material. It is commonly used to characterize fatigue behavior.

- High Cycle Fatigue (HCF): HCF occurs when the stress levels are relatively low, and a large number of cycles are applied to the material before failure. The S-N curve for high cycle fatigue generally shows a distinct endurance limit, below which the material will not fail regardless of the number of cycles.

- Low Cycle Fatigue (LCF): LCF occurs when the stress levels are higher, and failure happens after a relatively small number of cycles. The S-N curve for low cycle fatigue typically does not exhibit an endurance limit, and the material's strength continuously decreases with an increasing number of cycles.

3. Fracture and High/Low Cycle Fatigue:

High and low cycle fatigue are both mechanisms that lead to material failure under cyclic loading conditions. In high cycle fatigue, failure occurs due to the accumulation of microcracks and damage over a large number of cycles, often resulting in surface cracks and brittle fractures. In low cycle fatigue, failure occurs due to the rapid propagation of cracks in a relatively small number of cycles, leading to more ductile fracture modes.

4. Technical problem with your product:

I apologize, but as an AI language model, I don't have access to information about specific products or technical problems unless you provide me with more context or details about your product. If you could elaborate on the technical issue you're facing, I'd be more than happy to try and help you with a solution or guidance.

Tell me about yourself. What is difference between plane stress and plane stress condition? Draw S-N curve (High cycle and low cycle). How fracture is related to high and low cycle fatigue? What technical problem is our product?

Popular interview questions of Engineer

Top HR questions asked in Rolls-Royce Engineer