Question

2.How can you correlate the number of cycles to fatigue and applied loads with the fatigue behaviors.

Low cycle fatigue has lower load and low number of cycles to failure

None

High cycle fatigue has lower loads and lower number of cycles to failure

Low cycle fatigue has high loads and high number of cycles to failure

High cycle fatigue has higher loads and relatively low number of cycles to failure

Answer 1

Answer:

• LCF ( Low Cycle Fatigue ) is developed due to high plastic strains under a low number of  cycles .
• HCF ( High Cycle Fatigue ) is developed due to low plastic strain under high number of cycles.

Now, strain is the amount of deformation take place inside a material when external force or load is applied. In general strain depends on two factors :

1. The externally applied force or load
2. Total resistance developed within the material to oppose the load i.e. the stress which is equal to the load.

When higher load is applied stresses may exceed the yield strength and cause large plastic deformation i.e. large plastic strain.

And when lower load is applied the stresses are also lower than the yield strength of the material and hence the plastic strain is lower.

Hence we can conclude  the fatigue behaviors as:

• LCF ( Low Cycle Fatigue ) has higher loads and low number of  cycles .
• HCF ( High Cycle Fatigue ) has lower loads and high number of  cycles .

So, the correct answer would be none among the given choices.