Question

Why is the stress intensity factor of materials very important?

Answer 1

Ans. Stress intensity factor of the materials is very important property which is generally used in the design process of machine element or in any suitable application.

It is defined as the localization of high stresses due to irregularities in the component and abrupt changes in the cross section.

Due to stress intensity some reduction in the endurance limit is achieved and any discontinuity in a member affects stress distribution and this discontinuity increases the stress magnitude.

Geometric stress intensity factors can be used to estimate the stress amplification in the vicinity of a geometric discontinuity.

For example Kt( theoretical stress intensity factor) is used to relate the maximum stress at the discontinuity to nominal stress.

Kts is used for shear stresses.

Stress intensity factor used for cyclic loading is less than the theoretical stress intensity factor due to notch sensitivity of material.

Notch sensitivity is the extent to which sensitivity of material to fracture is increased by presence of surface irregularities such as notch , sudden change in area, crack or a scratch etc.

Hence stress intensity factor becomes very important in understanding the behavior of material under loads , estimating stress values, and life of materials. this further can be used for design purpose.