Fatigue crack growth

Crack propagation rate is not linear or constant. It is exponential. This is the Paris Law. However, if we plot crack growth rate and range in stress intensity on log axes then we observe a linear region. This is the Paris Region. We can differentiate the variables of the crack growth equation and integrate both sides to solve for the number of cycles until failure.

[@usernumbereighteen]

Thank you. This helped clear up 4 hours of me getting nowhere

[@TaylorSparks]

My pleasure!!

[@janleutner11]

Great comprehensive video, thanks!

[@lucasgrego123]

Thank you for explaining this topic so clearly!

[@captainvlog]

thank you. It's great these videos are short and to the point.

[@Andme20]

Awesome video, thanks!

[@ramdhiwakarseetharaman5989]

Thank you so much Taylor. Can you please give the source link for Table 6.3 at the end of the video ?

[@christhompson7371]

Hi Taylor. Please could you provide a full reference for the Barsom ‘n’ and ‘A’ tabulated values (7 min 24s). Thanks.

[@skyecooleyartwork]

Why is the linear portion (Region II ?) important? Why do we only consider Region II and ignore the non-linear portions of the log-log curve above and below?

[@TaylorSparks]

You are absolutely right that all three regions are important. Before we could do advanced modelling, the steady state middle region was simply the easiest to model since it was linear.

[@captainvlog]

Do we have to make an adjustment for the net section as the crack starts to become larger in determining the critical crack length?

[@TaylorSparks]

Yes. Paris law only works for the steady state region not the initial or the final regions

[@hadjerdellil858]

Sir, may i request your slide please if it is possible . Thanks

[@TaylorSparks]

Sure, shoot me an email.

[@HopeScreen]

rate of crake propagation increases with increase in mean stress or not?

[@TaylorSparks]

Yes