Brittle crack growth in normally ductile materials

In summary, the conversation discusses the use of drilling holes at the ends of a crack in load bearing plates to reduce internal stresses and prevent further growth. The question is posed if there are any specific instances where this method was used successfully to prevent failure and increase service life. An industrial example is mentioned and a formula for stress concentration is provided. The conversation also mentions the use of this method in aircraft maintenance to prevent larger failures.
  • #1
C0rnNutts
1
0
Hey guys,
I'm new here so please be easy on me if I break any "unwritten" rules.
I'm doing a design study on brittle crack growth in ductile materials. As I understand it, when a macroscopic crack is found in a load bearing plate, holes can be drilled at each end to reduce the internal stresses at the crack tips and therefor arrest the growth. My question is: Does anyone know of a specific instance where this method was used to prevent failure and increase service life? Alternatively, an instance where this method could have been used to prevent a failure but was not?
Thanks in advance!
 
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  • #2
Does anyone know of a specific instance where this method was used to prevent failure and increase service life?
We hillbillies do it all the time on our shovels and tractor fenders.

An industrial example is mentioned around page six here:

http://pbadupws.nrc.gov/docs/ML0134/ML013400370.pdf

about page 22 is a formula for stress concentration around an elliptical crack arresting hole.
Surely a search engine will take you places.. just have to feed it the right keywords. Maybe that report will help you with vocabulary.
 
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  • #3
Drilling a hole to arrest a crack is almost routine in aircraft maintenance.
Usually the specifications allow for small failures, but larger ongoing breaks are taboo. Do note that there are procedures to ensure that this does not cause additional problems.
 

What is brittle crack growth?

Brittle crack growth refers to the propagation of cracks in materials that are normally considered ductile, or able to deform without breaking. This type of crack growth occurs when the applied stress exceeds the material's strength, causing it to fracture abruptly.

What causes brittle crack growth in normally ductile materials?

Brittle crack growth can be caused by a variety of factors, including high stress concentrations, sharp notches or defects in the material, and exposure to extreme temperatures. These factors can weaken the material and make it more susceptible to brittle fracture.

How does brittle crack growth affect the mechanical properties of a material?

Brittle crack growth can significantly reduce the strength and toughness of a material. It can also lead to sudden and catastrophic failure, making it a major concern in engineering and design.

What methods are used to prevent or mitigate brittle crack growth?

There are several methods that can be used to prevent or mitigate brittle crack growth in materials. These include using materials with higher ductility and toughness, avoiding sharp notches and stress concentrations, and implementing design changes such as adding fillets or reducing sharp corners.

What research is being done on brittle crack growth in normally ductile materials?

There is ongoing research in the field of materials science and engineering to better understand the mechanisms of brittle crack growth and develop new methods for preventing or controlling it. This includes studying the effects of different types of stress and strain on crack growth, as well as developing new materials with improved properties.

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