Flap Peening

[midsidenode]

Can someone explain to me what flap peening is? And, if possible, direct me to a decent paper explaining the process in greater detail?
thanks,
msn

 

[arunmrao]

Google "flap peening" 6320 results in 0.19 secs.

 

[swall]

Yes, it looks hokie, but the process has been validated for shot peen repairs in aerospace apps.

 

[midsidenode]

That's exactly what I'm considering here. I have a primary structural component that has sustained a "gouge". The component will cost a fortune to replace but could be vulnerable to fatigue if the damage is left un-attended to.

 

[prdave00]

One of the aforementioned Google hits,

http://www.shotpeener.com/library/pdf/1999055.pdf,

has a pretty detailed explanation.

 

[tbuelna]

midsidenode,

Depending upon how your "gouged" part is loaded, peening may or may not help. Any type of peening, whether shot, laser, flap, etc. improves fatigue life by putting compressive pre-stress into surfaces that experience cyclic tensile loads. Peening is only effective if the surface is subjected to tensile stress.

Since fatigue failure fractures tend to form at points of high localized surface tensile stress, the peening is effective because the surface won't be subject to tensile stress until the peening's compressive preload is relieved. Thus controlling the amount of compressive preload resulting from the peening operation is very critical if it must agree with your supporting analysis.

Peening, regardless of the method, is not an exact science. The process is usually done several times on sample parts using "Almen" test strips and "peen scan" coatings to establish the correct coverage and intensity for the desired results. Getting this process right and validating the results on a single parts with the first try would not seem likely.

Hope that helps.
Terry