The Effect of Peening on the Fatigue Life of 7050 Aluminium Alloy
The Effect of Peening on the Fatigue Life of 7050 Aluminium Alloy
The Effect of Peening on the Fatigue Life of 7050 Aluminium Alloy
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DSTO-RR-0208<br />
A.4. Surface Roughness<br />
<str<strong>on</strong>g>The</str<strong>on</strong>g> measurements <str<strong>on</strong>g>of</str<strong>on</strong>g> surface roughness used in this report are standard measurements<br />
produced by a laser surface pr<str<strong>on</strong>g>of</str<strong>on</strong>g>iler. <str<strong>on</strong>g>The</str<strong>on</strong>g> values are based <strong>on</strong> German DIN standards but<br />
typical <str<strong>on</strong>g>of</str<strong>on</strong>g> roughness measurements specified in numerous machining handbooks.<br />
Z 1<br />
Z 2 = R max<br />
Z 3<br />
Z 4<br />
L<br />
R max = <strong>the</strong> largest single roughness depth within <strong>the</strong> evaluati<strong>on</strong> length. <str<strong>on</strong>g>The</str<strong>on</strong>g> required<br />
standard is DIN 4768<br />
R z = mean value <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> single roughness depths “Z” <str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>secutive sampling lengths. <str<strong>on</strong>g>The</str<strong>on</strong>g><br />
required standard is DIN 4768<br />
R z = (Z 1 + Z 2 + Z 3 + ….. + Z n )/n<br />
R a = is <strong>the</strong> arithmetic mean <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> areas <str<strong>on</strong>g>of</str<strong>on</strong>g> all pr<str<strong>on</strong>g>of</str<strong>on</strong>g>ile values <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>the</strong> roughness pr<str<strong>on</strong>g>of</str<strong>on</strong>g>ile.<br />
R a = [Integral {y(x)}dx] /L<br />
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