Crack Paths 2009

200mm

Radius 1 8 m m

6.35mmdiameter hole reamed

4 4 m m

3 2 m m

5 6 m m

6 5 m m

1 0 m m

Figure 3. The high specimen ( t K

).

K

= 68.2

tn

1 3 . 8 2 5 m m

1 0 m m

1 m m

3 . 1 7 5 mrmadius

2 0 0 m m

).

Figure 4. The mid specimen ( t K

= 13.2 t n K

230mm

127mmRadius (5’)

1 5 m m

6 5 m m

6.35mm

Figure 5. The low specimen ( t K

06.1= t n K ).

Table 1. Mechanical properties of 7050-T7451.

Property

Value

Young’s modulus

71000 [MPa]

Tensile Strength

482.6 [MPa]

Yield Strength

413.7 [MPa]

Poisson’s ratio

0.33

Fracture toughness

35.71 [MPa√m]

Spectrum F C GTesting

All specimens were subjected a modified version of a fighter aircraft wing root bending

momentspectrum. Marker-loads were inserted into the spectrum just before one of the

highest loads and between the four preceding tensile loads to facilitate the Quantitative

Fractography (QF) method for the measurement of the crack growth [17].

Notch Plastic Zone Sizes of the Specimens

Notch plastic zone sizes (NPZS) along the crack plane for the three types of specimens

were calculated by three dimensional FEM.Figure 6 shows the curves of NPZSagainst

1178