Issue 36

R. Citarella, Frattura ed Integrità Strutturale, 36 (2016) 160-167; DOI: 10.3221/IGF-ESIS.36.16

The modelled specimen is representative of the riveted joint existing between the upper shell and the lower shell on the front fuselage section, manufactured by AerMacchi for the Dornier Do328 aircraft (Fig. 2a). The corresponding DBEM model is illustrated in Fig. 2b, where internal points are placed in correspondence of the strain gauge locations (Fig. 2a) in order to compare the numerical and experimental strains and assess the model accuracy. The distance from the panel edge to the first hole was chosen from the experimenter equal to 10 mm, giving a total panel width W=280 mm (Fig. 2a). The four holes close to the plate border were cold worked in order to avoid crack initiation during the fatigue test (in Fig. 2a, holes with crack tips N. 1, 28, 29, 56) or at least strongly retard crack propagation [8]. The remote applied load is t =100 MPa (Fig. 2b) and the material properties are: Young modulus E=72500 MPa and Poisson ratio .33   .

29

56

28

1

(a)

Hole with no modelling of inside pin

Hole with explicit modelling of inside pin

Line of internal points in correspondence of strain gauge positions

(b) Figure 2 : Butt joint sketch (a) with highlight of strain gauge positions and crack tip numbering (N. 1:28 in the lower hole row and N. 29:56 in the upper cracked hole row); DBEM uncracked model (b) with highlight of internal spring (yellow symbols), internal points and hole constraints (green symbols).

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