Issue 53

L. Hadid et alii, Frattura ed Integrità Strutturale, 53 (2020) 1-12; DOI: 10.3221/IGF-ESIS.53.01

direction, the normal stresses of tension are higher at the defect/metal interface (when θ = 0° and θ = 180°) and very low in the zone far from the plane of the alumina-silver junction (when θ = 90°) (see Fig. 8(c)). A contrary behaviour is observed along the z -direction; indeed, the compression stresses are intensively concentrated in ceramics,(when θ = 90°), while their level decreases considerably in the mid of this interface (when θ = 0° and θ = 180°) (see Fig. 8(d)). The tangential stresses are most significant specific to the xoy planes of the assembly. The highest stresses are localized at θ = 45° and 135° (see Fig. 8(e)).

10 20

(a)

Metal

(b)

160

P = 50 MPa P = 70 MPa P = 100 MPa

180 o

0 o

-50 -40 -30 -20 -10 0

Ceramic

120

Path2

80

S XX (MPa)

S equi (MPa)

40

P = 50 MPa P = 70 MPa P = 100 MPa

0 30 60 90 120 150 180 0

0 30 60 90 120 150 180

Peripheral Angle 

Peripheral Angle 

120 150 180

0 30 60 90 120 150 180 -50 -40 -30 -20 -10 0 10 (d) S ZZ (MPa) Peripheral Angle  P = 50 MPa P = 70 MPa P = 100 MPa

(c)

P = 50 MPa P = 70 MPa P = 100 MPa

30 60 90

S YY (MPa)

0 30 60 90 120 150 180 0

Peripheral Angle 

10 15

(e)

0 5

-15 -10 -5

S XY (MPa)

P = 50 MPa P = 70 MPa P = 100 MPa

0 30 60 90 120 150 180

Peripheral Angle 

Figure 8: Variation of equivalent, normal and shear stresses according to peripheral angle and mechanical loading.

Effect of defect geometry The effect of the defect form, which is defined by the x/y ratio, is analysed, and the effect of the defect volume on the distribution of equivalent and normal stresses near to the interface with metal is characterized. This analysis is made for an invariable size x along path 1 (see Fig. 1). The obtained results are represented in Figs. 9 and 10.

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