PSI - Issue 13

Saeed Mousa et al. / Procedia Structural Integrity 13 (2018) 686–693 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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3. Experimental results

Figure 1 shows the load versus displacement of the Al1100-brass-Al1100 sandwich composites at rolling speed of 45 rpm and 60% thickness reduction. The adhesion strength of sandwich composite with grit 80 sandpaper Al1100 was 4.26 N/mm. The sandpaper produced surfaces with high asperities and deep valleys, which directly affected the mechanical interlocking at the bond interface (Ekici at el., 1999). The peaks and valleys of the surface enhance the bond strength due to the increase in effective area (Lesuer, D. R., et al., 1996). In order to produce a robust bonding between the layers, sandpapers with grit 80 was used to roughen the Al1100 surfaces. Figure 2 shows the Al1100 sample roughened surface. The initial surface roughness of the as-received Al1100 sheet had Ra = 0.6 µm. After using sandpapers of grit 80 and 50, the surface roughness values changed to 3.75 µm, 5.63 µm, respectively.

(b)

(a)

Averageload

500 µm

500 µm

Figure 2: Optical microscopic images of the Al1100 roughened with different sandpapers grit sizes: (a) GRIT 80 (Ra=3.75 µm), (b) GRIT 50 (Ra=5.63 µm).

Figure 1: P-  curve of a peel testfor the Al1100-brass-Al1100 sandwich composites at rolling speed of 45 rpm and 60% thickness reduction.

4. Numerical analysis

The Al1100-brass-Al1100 sandwich composite is simulated with isotropic material properties with using the mechanical properties in table 1. The numerical study divided into two phases. In the first phase, the effect of contact area of Al1100-brass-Al1100 composite by changing its width and the effect of aluminum strips thickness, t al , on the peeling behavior have been studied. In the second phase, the effect of the presence of imperfection in the Al1100 brass interface on the peeling behavior has been studied. The dimensions of used Al1100-brass-Al1100 sandwich composites are shown in Table 2.

Table 2: Sandwich of Al1100-brass-Al1100 composites geometry

Symbol

Value

Describtion

L

60

al-brass-al sandwich composites length (mm) al-brass-al sandwich composites width (mm)

W t al t br

20, 24, 28, 32, 36 and 40 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7

Aluminum strips thickness (mm)

0.2

Brass sheet thickness (mm)

D

0.5, 1, 1.5, 2, 3, 4, 5 and 6

The imperfection hole diameter (mm)

4.1. Mesh and boundary condition Linear 8-node hexahedral brick elements (C3D8R) with a reduced integration scheme is used to simulate the Sandwich of Al1100-brass-Al1100. The displacement control is used in the present work. The load is applied at the edge of each aluminium strips. Progressive failure analyses of the finite element models were performed using the Abaqus/Standard codes (2016). The effect of mesh density is considered in the present work. The Progressive failure Model is described in the following section.