Issue 46

M. El Habiri et alii, Frattura ed Integrità Strutturale, 46 (2018) 34-44; DOI: 10.3221/IGF-ESIS.46.04 38 equivalents stresses SQV. The figure reveals the significant difference between the equivalent stress at exit and entry surfaces. These stresses decrease and present constants variations from 6 mm to the expanded hole. Also, the equivalent stress field at the exit surface is dramatically increased witch is shown after the exit of the pin (Fig. 6.c). -500 -400 -300 -200 -100 0 100 200 0 2 4 6 8 10 12 Distance from hole (mm) Tangential residuals stresses (MPa) Exit face Mid-plane position Entrance face Figure 4: Tangential residual stress at different through-thickness positions for 6.32 mm in thick of plate. 0 60 120 180 240 300 360 420 0 2 4 6 8 10 12 Distance fromhole (mm) Equivalent Von Mises stresses (MPa) Exit face Mid-plane position Entrance face Figure 5: Von-Mises equivalent stress along the path of growth. Tangential residual stress distribution established from the finite element analysis shows that it not uniform throughout the thickness of a cold expanded hole of finite plate (Fig. 7). Significant compressive tangential residual stress is produced between tapered pin and hole. This shows beneficial effect of induced friction between aluminium alloy plate and steel pin at free surface of hole. The evolution of tangential residuals stresses throughout thickness can be described by a polynomial equation shown above. 2 15.55 148.45 99.1 a a   =  −  − (1) “a” present parameter variation of the thickness from the entrance face to the exit face