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LOCAL STRAIN ENERGY DENSITY AND FATIGUE STRENGTH OF WELDED JOINTS. Paolo Lazzarin e Filippo Berto Università di Padova, DTG Vicenza. Weld bead geometry cannot, by its nature, be precisely defined. Parameters such as bead shape and toe radius vary from joint to joint.
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LOCAL STRAIN ENERGY DENSITY AND FATIGUE STRENGTH OF WELDED JOINTS Paolo Lazzarin e Filippo Berto Università di Padova, DTG Vicenza
Weld bead geometry cannot, by its nature, be precisely defined. Parameters such as bead shape and toe radius vary from joint to joint. • Conventional welding techniques result in very small values for the toe radius. • In the present contribution the weld toe region is modeled as a sharp, zero radius, V-shaped notch. • The intensity of asymptotic stress distributions obeying Williams’ solution are quantified by means of the Notch Stress Intensity Factors (NSIFs).
Mode I stress distribution is (Lazzarin and Tovo, 1998): Mode II stress distribution is:
2a=180°ground butt welded joints 2a=135°
t d t t F O t F L > 100 d r r keyhole, rs=0.05 mm crack, r=0 +q +q O O Giunti a semplice sovrapposizione
u=0 l y,v v=0 x,u l l
v=0 y,v u=0 slit x,u l l