Controlling Parameters of Residual Stresses and Deformations in Welded Thin Cylindrical Shells

Abstract

The present paper is concerned with the residual stresses and deformations caused by a circumferential and/or longitudinal welding of thin-walled cylindrical shell of mean radius α, wall thickness h arid length l. Based upon experimental data by GMA welding process and analytical results by the previous papers, controlling parameters or combined effect of heat input and size of cylinder on the residual stresses and deformations are discussed.
In the circumferential-welded cylinders, the residual stresses σ_θ/σ_y, σ_x/σ_y in circumferential and longitudinal directions and deflections ω/aε_y at a distance x/√ah from the weld centerline are determined by the two parameters,
Heat input parameter H_θ=Q/cρh√ah
Size parameter β_θ=l/√ah
, where σ_y, ε_y, c and ρ are yield stress, yield strain, specific heat and density of the material respectively, and Q is net heat input per unit weld length. When the size parameter β_θ exceeds a critical value, (β_θ)_cr, depending upon the heat input parameter H_θ, the residual stresses and deformations are determined uniquely by the heat input parameter H_θ.
In the longitudinal-welded cylinders, the residual stresses σ_x/σ_y, σ_θ/σ_y, and deflections √h/a^ω/lε_y at an angle θ from the weld centerline on the mid-cross seetion are decided by the parameters,
Heat input parameter H_x=Q/2cρπah
Size parameter β_x=(l/a)√h/a
In the range that the size parameter β_x is larger than its critical value, (β_x)_rc≅3, only one controlling parameter is the heat input parameter H_x.
When the size parameters exceed their critical value, the residual stresses and deflections are expressed as functions of the heat input parameters. The calculated values are approximately agreed with the experimental results.