Effects of Sheet Thickness on the In-Plane Stretch Forming Limit in an Aluminum Sheet

概要

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An investigation concerning the effects of sheet thickness on the in-plane stretch forming limit in 1 100 aluminum sheets with thicknesses of 0.5 to 1.0 mm, prepared by electropolishing, has been carried out experimentally and analytically. Development of surface roughness is represented by a linear relation between surface roughness are observed. However, the forming limit which depends on the thickness is observed, and less thickness results in a decreased forming limit. Good agreement between measured and theoretical strains from modified M-K theory is obtained. The thickness dependence of a half angle of pointed vertex, θ_0, is introduced in Gotoh theory, assuming that the onset of localized necking in a sheet is the result of a bifurcation from a state of uniform deformation. The values of θ_0 are in the range between 70 and 90 degrees in all the materials examined and satisfy the relation θ_0=π/2-q_1ε^^-^<q0>, in which the coefficients q_0 and q_1 are material constants.
一般社団法人日本機械学会の論文
1988-10-15