METHOD FOR DETERMINING STRETCH FLANGE LIMIT STRAIN AND METHOD FOR ASSESSING PRESS FORMING FEASIBILITY

摘要

The method for specifying the limit strain of the stretch flange according to the present invention is characterized in that the stretch flange limit strain is calculated by using a distortion gradient in the direction from the end of the metal plate toward the inward direction and a strain gradient in the plate thickness direction of the metal plate crossing the load direction , So that the relationship of the following expression is satisfied._{ε θlim = A [a · Δε} θ / Δr + b · Δε θ / Δt] + c However, ε _θlim : extension flange limit distortion (plate edge tangential direction) Δε _θ / Δr: Distortion gradient in the inner direction ?? / _? T: Distortion gradient in the plate thickness direction A, a, b: Influence factor c: Limit distortion when the distortion gradient is 0 (zero)