Fig. 4
From: Effect of die fillet radius on tube thinning in free bending

Measurement of pipe wall thickness and cross-sectional distortion: (a) measurement of pipe wall thickness (b) measurement of cross-sectional distortion.
From: Effect of die fillet radius on tube thinning in free bending

Measurement of pipe wall thickness and cross-sectional distortion: (a) measurement of pipe wall thickness (b) measurement of cross-sectional distortion.