In many applications, bending of extruded profile is used in many automotive applications, i.e. bumper, space frame etc. One of the main challenges in profile forming is to reduce profile distortion due to bending operations. There are some profile distortions, i.e. sagging, springback and buckling. Buckling will no be covered in this analysis. Sagging occurs at upper and inner flange due to longitudinal stress that pulls them toward the profile centre. The web of the profile distorted due to transferred moment from the upper and lower flange. Mandrel can be used to prevent sagging. There are other alternative solutions in order to prevent sagging, i.e. with application internal pressure. This technique has been developed by Miller [4] for stretch bending operation. The results show that sagging can be prevented entirely but internal pressure almost has no effect to springback. The objective of current study is to define internal pressure that is applied during pure bending operation that can prevent sagging.

Kiriman dari Henry Ako Tampubolon

In many applications, bending of extruded profile is used in many automotive applications, i.e. bumper, space frame etc. One of the main challenges in profile forming is to reduce profile distortion due to bending operations. There are some profile distortions, i.e. sagging, springback and buckling. Buckling will no be covered in this analysis. Sagging occurs at upper and inner flange due to longitudinal stress that pulls them toward the profile centre. The web of the profile distorted due to transferred moment from the upper and lower flange. Mandrel can be used to prevent sagging. There are other alternative solutions in order to prevent sagging, i.e. with application internal pressure. This technique has been developed by Miller [4] for stretch bending operation. The results show that sagging can be prevented entirely but internal pressure almost has no effect to springback. The objective of current study is to define internal pressure that is applied during pure bending operation that can prevent sagging.

BENDING OF BEAM

Analysis is conducted on plane strain condition

because the width of the beam is infinite. Plane strain analysis is based on the work of Hill [1] and Marciniak [2]. Profile forming is derived from beam bending analysis. Therefore, it is necessary to derive stresses from beam bending analysis first. Assuming the radius of curvature is relatively large compare to thickness of the beam. The flat beam with infinite width will be bent with subjected to pure bending moment (M).

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