# Finding initial length of a bended plastic sheet (Bend Allowance)

I have a 1.5 mm thick plastic sheet part which hast to be bent at a joint 0.3 mm thick by ~ 10 Deg. I know (found from design drawing) compressed and stretched lengths of the joint. How can I find the length of the joint in non-bent (flat) position so that when it is bent the compressed and stretched joint lengths have the initial known lengths ?

• I think my problem is similar to mechanical beam problems where one end is fixed, since I also assume that right end is fixed. Furthermore, I have taken that compressed and stretched lengths form concentric circular arcs and assumed that the neutral axis which does not change in length (based on the answer to engineering question #2693) goes trough the middle of the joint, is also circular arc and concentric with the above compressed/stretched arcs. From the construction I can find the lengths of this neutral line which is then the length of the joint in non-bent (flat) position. – miquo Jul 21 '16 at 21:54