As noted in Fig. 7.16, the state of stress shifts from plane stress to plane strain as the ratio of length-of-bend to sheet thickness increases. Explain why. This situation….
Explain why scalloping occurs.
In opening a can using an electric can opener, you will note that the lid often develops a scalloped periphery. (a) Explain why scalloping occurs. (b) What design changes for the can
opener would you recommend in order to minimize or eliminate, if possible, this scalloping
effect? (c) Since lids typically are recycled or discarded, do you think it is necessary or worthwhile to make such design changes? Explain. By the student. The scalloped periphery is
due to the fracture surface moving ahead of the shears periodically, combined with the loading
applied by the two cutting wheels. There are several potential design changes, including
changing the plane of shearing, increasing the speed of shearing, increasing the stiffness of the
support structure, or using more wheels. Scallops on the cans are not normally objectionable,
so there has not been a real need to make openers that avoid this feature.