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.