DOUBLE AND SIMPLE SHEAR

[airmail]

Hi people:

Could somebody explain me the difference between simple and double shear in order to calculate riveted joints?

As far as I know, three pieces riveted together are a double shear example. Only two pieces riveted are simple shear. Am I right?

And if I´m right, in double shear all pieces works in that way or only the middle one can be sized as a double shear.

Cheers!

 

[UcfSE]

Your statement is not necessarily correct. Three pieces may be connected in single or double shear. Double shear is more likely though. The words "single" and "double" refer to how many shear planes through the fastener are loaded in shear. A lapped joint with 2 members pulling in opposite directions would result in single shear on the bolt holding them together because all of the shear force is distributed across the bolt's cross section at one location, what we term "single shear". With 3 members in a lap splice, the outter two pulling the opposite dircetion of the inner member, the shear force is distributed across the cross section of the bolt in two locations, what we term "double shear".

The "double" and "single" shear terms apply only to the fastener. The members should be designed for the force they "see". In my above double shear example, the outter two members would each feel half of the pulling force and the inner member would feel all of the pulling force. Drawing a free-body diagram will help make that more clear for you.

 

[yates]

Very often the term 'single or double shear' refers to the required bolt testing method and not necessarily the most common type of joint the bolt is used in. As UcfSE points out, the most likely application is double shear which is why the majority of bolt specifications call for a double shear test instead of a single shear test. If rupture occurs during this test the likelihood of broken fragments flying about is also slightly less in a double shear test.