7.54 b. Bearing failure - elongation of the fastener hole due to the imposed bearing stress. c. Tear out - failure of the material surrounding the fastener hole in shear. d. Tensile failure - failure of the material between holes in a fastener row due to tension. Each of these failure modes imposes a constraint upon the number and placement of the fasteners used. In any of the four types of failure the average stress is given by: p CJ ; A where Pis the load per bolt in newtons and A is the area of the cross section subject to failure in m 2 • In the following analysis the bolts will be considered in single shear and will be assumed to be rigid in bending. The joined members will also be considered rigid in bending. 1. For the case of bolt or rivet shear the area of interest is the cross sectional area of the bolt: rrd 2 A ; --.r d; bolt diameter The shear stress is then given by: CJ s 4(1.2P) ~ P; load per bolt (newtons) 2. In the case of bearing failure the load is assumed to be uniformly distributed over the area td. Thus, the average bearing stress is simply: 1.2P CJbr; td 3. A tear out failure involves the failure in shear over an area 2 t x, giving the tear out stress: CJ ' s 1. 2P 2tx
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