What are the factors that affect the calculation of fastener flexibility coefficient?

The main factors affecting the calculation of the flexibility coefficient of fasteners such as pressure riveting screws are: the geometric size of the fastener, the stiffness of the fastener material, the geometric size of the base and the strip, and the stiffness of the base and the strip material.
In the actual structure, the ratio of the diameter of the fastener to the effective length d/l=l-2 can be regarded as a very "stubby" beam, and the shear stress has a great influence on its deformation. In practical applications, the deformation and stress states of fasteners and the edges of their holes are extremely complicated, and it is difficult to describe them with simple mathematical expressions. In order to find a way to calculate the load transferred by the fastener, the following assumptions need to be made:
(1) The deformation of any part of the structure is completely within the range of linear elasticity;
(2) Ignoring the influence of friction and assembly stress, fasteners can effectively transmit loads;
(3) All plates are in a state of plane stress and only bear normal stress and shear stress in the plane.

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