EXAMPLE

An eyebolt 1 and tubular sleeve 2 are supported by the plate 3 as in (a), (b) below.
Initially the nut is just finger tight ( 'snubbed' - there are no gaps in, and no appreciable loads on the assembly).
Subsequently the nut is tightened by screwing it a known distance Δ along the thread, then the temperature of the sleeve only is increased by t, and finally the load P is suspended from the eye.
Given the axial stiffnesses k1 and k2, resolve the indeterminacy in the final loaded state.
indeterminate bolted joint
The washer and support plate 3 are thin - ie. very short axially compared to the bolt and sleeve - and therefore relatively rigid since k is proportional to 1/L. It follows that the only deformations of significance are those of the bolt 1 and sleeve 2.
The sequence of load application (heat, tightening, external load) is irrelevant in this elastic analysis - what matters is the final loaded state after all three have been applied. The significant deformations (δ1, δ2) in this final loaded state are assumed to be as shown in (b) in which deformations are grossly exaggerated in order to clarify compatibility constraints. Other deformation assumptions may be equally valid - the result should not be affected by the assumption provided any subsequent analysis is consistent with the assumption. More of this anon.
Emphasising this point once more -

Compatibility
By the assumptions of sketch (b) :
δ1 represents the unknown extension of the (great majority of the) eyebolt 1
δ2 represents the unknown extension of the cylindrical sleeve 2, and
Δ is the known nut movement along the thread.
For the components to remain in contact - ie. for compatibility - the geometry of (a) and (b) requires that :-

( i)      δ1 - δ2  =   Δ

Equilibrium
Before the components are examined individually, all externals on the assembly must be known. The given external load P applied to the eye is supported by the plate 3, hence a known upward load P appears on the free body (b) of the assembly. The support must also exert a bending moment on the plate to equilibrate the P-couple, but this is neglected here as having no bearing on resolution of the indeterminacy - eg. if the cantilevered plate 3 droops then the other components undergo rigid body motion which does not affect the relative motion between 1 and 2.

Free bodies of the separate components are now prepared - (c), (d), (e) - in which the unknown action/reaction at each contact is identified conveniently by the indices of the two components in contact. No components are stuck together so the action/reactions must be 'pushes' on the contacting components - hence F12 is shown in free body (c) pushing on component 1, and on free body (d) pushing on component 2. This force is the resultant of (presumably uniform) pressure over the annular contact area - the washer's purpose is to distribute this pressure evenly.
There are three contacts 1-2, 2-3, 3-1 between the three components, hence the three contact resultants F12, F23, F31 appear on the three free bodies. Equilibrium of all three free bodies requires that :-

( ii)       F12 -  F31   =   P
( iii)     F12 = F23

It is noted particularly from the free bodies (c), (d) that :

If it is not clear from free body (c) that the eyebolt is tensioned by F12 and not by F31, then the flow analogy should be applied or free bodies drawn cutting the shank of (c) and embracing either end of the bolt.
 
Constitutive Laws
Equation ( 2a) is applied to each deformable component, ensuring that the signs in the constitutive equations tally with the senses of loads and deformations used in the previous two steps.

Eyebolt 1       From above, the eyebolt is subjected to a tensile load F12 and suffers a tensile deformation δ1, so the constitutive law ( 2a) consistent with compatibility, equilibrium and constant temperature is :-

( iv)     δ1   =   F12 / k1       ;       k1 = ( A E / L )1

Sleeve 2       From above, the sleeve is subjected to a compressive load F12 and a temperature rise t, and suffers a tensile deformation δ2, so by inspection or by adhering to a positive tensile convention, the form of ( 2a) consistent with compatibility, equilibrium and temperature rise of this component is :-

( v)       δ2   =   - F12 / k2 +   L2α2t       ;       k2 = ( A E / L )2

Solution
Resolving the indeterminacy by solving the five equations for the three unknown forces and two unknown deformations gives :-

( vi)     F12   =   Fo     where the known initial load is defined as   Fo   =   ke ( Δ +   L2α2t )
in which the equivalent series stiffness ke is given by 1/ke = 1/k1 + 1/k2
Fo is called the initial load because it is due to nut tightening and heating before the external load P is applied.

This result seems ridiculous since it has F12 (the only failure agent in both 1 and 2) completely independent of the applied load P - ie. the load may be raised out-of-hand with no adverse effects on bolt or sleeve !!!

??? What's wrong with the analysis ???

The channel for the flow analogy is shown at (f) here; the restrictive annular areas are arrowed. force paths in bolted joint Two distinct force paths are suggested in (g) - that of P from the eye directly into the support and byepassing the bolt shank and sleeve, and that of the self-equilibrating initial load Fo in the bolt shank and sleeve. These make physical sense as no external support is necessary to cater for a temperature rise of the sleeve or for a tightening of the nut - these effects, embodied in Fo, are resisted internally in the assemblage. Note that the force paths have been greatly simplified here to avoid confusion in the sketch.

The two forces F12 and F31 are graphed against increasing external load P in (h).
F12 is constant at Fo from ( vi) while from ( ii) F31 drops off from this value in proportion to P, until it becomes zero when P reaches a value of Fo. But F31 is the force between eyebolt and support; it cannot be negative (there is no adhesive to enable the eyebolt to pull down on the support). The physical interpretation of F31 reaching zero is that contact between eyebolt and support is lost as indicated by ( j).
This then is the reason for the apparent anomaly in the foregoing analysis. The analysis is perfectly correct - but only within the limitations of its assumption, implicit in the free bodies (c) and (e), that contact between 1 and 3 is maintained and F31 > 0.
This assumption should not be confused with the unrelated deformation assumption of (b).

If it is desired to increase the load P at which contact is lost, then (h) indicates that Fo must be raised, probably by further nut tightening, Δ. After contact is lost (P > Fo) the arrangement is statically determinate and component loads can be found immediately from equilibrium only. Setting F31 = 0 and F12 = P in the free bodies (c), (d) and (e) demonstrates that all components transmit the external load P. This is confirmed physically by the force path ( j).

Having found the force F12 transmitted through the bolt eg. the bolt's safety can be assessed from the tensile design equation ( 1b) applied to the component 1 :
          n1     =     (AS/P)1     =     Ac1S1/F 12     ;               F12     =     maximum( P, Fo)     from (h).


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