Impact of Nonlinearity of The Contact Layer Between Elements Joined in a Multi-Bolted System on Its Preload

Abstract

The paper deals with modelling and calculations of asymmetrical multi-bolted joints at the assembly stage. The physical model of the joint is based on a system composed of four subsystems, which are: a couple of joined elements, a contact layer between the elements, and a set of bolts. The contact layer is assumed as the Winkler model, which can be treated as a nonlinear or linear model. In contrast, the set of bolts are modelled using simplified beam models, known as spider bolt models. The theorem according to which nonlinearity of the contact layer has a negligible impact on the final preload of the joint in the case of its sequential tightening has been verified. Results of sample calculations for the selected multi-bolted system, in the form of diagrams of preloads in the bolts as well as normal contact pressure between the joined elements during the assembly process and at its end, are presented.

Impact of nonlinearity on bolt forces in multi-bolted joints: A case of the assembly stage

“…Then, it can be assumed that typically nonlinear characteristics of the normal deformation may be replaced by linearized counterparts. This theorem is established in the present study, which contains a continuation of the theme of modeling multi-bolted joints in the assembly stage inaugurated in the previous paper [13].…”

“…The concept of the modeling method of multi-bolted joints used in this paper is presented in [13]. The joint model is made up of a flexible flange that is connected to a rigid support using k bolts, as shown in Figure 1.…”

“…However, it is possible to carry out this procedure in a few passes, for example following the recommendations given in [33]. Linear characteristics of the springs forming the contact layer are specified by the following function defined on the basis of experimental tests [13]: The calculation results are presented in the graphs shown in Figure 6, in which force variations in the bolts during the pre-tensioning process are presented according to the following scheme: The calculated values of each bolt preload during and at the end of the pre-tensioning process are compared with their experimental values [32]. The relative evaluation of the final bolts preload values can be carried out using the Z rate:…”

“…This applies in particular bolts. Some theoretical studies on the process of pre-tensioning of the asymmetrical multi-bolted joint, consisting of a flange fixed to a rigid support, has been published in the previous paper [13]. The bolts were then treated as elements with a rigid head.…”

Finite Element Modelling of a Pair of Flexible Elements Contact Preloaded and Externally Loaded with an Arbitrary Force

“…3). The calculations are carried out in an iterative process in which the following condition is checked [17]: (4) where: R j is the reaction in the j-th non-linear spring, R' j is the reaction in the j-th nonlinear spring after the linearization, and e 1 is the relative error. In the operational state, the preloaded contact joint is loaded with an external force.…”