Multi-bolted Connections Research Articles

Modelling Nonlinear Multi-Bolted Systems on the Assembly State

Modelling and calculations of asymmetrical nonlinear multi-bolted connections treated as a system composed of four subsystems are presented. These subsystems are: a couple of joined elements (a flange and a support), a contact layer between the elements, and a set of bolts. The physical model of the system on the assembly state is described taking into account the bolt preloading conducted according to a specific sequence. For the modelling the finite element method is used. The flange and the support are built with spatial finite elements. The contact layer is formed as a nonlinear Winkler model, and the set of bolts are modelled using simplified beam models (named as rigid body bolt models). The calculation model is presented, by means of which changing force values in the bolts during the preloading of the system and at its end can be determined. Results of calculations for the exemplary multi-bolted system are presented.

An Analytical Method for Determining the Load Distribution of Single-Column Multibolt Connection

The purpose of this research was to investigate the effect of geometric variables on the bolt load distributions of a cold-formed steel bolt connection. The study was conducted using an experimental test, finite element analysis, and an analytical method. The experimental study was performed using single-lap shear testing of a concentrically loaded bolt connection fabricated from G550 cold-formed steel. Finite element analysis with shell elements was used to model the cold-formed steel plate while solid elements were used to model the bolt fastener for the purpose of studying the structural behavior of the bolt connections. Material nonlinearities, contact problems, and a geometric nonlinearity procedure were used to predict the failure behavior of the bolt connections. The analytical method was generated using the spring model. The bolt-plate interaction stiffness was newly proposed which was verified by the experiment and finite element model. It was applied to examine the effect of geometric variables on the single-column multibolt connection. The effects were studied of varying bolt diameter, plate thickness, and the plate thickness ratio (t2/t1) on the bolt load distribution. The results of the parametric study showed that thet2/t1ratio controlled the efficiency of the bolt load distribution more than the other parameters studied.

Design of multi-bolted joints to prevent self-loosening failure

The rotational self-loosening of bolted joints under cyclic loading is a process, which means a screw rotation against the assembly direction by periodic load cycles. Thus, the preload balance is released and the clamping function is no longer maintained. The effect is well known, but prevention is usually performed experimentally only after occurrence of self-loosening events. The paper gives a systematic presentation of the dimensioning and the possibility to consider self-loosening in the development process. The procedure for self-loosening dimensioning and the influences are demonstrated with safety-relevant multi-bolted connections from the automotive industry. The aim of this paper is to provide a numerical design method with finite element analysis for detecting and understanding of the self-loosening process at bolted joints. Another focus of the work is to investigate the self-loosening behaviour under combined loading with a superposition of translation and rotation. Combined loading can lead to self-loosening even before reaching the limit of self-loosening for transverse loading. The computational results of the numerical simulation (FEA) are compared with experimental investigations.

Non-linearity of the contact layer between elements joined in a multi-bolted connection and the preload of the bolts

The paper presents modeling and calculations of multi-bolted connections at the assembly stage on an example of the engine cylinder head-block connection. The physical model of the connection was introduced as a combination of three subsystems: the set of bolts, the joined element and the contact layer between the joined element and the rigid support. The finite element method (FEM) was used for the modeling. Bolts were replaced with hybrid elements. The joined element was modeled with spatial finite elements. The Winkler model of the contact layer has been taken into consideration. The truth of the theorem has been examined, according to which non-linearity of the contact layer has a negligible impact on the final values of the bolt forces in the case of sequential preloading of the multi-bolted connection. The results of the calculations of a selected multi-bolted connection have been compared with the experimental results.

Rational Model for Multibolted Connections for GFRP Members

Bolted connections are most suitable for civil engineering applications since they are easy to inspect, have low construction costs, are easy to manufacture, and offer reliability compared with bonded joints. However, using advanced composite material members with unidirectional fibers could create a state of high stress concentration around the bolt holes due to their inherent geometric discontinuities. Due to a lack of information and the need for understanding the mechanism of these connections, a comprehensive experimental and analytical investigation was conducted at the University of Manitoba to study and to determine the behavior of bolted connections using glass fiber-reinforced plastic (GFRP) structural members. Based on the test results and observed behavior, a design procedure is introduced that accounts for the material orthotropy, pseudoyielding capability, and other factors that influence the connection behavior. The proposed rational model is capable of predicting the ultimate capacity of the multibolted connection and the failure mode. The generic nature of the proposed design guidelines can be applied to a multitude of composite material systems.

Multibolted Joints for GFRP Structural Members

For the past few decades, aerospace industry was the major user of advanced composite materials. Recently, civil engineers and the construction industry began to realize the potential of these materials in providing remedies for many problems associated with deterioration and corrosion of infrastructures. In light of this, a comprehensive experimental investigation was conducted at the University of Manitoba to study the behavior of multibolted connections using glass fiber-reinforced plastic members. A total of 105 multibolted double shear lap connections were tested. The effect of various parameters including the width of the structural member, edge distance, number of bolts, bolt pattern, pitch, thickness of the members, and direction of fibers with respect to the applied load were examined. This paper analyzes the experimental program, test results, and the various modes of failure as affected by the previously noted parameters.

Finite element analysis of bolted connections for PFRP composites

Structural applications of composite laminates are increasing with the drive for high strength, lightweight component design. These applications usually require joining composites either to composites or metals. Most commonly, joints are formed using mechanical fasteners. Therefore suitable prediction methods must be developed to determine failure strength and failure modes of these bolted connections. In this paper, three-dimensional finite element analysis is conducted on single and multi-bolted connections to determine the failure process, ultimate load and load distribution among the fasteners, taking into consideration bolt-hole contact problem in the finite element model. The strength analysis is based on Tsai-Wu tensor polynomial failure criterion which is applied to the laminate as a whole.