Thermal strength analysis of a steel bolted connection under bolt loss conditions

The aim of the paper is to analyse an exemplary bolted connection under the conditions of loss of bearing capacity of some fasteners in the connection. The presented tests are numerical and concern an asymmetric bolted connection. The joined elements in the connection were modelled as 3D finite elements, and the fasteners were treated as hybrid models consisting of rigid heads and nuts, and flexible beams between them. The bolted connection was first preloaded according to six different tensioning orders using a standardised force. After all bolts were tensioned, the selected bolts were removed, simulating bolt damage. The connection was then tested for external loads with temperatures ranging from 20 to 600°C. The influence of loosening the connection on the load in the remaining bolts at the operational stage of the connection was investigated. The calculation results were compared with the test results for a healthy bolted connection. It was shown that the bearing capacity of the connection in the damaged state decreased by 13%

Effects of nonlinearity of a contact layer between elements joined in a multi-bolted connection on preload values in bolts

In the paper, modelling and calculations of an asymmetrical multi-bolted flange connection atthe assembly stage are presented. A physical model of the joint is based on a flexible flange element that is connected with a rigid support by means of linear spring elements which substitute bolts. Between the flange element and the support, the linear Winkler model of a contact layer is taken into consideration. Through example of a few multi-bolted connections, influence of nonlinearity of the contact layer between joined elements on computational values of the bolt preloads has been investigated. Results obtained from the calculations are compared with experimental results described in [1].[b]Keywords[/b]: multi-bolted connections, assembly condition, preloa

FE-MODELLING OF A CONTACT LAYER BETWEEN ELEMENTS JOINED IN PRELOADED BOLTED CONNECTIONS FOR THE OPERATIONAL CONDITION

Modelling and calculations of a contact layer between elements joined in a preloaded bolted connection for the operational condition are presented. The physical model of the bolted connection is based on a flexible flange element that is joined with a rigid support by means of the no-bolt model (at the assembly stage) or the rigid body bolt model (at the operational stage). The contact layer between joined elements is described as the nonlinear Winkler model. The contact joint model considering an experimental normal elastic characteristic is presented. Examples of normal contact pressure and normal contact deformations distributions are contained

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

In the paper, the numerical tests of the contact of a pair of flexible elements were presented. The non-linear phenomena occurring in the contact zone of two elements have been considered separately for the assembly and operational condition of the joint. The physical and mathematical models of the contact joint created using the finite element method were proposed. The contact joint is treated as a system composed of the subsystems: two of them are joined elements and the third one is the contact layer between the elements. The calculations results for the selected contact joint were given

Determination of Bolt Forces and Normal Contact Pressure Between Elements in the System With Many Bolts for its Assembly Conditions

The paper put forward a thesis that modelling dissymmetric non-linear multi-bolted connections as a system is possible. Modelling of the systems composed of four subsystems on the assembly state was presented. These subsystems included: a couple of joined elements (a flange and a support), a contact layer between them, and bolts. The physical model of the system was described considering the tightening of bolts according to a specific sequence. In this model: the flange and the support were built using spatial finite elements, the contact layer was formed as the non-linear Winkler model, and the bolts were replaced with simplified models made of flexible beams. The calculation model which can be applied to determine the changes in bolt forces, as well as in the normal contact pressure between the joined elements during the tightening of the system and at its end, was presented. The results of sample calculations for the selected multi-bolted system were shown

Wyznaczanie normalnych charakterystyk podatnościowych styku powierzchni o określonej strukturze geometrycznej

In the paper, a method for determination of a normal flexibility characteristic of the contact between elements joined in a multi-bolted connection is presented. Research were carried out using equivalent samples, which substitute joined elements. An assessment of the surface texture of the samples and the joined elements is accomplished. An experimental function between normal contact pressure and normal contact deformations for investigated elements is appointed.[b]Keywords[/b]: surface texture, multi-parameter analysis, normal flexibility characteristic, multi-bolted connectio

Effect of Atmospheric Conditions on the Tightening Behaviour of HV Galvanised Bolts in Structural Bolt Sets

The aim of this article is to investigate the effect of atmospheric conditions on the tightening behaviour of HV bolts in structural bolt sets. The article describes the results of experimental tests carried out for bolt sets of a selected type. The parts of the joined sets were stored according to the specified six different conditions for four weeks before assembly. Paper, cardboard boxes and anticorrosion foils were used as protection against atmospheric conditions. The behaviour of unassembled and assembled bolt sets was also taken into account. The variation in the friction coefficient depending on the clamping force and storage conditions of the bolt sets was demonstrated. This applies both to the contact between the joining elements on the threaded surfaces and to the area between the bolt head and the bearing surface of the nut and washer

Determination of normal flexibility characteristics of surfaces' contact with the specified surface texture

In the paper, a method for determination of a normal flexibility characteristic of the contact between elements joined in a multi-bolted connection is presented. Research were carried out using equivalent samples, which substitute joined elements. An assessment of the surface texture of the samples and the joined elements is accomplished. An experimental function between normal contact pressure and normal contact deformations for investigated elements is appointed.[b]Keywords[/b]: surface texture, multi-parameter analysis, normal flexibility characteristic, multi-bolted connectio

Testing the Mechanical Properties of High-Strength Zinc-Coated Bolts: FEM Approach

High-strength zinc-coated bolts are used as fasteners in prestressed multi-bolted connections. This communication deals with modelling such bolts using the finite element method. The analyses were performed for a zinc-coated M12 HV10.9 bolt. Coatings with the following thicknesses were considered: 40, 60, 84 and 92 µm. The influence of coating thickness on the selected mechanical properties of the bolt was investigated. The corresponding properties of an uncoated bolt were taken as a reference. It is shown that the use of a zinc coating with a standardised thickness is associated with a reduction in bolt stiffness of up to 11.2%

Concept of an innovative technological line for the processing of linear profiles

The paper presents the concept of an innovative technological line intended for the processing of long linear profiles used in engineering steel and aluminium structures, which can be both hollow and open section profiles. The line is set up with seven main sections: profile loading system, input roller conveyor, plasma arc cutting section, circular saw cutting section, robot welding section, output roller conveyor and profile packaging system. The assumptions adopted to create the concept of the techno-logical line were specified. A block diagram of the line and drawings showing the structure of its selected elements were depicted. The features of the technological line documenting its product and process innovativeness were indicated. The proposed technological line is built in the AGICO Group company, but it can also be successfully implemented in other companies dealing with the processing of long linear profiles