Modelling the Effect of Preload in a Lap-Joint by Altering Thin-Layer Material Properties Nidhal Jamia, Hassan Jalali, Michael I. Friswell, Hamed Haddad Khodaparast, and Javad Taghipour Abstract The joints in an assembled structure represent a significant source of energy dissipation and may lead to overall stiffness variation, which may affect high cycle fatigue failure. Many approaches have been developed to model and simulate the dynamics of bolted joint structures. However, the inherent dynamics of the contact interfaces still need further investigation in order to be able to generate accurate models to predict the behaviour in the contact interface. In this paper, the modelling of the contact interface of a bolted lap-joint and the prediction of its pressure distribution are considered using 2D and 3D FE models. A 3D finite element model with solid elements is developed to simulate the behaviour of the contact interface. The model is a modified thin-layer element where the material properties of a thin layer are distributed over the contact interface. Due to the high computational cost of the 3D model, a reduced-order model is proposed for the lap-joint in which beam elements are used. The material properties are introduced in these models to account for the variability in the contact parameters. Finally, experimental modal properties were used to identify the joint parameters. A good agreement is obtained between the detailed model and the reduced-order model in the prediction of the pressure distribution in the contact interface. Keywords Pressure distribution · Bolted lap-joint · Detailed model · Modified thin-layer element · Joint parameters 1 Introduction In almost all practical mechanical structures, there is at least one mechanical joint. After more than half century of efforts on modelling the hysteretic behaviour of jointed structures, it is still one of the most complicated tasks in structural dynamics. Modelling and investigating the behaviour of mechanical joints have received considerable attention. These efforts have been intensified during recent decades due to progress in computational tools and experimental equipment. Bograd et al. [1] reviewed various identification approaches developed to model the dynamics of mechanical joints. Iwan [2] presented a model to investigate the yielding behaviour of continuous and composite materials and structures by complementing and extending some of the earliest works [3–7]. Iwan models are capable of predicting both transient and steady-state yielding behaviour of jointed structures. The Iwan model is one of the most important mathematical formulations introduced to predict the dynamic behaviour of joint contact interfaces. Ref. [8] gives an overview of the Iwan model for mechanical jointed structures and presents a reduced-order model to investigate the qualitative properties of such systems using a small number of parameters. Many research works have been carried out based on this model. Segalman and Starr [9] compared various constitutive models of joints and discussed how the Iwan model can represent the properties of Massing models. Segalman [10] and Li and Hao [11] developed a four-parameter Iwan model and a six-parameter Iwan model, respectively, to investigate the dynamic response of lap-jointed structures. Quinn and Segalman [12] investigated the applicability and performance of the series-series Iwan model in predicting the dynamics of jointed structures. There are various identification methods introduced in the literature for modelling the dynamic behaviour of jointed structures [13–17]. Ahmadian and Jalali [13] suggested modelling the dynamics of bolted lap-joints by introducing a N. Jamia ( ) · M. I. Friswell · H. H. Khodaparast · J. Taghipour Faculty of Science and Engineering, Swansea University, Swansea, UK e-mail: nidhal.jamia@swansea.ac.uk; m.i.friswell@swansea.ac.uk; h.haddadkhodaparast@swansea.ac.uk; j.taghipour.967687@swansea.ac.uk H. Jalali Department of Mechanical and Construction Engineering, Northumbria University, Newcastle upon Tyne, UK e-mail: hassan.jalali@northumbria.ac.uk © The Society for Experimental Mechanics, Inc. 2022 G. Kerschen et al. (eds.), Nonlinear Structures & Systems, Volume 1, Conference Proceedings of the Society for Experimental Mechanics Series, https://doi.org/10.1007/978-3-030-77135-5_25 211
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