Mechanical Systems and Signal Processing Mechanical Systems and Signal Processing 21 (2007) 2318–2334 Generic element formulation for modelling bolted lap joints Hamid Ahmadian , Hassan Jalali School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran Received 30 November 2005; received in revised form 15 July 2006; accepted 20 October 2006 Available online 4 December 2006 Abstract Joints have significant effects on the dynamic response of the assembled structures due to existence of two non-linear mechanisms in their interface, namely slipping and slapping. These mechanisms affect the structural response by adding considerable damping into the structure and lowering the natural frequencies due to the stiffness softening. Neglecting these effects in modelling of joints produces errors in predictions of the structure responses. In this paper, a non-linear generic element formulation is developed for modelling bolted lap joints. The generic element is formed by satisfying all conditions that are known for a joint interface and hence providing a non-linear parametric formulation for the families of allowable joint models. Dynamic response of the developed model for the assembled structure including the generic joint interface element is obtained using the incremental harmonic balance (IHB) method. The generic parameters of the joint are identified by minimising the difference between the model response obtained from IHB method and the observed behaviour of the structure. The procedure is demonstrated by modelling an actual structure containing a single lap bolted joint in the middle. The frequency responses of the structure around the first two resonance frequencies are measured by exciting the structure using a sinusoidal force at each individual frequency. The measured responses are compared with the predictions of the model containing a parametric generic joint element. The parameters of the joint interface model are successfully identified by minimising the difference between the measured responses and the model predictions. r 2006 Elsevier Ltd. All rights reserved. Keywords: Generic element model; Joint interface modelling; Joint softening effects; Incremental harmonic balance method 1. Introduction Joints are essential parts of every compound structure and play a significant role in its dynamical response. The added flexibility introduced by the joints heavily affects the structure behaviour and when subjected to dynamic loading, most of energy is dissipated in the joints. Formulating the joint behaviour representing the physical merits involved in the joint interface is critical in modelling any compound structure. The two most common mechanisms involved in the joint interface are frictional slip, and slapping [1]. These mechanisms have their own characteristic features, e.g., frictional slip becomes saturated at very high amplitudes and slapping pushes energy from low-to-high frequencies. The common effects of these mechanisms in the joint behaviour are the stiffness softening, which manifest itself in the decrease of the resonance frequency as the ARTICLE IN PRESS www.elsevier.com/locate/jnlabr/ymssp 0888-3270/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ymssp.2006.10.006 Corresponding author. Tel.: +98 21 77491228-9; fax: +98 21 77240488. E-mail address: [email protected] (H. Ahmadian).
Generic element formulation for modelling bolted lap joints
Jul 01, 2023
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