Flow induced excitation forces in heat exchangers cause tube-support interactions. The long-term interaction is an important phenomenon which may cause fretting-wear of the tubes. Experimental tests of the interaction show the occurrence of stick-slip intermittent behavior in the tube response. Many factors are involved to precisely predict the interaction behavior including flow excitation forces, impact and friction forces. One of the explanations behind the intermittent stick-slip behavior may be interpreted by refinements in the conceptual choice of friction model and coefficient of friction. Therefore, among the factors above, the incorporated friction model plays an important role in the determination of the level of fretting-wear in the system. The friction model should satisfy two important criteria: the first important aspect is the strategy of the friction model to detect the cessation of sticking, the beginning of partial slipping and establishment of the sliding region. The second important aspect is defining a friction coefficient function for the entire system response to precisely represent the transient stick-slip regions. In the present work, the velocity limited friction model was compared with the LuGre model which is a rate dependent friction model. The effect of varying the break-away force and Stribeck effect on the stick-slip region was also investigated. Furthermore, the criteria to demarcate the stick-slip region in the LuGre model are discussed and a different method to incorporate the Stribeck effect and presliding damping in the Dahl friction model are proposed. Finally, a new hybrid spring-damper friction model inspired by the Cattaneo-Mindlin stress distribution in the contact region is proposed.

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