Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations

Abstract

The aim of the present study is to consider the idea of using polyurethane flexible adhesive in to reduce the vibrations in structures exposed to dynamic loads and evaluate their damping properties in relation to large deformations. Firstly, two aluminium cantilever beams, simulating structural elements (without and with polyurethane layer in the form of tape), were analysed, in order to check the damping of the unconstrained polymer layer. In the second stage of the study, a composite beam consisting of two aluminium flat beams bonded with polymer adhesive was considered, so as to check the damping of the constrained polymer layer. Dynamic parameters, such as modes of free vibrations, corresponding natural frequencies and damping ratios, were determined and compared. The third stage of the investigation was aimed at solving the problem of the additional mass of the applied polymer layer, which influences the frequencies and damping of the tested structure. A special separating procedure is proposed that makes it possible to calculate the corrected real values of the polymer layer’s damping. The results of the study clearly show that the response of the composite aluminium beam with and without polymer adhesive layer is mainly influenced by the layers’ thickness and the large strain deformation, in terms of its damping characteristics. The use of polymer adhesive layers in constrained and unconstrained conditions leads to a significant reduction in the vibrations of tested beams, while preserving their stiffness at nearly the same level. The applied analysis procedure made it possible for us to separate the damping properties of the analysed polymer layers and evaluate them independently with respect to the influence of integrated structural elements on damping.

Durability of PS-Polyurethane Dedicated for Composite Strengthening Applications in Masonry and Concrete Structures

“…Various types of PU mass in the PUFJ technology for fast bonding of prefabricated PU laminates to concrete RC frames [8,9]. Ductile properties of PU materials and their damping ability have been tested in steel and aluminum structures as adhesive bonding layers [10,11]. The ability of flexible PU adhesives to redistribute shear stress over a large area, unlike stiff epoxy [12] and mineral adhesives [13], caused the development of these adhesives in the composite strengthening of masonry and concrete structures.…”

Finite element modeling of plastic hinges based on ductility demand‐capacity method using nonlinear material for dynamic analysis

“…A plastic hinge does not allow for rotation under loads smaller than that which plasticizes the hinge, but under greater loads it transmits the boundary moment and allows for rotation, see Zhao et al 26 For supports made of concrete, taking into account the concept of plastic hinges, correct plastic analysis requires the use of a plastic‐degradable model of concrete. In this model, during element loading, the load‐bearing capacity limit is reached as a result of degradation of the material from the increase in external load, and consequently, the load‐bearing capacity is lost due to the increase in plastic deformation, see Lubliner et al, 21 Lasowicz et al, 27 Stręk et al, 28 and Oller et al 29 This is a very important element of the analysis, thanks to the location of the place where the support material degrades the fastest and to the greatest extent, it is possible to determine the place where plastic hinges are formed. This is due to the fact that where concrete loses its load‐bearing capacity, reinforcement (i.e., steel) starts to play a major role in transferring the loads.…”

Architectural and Urban Planning Solutions for the Protection of Heritage Buildings in the Context of Terrorist Attacks: Following the Example of Passive Protection Systems

“…In recent years, several studies on the mechanical characteristics of laminated glass with PVB interlayers have been carried out, assisted by theoretical analyses [19][20][21][22][23][24][25], experimental methods [26][27][28][29][30][31][32][33][34], as well as numerical simulations [27,[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53]. Primarily, Xu et al [31][32][33][34] have carried out experimental studies concerning the experimental prediction of braking and the formation of cracks in the glass layer.…”