Virtual prototyping of high damping multilayer coating solutions for industrial applications

Specifically designed and optimized multi-layered coating solutions can be adopted to obtain composite components with high stiffness, high resistance and effective vibration damping capabilities. In particular the adoption of multi-layer coating solutions, designed to maximize dissipative actions at the interface between different layers, offers significant advantages with respect to a single layer coating approach. The use of single layer coating technology often results in thick coating layers that produce undesired alterations in the geometrical and mechanical properties of the component. By maximizing the dissipative actions between relatively thin layers high damping multi-layer coating solutions can be obtained, with limited alteration of the uncoated component geometry, stiffness and strength properties. In this work different high damping multi-layer coating solutions are presented and a virtual prototyping and experimental validation design procedure is discussed. An extensive measurement campaign, consisting on estimating the frequency response function of coated and uncoated slender beam test specimens, is made in order to investigate the effectiveness of different coating material choices, to be adopted in multi-layer coating solutions. Different coating material solutions, such as single and dual component epoxy resin, cyanoacrilate based, ceramic-based polymeric, metal oxide and nitrides coating solutions are taken into account. The various solutions are applied by means of different manufacturing methods such as screen printing, anodization and plasma based deposition technologies. Some frequency dependent damping estimators, defined by the authors in previous works, are evaluated over a wide frequency range. An identification procedure, making use of a multi-layer beam model that takes into account of the dissipative actions at the interface between the layers, is applied to the measurement data in order to find the unknown parameters modeling the inter-layer hysteretic dynamical actions at the interface between two different layers. The identification procedure is first tested on numerically simulated specimen examples with the addition of noise to evaluate the robustness of the identification technique before applying it to true experimental measurements. Then the coating materials property estimates and the damping experimental estimates, obtained from reference tri-layer symmetric beam specimens, are used as input of the previously validated numerical identification procedure. The optimal value of the parameters that define slipping and dissipative actions at the interface between different layers, modeled by means of complex interlaminar impedances, are identified. The identified parameters are used with a multi-layer beam virtual prototype model to simulate the damped free and forced vibrational response of different multi-layer composite beam specimen architectures. Different coating solution virtual prototypes, obtained by varying the coating layer architecture, i.e. the number of layers, materials and thickness values, are compared by means of the evaluation of the previously cited damping estimator. The more effective coating solutions are selected, some multi-layer beam specimens are prepared accordingly and tested by means of dynamic mechanical measurements. The experimental measurement results are used to validate the proposed prototyping procedure. Some industrial application examples, consisting on the application of some of the effective coating solution previously found on the casing of a mechanical pump are presented. The vibrational and acoustic response of these coated solutions working in real operating conditions is experimentally evaluated and compared with respect to the same results obtained from within the uncoated solutions. A discussion and a critical analysis is presented.