This paper presents a theoretical study of the parameters that influence sandwich-type constrained layer damper design. Although there are different ways to reduce the noise generated by a railway wheel, most devices are based on the mechanism of increasing wheel damping. Sandwich-type constrained layer dampers can be designed so their resonance frequencies coincide with the wheel's resonant vibration frequencies, and thus the damping effect can be concentrated within the frequency ranges of interest. However, the influence of design parameters has not yet been studied. Based on a number of numerical simulations, this paper provides recommendations for the design stages of sandwich-type constrained layer dampers.

The acoustic reductions achieved with the current damping solutions for railway wheels that appear in the state of the art were obtained with different railway wheel designs, under different measurement scenarios (laboratory and on track), under different testing conditions, making it impossible to compare these damping solutions in a straightforward manner. The aim of this paper is to analyse, measure and estimate the behaviour of damping solutions installed on the same railway wheel and under the same testing conditions. Experimental measurements were carried out in the laboratory on wheels that are currently in use in metro lines. Damping solutions that were evaluated are ring damper, friction damper and sandwich-type constrained layer damper. Results show that ring and friction dampers are dependent on the applied preload and that they can only dissipate energy at high frequencies. Sandwich-type constrained layer dampers are the only damping solution that can add damping at low frequencies, but it is essential that they be properly designed in order to significantly increase the final wheel damping.

In addition to the engineering knowledge base that has been traditionally taught, today's undergraduate engineering students need to be given the opportunity to practice a set of skills that will be demanded to them by future employers, namely: creativity, teamwork, problem solving, leadership and the ability to generate innovative ideas. In order to achieve this and educate engineers with both in-depth technical knowledge and professional skills, universities must carry out their own innovating and find suitable approaches that serve their students. This article presents a novel approach that involves university-industry collaboration. It is based on creating a student community for a particular company, allowing students to deal with real industry projects and apply what they are learning in the classroom. A sample project for the German sports brand adidas is presented, along with the project results and evaluation by students and teachers. The university-industry collaborative approach is shown to be beneficial for both students and industry.

This paper presents what we call the Multiple Approach Experimental Project (MAEP), a project based on the model-building approach to learning. The MAEP complements theoretical lectures by placing students in a real situation where they design and build a physical structure. A total of 65 students divided into 24 teams voluntarily took part in the competition. Assessments from students who participated in the MAEP along with assessments from the instructors who implemented it are presented. Results show that the MAEP was welcomed and that the objective of engaging students in the subject was met.

This paper presents a change made to the lecturing approach used within a specific course. The new lecturing approach is based on a non-linear structure where each lesson combines concepts from different topics, in contrast to the traditional linear structure in which each topic is treated separately. The objective of the non-linear approach is to increase student dynamism and motivation and to foster teacher-student dialog. Assessments from students who were taught according to the traditional linear structure along with assessments from students who were taught under both the linear and non-linear approaches are presented. Results show that the non-linear lecturing approach was welcomed and led to a higher degree of student dynamism and motivation and to more tea-cher-student dialog.

This paper presents the modelling and design of a constrained layer damper to eliminate squeal noise in a particular tram. Even though resilient wheels are installed in every bogie, squeal noise is generated at the frequency of 780-800 Hz due to the small radius curves that the tram has to draw. Tuned constrained layer dampers provide a solution to this particular problem. Butyl rubber is chosen as the viscoelastic material for the damper, and conventional steel is used for the metallic sheets. The modelling approach and the final design of the damper are presented, together with evaluation of its performance in a real application. Experimental measurements on track have demonstrated that the constrained layer damper is properly tuned to the squealing frequency and that there is a significant reduction in noise when the proposed damper is attached to the wheels.

This paper presents a procedure for predicting the damping added to a railway wheel when sandwich-type dampers are installed. Although there are different ways to reduce the noise generated by a railway wheel, most devices are based on the mechanism of increasing wheel damping. This is why modal damping ratios are a clear indicator of the efficiency of the damping device and essential when a vibro-acoustic study of a railway wheel is carried out. Based on a number of output variables extracted from the wheel and damper models, the strategy explained herein provides the final damping ratios of the damped wheel. Several different configurations are designed and experimentally tested. Theoretical and experimental results agree adequately, and it is demonstrated that this procedure is a good tool for qualitative comparison between different solutions in the design stages.

This paper presents a vibro-acoustic characterization of a railway wheel in the frequency domain with and without damping solutions. From a simple vibrational measure where modal damping ratios are calculated, the sound pressure at a certain distance from the railway wheel is predicted, avoiding time-consuming and expensive acoustic measurements. The approach is based on FEM (finite element method) and makes use of the submodeling technique which consists of decoupling the calculation first into a structural response, and then into the acoustic emission. This decoupling allows damping in the structure to be introduced in terms of modal damping ratios instead of Rayleigh damping, a commonly used approach that is, nonetheless, not very accurate. Due to the use of infinite elements in the boundaries, the size of the acoustic mesh is reduced to an ellipsoid surrounding the structure, thus decreasing calculation time. The results are compared with experimental measurements with satisfactory agreement. Thus, the approach described becomes a powerful tool to compare different damping treatments and to make a decision on which solution could be adopted in a particular application.