Energy Flow (Bond Graph) Dynamic Modeling of Cartesian-Frame FFF 3-D Printer Gantry

Energy flow (bond graph) modelling gives important information about the flow of energy to each component of a dynamic system and is especially useful for complex non-linear mechanical systems. This work presents a systematic development of a bond graph model of fused filament fabrication (FFF) 3D printer gantry. The model incorporates structural and belt stiffness, damping and input torque. The model was checked for correctness and causality using the 20-SIM software. The model was further validated using MATLAB-Simulink using parameters obtained for an example printer characterized in a lab environment. The bond graph model gives a unique view into modelling of the extruder carriage dynamics in FFF and can be applied to specific problems. It will also give interesting information on the controllability and system integration of the printer hardware.Mechanical Engineerin

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Active suspension co-design for lateral stability of rail vehicles

Railroad transportation is one of the most cost-effective and energy-efficient modes of land transportation. With an eye toward improving these efficiencies, many efforts have focused on developing high speed railways. Traditionally railways have utilized passive suspension systems, but maintaining dynamic stability at higher speeds demands enhancements to existing rail vehicle suspensions. One strategy to improve dynamic performance is to incorporate active or semi-active elements, such as force actuators or variable dampers, within the suspension system. Modern day road and rail vehicles often utilize such actively-controlled suspensions to improve stability, ride comfort and ride quality at high speeds. The dynamic performance of such mechatronically-controlled suspension systems is related closely to the congruence of the design of passive elements in conjunction with the chosen control system strategy. Historically, design of controlled dynamic systems has followed a sequential process (mechanical design followed by control design). In the field of mechatronics, engineers typically use design rules or heuristics that help account for design coupling, but cannot produce system optimal designs. Passive elements are optimally designed first, followed by the addition of controllers for system performance improvements. New integrated design strategies are required to realize the full potential of such advanced complex dynamic systems and to capitalize on design coupling. This thesis aims to explore and apply a recently developed synergistic approach to design of controlled dynamic systems, called co-design. Theoretical models of existing partitioned, optimization-based design methods are compared to this combined active and passive system design strategy. Parameters for a reduced and a full-scale rail vehicle model are then designed using the developed optimal design formulations. Different control techniques within the co-design framework are tested and compared. Typically feedback controllers are required for actual implementation of control strategies. Early-stage co-design strategies are normally based on open-loop control, therefore, are limited for functional implementation. However, co-design methods provide designers with better knowledge about the true performance limits of dynamic systems, help them make more informed design decisions, and provide a foundation for development of implementable feedback control systems. The results obtained in this thesis show significant improvements achieved by co-design strategies over passive system design and sequential design approaches. The results also demonstrate the potential of this framework in helping systematic selection of optimal plant design variables, controller architecture, and implementable control techniques. Future work includes designing practical feedback controllers built upon results from co-design strategies for rail vehicles using non-linear vehicle models to provide a complete active rail suspension solution

Effect of Rapid Drawdown on the Stability of Railway Embankments

The rapid drawdown of water level adjacent to a clay slope under railway embankments reduces the stability of these slopes, which results in further safety implications when a freight train is passing through this area. Thus, to enhance the safety and stability of a clay slope under both rapid drawdown and a moving freight train conditions requires in-depth investigation, which has not been done before. This work is focused on the coupled drawdown analysis with slope stability assessment under undrained conditions using 2-dimensional models through the finite element shear strength reduction (FE-SSR) method. A series of parametric studies were performed including the identification of key factors, such as geometric characteristics of the slope, rapid drawdown ratios, and freight train speeds. The control variable method was introduced to individually study each parameter and its effect on slope stability. For slopes with different geometric parameters and rapid drawdown ratios, maximum safe train speed information is presented for slopes with a minimum factor of safety of 1.3. Noticeably, a slope with 3H:1V slope inclination, and 3-m railway embankment has shown excellent results in terms of high maximum safe train speeds under the studied conditions. As a contribution, this study provides maximum safe train speed information for a slope with different geometric parameters and rapid drawdown ratios, which can be used as a reference for safe freight train operations

Development of a control scheme for a quarter car test rig

Road holding performance and vibration isolation of an automobile are some of the most important criteria for human perception of ride quality. For this, the accurate estimation of car body vibration is a prerequisite. A 2-DOF quarter car is a simple, but still reasonable approach to study the dynamic behaviour of a car body. This thesis illustrates the development of control scheme hardware for a quarter car model based on an existing test rig. The test rig parameters are estimated using different static and dynamic tests. The parameters are then used to develop a passive nonlinear model for the test rig. A similar linear model is used to develop an idealized controller. The controller is then applied to the nonlinear simulation model to make it active, and its performance is found to be slightly better at low frequencies for the nonlinear model. The actuator dynamics are then included in the active model to make it realistic. A comparative study of the ideal and realistic model shows that the realistic active model generally shows better ride quality, specially at high frequencies. This model will offer the future researchers a realistic control scheme for the quarter car test rig. The thesis shows the implementation of a new software (20-sim 4C) and hardware system to allow control signals to be sent from the simulation software to the physical quarter car, and verification of the software and hardware by controlling a voice coil actuator using pulse-width modulation to follow a position command signal and then a force command signal. It is observed that as the frequency of the command signal increases, the amplitude loss in the response increases. The actuator can generate only about 5 N force when the frequency of the force command signal is above about 10 Hz. A more robust actuator with higher bandwidth will be required for hardware replication of the maximum potential active suspension benefit predicted by the simulation models

Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields

Innovations in Road, Railway and Airfield Bearing Capacity – Volume 2 comprises the second part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field

Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields

Innovations in Road, Railway and Airfield Bearing Capacity – Volume 3 comprises the third part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version

Review: optical fiber sensors for civil engineering applications

Optical fiber sensor (OFS) technologies have developed rapidly over the last few decades, and various types of OFS have found practical applications in the field of civil engineering. In this paper, which is resulting from the work of the RILEM technical committee “Optical fiber sensors for civil engineering applications”, different kinds of sensing techniques, including change of light intensity, interferometry, fiber Bragg grating, adsorption measurement and distributed sensing, are briefly reviewed to introduce the basic sensing principles. Then, the applications of OFS in highway structures, building structures, geotechnical structures, pipelines as well as cables monitoring are described, with focus on sensor design, installation technique and sensor performance. It is believed that the State-of-the-Art review is helpful to engineers considering the use of OFS in their projects, and can facilitate the wider application of OFS technologies in construction industry