During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors’ knowledge and experience.

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A state-of-the-art review on magnetorheological elastomer devices

The need for building robots with soft materials emerged recently from considerations of the limitations of service robots in negotiating natural environments, from observation of the role of compliance in animals and plants [1], and even from the role attributed to the physical body in movement control and intelligence, in the so-called embodied intelligence or morphological computation paradigm [2]-[4]. The wide spread of soft robotics relies on numerous investigations of diverse materials and technologies for actuation and sensing, and on research of control techniques, all of which can serve the purpose of building robots with high deformability and compliance. But the core challenge of soft robotics research is, in fact, the variability and controllability of such deformability and compliance.

Stiffening in Soft Robotics: A Review of the State of the Art

Variable stiffness material and structural concepts for morphing applications

In this study, a magnetorheological elastomer (MRE) was manufactured and tested, and a MRE sandwich beam was also fabricated from a MRE between two thin aluminum layers An experimental test rig was set up to investigate the vibration response of the MRE sandwich beam under a non-homogeneous magnetic field The experimental results show that the first natural frequency of the MRE sandwich beam decreased as the magnetic field applied to the beam was moved from the clamped end of the beam to the free end of the beam It is also noted that the MRE sandwich beam had the capability to left shift the first natural frequency when the magnetic field was increased in the activated regions

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Experimental investigation of the vibration characteristics of a magnetorheological elastomer sandwich beam under non-homogeneous small magnetic fields

In this work the dynamic stability of a rotating three layered symmetric sandwich beam with magnetorheological elastomer (MRE) core and conductive skins subjected to axial periodic loads has been investigated using finite element method (FEM). The derived governing equation of motion is in the form of a multi-degree of freedom Mathieu–Hill's equation with complex coefficients. The instability regions of the sandwich beam for the principal parametric resonance case have been determined by using the harmonic balance method. Effects of applied magnetic field, rotating speed, setting angle, hub radius, static load and dynamic load on the dynamic characteristics and instability regions of the sandwich beam are investigated. This work will find application in the passive and active vibration reduction of rotating sandwich structure using magnetorheological elastomer core, magnetic field and periodic axial load.

Dynamic stability of a rotating sandwich beam with magnetorheological elastomer core

The concept of vibration controllability with smart fluids within flexible structures has been of significant interest in the past two decades. Although much research has been done on structures with embedded electrorheological (ER) fluids, there has been little investigation of magnetorheological (MR) fluid adaptive structures. In particular, a body of research on the experimental work of cantilever MR beams is still lacking. This experimental study investigates the controllability of vibration characteristics of magnetorheological cantilever sandwich beams. These adaptive structures are produced by embedding an MR fluid core between two elastic layers. The structural behaviour of the MR beams can be varied by applying an external magnetic field to activate the MR fluid. The stiffness and damping structural characteristics are controlled, demonstrating vibration suppression capabilities of MR fluids as structural elements. MR beams were fabricated with two different materials for comparison purposes. Diverse excitation methods were considered as well as a range of magnetic field intensities and configurations. Moreover, the cantilever MR beams were tested in horizontal and vertical configurations. The effects of partial and full activation of the MR beams were outlined based on the results obtained. The controllability of the beam's vibration response was observed in the form of variations in vibration amplitudes and shifts in magnitudes of the resonant natural frequency.

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Vibration characteristics of MR cantilever sandwich beams: experimental study

An Innovative Self-learning Approach to 3D Printing Using Multimedia and Augmented Reality on Mobile Devices☆

Abstract Information Technology, communication, and innovation require specific, essential competencies that employers look for in engineers. Responding to this, Tecnologico de Monterrey has been implementing the Tec21 Educational model to foster students' competencies by involving them in challenge-based learning (CBL). The iWeek is one of the first implementations of this model, where students experience immersive learning for a whole week. This study presents the iWeek Innovation Challenge to improve students' innovation and information technology and communication skills through a CBL didactic technique. During this iWeek, a group of students developed efficient solutions with Microsoft Power Apps to solve real challenges confronting a global company. The results proved that students could quickly learn and apply knowledge and develop practical, innovative solutions to real problems in Industry. It was a revelation to the stakeholders to notice how fast students can become familiar with new information technology tools to propose solutions that positively impact the company. Strong partnerships between academia and industry are crucial to developing student disciplinary and transversal competencies by challenging them to solve real-life problems in real-world environments. This work presents a roadmap for planning and designing a CBL iWeek with an educational partner from Industry. It includes the implementation details, assessment instruments, and results analysis. Finally, we also highlight the significant contributions of iWeek to explain the value of this immersive experience in the teaching–learning process. 

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iWeek experience: the innovation challenges of digital transformation in industry

Applied Academics is both a trend within pioneering educational institutions as well as a demand from the current generations of students at all levels. The first semesters of an engineering curricula focus on developing a solid theoretical basis in Mathematics, Physics and Programming before becoming immersed in practical projects. Therefore, first-year engineering students usually struggle to visualize the practical applications of their studies. Advancing towards an educational model based on competencies, the following workshop was an effort to increase engineering students’ engagement and to launch their development at a first stage. This interactive workshop was designed and implemented in an introductory engineering course where students were able to understand how a Star Wars BB8 commercial prototype droid is built and how it works. This droid worked as a great example of a well-known robot that integrates the different disciplines of the engineering programs involved in the workshop: Mechanical, Industrial, Automotive, Electrical, and Mechatronics. More than 600 freshmen took this workshop, which resulted in satisfactory outcomes. Results suggest that this kind of activity will prevent the abandonment of engineering studies. Students were really engaged in the workshop and showed curiosity and interest in understanding what was inside the famous robot and how it worked, given its innovative design. The students enjoyed the experience and realized the main differences between the engineering disciplines involved according to their application in this practical example. This workshop also helped them to reaffirm their decision on an Engineering Major and to motivate them to become skilled to be able to create this kind of technology.

First-year Engineering Students Engagement by Hands-on Experience with Star Wars Robotics

The Fourth Industrial Revolution (4IR) is a widely discussed concept even at levels such as the World Economic Forum (WEF). The need for higher education to respond to this is urgent, since the power of new 4IR technologies on positive social impacts or devastating damage to the environment is already upon us. Substantial changes to the science and technology curriculum are required to allow students to develop skills in the specific areas of Biotechnology, Genomics, Data Science, Artificial Intelligence, Robotics, Sustainability and Nanomaterials. Biotechnology and Sustainability are gaining more interest in all sectors, including education. Sustainable Development is one of the transversal knowledge and skills in the world of Engineering that has the potential to redesign education in the 4IR. In this study, we present the results of the implementation of a subject, Biology and Sustainable Development, available for all the academic programs of engineering within the framework of the new model Tec21, a flexible educational model. Our results show that granting the subject in the classroom either in person or in a synchronous digital system through FIT courses (Flexible, Interactive, and Technology) is of great importance for future studies of engineering students, regardless of the program they are enrolled in. Only the design of this type of materials based on the 4IR can prepare students for the new challenges facing the Engineering of the 21st Century.

Vianney Lara-Prieto

Papers

Vibration characteristics of MR cantilever sandwich beams: experimental study

An Innovative Self-learning Approach to 3D Printing Using Multimedia and Augmented Reality on Mobile Devices☆

iWeek experience: the innovation challenges of digital transformation in industry

First-year Engineering Students Engagement by Hands-on Experience with Star Wars Robotics

Designing the Curriculum for the 4IR: Working the Case of Biology and Sustainable Development in Bioengineering Courses