The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Climate change 2014 - Mitigation of climate change

A review of shape memory alloy research, applications and opportunities

Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201707035

Soft Robotic Grippers.

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.

/pdf/a-state-of-the-art-review-on-magnetorheological-elastomer-4upfpmpbpd.pdf

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

Review of state of the art in smart rotor control research for wind turbines

Magnetorheological elastomers (MREs) belong to the group of so-called smart materials, which respond to an external stimulus by changing their viscoelastic properties. Magnetorheological (MR) material can be fluid, gel or solid material like elastomer. The mechanical properties of the MR materials change when subjected to an external magnetic field. The MREs are interesting candidates for the active stiffness and vibration control of structural systems. The aim of this study was to increase the knowledge on the mechanical and viscoelastic properties of isotropic and aligned MREs. The focus was to clarify the changes in the elastic and vibration damping properties of both studied types of MREs when subjected to magnetic field. Another aim was to study the influence of the alignment of the magnetic particles on the composite properties with and without applied magnetic field. Isotropic and aligned MREs were prepared from silicone elastomer matrix with varying carbonyl iron content. The MREs were tested in bending and compression modes with sinusoidal dynamic loading. The 3-point bending experiments were carried out using a dynamic mechanical analyzer (DMA) in resonance for both isotropic and aligned MREs where the filler content varied from 0 to 30 vol.%. For characterizing the materials in compression with applied magnetic field, a special coil device was designed. Isotropic and aligned MREs with 30 vol.% of Fe were also characterized in dynamic compression with varying frequencies and strain amplitudes. The spring constant, elastic/shear modulus and damping ratio/loss factor values were calculated on the basis of the measured data with and without applied magnetic field.

The elastic and damping properties of magnetorheological elastomers

Magnetorheological elastomers (MRE) are interesting candidates for active vibration control of structural systems. In this study, spring elements consisting of magnetorheological elastomer were prepared and tested in dynamic compression to study the changes in their stiffness and vibration damping characteristics under the influence of a magnetic field. Aligned and isotropic magnetorheological elastomer composites were prepared using room temperature vulcanizing silicone elastomer as the matrix material and carbonyl iron as the magnetizable filler. Aligned MREs were prepared by curing the material under an external magnetic field. Aligned MREs were tested and the results were compared with isotropic composites with no preferred orientation. The mechanical properties of the MREs were tested in cyclic compression passively and with increasing magnetic flux density. The influence of the testing frequency and strain amplitude on the dynamic stiffness and damping properties was studied. It was noted that when measured in a magnetic field both the dynamic spring constants and the loss factor values of aligned MREs were increased compared to the zero-field values. The dynamic stiffness of aligned MREs increased with increasing testing frequency and it was tunable with magnetic flux density in the studied frequency range. The loss factor of aligned MREs was also tunable with the magnetic flux density but the absolute values also depend on the testing frequency. The dynamic stiffness of the aligned MREs measured in compression decreased with increasing strain amplitude, but the damping properties were not affected similarly. On the basis of these results, MREs are applicable as tunable spring elements for active vibration control.

http://iopscience.iop.org/article/10.1088/0964-1726/16/2/032/pdf

Dynamic compression testing of a tunable spring element consisting of a magnetorheological elastomer

/pdf/power-system-flexibility-for-the-energy-transition-part-1-6rhm4dw6am.pdf

Power system flexibility for the energy transition: Part 1, Overview for policy makers

Purpose




The purpose of this paper is to report on the developments in manufacturing soft magnetic materials using laser powder bed fusion (L-PBF).




Design/methodology/approach




Ternary soft magnetic Fe-49Co-2V powder was produced by gas atomization and used in an L-PBF machine to produce samples for material characterization. The L-PBF process parameters were optimized for the material, using a design of experiments approach. The printed samples were exposed to different heat treatment cycles to improve the magnetic properties. The magnetic properties were measured with quasi-static direct current and alternating current measurements at different frequencies and magnetic flux densities. The mechanical properties were characterized with tensile tests. Electrical resistivity of the material was measured.




Findings




The optimized L-PBF process parameters resulted in very low porosity. The magnetic properties improved greatly after the heat treatments because of changes in microstructure. Based on the quasi-static DC measurement results, one of the heat treatment cycles led to magnetic saturation, permeability and coercivity values comparable to a commercial Fe-Co-V alloy. The other heat treatments resulted in abnormal grain growth and poor magnetic performance. The AC measurement results showed that the magnetic losses were relatively high in the samples owing to formation of eddy currents.




Research limitations/implications




The influence of L-PBF process parameters on the microstructure was not investigated; hence, understanding the relationship between process parameters, heat treatments and magnetic properties would require more research.




Originality/value




The relationship between microstructure, chemical composition, heat treatments, resistivity and magnetic/mechanical properties of L-PBF processed Fe-Co-V alloy has not been reported previously.

Tomi Lindroos

Papers

The elastic and damping properties of magnetorheological elastomers

Dynamic compression testing of a tunable spring element consisting of a magnetorheological elastomer

Power system flexibility for the energy transition: Part 1, Overview for policy makers

Properties of soft magnetic Fe-Co-V alloy produced by laser powder bed fusion

Impact of power-to-gas on the cost and design of the future low-carbon urban energy system