Editorial:Mechanics of intelligent materials and structures

Recently, intelligent or smart materials and structures have been received more and more attention due to their distinguished multi-field coupling properties and wide applications in aerospace, automobiles, civil structures, medical devices, information storage, energy harvesting and so on. It is of academic challenge to fully understand the complex multi-field coupling behaviors of various smart materials and structures, and of engineering sig- nificance to enhance the performance and reliability of these materials and structures in industrial applications. The papers in the special topic of Mechanics of Intelligent Materials and Structures focus on the understanding of the electromechanical, magneto-elastic, and magneto-rheological coupling behav- iors and properties of smart materials and structures for applications in vibration control, resonators, and various functional devices.

Research progress of cholesteric liquid crystals with broadband reflection characteristics in application of intelligent optical modulation materials

Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors＇ many years＇ research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.

Materials Science-Technology and Intelligent Engineering

This paper analyses the peculiar acting mechanism of artificial neural network (ANN) tech, and explores the great immediate significence for the intelligent sci-tech (IST) to research and develop the nano-tech.

Biodegradable materials for bone defect repair

Compared with non-degradable materials,biodegradable biomaterials play an increasingly important role in the repairing of severe bone defects,and have attracted extensive attention from researchers.In the treatment of bone defects,scaffolds made of biodegradable materials can provide a crawling bridge for new bone tissue in the gap and a platform for cells and growth factors to play a physiological role,which will eventually be degraded and absorbed in the body and be replaced by the new bone tissue.Traditional biodegradable materials include polymers,ceramics and metals,which have been used in bone defect repairing for many years.Although these materials have more or fewer shortcomings,they are still the cornerstone of our development of a new generation of degradable materials.With the rapid development of modern science and technology,in the 21 st century,more and more kinds of new biodegradable materials emerge in endlessly,such as new intelligent micro-nano materials and cell-based products.At the same time,there are many new fabrication technologies of improving biodegradable materials,such as modular fabrication,3 D and 4 D printing,interface reinforcement and nanotechnology.This review will introduce various kinds of biodegradable materials commonly used in bone defect repairing,especially the newly emerging materials and their fabrication technology in recent years,and look forward to the future research direction,hoping to provide researchers in the field with some inspiration and reference.

Research status and development directions of intelligent drilling fluid technologies

By reviewing the current status of drilling fluid technologies with primary intelligence features at home and abroad,the development background and intelligent response mechanisms of drilling fluid technologies such as variable density,salt response,reversible emulsification,constant rheology,shape memory loss prevention and plugging,intelligent reservoir protection and in-situ rheology control are elaborated,current issues and future challenges are analyzed,and it is pointed out that intelligent material science,nanoscience and artificial intelligence theory are important methods for future research of intelligent drilling fluid technology of horizontal wells with more advanced intelligent features of"self-identification,self-tuning and self-adaptation".Based on the aforementioned outline and integrated with the demands from the drilling fluid technology and intelligent drilling fluid theory,three development suggestions are put forward:(1)research and develop intelligent drilling fluids responding to variable formation pressure,variable formation lithology and fluid,variable reservoir characteristics,high temperature formation and complex ground environmental protection needs;(2)establish an expert system for intelligent drilling fluid design and management;and(3)establish a real-time intelligent check and maintenance processing network.

Characteristics of Smart Concrete with Fiber Optical Bragg Grating Sensor

Based on the advantages of the fiber Bragg grating sensing technology,this paper presents a principle of a novel smart concrete with fiber optical Bragg grating sensor,analyses the theory and characteristics,illustrates the key technology and method to make the fiber Bragg grating sensor for the smart concrete,and proves the feasibility with experiments.The results indicate that the smart concrete with fiber Bragg grating sensors is feasible in the structure monitoring and damage diagnosing in the long run.

Sustainable Identities in the Technological Esprit of Architecture

Innovation and energy efficiency are the essential paradigms of the new technology and design culture, in the sustainable economic and social development, highlighting the performance of new technologies, systems and intelligent materials, such as sustainable identities in architectural envelopes. Then, contextualized sustainable architectural objectives favor material and energy flows, pointing to the constructive flexibility, identity and compatibility of technological innovation, which contrasts with climate change. So sustainable use of natural resources, renewable energy, in line with the principles of the 2030 Agenda for SDGs （Sustainable Development Goals）. The well-being of the community with the valorisation of places and the environment, indicates the technological excellence of architecture, synchronous with territorial metamorphoses. Thus, vision glass principles in the environmentally responsive wall, and engineered wall, in external awareness, cellular flooring for eco-efficiency. The methodologies indicate the applications of new design models for new constructions and regeneration, with dynamic, efficient and integrated envelopes integrated with renewable energy storage technologies, neomaterials and high performance insulating. Then HPP （high performance polymers） nanotechnologies are based on efficient pigments, intelligent bioPCM （PCM for phase change material） nano technologies, thermoregulators with high thermal inertia. The goal is towards an escalation of sustainable architectures that contrasts with climate change and pollution ofanthropic origin, for smart and sustainable growth.

Development of High-Speed On-Of Valves and Their Applications

With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.

Microbial self-healing of cracks in cement-based materials and its influencing factors

Cement-based materials are brittle and crack easily under natural conditions.Cracks can reduce service life because the transport of harmful substances can cause corrosion damage to the structures.This review discusses the feasibility of using microbial self-healing agents for crack healing.Tubular and spherical carriers can be used to load microbial self-healing agents and protect microbes,which prolongs the self-healing time.The area self-healing ratio,permeability,mechanical strength,precipitation depth method,numerical modeling,and ultrasonic method can be employed to identify the self-healing effect of cracks.Moreover,the self-healing mechanism is systematically analyzed.The results showed that microbial self-healing agents can repair cracks in cement-based materials in underground projects and dam gates.The difficulties and future development of self-healing cracks were analyzed.A microbial selfhealing agent was embedded in the cement-based material,which automatically repaired the developing cracks.With the development of intelligent building materials,self-healing cracks have become the focus of attention.

Review of some recent progress on materials science researches in China

New materials have become one of the most important and fastest-growing industries all over the world.Important progress in materials science and technology has produced profound influences on the national economy,daily life and national defense of our country.In this paper,we review the state of the art of materials science and technology in China,with emphasis on recent research focuses and advanced technology.

π-Conjugated cyanostilbene-based optoelectric functional materials

π-Conjugated organic luminescent materials are essential components for modern optical and photoelectric research.This review mainly probes into the recent work in the progress of smart π-conjugated organic systems in the form of cyanostilbene and its derivatives,which can regulate its excellent features in response to a variety of physical or chemical stimuli（e.g.viscosity,light,magnetism,electric field,polarity,pH and solvent environment）.As a result of its extensive applicability and adaptability,cyanostilbene and its derivatives have been planted into different structural architectures such as polymers,functional nanoparticles,solid membranes,supramolecular systems and so on.This review will first give a general description of the preparation and characterization of cyanostilbenebased optoelectric luminophores and then focus on their peculiar functional properties in the need for advanced material applications,such as AIEE（aggregation-induced enhanced emission effect）,solidstate emission,photovoltaics,photolithography and photochromism to be further processed afterwards.The purpose of this review is to give a platform of practical organic materials,mostly cyanostilbene and its derivatives,based on stable aromatic derivatives,to contribute to the booming of modern π-conjugated photoelectric materials that integrate with contemporary physics,material chemistry,bioengineering,medical science and aerospace altogether.

ANALYTICAL SOLUTIONS FOR A ONE-DIMENSIONAL CHEMO-MECHANICAL COUPLING PROBLEM

Chemo-mechanical coupling exists in a lot of intelligent materials including hy- drogels, biological tissues and other soft materials. These materials are able to respond to ex- ternal stimulus, such as temperature, chemical concentration, and pH value. In this paper, a one-dimensional theoretical model for chemo-mechanical coupling is proposed for analyzing the uniaxial stress/strain state of coupling materials. Based on the chemo-mechanical coupled gov- erning equation, the displacement function and concentration function are derived and the stress and chemical potential are obtained. It is shown that the present chemo-mechanical theory can characterize the chemo-mechanical coupling behavior of intelligent materials.

Surface roughening of Nafion membranes using different route planning for IPMCs

In this paper,three different roughening route planning methods(free coarsening,vertical coarsening,circling coarsening)were designed to pre-treat the basement membrane.The platinum IPMC was prepared by electroless plating to observe their surface morphology and test their performances such as output displacement and blocking force.The results show that the platinum electrode of the vertical coarsening route planning of IPMC is distributed in the shape of fish scales and is the most compact and regular on the surface electrode.The thickness of the platinum electrode layer is about 13μm,the maximum output displacement is 54.89 mm,the blocking force of 15.46 mN,and the maximum strain energy density of the IPMC of 2.44 KJ/m^(3).Vertical coarsening route planning can significantly improve the electrodynamic properties of IPMC,and it is recommended that the surface roughening of IPMC be utilized in the research and application of IPMC.It lays a certain experimental foundation for the performance improvement and innovation research and development of IPMC in the subsequent stage.

Design,modeling,and control of morphing aircraft:A review

A morphing aircraft can adapt its configuration to suit different types of tasks,which is also an important requirement of Unmanned Aerial Vehicles(UAV).The successful development of an unmanned morphing aircraft involves three steps that determine its ability and intelligent:configuration design,dynamic modeling and flight control.This study conducts a comprehensive survey of morphing aircraft.First,the methods to design the configuration of a morphing aircraft are presented and analyzed.Then,the nonlinear dynamic characteristics and aerodynamic interference caused by a morphing wing are described.Subsequently,the dynamic modeling and flight control methods for solving the flight control problems are summarized with respect to these features.Finally,the general as well as special challenges ahead of the development of intelligent morphing aircraft are discussed.The findings can provide a theoretical and technical reference for designing future morphing aircraft or morphing-wing UAVs.