Proceedings of 2023 the 6th International Conference on Mechanical Engineering and Applied Composite Materials

The heat treatment processes suitable for agricultural machinery wear-resistant parts made of 34MnB5 steel were studied and determined, and the properties were compared with those of imported products. The results indicate that the hardness of 34MnB5 agricultural machinery wear-resistant parts prepared by heat treatment technology in this study is more than 51 HRC, the impact energy at normal temperature is more than 16 J, the tensile strength is more than 1900 MPa, and the elongation after breaking is more than 10%, which has good comprehensive mechanical properties and wear-resistant properties.

This study investigates the effects of thermo mechanical control process (TMCP) on the microstructure and properties of 10B21 cold heading steel. The results show that, in the temperature range of 800–900 °C with subsequent appropriate slow cooling processes, the wire drawing temperature has a relatively small impact on its mechanical properties. The tensile strength can remain stable in the range of 489-507 MPa, the elongation can be above 27%, and the reduction in area can reach 68%. Under different process conditions, the material exhibits good cold deformation capabilities, meeting the requirements for 1/3 cold heading. The wire drawing temperature significantly affects the thickness of the oxide scale on the material. When the wire drawing temperature is lowered, the oxide scale thickness can be reduced from 37–51 μm at 900 °C wire drawing to 13-22 μm, catering to the process requirements for different oxide scale removal methods.

A correlation study and analysis were carried out on the microstructure, mechanical properties, and hardness of 20CrMo alloy steel with different secondary quenching processes. The results indicate that, when subjected to secondary quenching in the temperature range of 775–850 ℃, as the quenching temperature increases, the tensile strength of 20CrMo increases while its ductility decreases. The increment in hardness is higher when quenched at 800–825 ℃ compared to other temperature ranges, primarily due to variations in the post-quenching phase structure and proportions. At a secondary quenching temperature of 775 ℃ and tempering at 150–200 ℃, the material exhibits a good balance between strength and ductility. It achieves a tensile strength of 1050 MPa and an elongation of over 15%, with a reduction in area exceeding 45%. Within the 150–200 ℃ low-temperature tempering temperature range, the influence of tempering temperature on the mechanical properties of 20CrMo alloy steel is limited.

Machining of droplet structure is of great importance and can be applied in a wide range of potential applications in material science, photonics, sensors, pharmaceuticals, and biotechnology. In this work, a low-cost but precise method is proposed for the high-volume production of droplets with monodispersed inner cores that form an ordered structure of the droplet. By simply applying heating or cooling, the surrounding solution can be injected into the host droplet to form its inner cores. The injection is found to attribute to the thermal induced Marangoni effect, where both the injection site and efficiency can be regulated through the introduced temperature gradient. Compared to conventional techniques, the proposed method process droplet structure in a non-contact, bottom-up and in situ manner. As a result, it presents various benefits such as low cost, high productivity, good compatibility and great flexibility.

We study the anti-plane shear waves in a domain consisting of two rigidly connected elastic layers, taking into account the surface effects on both faces. The elastic properties of both layers are different. Accounting for both the surface stresses and the surface inertia within the Gurtin–Murdoch surface elasticity, we derive the dispersion equation corresponding to the exponential decay of waves in the layers from the faces. The effects of surface stresses and inertia, the layer thickness as well as of the ratio of shear moduli of the layers on the dispersion curves are analyzed. The procedure for estimating the surface shear modulus and density is proposed.

In order to improve the anti-shock performance of underwater target, composite materials have been widely used. A numerical model of near-field underwater explosions associated with shaped charges was developed based on the Coupled Eulerian-Lagrangian (CEL) method. The damage modes of composite Q235 steel/SiC ceramic/UHMWPE sandwich plates were compared. According to material properties, a new composite sandwich plate was proposed-Q235 steel/UHMWPE/SiC ceramic/UHMWPE composite sandwich plate. The effect of different material mass ratios on the protective effect of composite sandwich plates was analyzed. The results show that new composite sandwich plate underwater explosion impact resistance, anti-projectile performance greatly improved. The composite sandwich plate with proper mass ratio has superior resistance to shaped charge underwater explosion. Composite sandwich plate with faceboard UHMWPE 48.06 mm, SiC ceramic 14.63 mm and backboard UHMWPE 48.06 mm is the most effective. This pressure hull has the greatest decrease in head velocity of metal jet. The as above results can provide a reference for naval construction of pressure hull for underwater target.

To address the problem of the existing control methods of heavy vehicle magnetorheological suspension system, such as model parameter uncertainty and system itself and external pavement disturbances. A linear active disturbance rejection control method of the 1/4 heavy vehicle magnetorheological suspension system is proposed, and it designs the extended state observer and controller, by using singular perturbation theory, it is proved that the proposed controller can make the closed-loop system asymptotically stable. According to simulation analysis, under the condition that the random pavement input is class E pavement, when the control gain is increased, the relative displacement, control quantity and total disturbance estimation of the vehicle suspension are reduced, and the control gain also has a certain influence on the sprung mass acceleration and the dynamic tyre deformation. The linear active disturbance rejection control magnetorheological suspension is quantitatively compared with passive suspension and PID magnetorheological suspension, the RMS value in sprung mass acceleration decreased by 25.6 and 3.7%, suspension working space decreased by 6.1 and 1.2%, and dynamic tyre deformation decreased by 16.9 and 0.8%. Therefore, the performance of linear active disturbance rejection control magnetorheological suspension is obviously better than that passive suspension and PID magnetorheological suspension, and linear active disturbance rejection control method has fewer adjustment parameters and less dependence on the model, so it can be widely used in practical engineering.

In this paper, we propose and discuss an indirect parameter calculation method for studying the heat dissipation model of a direct air-cooling system with finned tubes. Firstly, in order to obtain process parameters, the mathematical model is established and actual samples are measured, and then process parameters are computed using regression analysis. Subsequently, temperature reduction experiments are simulated using process parameters. Furthermore, the simulated data is compared with the actual measurement data from the temperature reduction experiments, with the results subsequently discussed. Finally, we discovered that the finned tube temperature prediction model can be improved to some extent through the indirect parameter acquisition method.

This study examines the variations in power before and after adjustments to the Vehicle Modification (VM) value to evaluate the impact of power enhancement on vehicle performance and dynamics. To achieve this objective, we replaced the original computer control system with the RC1 from aRacer SpeedTdk and conducted experimental observations using the Dynostar motorcycle chassis dynamometer. This chassis dynamometer features different inertia rollers to accommodate various engine displacements, ensuring the accuracy of experimental results.

The stiffness of a machine tool directly affects the accuracy of the processed parts. The stiffness analysis of a machine tool is an essential task in the design and manufacturing process of a machine tool. The calculation methods for machine tool stiffness are constantly updated. Initially, static analysis was conducted on machine tool modeling based on traditional formulas of theoretical mechanics and the geometric structure of the machine tool. In recent years, finite element methods were used to calculate the static stiffness of the machine tool. A lot of research has found that there is a significant difference between the dynamic and static stiffness of machine tools during operation, calculation and analysis of the dynamic stiffness of machine tools have been carried out by finite element analysis software. This article provides a brief introduction to the stiffness calculation methods of the machine tools.

In engineering, the working process of many devices often includes friction between the workpiece and the object, or between the loose material and the workpieces. However, the frictional resistance is not revealed clearly, either the effect of vibration on friction from the vibration liquefaction perspective. For the vibratory pile system, people mostly focus on examining the pile end resistance in the sinking pile resistance in the past, ignoring or simplifying its peripheral friction. In the actual working situation, the vibration pile is to overcome the frictional resistance on the pile side and the pile resistance by vibration. The frictional resistance on the pile side by the surrounding soil is a non-linear force that cannot be ignored. In this paper, we focus on the nonlinear dynamics analysis of vibratory pile system and study the vibratory frictional characteristics between pile-soil and its nonlinear dynamics under different parameters, such as excitation frequency of exciter, excitation amplitude and soil stiffness of vibratory pile system.

Machine tools are called machine making machines. To maintain specified tolerance, the machine tools need to have great accuracy than the tolerances of the manufactured parts. Therefore, the machine tool stiffness plays an important role in accuracy. The stiffness of a machine tool system has three main groups of parts, the stiffness of the whole machine, the stiffness of components, the stiffness of joints especially the movable joints. A brief review of basic stiffness analysis method of machine tool is studied in this paper.

With the policy drive for the development of clean energy in China, wind turbine (WT) has experienced rapid growth due to its unique advantages. Bearings play a significant role in transmission and supporting, with high failure frequency. Compared with rolling bearings, Sliding bearings have advantages such as high reliability and high tolerance to impurities. Accordingly, sliding bearings are increasingly popular in WT. While wear is the fundamental type of damage leading to failure in sliding bearings. Therefore, studying mixed lubrication is of great significance for the development of the entire wind energy industry. This paper summarizes the research status of mixed lubrication in sliding bearings, and analyzes the main challenges and future development of sliding bearings in wind turbines.

GH4169 alloy was smelted with three return ratio of 70% chip, 70% block, 25% block + 45% chip. Chemical composition and mechanical properties of the smelted alloy were analyzed and compared with the new compound GH4169. The results show that the nitrogen content of the three returned alloys is basically the same but higher than that of the new alloy, and the oxygen content of the three returned alloys reaches the level of the new alloy. The size and quantity types of inclusions smelted by three kinds of return alloy are basically the same, which are slightly higher than those smelted by new alloy. The nitrides in return alloy are mainly TiN, NbN and inclusions, and single-layer composite inclusions Ti(C,N)–NBC and multilayer complex inclusions (Mg, Al) O–Ti (C, N)–(Mo, Nb). The strength of the three return alloys is similar to that of the new alloys at room temperature and 650 ℃. At 650 ℃/725 Mpa, the durability of the alloy is much higher than the technical requirements and close to the new material alloy.

The TIG and MIG welding tests and chloride ion corrosion tests were carried out for Hastelloy C276 in order to analyze the mechanical properties, surface morphology, corrosion rate and corrosion mechanism of the deposited metal. The results show that the TIG welding droplet has a 140° angle with the base material which is not wetted and small pores are easily formed during the welding process. The corrosion resistance and elongation of the deposited metal are low, and the corrosion rate increases to 0.11 g/cm2 * h. With the increase of welding power, the dendrite spacing and dendrite segregation of deposited metal can be significantly increased and the corrosion resistance can be reduced. Solution treatment can significantly improve the corrosion resistance of deposited metal with the corrosion rate decreases from 0.02 to 0.008 g/cm2 * h. Slow cooling results in the precipitation of μ phase which deteriorates the corrosion resistance and mechanical properties of the material.

In this work, the segregation and homogenization organization of as-cast Ni–Co based superalloys with 4, 5 and 6% Nb contents are investigated, respectively. It’s found that the Nb element is the main cause of segregation in Ni–Co alloys, which is mainly attributed to the high melting point and slow solidification rate of Nb, resulting in the alloy being very susceptible to macroscopic segregation, and the content of Nb should be controlled within 5%. By means of high-temperature homogenization, which is heating at 1150 °C for 48 h, the dendritic structure can be completely eliminated and macroscopic segregation can be eliminated, but the high temperature leads to the formation of refractory compounds, such as NbC or TiN, and the amount of refractory compounds increases with the increase of Nb content. In addition, when the Nb content exceeds 5%, it leads to the formation of the Laves phase, which is detrimental to the thermoplasticity of the alloy.

In recent years, the field of materials science has witnessed a paradigm shift, transitioning from the conventional use of homogeneous materials towards the innovative realm of gradient composite materials. This transformation has been significantly catalyzed by the rapid advancements in additive manufacturing technologies, making gradient materials a focal point of contemporary research. This paper presents a comprehensive exploration into the development of a state-of-the-art 3D printer and a specialized dual-component printhead tailored for the precise manufacturing of gradient materials. Accompanying this technological innovation, we introduce a sophisticated design software founded on voxelized digital models and establish a robust viscoelastic transport relaxation mechanical model. Additionally, we propose a model-based control methodology that achieves unparalleled precision in material extrusion control, validated through meticulous experimental and parameter identification processes. To underscore the practical implications of gradient materials, we design a representative mechanical application case, effectively demonstrating their remarkable efficacy in mitigating stress concentration issues. The validity of our approach is rigorously substantiated through a combination of simulation and mechanical experiments. In essence, this paper serves as a pioneering contribution to the domain of continuous gradient materials via 3D printing, effectively addressing the pivotal challenge of transport accuracy and laying a solid foundation for the future development of this cutting-edge field.

In order to obtain the meso-damage model and constitutive model of polymer bonded explosive under impact load, based on the first-level light gas gun, the confined impact damage experiment of PBX-JH14C was designed to obtain the stress history curves at different velocities. Scanning electron microscopy (SEM) was used to observe the microscopic morphology of the recovered samples. The results showed that the internal damage of PBX-JH14C under confined impact was mainly trans-granular fracture. The VUMAT was developed based on viscoelastic statistical crack model, and was inserted into ABAQUS to conduct numerical simulation of SHPB experiment. The validity of the model and parameters was verified by comparing the experimental results, and the confined impact test was further simulated to analyze the damage degree of PBX-JH14C at different speeds. The numerical simulation is in good agreement with the experimental results, indicating that the constitutive model can describe the mechanical properties of the explosive under different loading conditions, and the damage degree of PBX-JH14C increases with the increase of velocity.

The efficiency and quality of a complex aluminium extrusion mould design can be largely improved based on reusing the relevant design knowledge recommended based on design context. This kind of design knowledge is embedded in engineering designers’ brain, supporting design tasks like requirement analysis, embodiment design, simulation result evaluation, which is significant in achieving intelligent design. However, it is a kind of tacit knowledge that is difficult to capture and reuse, in a way of intelligent recommendation. To fill this gap, this paper proposed a method on capturing this kind of tacit design knowledge for efficient reuse. Firstly, a knowledge representation model is built in terms of the requirement, function, behaviour, structure, and design evolution of the extrusion mould design, guiding the capture and representation of design knowledge. Then, the design context for the design knowledge is studied and constructed for the effective reuse of design knowledge. Finally, a recommendation system based on design context is designed and developed for the implementation of design reuse. The evaluation results on this method have shown its feasibility and effectiveness on design knowledge representation and reuse.

The widespread demand for polymer composites in various branches of mechanical engineering has led to an increased need for these materials. However, the issues of recycling of these materials, especially materials based on thermosetting matrices, have not been properly studied due to their long operating cycles. Additionally, traditional methods of recycling cannot be applied to polymer composite materials (PCMs) while preserving the properties of the filler. At the end of its service life, the carbon fiber reinforced plastic still contains filler. The reuse of this filler in the production cycle can significantly reduce manufacturing costs. This study focuses on the recycling process of PCMs based on carbon fiber and epoxy binder using supercritical ethanol as the medium. Solvolysis was conducted in a high-pressure reactor equipped with a 25 ml fluoroplastic liner. The solvolysis, performed at 250 °C. Salts of various metals were used as catalysts. In some experimental series, cleaned carbon fibers were successfully obtained, which were subsequently returned in the production of new polymer composite materials. The investigation into the strength of carbon fiber plastics revealed that materials derived from recovered fibers maintained their properties. Moreover, through processing in a supercritical ethanol environment with the presence of SnCl2, there was a 5% increase in bending strength. This finding highlights the potential for enhancing the mechanical properties of recycled polymer composites, contributing to both sustainability and cost-effectiveness in the production cycle.

In this study, TiO2 reinforced polyimide nanocomposites were successfully fabricated at varying TiO2 nanoparticles concentrations via spark plasma sintering process. The morphology of the samples were characterized by scanning electron microscopy (SEM). The nanomechanical, tribological, and dielectric/electrical properties of the sintered samples was examined using nanoindentation tester, tribometer, and LCR meter equipment, respectively. The SEM results indicate that the TiO2 nanofillers were equally diffused into polyimide matrix without agglomeration, hence the better interfacial bonding between the matrix and the nanofillers. Result shows that the hardness and elastic modulus of TiO2/polyimide composite sample with 6wt% TiO2 addition was improved by 179.3 and 76.4%, respectively, meanwhile, further addition of the nanoparticles above 6wt%, 314% improvement in hardness and 59.5% improvement in modulus was recorded compared to that of the pristine polyimide (PI). The reason for the decrease in modulus beyond 6wt% was the dosage contents of TiO2 particles and poor stress transfer within the nanocomposites with 8wt% TiO2 particles as elastic properties of composites depends on load transfer mechanism. In addition, the tribology and insulation performances of the virgin PI were also improved with the introduction of the TiO2 nanoparticles. Finally, the results indicate the cost-effective measure of fabricating PI nanocomposites and its potential for mechanical loadbearing, anti-wear, and insulation applications.

Corn starch was modified by different methods (acetylation, esterification and amination). The effects of different modification methods on the structure and physicochemical properties of starch were investigated. Four kinds of starches were reacted with copper respectively, and the influence of four kinds of starches on the preparation of copper was investigated under the condition of different addition amounts. Including the morphology and antibacterial effect of copper, it provides a reference for the selection of starch/copper in the future research. In this paper, the structure, morphology and thermodynamic properties of four kinds of starch and modified starch/copper were characterized and analyzed, and the antibacterial properties of starch/copper were tested by enzyme labeling. The results show that: After starch was modified in different ways, its internal crystal structure changed, but the change was small. After modification, the hydrophobicity of starch was improved, and the contact Angle was about 40°. The thermodynamic properties are also improved, and the esterification effect is better. In terms of morphology, the surface of the original starch particles is smooth and most of them are irregular, while the modified starch morphology changes obviously and the particle structure is destroyed. Under the condition of adding the original starch, the copper morphology is mostly irregular, but after adding the modified starch, the copper with hexahedral morphology can be obtained. In addition, the antibacterial effect of starch/copper was not significantly related to the different dosage, and the modification of starch had a certain effect on the antibacterial effect, in contrast, amylamine/copper had the best effect.

The effect of two types of carbon nano fillers with different topology characteristics were studied on the toughness of imidazole/epoxy (IMI/EP) resin system. The influence of nano particles on fracture toughness (KIC), energy (GIIC), thermal mechanical properties (DMA), and curing behaviors were investigated. Both KIC and GIIC were increased after the addition of nano fillers. The improvement of GIIC was different by the nano carbon fillers Topology. The dispersion and enhancement effect improved as nano particle dimensions decreased. The mechanisms of these improvements in toughness were explored using optical microscopy (OM) and scanning electron microscopy (SEM). It was revealed that the improvement of fracture toughness with addition of nano particles was due to debonding and deformation of the nano particles. Subsequently, the crack growth was hindered by the nano particles, and the stress energy at crack tip was released by crack deflections, particles deformation and particles rupture. Finally, the curing behavior of the epoxy resin with different types of nano particles were studied using DSC. The crosslinking reaction rate slowed down with the addition of Carbon nano fibers (CNF), but increased with graphene oxide (GO).

The active vibration control of a composite piezoelectric cantilever beam is investigated in this paper. The intermediate layer of the beam is made of the graphene platelets reinforced porous nanocomposite, and the piezoelectric actuator and sensor adhere to the top and bottom surfaces of the intermediate layer. The symmetric distribution (PD-X and PD–O) and uniform distribution (PD-U) of porosity are taken into account. The graphene platelets used to enhance material properties consider three distribution forms, the symmetric pattern (GPL-X and PD–O) and uniform pattern (GPL-U). Computing the effective Young's modulus, Poisson's ratio and mass density by the Halpin–Tsai model and the rule of mixture for all distributions, respectively. Then, the motion equation of the composite piezoelectric cantilever beam is derived using Lagrange's principle by von Karman's nonlinear shear deformation theory. In order to achieve vibration reduction effect, the active vibration control is applied with a velocity feedback control algorithm. Initially, the computed outcomes are cross-referenced with extant literature to validate the accuracy of the employed solution methodologies. Subsequently, an in-depth analysis is undertaken to elucidate the impacts of diOOerse material parameters and feedback control gains on the active vibration control efficacy of the piezoelectric beam reinforced with Graphene Platelets within a porous nanocomposite framework.

Energy self-powered e-skin is the key to future and sustainable directions, with products for ergonomics, rehabilitation equipment and assistive rehabilitation equipment. The system is based on the groundbreaking discovery of a frictional nano self-powered transparent antibacterial e-skin. The e-skin is an innovative design with a patented construction for detecting pressure values and tensile strain. The conventional textile material is adsorbed on the conductive material to provide an innovative and low cost process. The Body Verification section of the Friction Nano Self-Powered Transparent Antimicrobial E-skin System describes the Friction Nano Self-Powered Transparent Antimicrobial E-skin System, which can be stretched from 0%-100% to allow for greater customization of any part of the body and can be cut and applied based on the volume of the module required. The innovative modularity of this project allows for low cost, low volume production process, small footprint, customizable size, improved experimental efficiency, and increased experimental efficiency in a multi-angle and multi-functional manner. This is a promising technique used in medicine to consolidate and improve clinical rehabilitation of patients.

The physical model of air floating support is established, and calculation formulas of air supply pressure, air film thickness and throttle hole diameter are derived from the formula. The maximum amplitude of the vibration of the glass substrate is measured under the condition of constant air film thickness and constant diameter of the throttle hole, respectively, and the influence law of the main parameters of the air floating system on the maximum amplitude of the micro-vibration of the glass substrate is obtained. On this basis, the main parameters of an engineering prototype air floating system were designed as follows: air film thickness 50 μm, air supply pressure 220 Pa, throttle hole diameter 0.25 mm, and the prototype air floating support system was developed. The test results of the developed prototype of the air floating show that the maximum amplitude of the glass substrate is 0.31 μm, which is less than the design requirement of 1 μm. The experimental results show that the air floating support prototype meets the design index requirements.

In a variety of mechanical equipment, bearings play a vital role. When the mechanical equipment is in high-speed operation, the importance of the bearing is more prominent, because it is not only used to support and locate the rotary axis, but also directly affects the bearing capacity of the entire system and the working life of the important mechanical parts. To fulfil the prerequisites of high-speed mechanical equipment for precision and load-bearing capacity, tapered roller bearings came into being. This type of bearing has many advantages: tapered roller bearings roller and inner and outer ring raceways are tapered, can withstand radial and axial loads, so the transmission accuracy is higher; tapered roller bearings structure is more reasonable, can withstand larger radial and axial loads, bearing capacity; tapered roller bearings rolling body and the raceway contact area is large, the coefficient of friction is small, so the friction in high-speed operation heat is small, smooth operation; tapered roller bearings and raceway contact area is large, friction coefficient is small, so in high speed running small, smooth operation. Tapered roller bearings demonstrate outstanding performance and enjoy extensive utilization in high-speed railroad, aerospace, heavy machinery and other fields. In this paper, the tapered roller bearings in a 2.8 MW wind power gearbox are taken as the research object, and the bearing thermodynamic model is constructed in Matlab Simulink. The kinetic equations of the outer ring and inner ring of the bearing are solved.

A two-step pre-aging treatment of 6A16 aluminum was designed in this paper. The mechanical properties were tested. The microstructure was characterized using DSC and TEM. The precipitation kinetic of strengthening phase was calculated. The results show that after (550 ℃, 5 min solid solution) + (100 ℃, 5 min + 180 ℃, 5 min) (multi-step pre-aging) heat treatment, the yield strength of the 6A16 aluminum alloy is 150 MPa, elongation of 24.4%, and the bake hardenability value is 114 MPa after paint-bake treatment. According to the calculation, the precipitation activation energy of β″ phase for the alloy is lower than that of T4 processed, which is 62.24 and 97.72 kJ/mol respectively. While the secondary aging temperature is 180 ℃ and 200 ℃, which is beneficial to the precipitation of precipitates in low temperature paint process. The multi-step pre-aging treatment could enhance the nucleation rate of GP zones when the secondary aging temperature is higher than 180℃, and promote the precipitation of effective β″ strengthening phase during paint-bake treatment, which the rapid aging response will be realized during the paint baking.

This paper studies the vibration problem of the guideway girder of a high-speed maglev train during a double line intersection. Established a dynamic model of the high-speed maglev train and a finite element model of the double guideway girder pier. Calculated the dynamic response of the guideway girder under different speeds, support stiffness, and intersection conditions. The results show that when the operating speed exceeds 400 km/h, the dynamic response of the guideway girder significantly increases; The mid span deflection and vertical acceleration of guideway girder under intersection conditions are greater than those under unidirectional operation, but the deflection is more sensitive to intersection conditions; The deflection of guideway girder decreases with the increase of support stiffness, and the design of guideway girder should strive to increase the support stiffness as much as possible.

In order to investigate the propagation and isolation mechanisms of elastic waves, we propose a programmable curved beam periodic structure (PCBPS). The PCBPS is assembled by a unit cell containing bistable curved beams, which is equivalent to a spring oscillator system, and is used to analyze the principle of bandgap formation. We employ the finite element method (FEM) and theoretical analysis to validate the proposed equivalent model. By equating the spring oscillator system, we compute closed-form solutions to demonstrate the accuracy and predictability of the dispersion relation. Our results show that the spring-oscillator model can accurately predict the structural bandgap of PCBPS while obtaining the effect of the geometrical parameters of the unit cell on the structural bandgap. The ideas presented and the results obtained have significant potential for designing functional structures and facilitating the practical application of periodic structures for wave insulation and propagation control in different frequency ranges.

Targeted to a fixed multi-pad journal bearing in the wind turbine (WT) main shaft, this paper establishes a numerical model using the dimensionless steady-state Reynolds equation on account of journal misalignment, in which the Reynolds equation is discretized utilizing the finite difference method and solved using the ultra-relaxation iterative method. Considering that the WT is usually subjected to a large vertical load during operation, this will lead to a large misalignment angle, which has a non-negligible impact on the performance of the journal bearing. Consequently, an analysis was conducted on the variations in oil film pressure distribution on each bearing pad and the associated changes in bearing capacity under diverse misalignment angles. Simultaneously, the influence of different pad arrangement modes is also taken into account, and the load-bearing performance of sliding bearings under different bearing arrangement modes is analyzed. The results show that only specific pads generate fluid dynamic pressure. Furthermore, the performance of the bearing is significantly affected by both journal misalignment and pad arrangement, even when eccentricity remains constant.

In this present, the PHS2000 steels coated with Al–Si coating were carried out by laser de-coating and then laser welded with filler wire. Compared to direct laser welding, better welds were obtained after hot stamping. In the coated joint, the microstructure in the fusion zone consisted of ferrite and lath martensite, and Al segregation occurred near the fusion line. The hardness of lath martensite and ferrite was 547.6 and 275.0 HV0.5, respectively. The tensile specimen fractured along the fusion line, and the ultimate tensile strength and total elongation were 1561.6 MPa and 1.33%, respectively. After removing the Al–Si coating and using filler wire, the microstructure in the fusion zone was all lath martensite, and the Al segregation was eliminated. The hardness of lath martensite increased to 577.2 HV0.5. Meanwhile, the Al content decreased from 1.86% in ferrite to less than 0.06% in lath martensite. The ultimate tensile strength and total elongation increased to 1832.7 MPa and 6.35%, respectively. The failure of the joint was controlled by dimple-type fracture.

X-ray diffraction and Raman studies of human femur in knee compartment under osteoarthritis conditions are performed. The measurements have demonstrated the systematic site-dependent changes in crystal cell parameters and molecular dynamics in calcium hydroxyapatite in subchondral bone. To investigate the origin of the changes and to link them with the mechanical loads in the skeleton, relationships between the site-dependent changes in crystal cell volume and Raman shifts of the symmetric P–O stretching of PO43− ions are examined. Small but distinct displacements of the v1PO43− band in the Raman spectra of subchondral bone on the proximal side are detected and assigned with the expansion of crystal cell and the peculiarities of biomechanics in knee joint. Combination of X-ray diffraction and Raman probing of mechanical loads in subchondral bone is discussed.

In the context of industrialization 4.0, the manufacturing industries of various countries are developing in the direction of automation, integration and flexibility, and the apply of intelligent industrial robots to gradually replace manual production has become inevitable. As the earliest robot, industrial robot has become an important part of intelligent manufacturing equipment. In this paper, firstly, the background and significance of the emergence of industrial robots are elaborated. Secondly, its current research status is analyzed, and then the classification of commonly used industrial robots is explained, and then the research status of the key technologies of industrial robots is summarized. Finally, the future development prospect of industrial robots is forecasted.

In order to enhance the external operability and stability of spherical robots, a spherical shell unfolding mechanism is used to increase the contact area between the spherical robot and the ground, thereby enhancing stability. The introduction of unfolding mechanisms has improved the operability of spherical robots in external environments. A compact spherical robot with two forms of unfolding and closing was designed by introducing a gear rack unfolding mechanism. Establish a kinematic model and conduct kinematic analysis on the dual shaped spherical robot in both open and closed states, laying a foundation for later research.

A general methodology for dynamic obstacle avoidance and optimal path planning of delivery robot is presented in this paper. The three-dimensional model of general environment and optimal distribution path planning of robot path planning in buildings and actual working environment are established by using grid method and path weighting method. The optimal dynamic intelligent distribution path with the minimum time or energy consumption target and the obstacle avoidance of sudden obstacles has been obtained by introducing the ant colony algorithm and artificial potential field method. The model has been applied in the simulation of material distribution in three-story building. The results indicate that the present methodology can not only be used to obtain the optimal distribution routing of material handling robot, but also to avoid sudden obstacles. Therefore, it is a practical reliable and effective modern method which lays a solid foundation for the popularization of logistics distribution robots.

An innovative method of general principle scheme for parasitic glass curtain wall cleaning robot is presented in this paper. According to the actual needs, the functional tree and functional meta-solution database of the glass curtain wall cleaning robot are established. The solution algorithm of the multi-level principle motion scheme is constructed based on the fractal theory, and the intelligent solutions of various principle schemes of the parasitic glass curtain wall cleaning robot under various constraints are realized. The comprehensive evaluation and scheme ranking are completed by entropy weight TOPSIS method. The analysis of design examples shows that this method can not only provide a reliable basis for designers to select the optimal scheme, but also realize the original intelligent design of this kind of equipment and improve the design efficiency.

Stroke-based “FAST” strokes are one of the main ways to cause ischemic disability due to long-term numbness in the lower extremities. Researchers have studied and clinically tested and evaluated traditional lower extremity exoskeletons in a field test manner yielding a rehabilitation efficiency of only 27%. The research is based on an overview and testing study of the human–computer interaction-based lower limb exoskeleton system, human–computer interaction-based lower limb exoskeleton human–computer interaction performance and system data processing, and assessment and gait analysis of human–computer interaction-based lower limb exoskeleton biomechanics. It is also compared with state-of-the-art instrumentation and robot-assisted technologies. The researchers first describe the results achieved on human–computer-interactive lower extremity exoskeletons versus the shortcomings of current evaluations and based on the identified clinical needs and opportunities offered by robotic devices, we propose future directions for rehabilitation robotics research. The review and recommendations provided in this paper are intended to guide the design, validation, and translation to the clinic of the next generation of robotic-assisted functional assessment.

The wall climbing robot for storage tank cleaning uses polyurethane integrated wheels. The structural parameters of the polyurethane wheel affect the compression deformation of the wheel. If the compression deformation is too small, it will reduce the frictional force between the wheel and the steel plate, causing a risk of slipping. The article focuses on the research of the polyurethane wheel of the wall climbing robot for storage tank cleaning. Based on the three-parameter Mooney-Rivlin model, the parameters C10, C01, and C11 of the polyurethane material are determined by the compression test of the polyurethane. Based on the optimization goal, which is to maximize the compression deformation of the polyurethane wheel, optimize the parameters including thickness, radian and fillet of the polyurethane layer by Response Surface Methodology (RSM). Ultimately obtain the optimized size of the polyurethane layer that meets the requirements of actual working conditions.