摘要：The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion *** machining(ECM)is an efficient and low-cost technology for manufacturing theβ-CEZ *** ECM,the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the *** this study,the electrochemical dissolution behaviors of theβ-CEZ and Ti-6Al-4V(TC4)alloys in NaNO3solution are *** open circuit potential(OCP),Tafel polarization,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),and current efficiency curves of theβ-CEZ and TC4 alloys are *** results show that,compared to the TC4 alloy,the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for theβ-CEZ ***,the dissolved surface morphology of the two titanium-based alloys under different current densities are *** low current densities,theβ-CEZ alloy surface comprises dissolution pits and dissolved products,while the TC4 alloy surface comprises a porous honeycomb *** high current densities,the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than theβ-CEZ alloy ***,the electrochemical dissolution models ofβ-CEZ and TC4 alloys are proposed.

摘要：Bacterial infection is a major problem following bone implant ***,poly-l-lactic acid/carbon nanotube/hydroxyapatite(PLLA/CNT/HAP)bone scaffolds possess enhanced mechanical properties and show good ***,wesynthesizedsilver(Ag)-dopedCNT/HAP(CNT/Ag-HAP)nanohybrids via the partial replacing of calcium ions(Ca2+)in the HAP lattice with silver ions(Ag+)using an ion doping technique under hydrothermal ***fically,the doping process was induced using the special lattice structure of HAP and the abundant surface oxygenic functional groups of CNT,and involved the partial replacement of Ca2+in the HAP lattice by doped Ag+as well as the in situ synthesis of Ag-HAP nanoparticles on CNT in a hydrothermal *** result-ing CNT/Ag-HAP nanohybrids were then introduced into a PLLA matrix via laser-based powder bed fusion(PBF-LB)to fabricate PLLA/CNT/Ag-HAP scaffolds that showed sustained antibacterial *** then found that Ag+,which pos-sesses broad-spectrum antibacterial activity,endowed PLLA/CNT/Ag-HAP scaffolds with this activity,with an antibacterial effectiveness of 92.65%.This antibacterial effect is due to the powerful effect of Ag+against bacterial structure and genetic material,as well as the physical destruction of bacterial structures due to the sharp edge structure of *** addition,the scaffold possessed enhanced mechanical properties,showing tensile and compressive strengths of 8.49 MPa and 19.72 MPa,***,the scaffold also exhibited good bioactivity and cytocompatibility,including the ability to form apatite layers and to promote the adhesion and proliferation of human osteoblast-like cells(MG63 cells).

摘要：Blades are one of the important components on aircraft *** they break due to vibration failure,the normal operation of the entire engine will be ***,it is necessary to measure their natural frequency before installing them on the engine to avoid *** present,most blade vibration testing systems require manual operation by operators,which has high requirements for operators and the testing process is also very ***,the testing efficiency is low and cannot meet the needs of efficient *** solve the current problems of low testing efficiency and high operational requirements,a high-precision and high-efficiency automatic test system is *** testing accuracy of this system can reach ±1%,and the testing efficiency is improved by 37% compared to manual ***,the influence of compression force and vibration exciter position on natural frequency test is analyzed by amplitude-frequency curve,so as to calibrate servo cylinder and fourdimensional motion ***,the sine wave signal is used as the excitation to sweep the blade linearly,and the natural frequency is determined by the amplitude peak in the frequency ***,the accuracy experiment and efficiency experiment are carried out on the developed test system,whose results verify its high efficiency and high precision.

摘要：为了解决三维空间中的非线性动力学问题,本文提出了一种新的等几何实体单元,并通过张量分析中的坐标变换得到其非线性应变场.为了使所提出的单元能够无缝地应用于计算机辅助设计(CAD)和计算机辅助工程(CAE)系统中,采用三变量T样条作为等几何实体单元的基函数.借助Bézier投影法,提出了基于T样条的等几何实体单元的局部网格更新算法.在重要区域对网格进行局部细化以获得准确的结果,在重要区域以外对冗余单元进行粗化以提高计算效率.因此,非线性动力学分析中的计算效率和计算精度得到了平衡.三个静力学数值算例验证单元弹性模型的正确性.通过柔性摆仿真算例研究该单元的动力学特性.通过实验测试该单元解决非线性动力学实际问题的能力.应用局部网格更新算法进行柔性摆与障碍物碰撞接触的仿真.通过对计算结果和计算耗时的分析,研究基于局部变网格T样条的实体单元在非线性动力学问题中的有效性.

摘要：In this work,we propose incorporating the finite cell method(FCM)into the absolute nodal coordinate formulation(ANCF)to improve the efficiency and robustness of ANCF elements in simulating structures with complex local *** addition,an adaptive subdomain integration method based on a triangulation technique is devised to avoid excessive subdivisions,largely reducing the computational *** examples demonstrate the effectiveness of the proposed method in large deformation,large rotation and dynamics simulation.

摘要：Corrosion,more specifically,pitting corrosion happening extremely in marine environments,leads to lifespan of materials drastically decreasing in service,which causes enormous economic loss and even environmental disaster and *** the past decade,increasing efforts have been made to study the corrosion behaviors of materials in chloride-containing aqueous ***,this work provides an overview of recent progress in understanding the degradation mechanism and improving the corrosion resistance and corrosion-wear resistance of materials from bulk metal to surface treatment involving organic coating,metal and its alloy or compound *** particular emphasis is given to the periodic layered structures(PLSs),whose anti-corrosion properties outperformed others to some extent,wherever in terms of bulk metal or surface treatment,regardless of aggressive environment(corrosion or corrosion-wear conditions).Numerical simulation based on kinds of models at different scales is introduced to deeply understand the process of corrosion and/or corrosion-wear in chloride-containing aqueous *** experimental result with numerical simulation,the micro-galvanic corrosion dominated degradation mechanism of PLSs is critically *** of setups to realize corrosion-wear in laboratory are also *** last,future research and development are prospected,offering to develop a basic application of PLSs designed by corrosion protection methodology in the near future.

摘要：Walking is the most basic and essential part of the activities of daily living. To enable the elderly and non-ambulatory gait-impaired patients, the repetitive practice of this task, a novel gait training robot(GTR) was designed followed the end-effector principle, and an active partial body weight support(PBWS) system was introduced to facilitate successful gait training. For successful establishment of a walking gait on the GTR with PBWS, the motion laws of the GTR were planned to enable the phase distribution relationships of the cycle step, and the center of gravity(COG) trajectory of the human body during gait training on the GTR was measured. A coordinated control strategy was proposed based on the impedance control principle. A robotic prototype was developed as a platform for evaluating the design concepts and control strategies. Preliminary gait training with a healthy subject was implemented by the robotic-assisted gait training system and the experimental results are encouraging.

摘要：One of the reasons behind failed engineering surfaces and mechanical components is particle erosion wear;thus,to mitigate its happening,biomimetic engineering is the current state-of-the-art being ***,this paper reviews the literature and the development trends on erosive wear resistance that employ biomimetic methods as well as analyze the bio-inspired surface,the bio-inspired structure,the bio-based materials,the associated challenges,and the future ***,the feasibility of the multi-biological and perspective on the coupling biomimetic method for anti-erosion wear are *** is concluded that the design of anti-erosion materials or structures by the bio-inspired methods is of great significance in the development of engineering applications.

摘要：In order to solve the serious problems of seeds are covered by residual film and overhead by straw during no-till seeding,a seed furrow cleaning device for no-till maize seeding was developed,which adopted a collaborative cleaning method of rotating spring teeth and curved sliding *** movement process and motion trajectory of throwing residual film and straw were *** maximum distance of throwing to one side in horizontal and maximum height in vertical were *** motion trajectory of adjacent spring teeth was analyzed by Matlab,the motion trajectories of adjacent spring teeth at different speeds of 120 r/min,150 r/min and 180 r/min were achieved,the theoretical analysis results showed that the area of omitted area decreased with the increase of rotation *** on theoretical and simulation analysis of critical parameters,the forward speed of machine,rotation speed of spring teeth,and dip angle between spring teeth and rotary disc were selected as the influencing *** cleaning rate(SCR)and residual film cleaning rate(RFCR)were selected as the response values for three factors and three levels of orthogonal experiment *** optimal combination of the selected parameters was obtained,and the field test verification was also *** results showed that the rotation speed of spring teeth,forward speed and dip angle of spring teeth significantly affect SCR and RFCR were in decreasing *** field test results indicated that when forward speed was 6 km/h,rotation speed of spring teeth was 180 r/min and dip angle of spring teeth was 40°,SCR and RFCR were 88.27%and 84.31%,*** study provides a reference for the development of no-till seeder in Xinjiang and the northwestern regions of China.

摘要：Heavy-load transfer robots are widely used in automobile production and machinery manufacturing to improve production *** order to meet the needs of large billet transfer,a 4-DOF transfer robot is designed in this paper,which consists of parallel four-bar *** Jacobian matrix referring to the mapping matrix from the joint velocity to the operating space velocity of the transfer robot can be solved by the differential-vector *** mean value of the Jacobian matrix condition number in the workspace is used as the global performance index of the robot velocity and the optimization *** constraint condition is established based on the actual working *** the linkage length optimization is carried out to decrease the length of the linkage and to increase the global performance index of *** total length of robot rods is reduced by 6.12%.The global performance index of velocity is improved by 45.15%.Taking the optimized rod length as the mechanism parameter,the distribution of the motion space of the transfer robot is ***,the results show that the proposed method for establishing the Jacobian matrix of the lower-mobility robot and for the optimization of the rods based on the velocity global performance index is accurate and *** workspace distribution of the robot meets the design requirements.