Meter-Scale Thin-Walled Structure with Lattice Infill for Fuel Tank Supporting Component of Satellite:Multiscale Design and Experimental Verification

Lightweight thin-walled structures with lattice infill are widely desired in satellite for their high stiffness-to-weight ratio and superior buckling strength resulting fromthe sandwich effect.Such structures can be fabricated bymetallic additive manufacturing technique,such as selective laser melting(SLM).However,the maximum dimensions of actual structures are usually in a sub-meter scale,which results in restrictions on their appliance in aerospace and other fields.In this work,a meter-scale thin-walled structure with lattice infill is designed for the fuel tank supporting component of the satellite by integrating a self-supporting lattice into the thickness optimization of the thin-wall.The designed structure is fabricated by SLM of AlSi10Mg and cold metal transfer welding technique.Quasi-static mechanical tests and vibration tests are both conducted to verify the mechanical strength of the designed large-scale lattice thin-walled structure.The experimental results indicate that themeter-scale thin-walled structure with lattice infill could meet the dimension and lightweight requirements of most spacecrafts.

VIBRATION IN HIGH-SPEED MILLING OF THIN-WALLED COMPONENTS

To investigate the vibration principle in machining thin-walled components, a dynamic model for end milling of flexible structures is built based on considering the variations in the dynamic chip thickness and the differences between up-milling and down-milling. Two milling experiments verify the model. Experimental results show that the model can predict the milling force and displacements simultaneously in the dynamic milling process.

Fundamentals and Processes of Fluid Pressure Forming Technology for Complex Thin-Walled Components

A new generation of fluid pressure forming technology has been developed for the three typical structures of tubes,sheets,and shells,and hard-to-deform material components that are urgently needed for aerospace,aircraft,automobile,and high-speed train industries.in this paper,an over all review is introduced on the state of the art in fundamentals and processes for lower-pressure hydroforming of tubular components,double-sided pressure hydroforming of sheet components,die-less hydroforming of ellipsoidai shells,and dual hardening hot medium forming af hard-to-deform materiais Particular attention is paid to deformation behavior,stress state adjustment,defect prevention,and typical applications.In addition,future development directions of fluid pressure forming technology are discussed,including hyper lower-loading forming for ultra-large non-uniform components,precision for ming for intermetallic compound and high-entropy alloy components,intelligent process and equipment,and precise finite element simulation of inhomogeneous and strong anisotropic thin shells.

Topological Optimization Method for Aeronautical Thin-Walled Component Fixture Locating Layout

Fixture locating layout has a direct and influential impact on aeronautical thin-walled component(ATWC)manufacturing quality.The purpose is to develop a topological optimization method for ATWC fixture locating layout to minimize the manufacturing deformation.Firstly,a topological optimization model that takes the stiffness of ATWC as the objective function and the volume of the locating structure as the constraint is established.Secondly,ATWC and the locating structure are regarded as an integrated entity,and the variable-density method based topological optimization approach is adopted for the optimization of the locating structure using ABAQUS topology optimization module(ATOM).Thirdly,through a subsequent model reconstruction referring to the obtained topological structure,the optimal fixture locating layout is achieved.Finally,a case study is conducted to verify the proposed method and the comparison results with firefly algorithm(FA)coupled with finite element analysis(FEA)indicate that the number and positions of the locators for ATWC can be optimized simultaneously and successfully by the proposed topological optimization model.

High-efficiency forming processes for complex thin-walled titanium alloys components: state-of-the-art and perspectives

Complex thin-walled titanium alloy components play a key role in the aircraft,aerospace and marine industries,offering the advantages of reduced weight and increased thermal resistance.The geometrical complexity,dimensional accuracy and in-service properties are essential to fulfill the high-performance standards required in new transportation systems,which brings new challenges to titanium alloy forming technologies.Traditional forming processes,such as superplastic forming or hot pressing,cannot meet all demands of modern applications due to their limited properties,low productivity and high cost.This has encouraged industry and research groups to develop novel high-efficiency forming processes.Hot gas pressure forming and hot stamping-quenching technologies have been developed for the manufacture of tubular and panel components,and are believed to be the cut-edge processes guaranteeing dimensional accuracy,microstructure and mechanical properties.This article intends to provide a critical review of high-efficiency titanium alloy forming processes,concentrating on latest investigations of controlling dimensional accuracy,microstructure and properties.The advantages and limitations of individual forming process are comprehensively analyzed,through which,future research trends of high-efficiency forming are identified including trends in process integration,processing window design,full cycle and multi-objective optimization.This review aims to provide a guide for researchers and process designers on the manufacture of thin-walled titanium alloy components whilst achieving high dimensional accuracy and satisfying performance properties with high efficiency and low cost.

Sheet Bulk Forming of Thin-Walled Components with External Gearing through Upsetting Using Controllable Deformation Zone Method

Sheet-bulk metal forming(SBMF)is a promising process for manufacturing complex sheet components with functional elements.In this study,the entire forming process for a typical thin-walled component with external gearing is investigated,including sheet forming and bulk forming processes.Deep drawn cups are prepared during sheet forming;subsequently,upsetting is performed on the sidewall to form external gearing.The upsetting method performed is known as upsetting with a controllable deformation zone(U-CDZ).Compared with the conventional upsetting method,a floating counter punch with a counter force is used in the U-CDZ method such that the forming mechanism is changed into the accumulation of the deformation zone instead of deformation throughout the entire sidewall.The effects of the counter force and material flow are investigated to understand the mechanism.The forming quality,i.e.,the formfilling and effective strain distribution,improved,whereas a high forming load is avoided.In addition,a punch with a lock bead is used to prevent folding at the inner corner during the experiment.

Vibrations in High Speed Milling of Thin-walled Components

Thin-walled structures have been widely used in the aerospace industry.The dynamic interaction between the milling cutter and thin-walled workpiece can easily lead to vibration.This paper investigates the vibration caused during milling the thin-walled workpiece on the NC machining center,presents a theoretical milling vibration model of thin-walled beam.The model was verified by using milling experiments and numerical simulations.Some valuable conclusions are derived,this will be references to scientific research and guides to the vibration-free milling of thin-walled structures at different cutting speeds.

Recent Developments on Damage and Fracture of Thin-Walled Complex Components Produced by Spinning

The spinning technique has been widely used in the manufacture of aerospace thin-walled axisymmetric components because of its excellent formability. Damage and fracture,as the important defects that often occur and must be avoided in the forming and service stages of components,have attracted much attention of researchers. In this paper,the fracture behavior and laws of spinning components such as conical parts,tubular parts,and components with inner ribs are summarized,the typical coupled and uncoupled ductile fracture models are introduced,and their applications in spinning are analyzed. Meanwhile,the recent developments on the modified ductile fracture model in analyzing damage and fracture mechanisms of spinning are emphatically introduced. The results could provide guidance for the selection and establishment of appropriate ductile fracture models in the finite element simulation for the accurate prediction and analysis of fracture moment,location,form,damage mechanism,and evolution law,and help the development of precision spinning techniques for high-performance thin-walled complex components.

Collaborative manufacturing technologies of structure shape and surface integrity for complex thin-walled components of aero-engine:Status,challenge and tendency

Presently,the service performance of new-generation high-tech equipment is directly affected by the manufacturing quality of complex thin-walled components.A high-efficiency and quality manufacturing of these complex thin-walled components creates a bottleneck that needs to be solved urgently in machinery manufacturing.To address this problem,the collaborative manufacturing of structure shape and surface integrity has emerged as a new process that can shorten processing cycles,improve machining qualities,and reduce costs.This paper summarises the research status on the material removal mechanism,precision control of structure shape,machined surface integrity control and intelligent process control technology of complex thin-walled components.Numerous solutions and technical approaches are then put forward to solve the critical problems in the high-performance manufacturing of complex thin-wall components.The development status,challenge and tendency of collaborative manufacturing technologies in the high-efficiency and quality manufacturing of complex thin-wall components is also discussed.

定量CT测量身体组分在肝硬化门静脉高压并发症中的应用价值

目的:基于定量CT(QCT)探讨肝硬化患者身体组分定量指标与门静脉高压并发症的相关性及其应用价值。方法:纳入2021年11月-2023年2月于本院就诊的134例肝硬化患者,受试者均行腹部CT平扫,收集临床资料并用QCT Pro软件测量每例受试者L2/3层面皮下及内脏脂肪面积(SAT、VAT)、腰椎骨密度(BMD)、肝脏脂肪分数(Fat%-QCT)、L3椎体水平全腹肌和椎旁肌面积(SMA、PMA)及肌内脂肪面积并计算肌内脂肪含量(IMAC-S、IMAC-P)。在不同Child-Pugh分级中进行组间资料对比,并根据有无门静脉高压并发症将患者分为两组比较身体组分差异,Mann-Whitney U检验或Kruskal-Wallis H检验、t检验或单因素ANOVA检验、χ^(2)检验用于各组间基本资料与身体组分的差异性分析;采用二元Logistic回归分析与肝硬化门静脉高压并发症相关的QCT指标,采用受试者操作特征(ROC)曲线分析不同模型的识别效能。结果:Fat%-QCT、SAT、椎旁肌内脂肪面积、IMAC-P在不同Child-Pugh分级中差异有统计学意义(P<0.05);多因素Logistic回归分析显示SAT是肝硬化门静脉高压并发症的独立相关因素(P<0.05,OR为0.987);SAT、SAT联合全腹肌指标、SAT联合椎旁肌指标的ROC曲线下面积(AUC)分别为0.727、0.772、0.769(P<0.05),SAT联合全腹肌指标的敏感度及特异度分别为0.734、0.800,优于SAT、SAT联合椎旁肌指标,识别效能最高。结论:SAT减少是肝硬化门静脉高压并发症风险增加的独立危险因素,SAT联合全腹肌指标能较好地识别肝硬化门静脉高压并发症。

妊娠期高血压疾病孕早期风险因素的主成分、聚类及预测价值分析

目的 评估孕早期孕妇临床特征、血流动力学和循环血管生成蛋白指标对妊娠期高血压疾病(HDCP)的预测价值。方法 选取2022年1-6月于华中科技大学同济医学院武汉市中心医院行产前检查、孕12~13周、血压正常的单胎孕妇共252例为研究对象,剔除失访病例,根据在妊娠期间新发高血压的风险将其分为观察组(136例,新发高血压风险较高)和对照组(103例,新发高血压风险较低)。收集两组孕早期基础信息[体重指数(BMI)、心率(HR)、平均动脉压(MAP)]、血流动力学指标[每搏输出量(SV)、子宫动脉搏动指数(PI)、心输出量(CO)、总外周阻力(TPR)]和循环血管生成蛋白[胎盘生长因子(PLGF)、可溶性fms样酪氨酸激酶-1(sFlt-1)、可溶性内皮糖蛋白(s-Eng)、髓过氧化物酶(MPO)和内皮素(ET)]等,评估上述指标对HDCP的预测价值。结果 观察组BMI、MAP、HR、TPR、PI和s-Eng均高于对照组(P<0.05),观察组SV、CO、PLGF均低于对照组(P<0.05)。主成分分析表明,3个主成分占队列变异性的61%,第一主成分主要受TPR(22%)、s-Eng(16%)和CO(12%)的影响,第二主成分主要受BMI(33%)和MAP(19%)的影响,而MPO(18%)则主要影响第三主成分。对队列进行聚类分析识别出3个组:低风险组(127例)、中风险组(81例)和高风险组(31例)。预测HDCP效果较高的4个变量依次是TPR[曲线下面积(AUC)=0.96]、s-Eng(AUC=0.84)、MAP(AUC=0.92)和PLGF(AUC=0.89)。结论 TPR、s-Eng、MAP和PLGF对孕期发生HDCP有较高的预测价值,确定HDCP发生的风险因素对开发针对性的预防和抗高血压治疗方案具有重要意义。

Effect of assisted transverse magnetic field on distortion behavior of thin-walled components in WEDM process

Machining performance of thin-walled components made by aeronautical difficult-toprocess materials is a significant issue in the aviation manufacturing industry.Although wire electric discharge machining-low speed(WEDM-LS)is one of typical non-contact machining processes without macro cutting force,which does well in removing hardness and brittleness materials via pulsed discharge at high temperature,but few researchers have studied the thermal distortion behavior leading to a considerable geometric error in the WEDM-LS of thin-walled components.In this paper,a transverse magnetic field assisted method is applied for affecting the uniformity of discharge point distribution so as to reduce the distortion in WEDM-LS processing thin-wall component.First,the generation mechanism of this new distortion behavior and the impact mechanism of transverse magnetic field(TMF)on distortion are demonstrated by theoretical analysis.In order to further figure out the distortion behavior in the TMF-WEDM process,a new thermophysical model considering the discharge point distribution is established to simulate temperature field,residual stress field and distortion profiles.Then a large number of Taguchi experiments are carried out to investigate the influences of process parameters including pulse discharge energy(pulse on time,pulse off time,and current)and magnetic field strength on distortion in WEDM-LS.To comparatively analyze simulated and experimental results,the accuracy of established thermophysical model is verified within a relative error of 18.38%in distortion.Moreover,it can be revealed that transverse magnetic field contribute to significantly improve the longitudinal distribution uniformity with maximum increase of 12.32%at magnetic field strength:0.15 T,leading to significant reductions of 32.77%in distortion and 22.68%in recast layer.Eventually,we also presented the variation of residual stress and recast layer along thickness direction under different distortion behavior,which are in good agreement with that of distortion behavior.

复方中药组分抗糖尿病大鼠糖过氧化作用

目的证实复方中药组分防治糖尿病的有效性并探讨其作用机制。方法应用链尿菌素复制大鼠糖尿病模型,对复方中药组分进行了药效学实验观察,并对各组大鼠血液及某些组织作了一系列过氧化相关的指标测定。结果复方中药组分具有一定的降血糖作用,并可改善机体的过氧化状态。结论复方中药组分的治疗作用与其抗过氧化及抑制氧化应激反应密切相关。

薄壁不锈钢数码相机外壳液压成形工艺研究

数码相机外壳是形状复杂的非旋转体不规则结构薄壳形件,文章基于其工艺难点及形状特征分析,采用1Cr18Ni9Ti不锈钢板材进行了不同液压加载路径下的充液拉深成形实验,并结合有限元模拟,分析了液压加载与凸模运动的不同匹配关系对成形结果的影响;针对各种成形缺陷分析其产生原因,并确定了合适的成形工艺参数,模拟结果与实验吻合良好。在室温条件下,以1mm/s～2mm/s的凸模速度进行液压成形,在液压载荷最高为20MPa时,成功试制出表面质量好、结构精度高的薄壁不锈钢数码相机外壳。研究结果为复杂结构薄壳形件液压成形工艺参数的确定和优化设计奠定了基础,并为采用液压成形工艺生产和加工电子器件不锈钢外壳提供实验和理论依据。

变能量X射线多谱成像方法研究

常规固定能量的X射线成像方法,对于厚薄差异大的工业复杂异形工件,因成像系统动态范围受限,易出现过曝光和欠曝光共存现象,信息缺失,成像质量差。为此提出研究变能量X射线多谱成像方法,在常规的射线成像系统上,依据有效厚度与电压的匹配性改变X射线管电压,获取递变电压下的多谱图像序列,同时研究多谱序列信息提取与融合技术,实现射线图像动态范围的扩展,完整地再现复杂结构件的内部结构信息。实验表明,相对于12bit的成像系统,变能量X射线多谱成像方法有效地将系统动态范围扩展了3倍,实现了复杂结构件的X射线高动态成像。

复杂薄壁铝合金铸件磁动力真空调压铸造工艺研究

磁动力真空调压铸造技术是在电磁充型低压铸造技术的基础上发展而来的一种铸造技术,其充型能力强,补缩能力高。通过研究磁动力真空调压铸造中影响金属液充型能力的因素,如真空度和浇注系统等,得出了磁动力真空调压铸造法的最佳充型工艺参数。该技术尤其适合复杂薄壁铸件的高品质铸造,具有广阔的发展前景。

基于对数解调的递变能量CT成像方法

复杂结构件由于有效厚度差异大和成像系统动态范围受限,单一能量下的投影数据信息不完整,常用CT重建算法及不完全数据重建算法无法在数据缺失严重的情况,有效实现复杂结构件的CT重建.为此论文提出基于对数解调的递变能量CT成像方法.该方法在分析直接高动态CT成像所存在问题的基础上,提出利用对数变换压缩递变能量投影序列动态范围,并利用现有的基于图像灰度一致性的融合方法,计算融合加权系数,再经常规重建算法实现复杂构件的CT成像.论文并以某复杂仪表为对象,进行实验,相比传统的固定能量成像方式,CT信息完整,质量高.从而说明论文所提出的方法,能够实现CT系统动态范围的扩展,实现复杂结构件的高动态CT成像.

AGEs平台筛选中药及中药有效成分

目的 寻找抑制AGEs形成的中药及中药有效成分。方法 通过分析现有国内报道抑制AGEs形成的化合物的结构特点和作用机制 ,利用体外AGEs形成的模型 ,进行中药及中药有效成分的筛选。结果 川芎素、复方丹参注射液等中药及中药有效成分对体外AGEs形成有很好的抑制作用 ,大蒜素、维生素C等对体外AGEs的形成未见抑制作用 ,而维生素B1、维生素B6、维生素B12 对体外AGEs的形成有一定的促进作用。结论 具有能和AGEs的前体羰基化合物反应的中药及中药有效成分可以抑制体外AGEs的形成。

四要素教学设计模型的数字电子技术实验教学模式探索

数字电子技术实验课程内容体系庞杂,知识点联系松散,具有"复杂学习任务"的典型特征。将国际教学设计领域中的四要素教学设计模型--4C/ID引入到数字电子技术实验的教学实践中,构建了基于4C/ID的数字电子技术实验教学体系,探索了通过"即时性信息"解决"复杂学习任务"与"支持性信息"之间矛盾的教学方法,使其贯穿于研究性实验教学任务的全过程。通过4C/ID教学设计模型的引入,增强了学生在学习过程中的整体思维能力,为学生提供了更加有效的实验教学模式,培养了学生综合应用知识的能力。

复方中药组分对糖尿病大鼠非酶糖基化的影响

目的:证实复方中药组分防治糖尿病及糖尿病肾病、糖尿病心肌病的有效性以及探讨其作用机制。方法:应用链尿菌素复制大鼠糖尿病模型,对复方中药组分进行了药效学实验观察,并对各组动物的血液及某些组织作了一系列相关的指标测定。结果:复方中药组分具有一定的降血糖作用,并可降低血红蛋白、心肌、肾脏的糖化值。结论:复方中药组分通过抑制糖尿病大鼠的非酶糖基化,可防治糖尿病肾病和糖尿病心肌病。