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Determining casting defects in near-net shape casting aluminum parts by computed tomography

Jiehua LI, Bernd OBERDORFER, Daniel HABE, Peter SCHUMACHER

《机械工程前沿(英文)》 2018年 第13卷 第1期   页码 48-52 doi: 10.1007/s11465-018-0493-y

摘要:

Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.

关键词: near-net shape casting     aluminum parts     casting defects     low pressure die casting     die casting     semi-solid casting     computed tomography    

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0724-0

摘要: The internal structures of metallic products are important in realizing functional applications. Considering the manufacturing of inner structures, laser-based powder bed fusion (L-PBF) is an attractive approach because its layering principle enables the fabrication of parts with customized interior structures. However, the inferior surface quality of L-PBF components hinders its productization progress seriously. In this article, process, basic forms, and applications relevant to L-PBF internal structures are reviewed comprehensively. The causes of poor surface quality and differences in the microstructure and property of the surface features of L-PBF inner structures are presented to provide a perspective of their surface characteristics. Various polishing technologies for L-PBF components with inner structures are presented, whereas their strengths and weaknesses are summarized along with a discussion on the challenges and prospects for improving the interior surface quality of L-PBF parts.

关键词: laser-based powder bed fusion     polishing     internal structures     surface quality     surface features     post process     additive manufacturing    

Fixturing technology and system for thin-walled parts machining: a review

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0711-5

摘要: During the overall processing of thin-walled parts (TWPs), the guaranteed capability of the machining process and quality is determined by fixtures. Therefore, reliable fixtures suitable for the structure and machining process of TWP are essential. In this review, the key role of fixtures in the manufacturing system is initially discussed. The main problems in machining and workholding due to the characteristics of TWP are then analyzed in detail. Afterward, the definition of TWP fixtures is reinterpreted from narrow and broad perspectives. Fixture functions corresponding to the issues of machining and workholding are then clearly stated. Fixture categories are classified systematically according to previous research achievements, and the operation mode, functional characteristics, and structure of each fixture are comprehensively described. The function and execution mode of TWP fixtures are then systematically summarized and analyzed, and the functions of various TWP fixtures are evaluated. Some directions for future research on TWP fixtures technology are also proposed. The main purpose of this review is to provide some reference and guidance for scholars to examine TWP fixtures.

关键词: thin-walled part (TWP)     fixture     machining     fixture categories     fixture function    

Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0720-4

摘要: Aerospace aluminum alloy is the most used structural material for rockets, aircraft, spacecraft, and space stations. The deterioration of surface integrity of dry machining and the insufficient heat transfer capacity of minimal quantity lubrication have become the bottleneck of lubrication and heat dissipation of aerospace aluminum alloy. However, the excellent thermal conductivity and tribological properties of nanofluids are expected to fill this gap. The traditional milling force models are mainly based on empirical models and finite element simulations, which are insufficient to guide industrial manufacturing. In this study, the milling force of the integral end milling cutter is deduced by force analysis of the milling cutter element and numerical simulation. The instantaneous milling force model of the integral end milling cutter is established under the condition of dry and nanofluid minimal quantity lubrication (NMQL) based on the dual mechanism of the shear effect on the rake face of the milling cutter and the plow cutting effect on the flank surface. A single factor experiment is designed to introduce NMQL and the milling feed factor into the instantaneous milling force coefficient. The average absolute errors in the prediction of milling forces for the NMQL are 13.3%, 2.3%, and 7.6% in the x-, y-, and z-direction, respectively. Compared with the milling forces obtained by dry milling, those by NMQL decrease by 21.4%, 17.7%, and 18.5% in the x-, y-, and z-direction, respectively.

关键词: milling     force     nanofluid minimum quantity lubrication     aerospace aluminum alloy     nano biological lubricant    

Forecast method for used number of parts and components based on complex network

LIU Fu-yun, QI Guo-ning, YANG Qing-hai

《机械工程前沿(英文)》 2006年 第1卷 第4期   页码 479-484 doi: 10.1007/s11465-006-0064-5

摘要: Applying directed complex network to model the main structure of a product family, according to in-degree bi-logarithmic coordinate distribution curve and distribution rule of nodes of the network, in-degree evolving rule of nodes of the network is presented and analytic expression of in-degree probability density of nodes is derived. Through the analysis of the relation between existing kinds of components and existing product numbers, an expression of the relation between kinds of components and product numbers is derived. A forecast method for the increment of component numbers and parts based on the increment of products is presented. As an example, the component numbers of an industrial steam turbine product family is forecasted, forecast result verified and forecast error analyzed.

关键词: complex network     industrial     component     analytic expression     forecast    

The prediction technology study of fatigue life for key parts of a tracked vehicle’s suspension system

WANG Hongyan, RUI Qiang, HE Xiaojun

《机械工程前沿(英文)》 2007年 第2卷 第1期   页码 68-71 doi: 10.1007/s11465-007-0011-0

摘要: In allusion to fatigue life of a tracked vehicle torsion bar, a virtual prototype model of the tracked vehicle suspension system including a flexible torsion bar was built based on dynamic simulation software ADAMS. Node force and stress results of the torsion bar from last step simulation were acquired; taking into account the material characteristics and influential factors, fatigue life of the flexible body of the torsion bar was predicted. Engineering results can be acquired through the contrast of the result of virtual test and statistical fatigue.

关键词: dynamic simulation     simulation software     allusion     influential     material    

Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

《结构与土木工程前沿(英文)》 2023年 第17卷 第3期   页码 448-466 doi: 10.1007/s11709-022-0910-5

摘要: In this study, a numerical analysis was conducted on aluminum alloy reticulated shells (AARSs) with gusset joints under fire conditions. First, a thermal-structural coupled analysis model of AARSs considering joint semi-rigidity was proposed and validated against room-temperature and fire tests. The proposed model can also be adopted to analyze the fire response of other reticulated structures with semi-rigid joints. Second, a parametric analysis was conducted based on the numerical model to explore the buckling behavior of K6 AARS with gusset joints under fire conditions. The results indicated that the span, height-to-span ratio, height of the supporting structure, and fire power influence the reduction factor of the buckling capacity of AARSs under fire conditions. In contrast, the reduction factor is independent of the number of element divisions, number of rings, span-to-thickness ratio, and support condition. Subsequently, practical design formulae for predicting the reduction factor of the buckling capacity of K6 AARSs were derived based on numerical analysis results and machine learning techniques to provide a rapid evaluation method. Finally, further numerical analyses were conducted to propose practical design suggestions, including the conditions of ignoring the ultimate bearing capacity analysis of K6 AARS and ignoring the radiative heat flux.

关键词: aluminum alloy reticulated shell     gusset joint     numerical analysis     fire resistance    

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Chao Wang, Jun Chen, Jihua He, Jing Jiang, Qinyong Zhang

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 1065-1071 doi: 10.1007/s11705-019-1909-x

摘要: Micro-arc oxidation (MAO) is an efficient approach to improve the hardness, wear resistance, and other properties of aluminum alloys. In order to investigate the effect of the electrolyte concentration on the properties of MAO coatings for LY12 alloy, the voltage variation during the MAO process was recorded. The surface morphologies and phase compositions of the coatings produced with different electrolytes were investigated using scanning electron microscopy and X-ray diffraction, respectively. The roughness and thickness of the coatings were measured using a pocket roughness meter and an eddy-current thickness meter, respectively. The tribological performances of the coatings were investigated against GCr15 bearing steel on a ball-on-disc wear tester in open air. The results showed that with an increase in the Na SiO content, the working voltage of the MAO process decreased, the roughness and thickness of the coatings increased significantly, and the relative content of the -Al O phase decreased. With an increase in the KOH content, the working voltage decreased slightly, the roughness and thickness of the coatings increased slightly, and the α- and -Al O phase contents remained unchanged. The friction coefficient and wear rate of the coatings increased with an increase in the Na SiO and KOH concentrations. A decrease in the porosity and roughness and an increase in the α-Al O content of the coatings reduced their wear mass loss.

关键词: aluminum alloy     micro-arc oxidation     coating     electrolyte concentration     tribological performance    

Experimental investigation and design of aluminum columns with longitudinal welds

Yun WU, Qilin ZHANG

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 366-373 doi: 10.1007/s11709-011-0101-2

摘要: This paper presents an experimental investigation of longitudinally welded aluminum alloy I-section columns subjected to pure axial compression. The specimens were fabricated using 6061-T6 heat-treated aluminum alloy. The test program included 20 column tests which were separated into 2 test series of different types of welding sections. Each test series contained 10 columns. All the specimens were welded using the Tungsten Inert Gas welding method. The length of the specimens ranged from 442 to 2433 mm in order to obtain a column curve for each test series. The observed failure mode for the column tests includes mainly flexural buckling around the minor axis and the major axis by applying support except for one column (ZP1217-1) which buckled in the local zone and some columns which failed in the weld. The test strengths were compared with the design strengths predicted by the European Code and China Code for aluminum structures. The purpose of this paper is to present the tests results of two typically longitudinally welded I-section columns, and to check the accuracy of the design rules in the current specifications.

关键词: aluminum alloy     longitudinal weld     heat-affected zone (HAZ)     reduced strength zone (RSZ)     buckling     column     experimental study    

Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0737-8

摘要: Selective laser melting (SLM) is a unique additive manufacturing (AM) category that can be used to manufacture mechanical parts. It has been widely used in aerospace and automotive using metal or alloy powder. The build orientation is crucial in AM because it affects the as-built part, including its part accuracy, surface roughness, support structure, and build time and cost. A mechanical part is usually composed of multiple surface features. The surface features carry the production and design knowledge, which can be utilized in SLM fabrication. This study proposes a method to determine the build orientation of multi-feature mechanical parts (MFMPs) in SLM. First, the surface features of an MFMP are recognized and grouped for formulating the particular optimization objectives. Second, the estimation models of involved optimization objectives are established, and a set of alternative build orientations (ABOs) is further obtained by many-objective optimization. Lastly, a multi-objective decision making method integrated by the technique for order of preference by similarity to the ideal solution and cosine similarity measure is presented to select an optimal build orientation from those ABOs. The weights of the feature groups and considered objectives are achieved by a fuzzy analytical hierarchy process. Two case studies are reported to validate the proposed method with numerical results, and the effectiveness comparison is presented. Physical manufacturing is conducted to prove the performance of the proposed method. The measured average sampling surface roughness of the most crucial feature of the bracket in the original orientation and the orientations obtained by the weighted sum model and the proposed method are 15.82, 10.84, and 10.62 μm, respectively. The numerical and physical validation results demonstrate that the proposed method is desirable to determine the build orientations of MFMPs with competitive results in SLM.

关键词: selective laser melting (SLM)     build orientation determination     multi-feature mechanical part (MFMP)     fuzzy analytical hierarchy process     multi-objective decision making (MODM)    

A new regeneration approach to cation resins with aluminum salts: application of desalination by its

Zhigang LIU, Shaomin ZHU, Yansheng LI

《环境科学与工程前沿(英文)》 2012年 第6卷 第1期   页码 45-50 doi: 10.1007/s11783-010-0262-6

摘要: A novel method for the regeneration of cation exchange resins by aluminum (Al) salts was investigated in order to improve the regeneration efficiency of resins and reduce the dosage of regenerant. The influences of Al concentration and the pH of regeneration solution on resin transformation had been studied. The desalination experiments were carried out to evaluate the characteristics of the Al form resins. Experimental results showed that the regeneration rate of resins was strictly dependent on Al concentration and the pH of the solution. Compared to the conventional regeneration method, the Al form mixed bed exhibited the same desalination capability as the H form mixed bed (MB), and the total organic carbon (TOC) removal was up to 90%, clearly higher than that of the H form. Al salt solution could be utilized repeatedly to regenerate Al form resins.

关键词: aluminum (Al) form resins     desalination     mixed bed (MB)     regeneration    

Spatiotemporal evolution and driving factors for GHG emissions of aluminum industry in China

《能源前沿(英文)》 2023年 第17卷 第2期   页码 294-305 doi: 10.1007/s11708-022-0819-7

摘要: China’s aluminum (Al) production has released a huge amount of greenhouse gas (GHG) emissions. As one of the biggest country of primary Al production, China must mitigate its overall GHG emission from its Al industry so that the national carbon neutrality target can be achieved. Under such a background, the study described in this paper conducts a dynamic material flow analysis to reveal the spatiotemporal evolution features of Al flows in China from 2000 to 2020. Decomposition analysis is also performed to uncover the driving factors of GHG emission generated from the Al industry. The major findings include the fact that China’s primary Al production center has transferred to the western region; the primary Al smelting and carbon anode consumption are the most carbon-intensive processes in the Al life cycle; the accumulative GHG emission from electricity accounts for 78.14% of the total GHG emission generated from the Al industry; China’s current Al recycling ratio is low although the corresponding GHG emission can be reduced by 93.73% if all the primary Al can be replaced by secondary Al; and the total GHG emission can be reduced by 88.58% if major primary Al manufacturing firms are transferred from Inner Mongolia to Yunnan. Based upon these findings and considering regional disparity, several policy implications are proposed, including promotion of secondary Al production, support of clean electricity penetration, and relocation of the Al industry.

关键词: aluminum     material flow analysis     GHG (greenhouse gas) emissions     LMDI (logarithmic mean divisa index)    

Synthesis of aluminum nanoparticles as additive to enhance ignition and combustion of high energy density

Xiu-Tian-Feng E, Lei Zhang, Fang Wang, Xiangwen Zhang, Ji-Jun Zou

《化学科学与工程前沿(英文)》 2018年 第12卷 第3期   页码 358-366 doi: 10.1007/s11705-018-1702-2

摘要:

High energy density fuels are critical for hypersonic aerospace propulsion but suffer from difficulties of ignition delay and incomplete combustion. This research reports aluminum nanoparticles (Al NPs) assisted ignition and combustion of high energy density JP-10 fuel. Al NPs with a size of 16 nm were fabricated through a mild and simple method by decomposing AlH3·Et2O with the addition of a surfactant ligand. The uniform size distribution, nanoscaled size and surface ligand make Al NPs stably suspend in JP-10, with 80% NPs being dispersed in the liquid fuel after six months. A shock tube test shows that the presence of 1 wt-% Al NPs can significantly shorten ignition delay time at temperature of 1500 to 1750 K, promote the combustion, and enhance energy release of JP-10. This work demonstrates the potential of Al NPs as ignition and combustion additive for high energy density fuel in hypersonic applications.

关键词: aluminum nanoparticles     combustion     ignition     shock tube test     high energy density fuel    

中国金属导体“以铝节铜”前景

黄崇祺

《中国工程科学》 2012年 第14卷 第10期   页码 4-9

摘要:

“以铝节铜”是国际性趋势,进程各国有所不同,但只能是渐进式的。我国铝和铝合金在电力电缆上的应用与国外有较大差距,铝合金在架空线路上的应用尚有较大提升空间。铜包铝导体的应用有所发展,有关标准正在报批或制订之中,有待在使用中进一步考验,但回收时的铜、铝分离尚未找到具有技术经济效果的方法。铝包钢线近些年市场旺盛,生产日趋成熟,铝漆包线的生产近些年已有增长,通信领域的“光进铜退”将毫无悬念地继续推进。飞机上的“以铝节铜”已有实质性的进展。废杂铜和电工用废铝直接再生利用对节能环保具有重要意义。全国建立废旧铜、铝线的回收网络已势在必行。

关键词: 导体     以铝节铜     前景    

Experiment on aluminum alloy members under axial compression

Xiaonong GUO,Shuiping LIANG,Zuyan SHEN

《结构与土木工程前沿(英文)》 2015年 第9卷 第1期   页码 48-64 doi: 10.1007/s11709-014-0271-9

摘要: To improve the design methods of Chinese aluminum alloy members, experiment of 63 profiled aluminum alloy members, made of Chinese aluminum alloy 6061-T6, under axial compression is conducted in this paper. Valuable experimental data are obtained. At the same time, in order to obtain the relevant data, a large number of other experimental data from published papers and technical reports are collected and sorted out. 167 valid experimental data points are obtained finally. Furthermore, for the purpose of creating column curves, the aluminum alloy members under the axial compression, used in experiments, are analyzed by means of FEM. Based on the numerical results, 2 column curves are created by means of the numerical fitting method. The column curves are compared with the calculated data according to the experimental results for verification, and also are verified with the curves in design codes of several relevant countries. The numerical results show that the column curves obtained in this paper are valid and reliable.

关键词: aluminum alloy     column curve     compression members     overall stability coefficient    

标题 作者 时间 类型 操作

Determining casting defects in near-net shape casting aluminum parts by computed tomography

Jiehua LI, Bernd OBERDORFER, Daniel HABE, Peter SCHUMACHER

期刊论文

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

期刊论文

Fixturing technology and system for thin-walled parts machining: a review

期刊论文

Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological

期刊论文

Forecast method for used number of parts and components based on complex network

LIU Fu-yun, QI Guo-ning, YANG Qing-hai

期刊论文

The prediction technology study of fatigue life for key parts of a tracked vehicle’s suspension system

WANG Hongyan, RUI Qiang, HE Xiaojun

期刊论文

Numerical analysis of aluminum alloy reticulated shells with gusset joints under fire conditions

期刊论文

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Chao Wang, Jun Chen, Jihua He, Jing Jiang, Qinyong Zhang

期刊论文

Experimental investigation and design of aluminum columns with longitudinal welds

Yun WU, Qilin ZHANG

期刊论文

Build orientation determination of multi-feature mechanical parts in selective laser melting via multi-objective

期刊论文

A new regeneration approach to cation resins with aluminum salts: application of desalination by its

Zhigang LIU, Shaomin ZHU, Yansheng LI

期刊论文

Spatiotemporal evolution and driving factors for GHG emissions of aluminum industry in China

期刊论文

Synthesis of aluminum nanoparticles as additive to enhance ignition and combustion of high energy density

Xiu-Tian-Feng E, Lei Zhang, Fang Wang, Xiangwen Zhang, Ji-Jun Zou

期刊论文

中国金属导体“以铝节铜”前景

黄崇祺

期刊论文

Experiment on aluminum alloy members under axial compression

Xiaonong GUO,Shuiping LIANG,Zuyan SHEN

期刊论文