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High-performance grinding of ceramic matrix composites

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Nanotechnology and Precision Engineering 2024年第3期7卷 45-55页

作者： Jingfei Yin jiuhua xu Honghua Su College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Technology Center AECC Shenyang Liming Aero-engine Co.Ltd.Shenyang 110043China

Ceramic matrix composites(CMCs)are highly promising materials for the next generation of ***,machining of CMCs suffers from low efﬁciency and poor surfaceﬁnish,which presents an obstacle to their wider *** overcome these problems,this study investigates high-efﬁciency deep grinding of CMCs,focusing on the effects of grinding *** results show that both the sur-face roughness and the depth of subsurface damage(SSD)are insensitive to grinding *** material removal rate can be increased sixfold by increasing the grinding depth,while the surface roughness and SSD depth increase by only about 10%.Moreover,it is found that the behavior of material removal is strongly dependent on grinding *** the grinding depth is increased,ﬁbers are removed in smaller sizes,with theﬁber length in chips being reduced by about 34%.However,too large a grinding depth will result in blockage by chip powder,which leads to a dramatic increase in the ratio of tangential to normal grinding *** study demonstrates that increasing the depth of cut is an effective approach to improve the machining efﬁciency of CMCs,while maintaining a good surfaceﬁ*** provides the basis for the further development of high-performance grinding methods for CMCs,which should facilitate their wider application.

关键词： Ceramic matrix composite Grinding Surfaceﬁnish Subsurface damage Fiber breakage

Inverse identification of constitutive parameters of Ti_2AlNb intermetallic alloys based on cooperative particle swarm optimization

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Chinese Journal of Aeronautics 2018年第8期31卷 1774-1785页

作者： Linjiang HE Honghua SU jiuhua xu Liang ZHANG College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics

Ti_2AlNb intermetallic alloy is a relatively newly developed high-temperature-resistant structural material, which is expected to replace nickel-based super alloys for thermally and mechanically stressed components in aeronautic and automotive engines due to its excellent mechanical properties and high strength retention at elevated temperature. The aim of this work is to present a fast and reliable methodology of inverse identification of constitutive model parameters directly from cutting experiments. FE-machining simulations implemented with a modified Johnson-Cook（TANH） constitutive model are performed to establish the robust link between observables and constitutive parameters. A series of orthogonal cutting experiments with varied cutting parameters is carried out to allow an exact comparison to the 2 D FE-simulations. A cooperative particle swarm optimization algorithm is developed and implemented into the Matlab programs to identify the enormous constitutive parameters. Results show that the simulation observables（i.e., cutting forces, chip morphologies, cutting temperature） implemented with the identified optimal material constants have high consistency with those obtained from experiments,which illustrates that the FE-machining models using the identified parameters obtained from the proposed methodology could be predicted in a close agreement to the experiments. Considering the wide range of the applied unknown parameters number, the proposed inverse methodology of identifying constitutive equations shows excellent prospect, and it can be used for other newly developed metal materials.

关键词： Constitutive parameters Cooperative particle swarmoptimization Finite element modelling Inverse identification Ti2A1Nb intermetallic alloys

An investigation on adaptively machining the leading and tailing edges of an SPF/DB titanium hollow blade using free-form deformation

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Chinese Journal of Aeronautics 2018年第1期31卷 178-186页

作者： Zhengcai ZHAO jiuhua xu Yucan FU Zhiqiang LI College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Beijing Aeronautics Manufacturing Technology Research Institute Beijing 100024 China

Titanium hollow blades are characterized with lightweight and high structural strength, which are widely used in advanced aircraft engines nowadays. Superplastic forming/diffusion bonding （SPF/DB） combined with numerical control （NC） milling is a major solution for manufacturing titanium hollow blades. Due to the shape deviation caused by multiple heat and pressure cycles in the SPF/DB process, it is hard to manufacture the leading and tailing edges by the milling process. This paper presents a new adaptive machining approach using free-form deformation to solve this problem. The actual SPF/DB shape of a hollow blade was firstly inspected by an on-machine measurement method. The measured point data were matched to the nominal SPF/DB shape with an improved ICP algorithm afterwards, by which the point-pairs between the measurement points and their corresponding points on the nominal SPF/DB shape were established, and the maximum modification amount of the final nominal shape was constrained. Based on the displacements between the point-pairs, an accurate FFD volume was iteratively calculated. By embedding the final nominal shape in the deformation space, a new final shape of the hollow blade was built. Finally, a series of measurement and machining tests was performed, the results of which validated the feasibility of the proposed adaptive machining approach.

关键词： Adaptive machining Blade geometry Free-form deformation Reconstruction Titanium

Grinding performance evaluation of porous composite-bonded CBN wheels for Inconel 718

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Chinese Journal of Aeronautics 2014年第4期27卷 1022-1029页

作者： Chen Zhenzhen xu jiuhua Ding Wenfeng Ma Changyu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology

For high-efficiency grinding of difficult-to-cut materials such as titanium and nickel alloys, a high porosity is expected and also a sufficient mechanical strength to satisfy the ***, the porosity increase is a disadvantage to the mechanical strength. As a promising pore forming agent, alumina bubbles are firstly induced into the abrasive layer to fabricate porous cubic boron nitride（CBN） wheels. When the wheel porosity reaches 45%, the bending strength is still high up to 50 MPa with modified orderly pore distribution. A porous CBN wheel was fabricated with a total porosity around 30%. The grinding performance of the porous composite-bonded CBN wheel was evaluated in terms of specific force, specific grinding energy, and grinding temperature, which were better than those of the vitrified one under the same grinding conditions. Compared to the vitrified CBN wheel, clear straight cutting grooves and less chip adhesion are observed on the ground surface and there is also no extensive loading on the wheel surface after grinding.

关键词： Alumina bubbles Bending strength Cubic boron nitride (CBN)Porosity Specific force Specific grinding energy

Influence of alumina abrasive tool wear on ground surface characteristics and corrosion properties of K444 nickel-based superalloy

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Chinese Journal of Aeronautics 2022年第6期35卷 339-351页

作者： Min LI Jingfei YIN Linbo CHE Wenfeng DING jiuhua xu National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China

K444 nickel-based superalloy is an important material to manufacture the gas turbine due to its excellent mechanical properties at high temperatures and corrosion ***,grinding is the mostly used method for the surface finish of the K444 alloy ***,few studies worked on the effects of the abrasive tool wear on the ground surface characteristics and corrosion properties of K444 *** study uses two different-type alumina abrasive tools,i.e.,white alumina(WA)and microcrystalline alumina(MA)wheels,to grind the K444 *** influence of the alumina abrasive tool wear on ground surface characteristics and corrosion resistance performance are *** is discovered that the MA wheel presents a slighter wheel wear and higher self-sharpening than the WA *** to the WA wheel,the MA wheel has less material adhesion,which leads to a better surface *** the corrosion testing,the maximum corrosion depth is 80μm in the surface ground by the MA wheel but 100μm in the surface ground by the WA wheel,which demonstrates that the MA wheel grinding benefits the surface corrosion resistance of K444 ***,this study could provide a guide to selecting the abrasive tools and optimizing the grinding process of the K444 alloy.

关键词： Abrasive wheel wear Corrosion resistance Grinding K444 nickel-based superalloy Microcrystalline alumina

Tool Wear in Turning of Titanium Alloy after Thermohydrogen Treatment

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Chinese Journal of Mechanical Engineering 2012年第4期25卷 776-780页

作者： WEI Weihua xu jiuhua FU Yucan YANG Shubao College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The influence of hydrogen contents on the tool wear has been mainly focused on the flank wear of the common tool,and the influence of hydrogen contents on the rake crater wear（main wear type） of the tool,particularly for the fine granular material tool,has been less investigated *** this paper,for the purpose of researching the influence of hydrogen contents on tool wear,the titanium alloy Ti-6Al-4V is hydrogenated at 800 ℃ by thermohydrogen treatment technology and the turning experiments are carried out by applying uncoated WC-Co cemented carbide *** three-dimensional video microscope is used to take photos and measure tool *** results show that both of crater wear depth（KT） and average flank wear width（VB） firstly decreases and then increases with the increasing of hydrogen *** maximum reducing amplitude of KT and VB is about 50% and 55%,*** the given conditions,the optimum hydrogen content is 0.26%.It is considered that the reduction of cutting temperature is an important factor for improving tool wear after the Ti-6Al-4V alloy is properly ***,the reasons of hydrogen effect on the tool wear are chiefly attributed to comprehensive effect of hydrogen contents on microstructure,physical properties and dynamic mechanical properties of the Ti-6Al-4V *** proposed research provides the basic data for evaluating the machinability of hydrogenation Ti-6Al-4V alloy,and promotes practical application of thermohydrogen treatment technology in titanium alloys.

关键词： titanium alloy hydrogenation cutting temperature crater wear flank wear

Surface integrity evolution during creep feed profile grinding ofγ-TiAl blade tenon

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Chinese Journal of Aeronautics 2024年第8期37卷 496-512页

作者： Tao CHEN Xiaowei WANG Biao ZHAO Wenfeng DING jiuhua xu National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Gamma titanium-aluminum(γ-TiAl)intermetallic compounds are increasingly used in manufacturing key hot-end components(e.g.,blade tenon)in aero engines due to their high specific strength and lightweight *** feed profile grinding(CFPG)as a crucial precision process that is applied to produce the final profile of the blade ***,sudden surface burns and microcracks of machined c-TiAl blade tenon often occur because of its low plasticity and high strength during grinding processes,leading to poor surface *** this work,CFPG experiments based on the profile characteristics ofγ-TiAl blade tenon were performed and an associated undeformed chip thickness model considering grain–workpiece contact condition was established to explore the evolution of the surface ***,the surface integrity was analyzed at different positions of the blade tenon in terms of surface roughness and morphology,metallographic structure,microhardness,and residual *** show that the profile characteristics of blade tenon have a significant influence on machined surface integrity because of the thermomechanical effect at various detecting *** residual stress was established based on the undeformed chip thickness model considering the profile structure,with a prediction error of 10%–15%.The thermomechanical effect is more obvious at the bottom area,where the surface roughness,work hardening degree,and subsurface plastic deformation range are the largest,while the values at the bevel area are the *** on the undeformed chip thickness model,a residual stress finite element simulation was conducted by employing thermomechanical coupled *** addition,the error between the simulation and the experiment was between 10%–15%.Strain and strain rate equations were established through the relationship between material displacement and *** average strain and strain rate of the ground surface when ap is 1.0 mm are 18.8%and 33.2%l

关键词： Gamma titanium-aluminum intermetallic compounds Blade tenon Creep feed profile grinding Surface integrity Thermomechanical effect

Surface micro-texture on sapphire fabricated by laser ablation trajectory regulation

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Chinese Journal of Aeronautics 2022年第3期35卷 525-536页

作者： Quanli ZHANG Qiwen WANG Zhen ZHANG Yucan FU jiuhua xu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Fabrication of the surface micro-texture on the C-plane sapphire is undertaken by a355 nm Ultraviolet(UV)pulsed *** surface micro-textures of sapphire with different laser scanning line spacing ranging from 10 lm to 100 lm are obtained,where the selection range of scanning line spacing is controlled in the range of the groove width and plasma width to obtain a surface of high Peak-Valley(PV)value.A reasonable processing order is proposed to manufacture different types of surface micro-textures on sapphire by laser ablation trajectory *** the multiple-passes laser ablation of sapphire by the UV nanosecond pulsed laser,the scanning lines in each direction is treated as once *** this basis,the multiple processing can be carried out to avoid the influence of the subsequent scanning on the machined *** addition,the effect of different scanning line spacing on the PV value is quantified and different types of surface microtextures on sapphire,including the squares,the rhombuses and the hexagons,are successfully fabricated,which can be applied in the friction reduction or anti-reflection field.

关键词： Laser ablation trajectory Sapphire Scanning line spacing Surface micro-texture PV values

Cold expansion technology of connection holes in aircraft structures:A review and prospect

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Chinese Journal of Aeronautics 2015年第4期28卷 961-973页

作者： Fu Yucan Ge Ende Su Honghua xu jiuhua Li Renzheng College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics

As one kind of key anti-fatigue manufacture approaches with simplicity and effectiveness, the hole cold expansion technology satisfies the increasing needs for light weight and durability of aircraft *** can improve the fatigue life by several times at no additional weight *** hole cold expansion technology has been widely used in manufacturing and repairing of both fighters and commercial aircraft, and has become a research hotspot in the strengthening *** recent years, hole cold expansion process methods, residual stress around expanded holes, the behavior of fatigue crack initiation and propagation, and fatigue lives after cold expansion are researched extensively through lots of experiments and finite element simulations.A review on the hole cold expansion technology research status in the last twenty years is presented in this *** the analysis of the current characteristics and defects of the hole cold expansion technology, combined with the actual needs in design and manufacture of new-generation aircraft, development trends and novel research directions are presented for realizing precise and high-efficiency anti-fatigue manufacture.

关键词： Aircraft structure Cold expansion Connection hole Fatigue life Finite element simulation Residual stress