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Intelligent design of investment casting mold based on a hybrid reasoning method

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China Foundry 2009年第1期6卷 20-23页

作者： Jiang Ruisong Zhang Dinghua Wang Wenhu Bu Kun The Key Laboratory of contemporary design and Integrated Manufacturing Ministry of Education China Northwestern Polytechnical University Xi＇an 710072 China

A hybrid reasoning model was proposed in which CBR(case-based reasoning)was applied to the conceptual design and RBR(rule-based reasoning)was applied to the detailed design after research of the design process and domain knowledge of the aero-engine turbine blade investment casting mold design *** the conceptual design stage,the representation and retrieval technologies were researched which improve the retrieval ***,RBR was used to modify the retrieval *** experimentation shows that the approach in this study can be used to obtain a more satisfactory design result.

关键词： turbine blade investment casting mold intelligent design CBR RBR

Cutting tool temperature prediction method using analytical model for end milling

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Chinese Journal of Aeronautics 2016年第6期29卷 1788-1794页

作者： Wu Baohai Cui Di He Xiaodong Zhang Dinghua Tang Kai Laboratory of contemporary design and Integrated Manufacturing Technology Ministry of EducationNorthwestern Polytechnical UniversityXi’an 710072China Hong Kong University of Science and Technology Hong KongChina

Dramatic tool temperature variation in end milling can cause excessive tool wear and shorten its life, especially in machining of difficult-to-machine materials. In this study, a new analytical model-based method for the prediction of cutting tool temperature in end milling is *** cutting cycle is divided into temperature increase and decrease phases. For the temperature increase phase, a temperature prediction model considering real friction state between the chip and tool is proposed, and the heat flux and tool-chip contact length are then obtained through finite element simulation. In the temperature decrease phase, a temperature decrease model based on the one-dimension plate heat convection is proposed. A single wire thermocouple is employed to measure the tool temperature in the conducted milling experiments. Both of the theoretical and experimental results are obtained with cutting conditions of the cutting speed ranging from 60 m/min to100 m/min, feed per tooth from 0.12 mm/z to 0.20 mm/z, and the radial and axial depth of cut respectively being 4 mm and 0.5 mm. The comparison results show high agreement between the physical cutting experiments and the proposed cutting tool temperature prediction method.

关键词： Analytical model Cutting tool End milling Temperature prediction Tool temperature

Study on stable delivery of charged uniform droplets for freeform fabrication of metal parts

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Science China(Technological Sciences) 2011年第7期54卷 1833-1840页

作者： LUO Jun QI LeHua ZHOU JiMing XIAO Yuan YANG Fang School of Mechatronics Northwestern Polytechnical University Xi'an 710072 China Key Laboratory of contemporary design and Integrated Manufacturing Technology Ministry of Education Xi'an 710072 China

Electrostatic delivery of charged uniform metal droplets is a novel method to deposit metal parts with short process period and low cost. But the delivery process is unstable and delivery accuracy of charged droplets deteriorates because of actions of mutual interactions of closely charged droplets. A droplet generator with droplet charging and deflecting system has been established to find out the way for stably and accurately deflecting droplets. The parameters for generating uniform droplets were first studied. Then the droplet deflections and metal parts depositions with different charge methods were discussed. The results show that the unbalanced electrostatic repelling forces are the main factor to cause the unstable deflection of droplets. The droplets deflection distance can be predicted and controlled by balancing the repelling forces of charged droplets. The metal parts are stably deposited after combining the board charged pulse and substrate motion, indicating that the work can provide useful theoretical and experimental guide for droplet-based freeform fabrication.

关键词： electrostatic delivery uniform metal droplets metal parts freeform fabrication

Influence of TiB2 particles on machinability and machining parameter optimization of TiB2/Al MMCs

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Chinese Journal of Aeronautics 2018年第1期31卷 187-196页

作者： Ruisong JIANG Xinfa CHEN Renwei GE Wenhu WANG Guodong SONG The Key Laboratory of contemporary design and Integrated Manufacturing Technology Ministry of Education Northwestern Polytechnical University Xi'an 710072 China China Academy of Engineering Physics Mian'yang 621900 China

In situ formed TiB2 particle reinforced aluminum matrix composites （TiB2/Al MMCs） have some extraordinary properties which make them be a promising material for high performance aero-engine blade. Due to the influence of TiB2 particles, the machinability is still a problem which restricts the application of TiB2/Al MMCs. In order to meet the industrial requirements, the influence of TiB2 particles on the machinability of TiB2/Al MMCs was investigated experimentally. Moreover, the optimal machining conditions for this kind of MMCs were investigated in this study. The major conclusions are：（1） the machining force of TiB2/Al MMCs is bigger than that of non- reinforced alloy and mainly controlled by feed rate; （2） the residual stress of TiB2/AI MMCs is compressive while that of non-reinforced alloy is nearly neutral; （3） the surface roughness of TiB2/Al MMCs is smaller than that of non-reinforced alloy under the same cutting speed, but reverse result was observed when the feed rate increased; （4） a multi-objective optimization model for surface roughness and material removal rate （MRR） was established, and a set of optimal parameter combinations of the machining was obtained. The results show a great difference from SiC particle reinforced MMCs and provide a useful guide for a better control of machining process of this material.

关键词： Machinability Machining Metal matrix composites Parameter optimization TiB2 particles

Influence of leading edge with real manufacturing error on aerodynamic performance of high subsonic compressor cascades

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Chinese Journal of Aeronautics 2021年第6期34卷 220-232页

作者： Chi MA Limin GAO Haohao WANG Ruiyu LI Baohai WU School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National Key Laboratory of Aerodynamic design and Research Xi'an 710129China Key Laboratory of contemporary design and Integrated Manufacturing Technology of Ministry of Education Northwestern Polytechnical UniversityXi'an 710072China

To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compressor *** the limited samples,the leadingedge angle and leading-edge radius distribution forms were evaluated by Shapiro-Wilk test and quantile–quantile *** statistical characteristics provided can be introduced to later related *** parameterization design method B-spline and Bezier are adopted to create geometry models with manufacturing error based on leading-edge angle and leading-edge *** influence of real manufacturing error is quantified and analyzed by self-developed non-intrusive polynomial chaos and Sobol’*** mechanism of leading-edge manufacturing error on aerodynamic performance is *** results show that the total pressure loss coefficient is sensitive to the leading-edge manufacturing error compared with the static pressure ratio,especially at high ***,manufacturing error of the leading edge will influence the local flow acceleration and subsequently cause fluctuation of the downstream *** aerodynamic performance is sensitive to the manufacturing error of leading-edge radius at the design and negative incidences,while it is sensitive to the manufacturing error of leading-edge angle under the operation conditions with high incidences.

关键词： Aerodynamic performance Compressor cascade Limited measurement data Manufacturing error Uncertainty analysis

Research on Preschoolers’Comprehension of Safety Signs and Its Influencing Factors

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Journal of contemporary Educational Research 2024年第9期8卷 84-91页

作者： Na Qi Yuntao Li Jiehong Ding School of Art and design Xihua UniversityChengdu 610039Sichuan ProvinceChina Ruilian Kindergarten Changzhou 213011Jiangsu ProvinceChina

As an integral part of children’s safety education,safety signs hold significant importance for preschoolers’*** study aims to investigate the comprehension level of safety signs and its influencing factors among preschoolers and explore the role of background factors such as safety education in children’s learning of safety ***-seven preschoolers participated in the questionnaire investigation on 11 safety *** results were encoded by a binary method and subjected to descriptive analysis and multiple correspondence *** results indicated that preschoolers can understand symbols,but there is a certain degree of *** existing thematic education fails to improve their understanding of safety *** study provides a theoretical basis for improving and optimizing child safety education.

关键词： Preschoolers Safety signs Safety education

Stress analysis and damage evolution in individual plies of notched composite laminates subjected to in-plane loads

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Chinese Journal of Aeronautics 2017年第1期30卷 447-460页

作者： Hu Junshan Zhang Kaifu Cheng Hui Liu Ping Zou Peng Song Danlong The Ministry of Education Key Lab of contemporary design and Integrated Manufacturing Technology Northwestern Polytechnical University Xi'an 710072 China School of Mechanical Engineering Northwestern Polytechnical University Xi'an 710072 China

This work aims to investigate local stress distribution, damage evolution and failure of notched composite laminates under in-plane loads. An analytic method containing uniformed boundary equations using a complex variable approach is developed to present layer-by-layer stresses around the notch. The uniformed boundary equations established in series together with conformal mapping functions are capable of dealing with irregular boundary issues around the notch and at infinity. Stress results are employed to evaluate the damage initiation and propagation of notched composites by progressive damage analysis（PDA）. A user-defined subroutine is developed in the finite element（FE） model based on coupling theories for mixed failure criteria and damage mechanics to efficiently investigate damage evolution as well as failure modes. Carbon/epoxy laminates with a stacking sequence of [45°/0°/ 60°/90°]sare used to investigate surface strains, in-plane load capacity and microstructure of failure zones to provide analytic and FE methods with strong validation. Good agreement is observed between the analytic method, the FE model and experiments in terms of the stress（strain） distributions, damage evaluation and ultimate strength, and the layerby-layer stress components vary according to a combination effect of fiber orientation and loading type, causing diverse failure modes in individuals.

关键词： Damage evolution Failure mode Failure strength Layer-by-layer stresses User-defined subroutine

Integrated importance measure for multi-state coherent systems of k level

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Journal of Systems Engineering and Electronics 2013年第6期24卷 1029-1037页

作者： Xibin Zhao Shubin Si Hongyan Dui Zhiqiang Cai Shudong Sun Key Laboratory for Information System Security of Ministry of Education School of SoftwareTsinghua University Ministry of Education Key Laboratory of contemporary design and Integrated Manufacturing Technology School of MechatronicsNorthwestern Polytechnical University

To verify the effectiveness of the integrated importance measure （IIM） for multi-state coherent systems of k level, the definition and physical meaning of IIM are demonstrated. Then, the improvement potential and Δ-importance measures are generalized to multi-state coherent systems based on the system performance level, and the relationships between IIM and traditional importance measures are discussed. The characteristics of IIM are demonstrated in both series and parallel systems. Also, an application to an oil transportation system is given. The comparison results show that：（i） IIM has some useful properties that are not possessed by traditional importance measures; （ii） IIM is effective in evaluating the component role in multi-state systems when the component reliability and the failure rate are simultaneously considered.

关键词： multi-state coherent system system performance level integrated importance measure system reliability

Four-axis trochoidal toolpath planning for rough milling of aero-engine blisks

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Chinese Journal of Aeronautics 2019年第8期32卷 2009-2016页

作者： Ming LUO Ce HAH Hafiz M.HAFEEZ Key Laboratory of contemporary design and Integrated Manufacturing Technology(Northwestern Polytechnical University) Ministry of EducationXi’an 710072China Beijing Jingdiao Group Co. Ltd.Beijing 102308China

The Blade Integrated Disk(Blisk) is one of the key components in the aero-engine, it is generally manufactured by the multi-axis milling and almost 90% raw materials are removed. To avoid the full immersion of a cutter in the rough machining of a blisk channel, the trochoidal milling is a promising strategy since it can keep a small immersion angle in the rough milling process while maintaining the high machining efficiency. However, while toolpaths are being planned for the trochoidal milling process, the conventional methods are mainly for the planar machining area with fixed tool orientations, which cannot be used for complex channels where the multi-axis machining should be employed. To this end, this paper presents a four-axis trochoidal toolpath planning method with a ball-end cutter, and thus the blisk channel can be machined *** this to happen, the trochoidal paths are planned in the parametric domain and then mapped into the physical domain, with tool orientations controlled by the quaternion interpolation method to have smooth tool movement along the toolpaths. Both geometric simulation and physical milling experiments of the proposed method have convincingly demonstrated the validation of the proposed method.

关键词： Aero-engine Blisk Machining Toolpath planning Trochoidal milling