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Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

Frontiers of Mechanical Engineering 2022年第4期17卷 163-180页

作者： Sen YIN Yan BAO Yanan PAN Zhigang DONG Zhuji JIN Renke KANG Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments.In this study,a high-performance ultrasonic elliptical vibration cutting(UEVC)system is developed to solve the precision machining problem of tungsten heavy alloy.A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed,and its design process is greatly simplified.The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes.A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus,which is verified by finite element method.The vibration unit can display different three-degree-of-freedom(3-DOF)UEVC characteristics by adjusting the corresponding position of the unit and workpiece.A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit,which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2μm.Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system,which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词： tungsten heavy alloy ultrasonic elliptical vibration cutting Timoshenko’s theory resonant mode of bending finite element method

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Mechanical properties of tungsten heavy alloy and damage behaviors after hypervelocity impact

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Rare Metals 2014年第4期33卷 414-418页

作者： Zhe Wu Yang Zhang Chun-Mei Yang Qian-Jun Liu College of Mechanical and Electrical Engineering Northeast Forestry University College of Science Northeast Forestry University

93W-4.5Ni-l.5Fe-lCo （W） was prepared by powder metallurgic method, and then dynamic mechanical properties of this material were tested at high temperature by means of high-temperature split Hopkinson pressure bar （SHPB）. The results show that the material possesses high- dynamic mechanical properties, significant temperature effects, and strain hardening behaviors. Used two-stage light gas gun, the penetration test of 93W projectile was finished. After the completion of the test, through the microstructure observation of the residual 93W projectiles with the aid of scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, it can be found that there are obvious signs of hot melt existing on the surface of the projectile, a lot of adiabatic shear bands inside the projectile, and microcracks exist at the end of adiabatic shear bands. The test results show that adiabatic shear is the main form to cause the projectile failure and it is the emergence of the adiabatic shearing phenomenon that makes 93W display good self-sharpening property in the process of hypervelocity penetration. At the same time, the results of TEM observation show that there are high- density dislocations at the interface between W and Ni-Fe- Co-based alloy inside the 93W.

关键词： tungsten heavy alloy Dynamic compression Mechanical properties Adiabatic shear band

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Application of the Backpropagation Neural Network Method in Designing tungsten heavy alloy

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Journal of Beijing Institute of Technology 2006年第4期15卷 478-482页

作者：张朝晖王玮洁王富耻李树奎 School of Material Science and Technology Beijing Institute of Technology Beijing 100081 China

The model describing the dependence of the mechanical properties on the chemical composition and as deformation techniques of tungsten heavy alloy is established by the method of improved the backpropagation neural network. The mechanical properties＇ parameters of tungsten alloy and deformation techniques for tungsten alloy are used as the inputs. The chemical composition and deformation amount of tungsten alloy are used as the outputs. Then they are used for training the neural network. At the same time, the optimal number of the hidden neurons is obtained through the experiential equations, and the varied step learning method is adopted to ensure the stability of the training process. According to the requirements for mechanical properties, the chemical composition and the deformation condition for tungsten heavy alloy can be designed by this artificial neural network system.

关键词： tungsten heavy alloy material design backpropagation （BP） neural network

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Ultrashort-time liquid phase sintering of high-performance fine-grain tungsten heavy alloys by laser additive manufacturing

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Journal of Materials Science & Technology 2021年第31期90卷 30-36页

作者： Shangcheng Zhou Yao-Jian Liang Yichao Zhu Benpeng Wang Lu Wang Yunfei Xue School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China

Liquid phase sintering(LPS)is a proven technique for preparing large-size tungsten heavy alloys(WHAs).However,for densification,this processing requires that the matrix of WHAs keeps melting for a long time,which simultaneously causes W grain coarsening that degenerates the performance.This work develops a novel ultrashort-time LPS method to form bulk high-performance fine-grain WHAs based on the principle of laser additive manufacturing(LAM).During LAM,the high-entropy alloy matrix(Al_(0.5)Cr_(0.9)FeNi_(2.5)V_(0.2))and W powders were fed simultaneously but only the matrix was melted by laser and most W particles remained solid,and the melted matrix rapidly solidified with laser moving away,producing an ultrashort-time LPS processing in the melt pool,i.e.,laser ultrashort-time liquid phase sintering(LULPS).The extreme short dwell time in liquid(-1/10,000 of conventional LPS)can effectively suppress W grain growth,obtaining a small size of 1/3 of the size in LPS WHAs.Meanwhile,strong convection in the melt pool of LULPS enables a nearly full densification in such a short sintering time.Compared with LPS WHAs,the LULPS fine-grain WHAs present a 42%higher yield strength,as well as an enhanced susceptibility to adiabatic shear banding(ASB)that is important for strong armor-piercing capability,indicating that LULPS can be a promising pathway for forming high-performance WHAs that surpass those prepared by conventional LPS.

关键词： tungsten heavy alloy Laser additive manufacturing Liquid phase sintering

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Prediction and optimization of machining forces using oxley’s predictive theory and RSM approach during machining of WHAs

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Defence Technology（防务技术） 2019年第6期15卷 923-935页

作者： Chithajalu Kiran Sagar Tarun Kumar Amrita Priyadarshini Amit Kumar Gupta Mechanical Engineering Department BITS-PilaniHyderabad Campus

tungsten heavy alloys have come up as one of the best alternatives for high density fragmenting devices and armor piercing ammunition.Machining is mandatory for obtaining the final shapes of such kind of ammunitions.However,due to high density and elastic stiffness of WHAs,cutting forces will be higher than for most of the metals and alloys;thus,making the machining operation challenging.The machining variable,namely,cutting force components are significantly influenced by the cutting parameters.This paper makes use of Oxley’s predictive analytical model in conjunction with Johnson-Cook constitutive equation to predict forces under different speed and feed combinations during machining of 95 W tungsten heavy alloy.The cutting forces,so predicted by Ml,are considered as input data for the optimization of cutting parameters(cutting speed and feed)using Response Surface Method(RSM).

关键词： tungsten heavy alloy Machinability Response surface method Oxley’s method

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