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Crack propagation and damage evolution of metallic cylindrical shells under internal explosive loading

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DEFENCE technolOGY 2024年第9期39卷 133-146页

作者： Luo, Yusong Li, Weibing Li, Junbao Li, Wenbin Wang, Xiaoming nanjing univ sci & technol ZNDY Ministerial Key Lab Nanjing 210094 Peoples R China

This paper investigates the three-dimensional crack propagation and damage evolution process of metallic column shells under internal explosive loading. The calibration of four typical failure parameters for 40CrMnSiB steel was conducted through experiments and subsequently applied to simulations. The numerical simulation results employing the four failure criteria were compared with the differences and similarities observed in freeze-recovery tests and ultra-high-speed tests. This analysis addressed the critical issue of determining failure criteria for the fracture of a metal shell under internal explosive loads. Building upon this foundation, the damage parameter Dc, linked to the cumulative crack density, was defined based on the evolution characteristics of a substantial number of cracks. The relationship between the damage parameter and crack velocity over time was established, and the influence of the internal central pressure on the damage parameter and crack velocity was investigated. Variations in the fracture modes were found under different failure criteria, with the principal strain failure criterion proving to be the most effective for simulating 3D crack propagation in a pure shear fracture mode. Through statistical analysis of the shell penetration fracture radius data, it was determined that the fracture radius remained essentially constant during the crack evolution process and could be considered a constant. The propagation velocity of axial cracks ranged between 5300 m/s and 12600 m/s, surpassing the Rayleigh wave velocity of the shell material and decreasing linearly with time. The increase in shell damage exhibited an initial rapid phase, followed by deceleration, demonstrating accelerated damage during the propagation stage of the blast wave and decelerated damage after the arrival of the rarefaction wave. This study provides an effective approach for investigating crack propagation and damage evolution. The derived crack propagation and damag

关键词： Internal explosive loading Failure criterion Crack propagation Damage evolution Freeze-recovery test INTERMEDIATE PHASE SHEAR-BAND STEEL FRAGMENTATION DEFORMATION MECHANISM

Design and grindability assessment with cup shaped electroplated CBN wheel grinding turbine disc slots of powder metallurgy superalloy FGH96

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CHINESE JOURNAL OF AERONAUTICS 2024年第9期37卷 521-534页

作者： Li, Benkai Ding, Wenfeng Zhu, Yejun Li, Changhe Zhang, Yanbin Yang, Min Ma, Xiao Liu, Mingzheng Cui, Xin Qingdao univ technol Sch Mech Engn Qingdao 266520 Peoples R China nanjing univ Aeronaut & Astronaut Natl Key Lab Sci & Technol Helicopter Transmiss Nanjing 210016 Peoples R China nanjing Agr univ Coll Engn Nanjing 210031 Peoples R China

The machining surface integrity of aero-engine turbine disc slots has a significant impact on their fatigue life and service performance, and achieving efficiency and high-precision machining is still a great challenge. The high machining requirements of future aeroengine turbine disc slots will be difficult to satisfy using the broaching method. In addition, existing methods of slot machining face difficulties in ensuring surface integrity. This study explored a cup shaped electroplated Cubic Boron Nitride (CBN) abrasive wheel for profile grinding the turbine disc slots of FGH96 powder metallurgy superalloy. The matrix structure of the cup shaped abrasive wheel was designed and verified. A profile grinding experiment was conducted for fir-tree slots on a five-axis machining center. The accuracy and the surface integrity were analyzed. Results show that the key dimension detection results of the slots were within the allowable tolerance range. Meanwhile, an average surface roughness Ra of 0.55 lm was achieved, the residual stress was compressive, the plastic deformation layer thickness was less than 5 lm, and the hardening layer thickness was less than 20 lm. The research findings provide a new approach to machining the slots of aviation engine turbine discs and guidance for the high-quality processing of complex components. (c) 2023 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics.

关键词： Profile grinding Surface integrity Cup shaped CBN abrasive wheel Turbine disc slots FGH96 OF-THE-ART SURFACE INTEGRITY DYNAMIC RECRYSTALLIZATION FATIGUE SPEED MANUFACTURE PARAMETERS MECHANISM ALLOYS TOOLS

Study on the coupling calculation method for the launch dynamics of a self-propelled artillery multibody system considering engraving process

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DEFENCE technolOGY 2024年第9期39卷 67-85页

作者： Zhang, Shujun Rui, Xiaoting Yu, Hailong Dong, Xiaoli nanjing univ sci & technol Inst Launch Dynam Nanjing 210094 Peoples R China Natl Key Lab Complex Multibody Syst Dynam Nanjing 210094 Peoples R China

The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics, capable of addressing the challenges of complex modeling, diminished computational efficiency, and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems, such as self-propelled artillery. This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery. Recognizing the shortfall of overlooking the band engraving process in existing theories, this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system. This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery. Additionally, it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process. Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery, thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery. (c) 2024 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Self-propelled artillery Engraving process Multibody system dynamics Launch dynamics TRANSFER-MATRIX METHOD PROJECTILE 155 MM SIMULATION

Demonstration of LDPC-coded PS-64QAM OFDM employing novel bit-class distribution matching in a W-band RoF system

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CHINESE OPTICS LETTERS 2024年第8期22卷 080602-080602页

作者： Zhao, Haitao Xu, Bangning Xun, Wei Ren, Jianxin Chen, Shuaidong Zhang, Long Zhao, Li Liu, Bo nanjing univ Posts & Telecommun Sch Commun & Informat Engn Nanjing 210003 Peoples R China Fudan univ Key Lab Informat Sci Electromagnet Waves MoE Shanghai 200433 Peoples R China nanjing univ Informat sci & technol Inst Opt & Elect Nanjing 210044 Peoples R China

In this work, we proposed and experimentally demonstrated a novel probabilistic shaping (PS) 64-ary quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) with low-density parity-check (LDPC)-coded modulation in a W-band radio-over-fiber (RoF) system using envelope detection. The proposed PS scheme has the advantages of no complex multiplication and division operations and low hardware implementation complexity. In our experiments, the two-stage bit weight distribution matching-based PS-64QAM OFDM signals with a rate of 28.13 Gb/s transmission over 4 m wireless + 45-km standard single-mode fiber transmission can be achieved. The system performance is investigated under one LDPC code rate (3/4) and two PS parameter values (k k = 3 and 9). The experimental results show that the receiver power sensitivity and the system fiber nonlinear effect tolerance can be significantly improved compared with uniformly distributed OFDM signals.

关键词： probabilistic shaping two-stage bit weight distribution matching orthogonal frequency division multiplexing W-band radio-over-fiber system TRANSMISSION FIBER

Microfluidic preparation of surfactant-free ultrafine DAAF with tunable particle size for insensitive initiator explosives

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DEFENCE technolOGY 2024年第9期39卷 42-52页

作者： Yang, Bo Li, Rui Cao, Wei He, Si-min Zhu, Jincan Wu, Qi Ding, Heng Chen, Jin Wang, Weimiao Qiao, Zhiqiang Li, Xiaodong Yang, Guangcheng China Acad Engn Phys Inst Chem Mat Mianyang 621900 Peoples R China nanjing univ sci & technol Sch Chem Engn Nanjing 210094 Peoples R China Southwest univ sci & technol Mianyang 621010 Peoples R China

High purity and ultrafine DAAF (u-DAAF) is an emerging insensitive charge in initiators. Although there are many ways to obtain u-DAAF, developing a preparation method with stable operation, accurate control, good quality consistency, equipment miniaturization, and minimum manpower is an inevitable requirement to adapt to the current social technology development trend. Here reported is the microfluidic preparation of u-DAAF with tunable particle size by a passive swirling microreactor. Under the guidance of recrystallization growth kinetics and mixing behavior of fluids in the swirling microreactor, the key parameters (liquid flow rate, explosive concentration and crystallization temperature) were screened and optimized through screening experiments. Under the condition that no surfactant is added and only experimental parameters are controlled, the particle size of recrystallized DAAF can be adjusted from 98 nm to 785 nm, and the corresponding specific surface area is 8.45 m(2)g(-1) to 1.33 m(2)g(-1). In addition, the preparation method has good batch stability, high yield (90.8%-92.6%) and high purity (99.0%-99.4%), indicating a high practical application potential. Electric explosion derived flyer initiation tests demonstrate that the u-DAAF shows an initiation sensitivity much lower than that of the raw DAAF, and comparable to that of the refined DAAF by conventional spraying crystallization method. This study provides an efficient method to fabricate u-DAAF with narrow particle size distribution and high reproducibility as well as a theoretical reference for fabrication of other ultrafine explosives. (c) 2024 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Microfluidic preparation Screening crystallization conditions Narrow particle size distribution Low initiation sensitivity Ultrafine DAAF ASSISTED PRECIPITATION ENERGETIC MATERIALS SOL-GEL SIMULATION PLATFORM CL-20 HNS

Hybrid-integrated 200 Gb/s REC-DML array transmitter based on photonic wire bonding technology

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CHINESE OPTICS LETTERS 2024年第8期22卷 081401-081401页

作者： Ma, Yuxin Zhao, Jie Yang, Tongtong Mei, Yipeng Sun, Zhenxing Lu, Jun Li, Shaobo Ma, Xiang Chen, Xiangfei nanjing univ Key Lab Intelligent Opt Sensing & Manipulat Minist Educ Nanjing 210023 Peoples R China nanjing univ Natl Lab Solid State Microstruct Nanjing 210023 Peoples R China nanjing univ Coll Engn & Appl Sci Nanjing 210023 Peoples R China nanjing univ Inst Opt Commun Engn Nanjing 210023 Peoples R China nanjing univ Nanjing Univ Tongding Joint Lab Large Scale Photon Nanjing 210023 Peoples R China China Elect technol Grp Corp Res Inst 54 Opt Commun Res & Dev Ctr Shijiazhuang 050081 Peoples R China

An 8-channel hybrid-integrated chip for 200 Gb/s (8 x 25 Gb/s) signal transmission has been demonstrated. The channels are all within the O-band, and with a spacing of 800 GHz. The core of this chip is a monolithic integrated multi-wavelength laser array of 8 directly-modulated distributed feedback (DFB) lasers. By using the reconstruction equivalent chirp technique, multi-wavelength integration and asymmetric phase shift structures are achieved in the laser array. The output laser beams of the array are combined by a planar light-wave circuit, which is hybrid-integrated with the laser array by photonic wire bonding. Experiment results of this transmitter chip show good single-mode working of each unit laser, with a side- mode suppression ratio above 50 dB, and the modulation bandwidth is above 20 GHz. Clear eye diagrams are obtained in the lasers for 25 Gb/s non-return-to-zero modulation, which implies a total 200 Gb/s transmission rate for the whole chip.

关键词： direct modulation laser array reconstruction equivalent chirp photonic wire bonding hybrid integration LASER ARRAY SEMICONDUCTOR-LASER

Constitutive model of viscoelastic dynamic damage for the material of gas obturator in modular-charge howitzer

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DEFENCE technolOGY 2024年第9期39卷 203-216页

作者： Li, Zhonggang Chen, Longmiao Li, Yifan Jia, Yufeng Zhang, Quan nanjing univ sci & technol Sch Mech Engn Nanjing 210094 Peoples R China Shanxi North Machine Bldg Co Ltd Technol Ctr Taiyuan 030009 Peoples R China Kelong New Mat technol Co Ltd Res & Dev Dept Xianyang 712000 Peoples R China

In order to investigate the mechanical response behavior of the gas obturator of the breech mechanism, made of polychloroprene rubber (PCR), uniaxial compression experiments were carried out by using a universal testing machine and a split Hopkinson pressure bar (SHPB), obtaining stress-strain responses at different temperatures and strain rates. The results revealed that, in comparison to other polymers, the gas obturator material exhibited inconspicuous strain softening and hardening effects; meanwhile, the mechanical response was more affected by the strain rate than by temperature. Subsequently, a succinct viscoelastic damage constitutive model was developed based on the ZWT model, including ten undetermined parameters, formulated with incorporating three parallel components to capture the viscoelastic response at high strain rate and further enhanced by integrating a three-parameter Weibull function to describe the damage. Compared to the ZWT model, the modified model could effectively describe the mechanical response behavior of the gas obturator material at high strain rates. This research laid a theoretical foundation for further investigation into the influence of chamber sealing issues on artillery firing. (c) 2024 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Breech mechanism Gas obturator Polychloroprene rubber Constitutive model Strain rate Damage STRAIN RATES WIDE-RANGE POLYMERS BEHAVIOR PRESSURE

Supplementation with dimethylglycine sodium salt improves lipid metabolism disorder in intrauterine growth-retarded pigs

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ANIMAL NUTRITION 2024年第3期18卷 191-202页

作者： Bai, Kaiwen Jiang, Luyi Wang, Tian Zhejiang univ sci & technol Sch Biol & Chem Engn Hangzhou 310023 Peoples R China nanjing Agr univ Coll Anim Sci & Technol Nanjing 210095 Peoples R China Zhejiang Shuren univ Coll Biol & Environm Engn Hangzhou 310023 Peoples R China Zhejiang univ Inst Dairy Sci Coll Anim Sci Minist EducKey Lab Mol Anim Nutr Hangzhou Peoples R China

This study aims to elucidate the mechanism of lipid metabolism disorder in intrauterine growth retardation (IUGR) pigs and the potential alleviating effects of dimethylglycine sodium salt (DMG-Na). A total of 60 male newborn piglets were selected for this study. Within each litter, one normal birth weight (NBW) male piglet (1.53 +/- 0.04 kg) and two IUGR male piglets (0.76 +/- 0.06 kg) were chosen based on their birth weight. The piglets were divided into three groups for the study: NBW pigs received a PBS gavage and a common basal diet (NBW-C group), IUGR pigs received the same PBS gavage and common basal diet (IUGR-C group), and IUGR pigs received a 70-mg DMG-Na gavage along with a common basal diet supplemented with 0.1% DMG-Na (IUGR-D group). At 150 d of age, all piglets underwent euthanasia by exsanguination following electrical stunning, after which plasma, liver, and longissimus dorsi (LM) samples were promptly collected. The IUGR-D group demonstrated improvements in plasma parameters (P < 0.05), with lower triglyceride and free fatty acid (FFA) values, and hormone levels (P < 0.05), with lower growth hormone, insulin, and homeostasis model assessment of insulin resistance values. Restoration of lipid metabolism was observed (P < 0.05), with lower triglyceride and FFA, and higher hepatic lipase and total lipase values in the liver, and lower triglyceride and FFA values in the LM. Mitochondrial ETC complexes showed increased levels (P < 0.05), including higher complex III values in the liver, and higher complex I, complex III, and complex V values in the LM. Enhanced levels of energy metabolites were noted (P < 0.05), with higher NAD & thorn;, NAD & thorn;/NADH, adenosine triphosphate, and mtDNA values, and lower NADH values in the liver and LM. Additionally, meat quality parameters showed improvement (P < 0.05), with higher pH 24 h and a* values, and lower drip loss 48 h, L*, and b* values. The expressions of lipid metabolism and mitochondrial function-relate

关键词： Intrauterine growth retardation Pig Lipid metabolism Mitochondrial function Dimethylglycine sodium salt SKELETAL-MUSCLE MITOCHONDRIAL DYSFUNCTION PROMOTES

Microstructure development of Ti scaffold by laser powder bed fusion with chemical polishing and its mechanical properties, biocompatibility

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BIOSURFACE AND BIOTRIBOLOGY 2024年第2期10卷 52-62页

作者： Lu, Changfu Chen, Jing Ma, Teng Chen, Yuxin Zeng, Da Gan, Yiliang Yang, Youwen Double Med technol Inc Xiamen Peoples R China Jiangxi univ sci & technol Inst Addit Mfg Nanchang Peoples R China Tongling univ Key Lab Construct Hydraul Robots Anhui Higher Educ Tongling Peoples R China nanjing univ Coll Engn & Appl Sci Nanjing Peoples R China

Titanium (Ti) dental scaffolds are widely used in dental prosthetics due to their excellent mechanical properties and biocompatibility. However, conventional Ti scaffolds manufactured through machining often do not fit perfectly with the bone defect site. Laser powder bed fusion (LPBF) technology enables the personalised manufacturing of custom-made Ti scaffolds. A custom-made Ti scaffold was prepared using LPBF and its surface roughness was improved through chemical polishing. To enhance the surface roughness, a nitric acid mixed solution with a specific composition of HF: HNO3:C3H6O3 = 2:2:3 was used. The polishing mechanism was investigated by adjusting the F/Ti ratio to control the formation and dissolution of the oxide film. As a result, the surface of the Ti scaffold after polishing exhibited a smooth and flat appearance compared to the LPBF part, with a reduced surface roughness (Ra) of 1.23 +/- 0.19 mu m. The custom-made Ti scaffold also demonstrated favourable mechanical properties, with a bending strength of 335.18 +/- 33.62 MPa and stiffness of 2.13 +/- 0.21 GPa. Furthermore, in vitro cell tests confirmed the excellent biocompatibility of the custom-made Ti scaffold. The authors present a feasible strategy for the further clinical application of custom-made Ti scaffolds, offering enhanced surface properties and addressing the limitations of conventional machining methods.

关键词： additive manufacturing dental material property surface roughness GUIDED BONE REGENERATION ALLOY OPTIMIZATION PARAMETERS MEMBRANE BEHAVIOR