Drilling Machinability Evaluation on New Developed High-strength T800S/250F CFRP Laminates

Jinyang Xu,Ming Chen,Qinglong An,Xiaojiang Cai 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

The new developed high-strength CFRP laminates are widely employed in varieties of applications and are mainly used in main loadbearing structural components of large commercial aircrafts. Drilling is one of the important operations in manufacturing composite structure, often a final operation during assembly. Defects such as burrs and delamination in drilling of CFRP are always serious problems and lead to rejection and impose heavy loss. In the present research, the machinability of a new developed high-strength T800S/250F CFRP laminate is evaluated by using CVD coated twist drill and CVD coated dagger drill. The machinability was investigated in terms of drilling forces, burr defect, hole wall surface morphology and delamination damage. The results indicate that feed rate is the most significant factor affecting the machined surface finish followed by the spindle speed. The dagger drill showed excellent drilling performance than the twist drill and was more suitable for drilling of T800S/250F CFRP laminate. The results also highlight the importance of employing the high speed drilling to minimize the drilling-induced defects.

Self-healing capacity of damaged rock salt with different initial damage

Chen, Jie,Kang, Yanfei,Liu, Wei,Fan, Jinyang,Jiang, Deyi,Chemenda, Alexandre Techno-Press 2018 Geomechanics & engineering Vol.15 No.1

In order to analyze the healing effectiveness of rock salt cracks affected by the applied stresses and time, we used the ultrasonic technology to monitor the ultrasonic pulse velocity (UPV) variations for different initial stress-damaged rock salts during self-healing experiments. The self-healing experiments were to create different conditions to improve the microcracks closure or recrystallized, which the self-healing effect of damaged salt specimens were analyzed during the recovery period about 30 days. We found that: The ultrasonic pulse velocity of the damaged rock salts increases rapidly during the first 9 days recovery, and the values gradually increase to reach constant values after 30 days. The damaged value and the healed value were identified based on the variation of the wave velocity. The damaged values of the specimens that are subject to higher initial damage stress are still keeping in large after 30 days recovery under the same recovery condition It is interesting that the damage and the healing were not in the linear relationship, and there also existed a damage threshold for salt cracks healing ability. When the damage degree is less than the threshold, the self-healing ratio of rock salt is increased with the increase in damage degree. However, while the damage degree exceeds the threshold, the self-healing ratio is decreased with the increase in damage.

Biochar Amendment Effects on Nitrous Oxide and Net Greenhouse Gas Balance from an Acidic Vegetable Field In Southeast China

Jinyang Wang,Zhaozhi Chen,Yakov Kuzyakov,Zhengqin Xiong 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

The mechanical properties of rock salt under cyclic loading-unloading experiments

Chen, Jie,Du, Chao,Jiang, Deyi,Fan, Jinyang,He, Yi Techno-Press 2016 Geomechanics & engineering Vol.10 No.3

Rock salt is a near-perfect material for gas storage repositories due to its excellent ductility and low permeability. Gas storage in rock salt layers during gas injection and gas production causes the stress redistribution surrounding the cavity. The triaxial cyclic loading and unloading tests for rock salt were performed in this paper. The elastic-plastic deformation behaviour of rock salt under cyclic loading was observed. Rock salt experienced strain hardening during the initial loading, and the irreversible deformation was large under low stress station, meanwhile the residual stress became larger along with the increase of deviatoric stress. Confining pressure had a significant effect on the unloading modulus for the variation of mechanical parameters. Based on the theory of elastic-plastic damage mechanics, the evolution of damage during cyclic loading and unloading under various confining pressure was described.

A Coupling Method of Response Surfaces (CRSM) for Cutting Parameters Optimization in Machining Titanium Alloy under Minimum Quantity Lubrication (MQL) Condition

Zhiqiang Liu,Ming Chen,Jinyang Xu,Shu Han 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

This paper presents a new flexible method referring to coupling response surface methodology (CRSM) to acquire optimum cutting parameters in machining of difficult-to-cut titanium alloy under minimum quantity lubrication (MQL) condition. Cutting speed, feed rate and depth of cut are designed as three factors by using the Taguchi method, which are also subject to several constraints including processing efficiency, cutting force and surface quality. In addition, turning experiments of titanium alloy were performed in order to set up the model based on Taguchi experimental design and multiple regression method. ANOVA was carried out to prove the adequacy of the developed mathematical model and the influences of cutting parameters on constraints were also observed. The results indicated that the feed rate was the dominant factor affecting surface roughness and cutting forces, which were minimized when the feed rate and depth of cut were set to the lowest level, while cutting speed was set to the highest level. Moreover, the predicted values obtained by CRSM were in good agreement with the experimental values, which indicated that CRSM was an effective method to determine optimum cutting conditions for machining process under MQL condition.

Modulation method of parallel interleaved three‑level inverter considering neutral point potential and phase current balance

Ying Zhong,Weichao Li,Liang Zhou,Chen Deng,Jinyang Han 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.2

The capacity and equivalent switching frequency of parallel interleaved inverters can be increased, but there are problems with neutral point potential balance and parallel bridge circulating current. This paper regards the parallel three-level inverter as a five-level inverter and five-level space vector integrated modulation is applied. On this basis, a neutral-point potential control strategy based on the mid-point charge to calculate the adjustment factor k is proposed. By further meticulously partitioning specific sector regions, the selection method of redundant vectors in the switching sequence is optimized without increasing the switching times, and the midpoint voltage ripple is reduced. Then, the redundant state allocation in the process of splitting the five-level into three-level is used as a new degree of freedom to suppress the circulating current of the parallel bridge, therefore realizing the control of voltage and current sharing. Finally, simulation and experiments verify the correctness and effectiveness of the method.

Preparation and Study on Thermal Conductive Composites of Chlorinated Polyethylene Rubber Reinforced by Boron Nitride Particles

Junjie Shu,Ru Xia,Jiasheng Qian,JIBIN MIAO,LIFEN SU,Ming Cao,Hongyun Lin,Peng Chen,Jinyang Chen 한국고분자학회 2016 Macromolecular Research Vol.24 No.7

The composites of chlorinated polyethylene rubber (CM) filled with boron nitride (BN) were prepared and examined systematically. Scanning electron microscopy (SEM) was used to observe microscopic morphology of composites. Mechanical properties of composites were analyzed by a rubber process analyzer (RPA) and dynamic mechanical thermal analyzer (DMTA). Thermal conductivity as well as thermo stability of composites was improved by adding BN particles into the CM rubber. It was found that BN particles can reinforce the rubber matrix while they also break down the network of polymer chains and ruin the physical properties of the rubber matrix. During the dynamic compressing process, BN particles can transfer heat from the matrix and alleviate the heat build-up phenomenon. The BN/CM composites (volume content CBN=18%) with thermal conductivity 1.179 W/(m·K) and good flexibility (Elongation at break=320%) were prepared, which may be used as thermal interface materials in a dynamic compressing process.

Equilibrium, kinetic and mechanism studies on the biosorption of Cu2+ and Ni2+ by sulfur-modified bamboo powder

Tian Ai,Xiaojun Jiang,Hongmei Yu,Hong-Bo Xu,Dawei Pan,Qingyu Liu,Dongyu Chen,Jinyang Li 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.2

Two biosorbents were prepared using bamboo powder modified with mercaptoacetic acid and carbondisulfide, which exhibits strong adsorption properties for Cu2+ and Ni2+. The obtained materials were characterized byFTIR. Maximum adsorption for both metals was found to occur around pH 5.0-6.5. The kinetic data followed thepseudo-second-order model. The maximum adsorption capacities of Cu2+ and Ni2+ on mercaptoacetic acid modifiedbamboo powder determined from Langmuir isotherm were 103.97mg g−1 and 61.35mg g−1, respectively. While oncarbon disulfide modified bamboo powder were 128.21mg g−1 and 56.82mg g−1, respectively. The adsorption mechanismanalysis revealed that the most possible adsorption mode of Cu2+ was coordination, and Ni2+ was ion exchange. The obtained adsorbents could effectively remove Cu2+ and Ni2+ from industrial electroplating wastewater and could beused repeatedly for more than five cycles.