Performance of Rock-like Materials Containing Filled Kinked Fissures under Uniaxial Tension at Failure

Yulin Wu,Qianqian Dong,Jian He,Qiyang Chen 대한토목학회 2023 KSCE JOURNAL OF CIVIL ENGINEERING Vol.27 No.3

To investigate the tensile failure phenomenon of rock masses with filled natural defects, the mechanical behavior of 3D printed rock-like materials containing filled kinked fissures under uniaxial tension was identified. Different inclination angles of branch fissure were considered, and cement and gypsum slurry were selected as the infilling materials. It was found that filling materials enhanced the strength of the specimen, which presented to be cement filling > gypsum filling > no filling. The change of inclination angle of branch fissure had significant influence on the strength and failure mode of the specimen and the strength order was -135o> -45o > 90o and +45o > 90o > +135o. Two types of failure pattern, namely tip failure and non-tip failure, were observed in the experiment. Three types of newborn cracks were identified using a high-speed camera. The result achieved by using the digital image correlation technology indicated that different filling conditions led to the position change of high-strain zone. The displacement field of the filled specimen developed from being continuous to being discontinuous. Furthermore, the extended finite element method was adopted to simulate the filled and unfilled specimens, consistent with the experimental results. This study can provide a reliable reference for studying the tensile stress zones in rock exploration.

An Analysis Framework for Characterization of Electrical Power Data in Machining

Yulin Wang,Yan He,Yufeng Li,Ping Yan,Libin Feng 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Electrical power data of machining has become more and more vital due to the increasing concerns on the energy efficiency. As a kind of easily available real-time signal, electrical power data in machining involves diverse characteristics related to technical specification and operational production of machine tools and workpieces. To efficiently exploit the various characteristics involved in electrical power data, this paper proposes a framework to analyze characteristics of electrical power data in machining. Firstly, the sample experiment for turning the round stock on a lathe is carried out to investigate the characteristics implied in the real-time electrical power data. Based on it, a framework is derived to analyze characteristics from three aspects, energy-specific characteristic of machining, state-specific characteristic of machine tools and operation-specific characteristic of workpieces. The case with three scenarios is presented to demonstrate the potential applications of the framework, which is effectively utilized in analyzing energy consumption of machining, monitoring states of machine tools and automatically identifying the types of machining workpieces.

중국의 물-에너지-식량 종합 이용 효율성을 평가 연구

LU YULIN,HE YAN 한국디지털정책학회 2022 디지털정책학회지 Vol.1 No.2

2011년, 세계경제포럼(The World Economic Forum)은 물-에너지-식량을 세계 3대 위험군에 포함했다. 물-에너지- 식량은 국가의 발전 전략과 국민의 삶과 관계된다. 본 연구에서는 SBM-Malmquist 지수를 기반으로 중국의 2011-2020년 물-에너지-식량 종합 이용 효율성을 계산한다. 측정 결과를 살펴보면, 중국 전체 물-에너지-식량의 종합 이용은 효율성이 낮으 나 상승세를 보였다. 전국적으로 물-에너지-식량 종합 이용 효율성은 뚜렷한 차별성이 존재하며 전반적으로 동부> 중부> 서부 의 지리적 분포 구도를 보인다. 전국에 Beijing과 Shanghai만 진정한 유효에 이르고 기타 각 성의 투입과 산출 사이에는 모두 비효율 상태가 존재한다. 물-에너지-식량 종합 이용 효율성의 Malmquist 지수는 1.136으로 상승세를 보이며 기술효율과 기술 진보를 통해 중국의 물-에너지-식량 종합 이용 효율성의 향상을 이끌고 있다. 하루빨리 물-에너지-식량 문제에 있어 전략적 높이를 끌어올려 그 발전에 대한 정책적 지원을 해야 한다. 각 지역은 지역 간 조율기구를 설립해야 하며 각 성의 식량 생산량, 수자원 분포 등 문제에 따라 맞춤형 조치를 제정해 경제가 조방형 발전에서 녹색 발전으로 전환되도록 조속히 추진해야 한다. The World Economic Forum has included Water-Energy-Food among the three major risk groups in the world, and Water-Energy-Food is related to the development strategies of countries and the lives of their citizens. This study calculates the combined Water-Energy-Food use efficiency in China for 2011-2020 based on the SBM-Malmquist index. The results show that the overall combined Water-Energy-Food efficiency in China is low, but shows an upward trend. There is a clear variability in the combined Water-Energy-Food utilization efficiency in China, with an overall geographic distribution pattern of East > Middle > West. Only Beijing and Shanghai have reached the real above effective nationwide, and all other provinces have inefficiency between input and output. The Malmquist index of integrated Water-Energy-Food utilization efficiency is 1.136, with an up ward trend, and technical efficiency and technological progress lead the improvement of integrated Water-Energy-Food utilization efficiency in China at the sametime. The Water-Energy-Food issue should be raised to a strategic level as soon as possible, and policy support should be provided for its development. Each region should establish a cross-regional coordinating body to formulate targeted measures according to the province's food production and water distribution, so as to promote economic transformation from sloppy development to green development as soon as possible.

An Octree-Based Two-Step Method of Surface Defects Detection for Remanufacture

Yan He,Wen Ma,Yufeng Li,Chuanpeng Hao,Yulin Wang,Yan Wang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.2

Accurate and quick detection has a significant bearing on overall productivity of remanufacture. 3D scanning technologies have been widely applied in defects detection by comparing the damaged model with the nominal model. In this process, a huge amount of point cloud data is required to ensure detection accuracy whereas resulting in large storage space and long processing time of detection. This paper proposed an efficient two-step method based on octree to detect defects accurately and quickly for remanufacturing. In this method, the damaged point cloud and the nominal point cloud are first registered. Then a two-step detection approach is developed to extract the surface defects, coarse detection and detailed extraction, where the octree method is applied to create an effective topology of discrete points and perform the Boolean operation for defects extraction. In coarse detection, rough location and size information of the defects are acquired from the whole point cloud data. Based on coarse detected boundary box containing defects, the detailed extraction step is applied to extract corresponding defects shape accurately. The feasibility of proposed method was validated by using a case to detect defects of a damaged turbine blade and the detection results can be used to generate restoration tool path. The results show that the proposed method outperforms state-of-art defects detection methods, which can reduce time by 74.03% and reduce error by 36.86%, respectively.

Reliability of mortar filling layer void length in in-service ballastless track-bridge system of HSR

Binbin He,Sheng Wen,Yulin Feng,Lizhong Jiang,Wangbao Zhou 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.1

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train submodel was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h – 350 km/h train running speed, the limit values of grade Ⅰ, Ⅱ, and Ⅲ of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

DEA-Malmquist 지수를 이용한 중국 환경효율에 관한 평가 연구

LU YULIN,HE YAN 한국디지털정책학회 2022 디지털융복합연구 Vol.20 No.5

The DEA-BCC model. And the Malmquist index have been used, from static and dynamic perspectives, to measure the eco-efficiency of 30 cities and provinces in China from 2011 to 2020. The results shows that: the average static eco-efficiency of 30 cities and provinces in China is 0.643. Differences exists all over China. While Shanghai and Beijing are ecologically efficient, other 28 cities and provinces are faced with different extents of inefficiency. There are also differences among regions, which generally show the spatial distribution pattern with high efficiency in the eastern regions while low in the western regions. The Malmquist index of eco-efficiency in total 30 cities and provinces shows a healthy growth trend, and the technological progress. Acts as its main driving force. Therefore, eastern regions should enhance the. radiation capacity, strengthen the synergy among regions, give full play to. The advantages of each regions. It is sensible to improve the eco-efficiency by means of optimizing the industrial structure, enhancing the technological level and improving eco-efficiency of China and realizing green development. 본 연구는 중국 30개 성시를 연구 대상으로 하여 정태적, 동태적 두 가지 각도에서 연구의 시발점으로 하였으며, DEA-BCC 모델과 Malmquist 지수를 사용하여 2011~2020년 중국 30개 성시의 환경 효율성을 산정하였다. 연구에 따르면 중국 30개 성시의 정태 환경 효율성은 평균 0.643으로 전국 범위에서 뚜렷한 차이를 보인다. Beijing, Shanghai는 환경 효율성이 유효하고 나머지 28개 성시는 모두 차원이 다른 비효율 상태를 가지고 있다. 구역발전에서도 차별성이 있어 전반적으로 동고서저형 공간 구도를 보인다. 전국 30개 성시의 환경 효율성인 Malmquist 지수는 상승하는 성장세를 보이며 기술진보가 주요한 추진력이 된다. 향후 정책에서는 동부지역의 방사선 견인능력을 높이고 각 구역 간 시너지를 강화하여 구역 우위를 충분히 발휘해야 할 것이다. 그리고 산업구조 최적화, 과학기술 수준 제고, 전국 환경 효율성의 상승을 견인하여 녹색 발전을 실현한다.

Mechanism for the formation of α-Al₂O₃ and black CuO within the soft sparking coatings on Al-Cu-Li alloy by plasma electrolytic oxidation

Xiaorui He,Tian Feng,Yulin Cheng,Panfeng Hu,Zhengzhou Le,Zihua Liu,Yingliang Cheng 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

Helical gear multi-contact tooth mesh load analysis with flexible bearings and shafts

Chengwu Li,Yulin He,Xianxiong Ning 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.4

A multi-contact tooth meshing model for helical gear pairs considering bearing and shaft deformations is proposed. First, to easily incorporate into the system model, the complicated Harris’ bearing force-displacement relationship is simplified applying a linear least square curve fit. Then, effects of shaft and bearing flexibilities on the helical gear meshing behavior are implemented through transformation matrices which contain the helical gear orientation and spatial displacement under loads. Finally, true contact lines between conjugated teeth are approximated applying a modified meshing equation that includes the influence of tooth flank displacement on the tooth contact induced by shaft and bearing displacements. Based on the model, the bearing’s force-displacement relation is examined, and the effects of shaft deformation and external load on the multi-contact tooth mesh load distribution are also analyzed. The advantage of this work is, unlike previous works to search true contact lines through time-consuming iterative strategy, to determine true contact lines between conjugated teeth directly with presentation of deformations of bearings and shafts.

Analysis on natural vibration characteristics of steel-concrete composite truss beam

Lizhong Jiang,Yulin Feng,Wangbao Zhou,Binbin He 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.1

In order to study the natural vibration characteristics of steel-concrete composite truss beam (SCCTB), the influence of multiple factors such as interface slip, shear deformation and moment of inertia are considered. Afterwards, based on the Hamilton principle the vibration control differential equation and natural boundary conditions of SCCTB are deduced. By solving SCCTB differential equations of vibration control, an analytical calculation method is proposed for analyzing the natural vibration characteristics of SCCTB. The natural frequencies of SCCTBs with different degrees of shear connection and effective lengths are calculated by using the analytical method, and the results are compared against those obtained from ANSYS finite element numerical calculation method. The results show that the analytical method considering the influence factors such as interface slip, shear deformation and moment of inertia are in good agreement with those obtained from ANSYS finite element numerical calculation method. This evidences the correctness of the analytical method and show that the method proposed exhibits improvement over the previously developed theories for the natural vibration characteristics of SCCTB. Finally, based on the analytical method, the influence factors of SCCTB natural vibration characteristics are analyzed. The results indicate that the influence of interface slip stiffness on SCCTB's natural frequency is more than 10% and therefore cannot be neglected. Moreover, shear deformation has an effect of more than 35% on SCCTB’s natural frequency and the effect cannot be ignored either in this case too.

Vibration characteristic analysis of high-speed railway simply supported beam bridge-track structure system

Lizhong Jiang,Yulin Feng,Wangbao Zhou,Binbin He 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.6

Based on the energy-variational principle, a coupling vibration analysis model of high-speed railway simply supported beam bridge-track structure system (HSRBTS) was established by considering the effect of shear deformation. The vibration differential equation and natural boundary conditions of HSRBTS were derived by considering the interlayer slip effect. Then, an analytic calculation method for the natural vibration frequency of this system was obtained. By taking two simply supported beam bridges of high-speed railway of 24 m and 32 m in span as examples, ANSYS and MIDAS finite-element numerical calculation methods were compared with the analytic method established in this paper. The calculation results show that two of them agree well with each other, validating the analytic method reported in this paper. The analytic method established in this study was used to evaluate the natural vibration characteristics of HSRBTS under different interlayer stiffness and length of rails at different subgrade sections. The results show that the vertical interlayer compressive stiffness had a great influence on the high-order natural vibration frequency of HSRBTS, and the effect of longitudinal interlayer slip stiffness on the natural vibration frequency of HSRBTS could be ignored. Under different vertical interlayer stiffness conditions, the subgrade section of HSRBTS has a critical rail length, and the critical length of rail at subgrade section decreases with the increase in vertical interlayer compressive stiffness.