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Probing the effect of thickener microstructure on rheological and tribological properties of grease
Changjiang Zhou,Guanlin Ren,Xiaoqiang Fan,Yunyan Lv 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-
The thickener microstructure strongly determines the properties of lubricating grease. Here, four types ofgrease were synthesized through different thickeners (lithium complex soap, polyurea, calcium sulfonatecomplex soap, bentonite), thickening polyalphaolefin. The influence of the thickener microstructure onthe physicochemical, rheological, and tribological properties was evaluated. Results show that thelithium complex soap with a spiral fiber structure shows the best physicochemical properties and thehighest yield stress. The four greases show the shear-thinning behavior because of the deformation ofthe thickener structures. The calcium sulfonate complex soap with a dense porous structure presentsoptimal tribological properties because of the synergy effect of the thickener deposited film and thetribo-chemical reaction film.
Nonlinear wind-induced instability of orthotropic plane membrane structures
Changjiang Liu,Feng Ji,Zhoulian Zheng,Yuyou Wu,Jianjun Guo 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5
he nonlinear aerodynamic instability of a tensioned plane orthotropic membrane structure is theoretically investigated in this paper. The interaction governing equation of wind-structure coupling is established by the Von Kármán\'s large amplitude theory and the D\'Alembert\'s principle. The aerodynamic force is determined by the potential flow theory of fluid mechanics and the thin airfoil theory of aerodynamics. Then the interaction governing equation is transformed into a second order nonlinear differential equation with constant coefficients by the Bubnov-Galerkin method. The critical wind velocity is obtained by judging the stability of the second order nonlinear differential equation. From the analysis of examples, we can conclude that it\'s of great significance to consider the orthotropy and geometrical nonlinearity to prevent the aerodynamic instability of plane membrane structures; we should comprehensively consider the effects of various factors on the design of plane membrane structures; and the formula of critical wind velocity obtained in this paper provides a more accurate theoretical solution for the aerodynamic stability of the plane membrane structures than the previous studies.
Coupling of the 2D microtopography of tooth surface and transmission error
Changjiang Zhou,Zhonghua Wang,Siyu Chen 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.2
This paper provides a method coupling the 2D microtopography filtered by ISO Gaussian filter of spur gears, which is typically used in power transmission devices, and Transmission error (TE) together. A gearbox with certain transmission ratio is selected as a research object for analysis. This gearbox comprises a mathematical model of TE calculation based on the Monte Carlo method and the coordinate transformation method, which couples the 2D microtopography of spur gears and TE. Two TE models are established to study their effects on the coupling results: a) The single TE model, which means only one gear owns TE, and b) the synthetic TE model, which means both gears possess TE. The new model of the 2D microtopography of tooth surfaces can be utilized further to investigate the mechanism of engagement and the approximate contact position of asperities on the tooth surface. The new model is also significant in studying the tooth root bending stress.
Involutory and s+1-potency of linear combinations of a tripotent matrix and an arbitrary matrix
Changjiang Bu,Yixin Zhou 한국전산응용수학회 2011 Journal of applied mathematics & informatics Vol.29 No.1
Let A_1 and A_2 be n × n nonzero complex matrices, denote a linear combination of the two matrices by A = c_1A_1 + c_2A_2, where c_1, c_2 are nonzero complex numbers. In this paper, we research the problem of the linear combinations in the general case. We give a sufficient and necessary condition for A is an involutive matrix and s+1-potent matrix, respectively, where A_1 is a tripotent matrix, with A_1A_2 = A_2A_1. Then, using the results, we also give the sufficient and necessary conditions for the involutory of the linear combination A, where A_1 is a tripotent matrix, anti-idempotent matrix, and involutive matrix, respectively, and A_2 is a tripotent matrix, idempotent matrix, and involutive matrix, respectively, with A_1A_2 = A_2A_1..
Changjiang Shao,Jiann-wen Woody Ju,Guoqing Han,Yongjiu Qian 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.5
To determine the seismic applicability of a long-span railway concrete upper-deck arch bridge with concrete-filled steel-tube (CFST) rigid skeleton ribs, some fundamental principles and seismic approaches for long-span bridges are investigated to update the design methods in the current Code for Seismic Design of Railway Engineering of China. Ductile and mixed isolation design are investigated respectively to compare the structural seismic performances. The flexural moment and plastic rotation demands and capacities are quantified to assess the seismic status of the ductile components. A kind of triple friction pendulum (TFP) system and lead-plug rubber bearing are applied simultaneously to regularize the structural seismic demands. The numerical analysis shows that the current ductile layout with continuous rigid frame approaching spans should be strengthened to satisfy the demands of rare earthquakes. However, the mixed isolation design embodies excellent seismic performances for the continuous girder approaching span of this railway arch bridge.
Nonlinear wind-induced instability of orthotropic plane membrane structures
Liu, Changjiang,Ji, Feng,Zheng, Zhoulian,Wu, Yuyou,Guo, Jianjun Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5
The nonlinear aerodynamic instability of a tensioned plane orthotropic membrane structure is theoretically investigated in this paper. The interaction governing equation of wind-structure coupling is established by the Von $K\acute{a}rm\acute{a}n's$ large amplitude theory and the D'Alembert's principle. The aerodynamic force is determined by the potential flow theory of fluid mechanics and the thin airfoil theory of aerodynamics. Then the interaction governing equation is transformed into a second order nonlinear differential equation with constant coefficients by the Bubnov-Galerkin method. The critical wind velocity is obtained by judging the stability of the second order nonlinear differential equation. From the analysis of examples, we can conclude that it's of great significance to consider the orthotropy and geometrical nonlinearity to prevent the aerodynamic instability of plane membrane structures; we should comprehensively consider the effects of various factors on the design of plane membrane structures; and the formula of critical wind velocity obtained in this paper provides a more accurate theoretical solution for the aerodynamic stability of the plane membrane structures than the previous studies.
INVOLUTORY AND S+1-POTENCY OF LINEAR COMBINATIONS OF A TRIPOTENT MATRIX AND AN ARBITRARY MATRIX
Bu, Changjiang,Zhou, Yixin The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.1
Let $A_1$ and $A_2$ be $n{\times}n$ nonzero complex matrices, denote a linear combination of the two matrices by $A=c_1A_1+c_2A_2$, where $c_1$, $c_2$ are nonzero complex numbers. In this paper, we research the problem of the linear combinations in the general case. We give a sufficient and necessary condition for A is an involutive matrix and s+1-potent matrix, respectively, where $A_1$ is a tripotent matrix, with $A_1A_2=A_2A_1$. Then, using the results, we also give the sufficient and necessary conditions for the involutory of the linear combination A, where $A_1$ is a tripotent matrix, anti-idempotent matrix, and involutive matrix, respectively, and $A_2$ is a tripotent matrix, idempotent matrix, and involutive matrix, respectively, with $A_1A_2=A_2A_1$.
High-Strength Model Material Production for Structural Plane Replica and Its Shear Testing
Feng Ji,Changjiang Liu,Yu Zhang,Luobing Zheng,Kai Pan,Xun Tan 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.1
Shear strength parameters (c, φ) of a structural plane are the key factors for the stability assessment of rock masses. The shear strength parameters are obtained by a structure plane shear test carried out in laboratory. However, it is difficult to obtain test samples with the same surface morphology and to remove the effect of surface irregularity from test results. Based on the similarity principle and orthogonal test, this paper presents a new model preparation method for structural planes using a high-strength mold mixture material. Firstly, the original morphology of the structural plane is recorded by in situ measurement using a laser device and then the mold of the structural plane is reproduced using a 3D printer. Subsequently, a mix proportion test of the high-strength mold material is conducted using the orthogonal test, and the model of the structural plane is prepared by pouring this high-strength mixture material into the 3D mold. Ultimately, the shear strength parameters of this high-strength structural plane replica are obtained using a shear box test in the laboratory. The proposed method has particular advantages such as the preparation of multiple replicas for structure planes and the ability to obtain repeatable results.