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On the applicability of different adhesion models in adhesive particulate flows

Guanqing LIU, Shuiqing LI, Qiang YAO,

《能源前沿（英文）》 2010年第4卷第2期页码 280-286 doi: 10.1007/s11708-009-0062-5

摘要： An adhesion map provides quantitative criteria for the appropriate selection of adhesion models applicable to a specific adhesive contact problem of fine particles in complex particulate flows. In this paper, three different general adhesion models are used to construct adhesion maps. The applicable regimes on the adhesion map for different approximate adhesion models are determined according to their underlying limitations. It is found that the choice of general model has limited influence on the structure of a constructed adhesion map. On the contrary, the regime of application for each approximate model is sensitive to the approximation level. A three-dimensional, more intuitive adhesion map based on physical parameters of particles is also built. Finally, recent applications of adhesion models in discrete element method (DEM) investigations of fine-particle flow dynamics are briefly discussed.

关键词： adhesive contact van der Waals force adhesion model adhesion map DEM

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Calculating frictional force with considering material microstructure and potential on contact surfaces

XU Zhongming, HUANG Ping

《机械工程前沿（英文）》 2007年第2卷第4期页码 474-477 doi: 10.1007/s11465-007-0082-y

摘要： A method based on the energy dissipation mechanism of an Independent Oscillator model is used to calculate the frictional force and the friction coefficient of interfacial friction. The friction work is calculated with considering the potential change of contact surfaces during sliding. The potential change can be gained by a universal adhesive energy function. The relationships between frictional force and parameters of a tribo-system, such as surface energy and microstructure of interfacial material, are set up. The calculation results of the known experimental data denote that the frictional force is nearly proportional to the surface energy of the material, nearly inversely proportional to the scaling length, and independent of the lattice constant. The results agree with that of adhesion friction equations. They also agree with the experimental results performed with an atomic-force microscope under the ultra high vacuum condition.

关键词： coefficient dissipation mechanism universal adhesive interfacial Independent Oscillator

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Severe adhesive small bowel obstruction

null

《医学前沿（英文）》 2012年第6卷第4期页码 436-439 doi: 10.1007/s11684-012-0221-7

摘要：

Adhesive small bowel obstruction is a frequent cause of hospital admission. Water soluble contrast studies may have diagnostic and therapeutic value and avoid challenging demanding surgical operations, but if bowel ischemia is suspected, prompt surgical intervention is mandatory. A 58-year-old patient was operated for extensive adhesive small bowel obstruction after having had two previous laparotomies for colorectal surgery, and had a complex clinical course with multiple operations and several complications. Different strategies of management have been adopted, including non-operative management with the use of hyperosmolar water soluble contrast medium, multiple surgical procedures, total parenteral nutrition (TPN) support, and finally use of anti-adherences icodextrin solution. After 2 years follow-up the patient was doing well without presenting recurrent episodes of adhesive small bowel obstruction. For patients admitted several times for adhesive small bowel obstruction, the relative risk of recurring obstruction increases in relation to the number of prior episodes. Several strategies for non-operative conservative management of adhesive small bowel obstruction have already addressed diagnostic and therapeutic value of hyperosmolar water soluble contrast. According to the most recent evidence-based guidelines, open surgery is the preferred method for surgical treatment of strangulating adhesive small bowel obstruction as well as after failed conservative management. Research interest and clinical evidence are increasing in adhesions prevention. Hyaluronic acid-carboxycellulose membrane and icodextrin may reduce incidence of adhesions.

关键词： post-operative intraperitoneal adhesions adhesive small bowel obstruction adhesiolysis antiadhesion treatments hyperosmolar water soluble contrast medium

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Learning from biological attachment devices: applications of bioinspired reversible adhesive methods

《机械工程前沿（英文）》 2022年第17卷第3期 doi: 10.1007/s11465-022-0699-x

摘要： Many organisms have attachment organs with excellent functions, such as adhesion, clinging, and grasping, as a result of biological evolution to adapt to complex living environments. From nanoscale to macroscale, each type of adhesive organ has its own underlying mechanisms. Many biological adhesive mechanisms have been studied and can be incorporated into robot designs. This paper presents a systematic review of reversible biological adhesive methods and the bioinspired attachment devices that can be used in robotics. The study discussed how biological adhesive methods, such as dry adhesion, wet adhesion, mechanical adhesion, and sub-ambient pressure adhesion, progress in research. The morphology of typical adhesive organs, as well as the corresponding attachment models, is highlighted. The current state of bioinspired attachment device design and fabrication is discussed. Then, the design principles of attachment devices are summarized in this article. The following section provides a systematic overview of climbing robots with bioinspired attachment devices. Finally, the current challenges and opportunities in bioinspired attachment research in robotics are discussed.

关键词： adhesion bioinspired attachment biomimetic gripper climbing robot

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Thin-liquid-film evaporation at contact line

Hao WANG, Zhenai PAN, Zhao CHEN

《能源前沿（英文）》 2009年第3卷第2期页码 141-151 doi: 10.1007/s11708-009-0020-2

摘要： When a liquid wets a solid wall, the extended meniscus near the contact line may be divided into three regions: a nonevaporating region, where the liquid is adsorbed on the wall; a transition region or thin-film region, where effects of long-range molecular forces (disjoining pressure) are felt; and an intrinsic meniscus region, where capillary forces dominate. The thin liquid film, with thickness from nanometers up to micrometers, covering the transition region and part of intrinsic meniscus, is gaining interest due to its high heat transfer rates. In this paper, a review was made of the researches on thin-liquid-film evaporation. The major characteristics of thin film, thin-film modeling based on continuum theory, simulations based on molecular dynamics, and thin-film profile and temperature measurements were summarized.

关键词： meniscus thin film contact line disjoining pressure evaporation

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Modelling of dynamic contact length in rail grinding process

null

《机械工程前沿（英文）》 2014年第9卷第3期页码 242-248 doi: 10.1007/s11465-014-0305-y

摘要：

Rails endure frequent dynamic loads from the passing trains for supporting trains and guiding wheels. The accumulated stress concentrations will cause the plastic deformation of rail towards generating corrugations, contact fatigue cracks and also other defects, resulting in more dangerous status even the derailment risks. So the rail grinding technology has been invented with rotating grinding stones pressed on the rail with defects removal. Such rail grinding works are directed by experiences rather than scientifically guidance, lacking of flexible and scientific operating methods. With grinding control unit holding the grinding stones, the rail grinding process has the characteristics not only the surface grinding but also the running railway vehicles. First of all, it’s important to analyze the contact length between the grinding stone and the rail, because the contact length is a critical parameter to measure the grinding capabilities of stones. Moreover, it’s needed to build up models of railway vehicle unit bonded with the grinding stone to represent the rail grinding car. Therefore the theoretical model for contact length is developed based on the geometrical analysis. And the calculating models are improved considering the grinding car’s dynamic behaviors during the grinding process. Eventually, results are obtained based on the models by taking both the operation parameters and the structure parameters into the calculation, which are suitable for revealing the process of rail grinding by combining the grinding mechanism and the railway vehicle systems.

关键词： rail grinding contact length dynamic model Hamiltonian system grinding stone rail grinding car

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Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact

Houxin SHE, Chaofeng LI, Qiansheng TANG, Hui MA, Bangchun WEN

《机械工程前沿（英文）》 2020年第15卷第1期页码 133-150 doi: 10.1007/s11465-019-0557-7

摘要： This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system. The procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact interface. Thereafter, the computed nonlinear parameters are applied to rebuild the matrices of the coupling system, which can be easily solved to calculate the nonlinear mode characteristics by standard iterative solvers. Lastly, the derived method is applied to a cycle symmetry system, which represents a shaft–disk–blade system subjected to dry friction. Moreover, this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode characteristics. Numerical results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.

关键词： coupling vibration nonlinear mode original algorithm contact interface

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Towards Cr(VI)-free anodization of aluminum alloys for aerospace adhesive bonding applications: A review

Shoshan T. Abrahami, John M. M. de Kok, Herman Terryn, Johannes M. C. Mol

《化学科学与工程前沿（英文）》 2017年第11卷第3期页码 465-482 doi: 10.1007/s11705-017-1641-3

摘要： For more than six decades, chromic acid anodizing (CAA) has been the central process in the surface pre-treatment of aluminum for adhesively bonded aircraft structures. Unfortunately, this electrolyte contains hexavalent chromium (Cr(VI)), a compound known for its toxicity and carcinogenic properties. To comply with the new strict international regulations, the Cr(VI)-era will soon have to come to an end. Anodizing aluminum in acid electrolytes produces a self-ordered porous oxide layer. Although different acids can be used to create this type of structure, the excellent adhesion and corrosion resistance that is currently achieved by the complete Cr(VI)-based process is not easily matched. This paper provides a critical overview and appraisal of proposed alternatives to CAA, including combinations of multiple anodizing steps, pre- and post anodizing treatments. The work is presented in terms of the modifications to the oxide properties, such as morphological features (e.g., pore size, barrier layer thickness) and surface chemistry, in order to evaluate the link between fundamental principles of adhesion and bond performance.

关键词： aluminum Cr(VI)-free surface pre-treatments anodizing adhesive bonding

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Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

《机械工程前沿（英文）》 2013年第8卷第2期页码 150-159 doi: 10.1007/s11465-013-0266-6

摘要：

The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

关键词： brake disks heat flux heat-transfer coefficient Von Mises stress contact pressure

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Experimental study and numerical simulation on compressive buckling behavior of thin steel skins in unilateral contact

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

《结构与土木工程前沿（英文）》 2011年第5卷第3期页码 335-343 doi: 10.1007/s11709-011-0121-y

摘要： In this paper, a practical test and finite element analysis has been undertaken to further investigate the effects of contact buckling. A test rig was designed and constructed to record vertical and transverse deflections of compressively loaded steel skin plates. The boundary conditions were modeled as fully fixed. A finite element analysis was also undertaken using the software package Strand7. Results from both analyses have been examined and compared to data established from previous studies on contact buckling. Both the finite element analysis and practical results correlate well with this data. The result of the investigation has confirmed contact buckling theories and has foreshadowed the onset of the newly observed phenomenon of secondary contact buckling.

关键词： compressive buckling thin steel skins unilateral contact rigid constraints

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非连续接触下滚圈的接触压力及疲劳寿命预测

时彧,肖友刚,雷先明

《中国工程科学》 2006年第8卷第7期页码 54-57

摘要：

建立了非连续接触下筒体-滚圈接触压力的计算模型，得出了滚圈弯矩及弯曲应力计算公式。应用名义应力法和局部应力应变法，建立了滚圈疲劳寿命预测模型。通过实例分析，得出了如下结论：通过调窑，将滚圈的最大支承载荷控制在2500kN以内，能显著提高滚圈的疲劳寿命；在传统设计中，将滚圈支承角定为30°不合理；存在一个最佳滚圈支承角，此时滚圈疲劳寿命最大。

关键词：滚圈接触压力支承角疲劳寿命

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Performance of a hybrid anaerobic-contact oxidation biofilm baffled reactor for the treatment of decentralized

Minmin LIU,Ying ZHAO,Beidou XI,Li’an HOU,Xunfeng XIA

《环境科学与工程前沿（英文）》 2014年第8卷第4期页码 598-606 doi: 10.1007/s11783-013-0576-2

摘要： A novel hybrid anaerobic-contact oxidation biofilm baffled reactor (HAOBR) was developed to simultaneously remove nitrogenous and carbonaceous organic pollutants from decentralized molasses wastewater in the study. The study was based on the inoculation of anaerobic granule sludge in anaerobic compartments and the installation of combination filler in aerobic compartments. The performance of reactor system was studied regarding the hydraulic retention time (HRT), microbial characteristics and the gas water ratio (GWR). When the HRT was 24h and the GWR was 20:1, total ammonia and chemical oxygen demand (COD) of the effluent were reduced by 99% and 91.8%, respectively. The reactor performed stably for treating decentralized molasses wastewater. The good performance of the reactor can be attributed to the high resistance of COD and hydraulic shock loads. In addition, the high solid retention time of contact oxidation biofilm contributed to stable performance of the reactor.

关键词： combination filler contact oxidation biofilm food wastewater anaerobic baffled reactor

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A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication

null

《机械工程前沿（英文）》 2014年第9卷第2期页码 156-167 doi: 10.1007/s11465-014-0297-7

摘要：

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication (EHL) problems is presented. First, by introducing a special matrix splitting iteration method into the traditional compound direct iterative method, the full matrices for the linear systems of equations are transformed into sparse banded ones with any half-bandwidth; then, an extended Thomas method which can solve banded linear systems with any half-bandwidth is derived to accelerate the computing speed. Through the above two steps, the computational complexity of each iteration is reduced approximately from O(N3/3) to O(β2N), where N is the total number of nodes, and β is the half-bandwidth. Two kinds of numerical results of transient EHL line contact problems under sinusoidal excitation or pure normal approach process are obtained. The results demonstrate that the new algorithm increases computing speed several times more than the traditional compound direct iterative method with the same numerical precision. Also the results show that the new algorithm can get the best computing speed and robustness when the ratio, half-bandwidth to total number of nodes, is about 7.5%–10.0% in moderate load cases.

关键词： elastohydrodynamic lubrication transient line contact matrix splitting iteration method the Thomas method

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Contact of surfaces and contact characteristics of offset surfaces

CAO Lixin, GONG Hu, LIU Jian

《机械工程前沿（英文）》 2008年第3卷第3期页码 318-324 doi: 10.1007/s11465-008-0067-5

摘要： Based on differential geometry, the contact problems of two surfaces are discussed in this paper. The relationship between the contact status of two surfaces and that of offset surfaces are also analyzed. For a 5-axis NC machining, some research such as optimization of cutter location and calculation of the geometrical cusp height are important. The research results indicate that the relative normal curvature is an important geometrical invariant for describing the contact state of two surfaces. For point contact two surfaces, the calculation equation for the second order remained error is given. For line contact two surfaces, the condition of the second order line contact is that the principal directions and curvatures of the two surfaces are the same along the contact curve. If two surfaces keep the second order line contact, their two offset surfaces will also keep the second order line contact, and their third order remained errors are also uniform with that of the two offset surfaces.

关键词： relative important geometrical relationship geometrical invariant calculation

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Experimental and numerical study on microcrack detection using contact nonlinear acoustics

Xiaojia CHEN, Yuanlin WANG

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 137-141 doi: 10.1007/s11709-009-0028-z

摘要： This paper introduces a non-classical nonlinear acoustic theory for microcrack detection in materials, comparing contact nonlinearity with material nonlinearity. The paper’s main work concentrates on the experimental and numerical verification of the effectivity of contact nonlinear acoustic detection by using the contact nonlinear parameter , which can be represented by the ratio of the second-harmonic amplitude to the square of the first-harmonic amplitude. Both experiments and numerical tests are performed. The results show that is sensitive to the initiation of microcracks and varies with the development of the microcracks. The numerical test illustrates the decline of when microcracks penetrate each other.

关键词： microcrack detection contact nonlinearity numerical analysis