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Mechanical and geometric advantages in compliant mechanism optimization

Michael Yu WANG

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 229-241 doi: 10.1007/s11465-009-0066-1

摘要： This paper presents a focused examination of the mechanical and geometric advantages in compliant mechanisms and their ramifications in the design formulations of compliant mechanisms posed as a topology optimization problem. With a linear elastic structural analysis, we quantify mechanical (and geometric) advantage in terms of the stiffness elements of the mechanism's structure. We then analyze the common formulations of compliant mechanism optimization and the role of the external springs added in the formulations. It is shown that the common formulations using mechanical (or geometric) advantage would directly emulate at best a rigid-body linkage to the true optimum design. As a result, the topology optimization generates point flexures in the resulting optimal mechanisms. A case study is investigated to demonstrate the resulting trends in the current formulations.

关键词： compliant mechanisms     topology optimization     mechanical advantage     pseudo rigid-body mechanisms    

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Design and modeling of continuum robot based on virtual-center of motion mechanism

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0739-6

摘要： Continuum robot has attracted extensive attention since its emergence. It has multi-degree of freedom and high compliance, which give it significant advantages when traveling and operating in narrow spaces. The flexural virtual-center of motion (VCM) mechanism can be machined integrally, and this way eliminates the assembly between joints. Thus, it is well suited for use as a continuum robot joint. Therefore, a design method for continuum robots based on the VCM mechanism is proposed in this study. First, a novel VCM mechanism is formed using a double leaf-type isosceles-trapezoidal flexural pivot (D-LITFP), which is composed of a series of superimposed LITFPs, to enlarge its stroke. Then, the pseudo-rigid body (PRB) model of the leaf is extended to the VCM mechanism, and the stiffness and stroke of the D-LITFP are modeled. Second, the VCM mechanism is combined to form a flexural joint suitable for the continuum robot. Finally, experiments and simulations are used to validate the accuracy and validity of the PRB model by analyzing the performance (stiffness and stroke) of the VCM mechanism. Furthermore, the motion performance of the designed continuum robot is evaluated. Results show that the maximum stroke of the VCM mechanism is approximately 14.2°, the axial compressive strength is approximately 1915 N/mm, and the repeatable positioning accuracies of the continuum robot is approximately ±1.47° (bending angle) and ±2.46° (bending direction).

关键词： VCM mechanism     continuum robot     flexural joint     pseudo-rigid body model     cable-driven    

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Modeling of large-deflection links for compliant mechanisms

Zhonglei FENG, Yueqing YU, Wenjing WANG,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 294-301 doi: 10.1007/s11465-010-0019-8

摘要： The traditional pseudo-rigid-body model (PRBM) has one degree of freedom (DOF) and performs a good simulation to the tip locus of flexible links for compliant mechanisms on the basis of a parametric approximation method. In this study, a new approach of a two-DOF PRBM is proposed to simulate both the tip locus and tip deflection angle of large-deflection links for compliant mechanisms on the basis of the angular deflection approximation technique. A linear regression for the spring stiffness coefficient of the 2R PRBM using the optimization technique is presented. The advantage of the new model is well illustrated through a numerical comparison between the 1R and the 2R PRBM.

关键词： compliant mechanism     pseudo-rigid-body model (PRBM)     large-deflection link     angular deflection approximation    

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Numerical simulation of multi-body floating piers to investigate pontoon stability

Mostafa Shahrabi, Khosrow Bargi

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 325-331 doi: 10.1007/s11709-013-0209-7

摘要： The objective of this study is to develop a procedure to analyze the motions of a floating pier comprised of several pontoons that are modeled as rigid bodies and connected to each other by flexible and rigid connectors. Recently, the use offloating piers has increased because of their advantages, such as faster and higher-quality construction, seismic force isolation for a full-scale mooring system, low dependence on local soil conditions and tides, ability to relocate or reconfigure the pier modules during the operation period and 75-100 years of repair-free service. A floating pier consists of a pier, access bridge, mooring system and fender system, each of which comes in many variations to suit different usages and construction considerations. The typical loads used in the design of these piers are dead loads, live loads, mooring loads, fender loads and environmental loads induced by wind, currents and waves. For numerical simulation, three types of piers are used: passenger piers, light-cargo piers and semi-heavy-cargo piers. The selected piers consist of several large pontoons joined by pivots and have a pile-based mooring system. These piers are modeled by SAP2000software as two-dimensional frames that are linked together. As the first step, each type of pier is subjected to loading, and its general behavior is assessed. According to this behavior, the major load combinations are described for the design of piers and analyzed to determine the behavior of the modules. Lastly, according to the analysis results and the safe use and stability considerations, such as the maximum draft and longitudinal gradient, the dimensions of each module in each pier type are presented.

关键词： coastal structures     numerical simulation     floating pier     rigid pontoons     stability    

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Prevention and treatment of pancreatic fistula after pancreatic body and tail resection: current status

Li Jiang, Deng Ning, Xiaoping Chen

《医学前沿（英文）》 2020年 第14卷 第3期   页码 251-261 doi: 10.1007/s11684-019-0727-3

摘要： Postoperative pancreatic fistula (POPF) is the most common and critical complication after pancreatic body and tail resection. How to effectively reduce the occurrence of pancreatic fistula and conduct timely treatment thereafter is an urgent clinical issue to be solved. Recent research standardized the definition of pancreatic fistula and stressed the correlation between POPF classification and patient prognosis. According to the literature, identification of the risk factors for pancreatic fistula contributed to lowering the rate of the complication. Appropriate management of the pancreatic stump and perioperative treatment are of great significance to reduce the rate of POPF in clinical practice. After the occurrence of POPF, the treatment of choice should be determined according to the classification of the pancreatic fistula. However, despite the progress and promising treatment approaches, POPF remains to be a clinical issue that warrants further studies in the future.

关键词： pancreatic fistula     pancreatic body and tail resection     distal pancreatectomy    

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Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要： The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词： adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

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Laboratory experiment on using non-floating body to generate electrical energy from water waves

Arunachalam AMARKARTHIK, Srinivasan CHANDRASEKARAN, Karuppan SIVAKUMAR, Harender SINHMAR

《能源前沿（英文）》 2012年 第6卷 第4期   页码 361-365 doi: 10.1007/s11708-012-0210-1

摘要： This paper describes an innovative method of using a non-buoyant body to harness ocean waves. All the point absorbers are buoyant in nature and move up due to buoyancy and come down because of gravity. The point absorbers are designed to move along the waves to make the device efficient. These devices face excessive stress during the rough weather on account of the extreme motion of waves and cause the total device failure. The present study shows that using a non-buoyant body for conventional point absorber principle is much efficient and safer than any other device proposed till today. A small scale wave energy converter with non-buoyant body was designed, fabricated and tested in small scale wave maker. An electrical generator was coupled with the device to generate electrical energy from harnessed waves. The generator was electrically loaded and the generated power was measured. It was found from the experiments that the proposed device showed a significant improvement in electricity generation and safety during extreme conditions. In addition to the electricity generation, the characteristics of the device were also studied by using various wave and device parameters.

关键词： ocean wave energy     point absorbers     heaving body     non-floating object     heave response ratio     electrical energy generation    

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Lightweight design of an electric bus body structure with analytical target cascading

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0718-y

摘要： Lightweight designs of new-energy vehicles can reduce energy consumption, thereby improving driving mileage. In this study, a lightweight design of a newly developed multi-material electric bus body structure is examined in combination with analytical target cascading (ATC). By proposing an ATC-based two-level optimization strategy, the original lightweight design problem is decomposed into the system level and three subsystem levels. The system-level optimization model is related to mass minimization with all the structural modal frequency constraints, while each subsystem-level optimization model is related to the sub-structural performance objective with sub-structure mass constraints. To enhance the interaction between two-level systems, each subsystem-level objective is reformulated as a penalty-based function coordinated with the system-level objective. To guarantee the accuracy of the model-based analysis, a finite element model is validated through experimental modal test. A sequential quadratic programming algorithm is used to address the defined optimization problem for effective convergence. Compared with the initial design, the total mass is reduced by 49 kg, and the torsional stiffness is increased by 17.5%. In addition, the obtained design is also validated through strength analysis.

关键词： electric vehicle     body in white (BIW)     lightweight     analytical target cascading (ATC)    

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numerical simulation on compressive buckling behavior of thin steel skins in unilateral contact with rigid

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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Yesterday, Today and Future of the Engineering Management Body of Knowledge

Hiral Shah,Walter Nowocin

《工程管理前沿（英文）》 2015年 第2卷 第1期   页码 60-63 doi: 10.15302/J-FEM-2015009

摘要： Young engineers are often promoted to leadership roles such as a team leader or a manager within 3 to 6 years of graduating from an undergraduate degree in a technical area. To be competent and successful in their leadership role engineers need to update their engineering management knowledge and learn new skills. The purpose of engineering management body of knowledge (EMBOK) is to delineate the knowledge, skills, and competency areas that are applicable to the engineering management discipline. It basically answers the question, “What does it take to be an effective engineering manager?” The EMBOK is based on a validated study and can be used for curriculum development, certification exams, and professional development programs. This paper describes the 11 domains that are included in the EMBOK and discuss the future publication of the EMBOK Guide. American Society for Engineering Management (ASEM) offers two certification exams based on the EMBOK, Associate Engineering Manager (AEM) and Professional Engineering Manager (PEM).These certification exams can help an individual in the engineering management profession to show that they have kept up in the field and possess the necessary skills and competency to practice in the discipline. A detailed description of this certification program is included in this paper. The future of EMBOK and the certification program is also discussed.

关键词： body of knowledge     engineering management     certification exam     engineering manager     competency areas    

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New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Suman HAZARI, Sima GHOSH, Richi Prasad SHARMA

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1492-1508 doi: 10.1007/s11709-020-0679-3

摘要： Natural slopes consist of non-homogeneous soil profiles with distinct characteristics from slopes made of homogeneous soil. In this study, the limit equilibrium modified pseudo-dynamic method is used to analyze the stability of two-layered soil slopes in which the failure surface is assumed to be a logarithmic spiral. The zero-stress boundary condition at the ground surface under the seismic loading condition is satisfied. New formulations derived from an analytical method are proposed for the predicting the seismic response in two-layered soil. A detailed parametric study was performed in which various parameters (seismic accelerations, damping, cohesion, and angle of internal friction) were varied. The results of the present method were compared with those in the available literature. The present analytical analysis was also verified against the finite element analysis results.

关键词： layered soil     limit equilibrium method     seismic analysis     damping     PLAXIS    

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Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

《机械工程前沿（英文）》 2013年 第8卷 第3期   页码 291-297 doi: 10.1007/s11465-013-0255-9

摘要：

This work presents the existence of buckling mode switching with respect to the radius of concentric rigid ring support. The buckling mode may not be axisymmetric as previously assumed. In general, the plate may buckle in an axisymmetric mode but when the radius of the ring support becomes small, the plate may buckle in an asymmetric mode. The optimum radius of the concentric rigid ring support for maximum buckling load is also determined. Introducing internal rigid ring support, when placed at an optimal position increases the elastic buckling load capacity by 149.39 percent. The numerical results obtained are in good agreement with the previously published data.

关键词： buckling     circular plate     elastically restrained edge     rigid ring support     mode switching    

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导航卫星双向伪距时间同步

谭述森

《中国工程科学》 2006年 第8卷 第12期   页码 70-74

摘要：

针对卫星导航系统时间同步需求，提出了导航卫星双向伪距时间同步的理论根据，并就4种基本同步方法（双向无线电伪距同步方法, 星地双向激光伪距同步方法,双向卫星中继无线电伪距同步方法, 双向地球站中继无线电伪距同步方法）与应用进行了分析，与目前国际导航卫星时间同步通用方法相比,具有精度高, 方法简单，设备负担轻特点。

关键词： 导航卫星     伪距     时间同步    

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Finite element modeling of environmental effects on rigid pavement deformation

Sunghwan KIM,Halil CEYLAN,Kasthurirangan GOPALAKRISHNAN

《结构与土木工程前沿（英文）》 2014年 第8卷 第2期   页码 101-114 doi: 10.1007/s11709-014-0254-x

摘要： In this study, finite element (FE)-based primary pavement response models are employed for investigating the early-age deformation characteristics of jointed plain concrete pavements (JPCP) under environmental effects. The FE-based ISLAB (two-and-one-half-dimensional) and EverFE (three-dimensional) software were used to conduct the response analysis. Sensitivity analyses of input parameters used in ISLAB and EverFE were conducted based on field and laboratory test data collected from instrumented pavements on highway US-34 near Burlington, Iowa. Based on the combination of input parameters and equivalent temperatures established from preliminary studies, FE analyses were performed and compared with the field measurements. Comparisons between field measured and computed deformations showed that both FE programs could produce reasonably accurate estimates of actual slab deformations due to environmental effects using the equivalent temperature difference concept.

关键词： jointed plain concrete pavements (JPCP)     curling and warping     sensitivity analyses     rigid pavement analysis and design     finite element analysis (FEA)    

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Modeling of semi-rigid beam-to-column steel joints under extreme loading

C FANG, B A IZZUDDIN, A Y ELGHAZOULI, D A NETHERCOT

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 245-263 doi: 10.1007/s11709-013-0215-9

摘要： Joints play an important role in providing ductility for steel-composite structures subject to extreme loading conditions, such as blast, fire and impact. Due to sound energy dissipation capability and fabrication efficiency, semi-rigid joints have increasingly received attention during the last decade. This paper presents a component approach for modeling semi-rigid beam-to-column joints based on Eurocode3, where the post-elastic response, including component strain hardening and ultimate rotational capacity, is also considered. Failure criteria are defined based on the ultimate deformation capacity of components and bolt-rows. The model enables a direct integration of joint response into global frame models with the consideration of axial deformability, such that the interaction between bending moment and axial force within the joints can be realistically captured. In addition, elevated temperature can be considered in the joint model via the degradation of the component response. Through comparisons with available test data, the joint model is shown to have good accuracy, and the failure criteria are found to be reliable yet conservative. The strain hardening response of components is shown to have significant influence on the ultimate bending capacity of the joints, while neglecting it usually leads to a conservative prediction.

关键词： semi-rigid joint     component method     ductility     elevated temperature    

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标题 作者 时间 类型 操作

Mechanical and geometric advantages in compliant mechanism optimization

Michael Yu WANG

期刊论文

Design and modeling of continuum robot based on virtual-center of motion mechanism

期刊论文

Modeling of large-deflection links for compliant mechanisms

Zhonglei FENG, Yueqing YU, Wenjing WANG,

期刊论文

Numerical simulation of multi-body floating piers to investigate pontoon stability

Mostafa Shahrabi, Khosrow Bargi

期刊论文

Prevention and treatment of pancreatic fistula after pancreatic body and tail resection: current status

Li Jiang, Deng Ning, Xiaoping Chen

期刊论文

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

期刊论文

Laboratory experiment on using non-floating body to generate electrical energy from water waves

Arunachalam AMARKARTHIK, Srinivasan CHANDRASEKARAN, Karuppan SIVAKUMAR, Harender SINHMAR

期刊论文

Lightweight design of an electric bus body structure with analytical target cascading

期刊论文

numerical simulation on compressive buckling behavior of thin steel skins in unilateral contact with rigid

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

期刊论文

Yesterday, Today and Future of the Engineering Management Body of Knowledge

Hiral Shah,Walter Nowocin

期刊论文

New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Suman HAZARI, Sima GHOSH, Richi Prasad SHARMA

期刊论文

Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

期刊论文

导航卫星双向伪距时间同步

谭述森

期刊论文

Finite element modeling of environmental effects on rigid pavement deformation

Sunghwan KIM,Halil CEYLAN,Kasthurirangan GOPALAKRISHNAN

期刊论文

Modeling of semi-rigid beam-to-column steel joints under extreme loading

C FANG, B A IZZUDDIN, A Y ELGHAZOULI, D A NETHERCOT

期刊论文