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A simplified method for investigating the bending behavior of piles supporting embankments on soft ground

《结构与土木工程前沿（英文）》页码 1021-1032 doi: 10.1007/s11709-023-0952-3

摘要： In recent years, concrete and reinforced concrete piles have been widely used to stabilize soft ground under embankments. Previous research has shown that bending failure, particularly during rapid filling on soft ground, is the critical failure mode for pile-supported embankments. Here, we propose an efficient two-stage method that combines a test-verified soil deformation mechanism and Poulos’ solution for pile–soil interaction to investigate the bending behavior of piles supporting embankments on soft ground. The results reveal that there are three possible bending failure scenarios for such piles: at the interface between the soft and firm ground layers, at mid-depths of the fan zone, and at the boundary of the soil deformation mechanism. The location of the bending failure depends on the position and relative stiffness of the given pile. Furthermore, the effect of embedding a pile into a firm ground layer on the bending behavior was investigated. When the embedded length of a pile exceeded a critical value, the bending moment at the interface between the soft and firm ground layers reached a limiting value. In addition, floating piles that are not embedded exhibit an overturning pattern of movement in the soft ground layer, and a potential failure is located in the upper part of these piles.

关键词： bending behavior pile embankment soil−structure interaction failure mode

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Design, analysis, and neural control of a bionic parallel mechanism

《机械工程前沿（英文）》 2021年第16卷第3期页码 468-486 doi: 10.1007/s11465-021-0640-8

摘要： Although the torso plays an important role in the movement coordination and versatile locomotion of mammals, the structural design and neuromechanical control of a bionic torso have not been fully addressed. In this paper, a parallel mechanism is designed as a bionic torso to improve the agility, coordination, and diversity of robot locomotion. The mechanism consists of 6-degree of freedom actuated parallel joints and can perfectly simulate the bending and stretching of an animal’s torso during walking and running. The overall spatial motion performance of the parallel mechanism is improved by optimizing the structural parameters. Based on this structure, the rhythmic motion of the parallel mechanism is obtained by supporting state analysis. The neural control of the parallel mechanism is realized by constructing a neuromechanical network, which merges the rhythmic signals of the legs and generates the locomotion of the bionic parallel mechanism for different motion patterns. Experimental results show that the complete integrated system can be controlled in real time to achieve proper limb–torso coordination. This coordination enables several different motions with effectiveness and good performance.

关键词： neural control behavior network rhythm motion pattern

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Optimization of spatial structure designs of control rod using Monte Carlo code RMC

《能源前沿（英文）》 2021年第15卷第4期页码 974-983 doi: 10.1007/s11708-021-0769-5

摘要： Control rod is the most important approach to control reactivity in reactors, which is currently a cluster of pins filled with boron carbide (B₄C). In this case, neutrons are captured in the outer region, and thus the inner absorber is inefficient. Moreover, the lifetime of the control rod is challenged due to the high reactivity worth loss resulted from the excessive degradation of B₄C in the high flux area. In this work, some control rod designs are proposed with optimized spatial structures including the spatially mixed rod, radially moderated rod, and composite control rod with small-sized pins. The control rod worth and effective absorption cross section of these designs are computed using the Monte Carlo code RMC. A long-time depletion calculation is conducted to evaluate their burnup stability. For the spatially mixed rod, rare-earth absorbers are combined with B₄C in spatial structure. Compared with the homogenous B₄C rod, mixed designs ensure more sufficient reactivity worth in the lifetime of the reactor. The minimum reactivity loss at the end of the cycle is only 1.8% from the dysprosium titanate rod, while the loss for pure B₄C rod is nearly 12%. For the radially moderated design, a doubled neutronic efficiency is achieved when the volume ratio of moderator equals approximately 0.3, while excessive moderating may lead to the failure of control rods. The control rod with small-sized pins processes an enhanced safety performance and saves the investment in absorbers. The rod worth can be further enhanced by introducing small moderator pins, and the reactivity loss caused by the reduction of absorbers is sustainable.

关键词： control rod optimized spatial structure neutronic performance burnup stability

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Technology improvements and management innovations in construction of Xiluodu hydropower station on Jinsha River

Qixiang FAN

《工程管理前沿（英文）》 2017年第4卷第2期页码 231-237 doi: 10.15302/J-FEM-2017103

摘要： Hongtao ZHOU, Hongwei WANG, Wei ZENG. [J]. Front. Eng, 2018, 5(1): 78-87.Peter REDFERN, Hua ZHONG. [J]. Front. Eng, 2017, 4(2): 193-200.Ming-zhou Liu,Cong-hu Liu,Mao-gen Ge,Yuan Zhang,Qing-hua Zhu. [J]. Front. Eng, 2016, 3(2): 144-146.Chong-guang Feng,Hao Hu,Feng Xu,Jian Yang. [J]. Front. Eng, 2015, 2(2): 178-181.Yu Zhao,Sheng-quan Wang,Ke-chao Zhu. [J]. Front. Eng, 2015, 2(1): 35-38.Ru-gui Chen,Jia-meng Chen. [J]. Front. Eng, 2014, 1(1): 52-61.An Wang. [J]. Front. Eng, 2014, 1(1): 13-17.

关键词： super-high arch dam intelligent construction mass concrete temperature control structure behavior control anti-erosion concrete low-heat portland cement large-discharge and high-velocity spillway tunnels large scale underground powerhouse green hydropower station sustainable development Xiluodu hydropower station

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PID neural network control of a membrane structure inflation system

Qiushuang LIU, Xiaoli XU

《机械工程前沿（英文）》 2010年第5卷第4期页码 418-422 doi: 10.1007/s11465-010-0117-7

摘要： Because it is difficult for the traditional PID algorithm for nonlinear time-variant control objects to obtain satisfactory control results, this paper studies a neuron PID controller. The neuron PID controller makes use of neuron self-learning ability, complies with certain optimum indicators, and automatically adjusts the parameters of the PID controller and makes them adapt to changes in the controlled object and the input reference signals. The PID controller is used to control a nonlinear time-variant membrane structure inflation system. Results show that the neural network PID controller can adapt to the changes in system structure parameters and fast track the changes in the input signal with high control precision.

关键词： PID neural network membrane structure

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Static behavior of planar intersecting CFST connection in diagrid structure

Ling LI, Xianzhong ZHAO, Ke KE

《结构与土木工程前沿（英文）》 2011年第5卷第3期页码 355-365 doi: 10.1007/s11709-011-0125-7

摘要： Intersecting connection plays an important role in the new diagrid structural system for high-rise buildings. To investigate the static behavior of the intersecting connection of concrete-filled steel tubular (CFST) columns, a typical reduced-scale planner connection specimen is tested under monotonic axial compression. The failure modes, force mechanism and bearing capacity of intersecting CFST connections are analyzed further in the follow-up numerical simulation, considering influences of intersecting angle, elliptical plate and ring plate. Test and simulation results prove that, intersecting connection can develop fully plastic deformation and provide sufficient bearing capacity. Parametric analysis indicates that bearing capacity of planar intersecting CFST connection mainly depends on intersecting angle and thickness of elliptical plate, while the ring plate affects that little. Capacity estimation method for planar intersecting CFST connection is proposed basing on the capacity of the critical section which is located near intersecting center for a distance of steel tube radius, and the design suggestions is provided in the end of this paper.

关键词： diagrid structure concrete-filled steel tube planar intersecting connection experimental research mechanism analysis

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Compressive behavior and energy absorption of polymeric lattice structures made by additive manufacturing

Sheng WANG, Jun WANG, Yingjie XU, Weihong ZHANG, Jihong ZHU

《机械工程前沿（英文）》 2020年第15卷第2期页码 319-327 doi: 10.1007/s11465-019-0549-7

摘要： Lattice structures have numerous outstanding characteristics, such as light weight, high strength, excellent shock resistance, and highly efficient heat dissipation. In this work, by combining experimental and numerical methods, we investigate the compressive behavior and energy absorption of lattices made through the stereolithography apparatus process. Four types of lattice structures are considered: (i) Uniform body-centered-cubic (U-BCC); (ii) graded body-centered-cubic (G-BCC); (iii) uniform body-centered-cubic with -axis reinforcement (U-BCCz); and (iv) graded body-centered-cubic with -axis reinforcement (G-BCCz). We conduct compressive tests on these four lattices and numerically simulate the compression process through the finite element method. Analysis results show that BCCz has higher modulus and strength than BCC. In addition, uniform lattices show better energy absorption capabilities at small compression distances, while graded lattices absorb more energy at large compression distances. The good correlation between the simulation results and the experimental phenomena demonstrates the validity and accuracy of the present investigation method.

关键词： lattice structure polymer compressive behavior additive manufacturing simulation

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Thermal reffusivity: uncovering phonon behavior, structural defects, and domain size

Yangsu XIE, Bowen ZHU, Jing LIU, Zaoli XU, Xinwei WANG

《能源前沿（英文）》 2018年第12卷第1期页码 143-157 doi: 10.1007/s11708-018-0520-z

摘要： To understand the relation between different nanostructures and thermal properties, a simple yet effective model is in demand for characterizing the underlying phonons and electrons scattering mechanisms. Herein, we make a systematic review on the newly developed thermal reffusivity theory. Like electrical resistivity which has been historically used as a theory for analyzing structural domain size and defect levels of metals, the thermal reffusivity can also uncover phonon behavior, structure defects and domain size of materials. We highlight that this new theory can be used for not only metals, but also nonmetals, even for amorphous materials. From the thermal reffusivity against temperature curves, the Debye temperature of the material and the ideal thermal diffusivity of single perfect crystal can be evaluated. From the residual thermal reffusivity at the 0 K limit, the structural thermal domain (STD) size of crystalline and amorphous materials can be obtained. The difference of white hair and normal black hair from heat conduction perspective is reported for the first time. Loss of melanin results in a worse thermal protection and a larger STD size in the white hair. By reviewing the different variation of thermal reffusivity against decreasing temperature profiles, we conclude that they reflected the structural connection in the materials. Ultimately, the future application of thermal reffusivity theory in studying 2D materials and amorphous materials is discussed.

关键词： thermal reffusivity theory phonon behavior structure defects structural thermal domain (STD) size 2D material amorphous material

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Vibration control of a structure using Magneto-Rheological grease damper

Shinya SUGIYAMA, Tomoki SAKURAI, Shin MORISHITA

《机械工程前沿（英文）》 2013年第8卷第3期页码 261-267 doi: 10.1007/s11465-013-0268-4

摘要：

This paper describes an application study of Magneto-Rheological (MR) grease damper to a structure with three stories. MR fluid is known as one of successful smart materials whose rheological properties can be varied by magnetic field strength, and has been applied to various kinds of device such as dampers, clutches, engine mounts, etc. However, ferromagnetic particles dispersed in MR fluid settle out of the suspension after a certain interval due to the density difference between the particles and their career fluid. To overcome this defect, we have developed a new type of controllable working fluid using grease as the career of magnetic particles. Network of thickener in grease is expected to hold the magnetic particles and prevent them from settled down. No or little sedimentation was observed in MR grease whose characteristics could be controlled by the magnetic field strength. MR grease was introduced into a cylindrical damper and its performance was studied. As a result, it was confirmed that the damping force of MR grease damper could be controlled by the applied electric current to the coil in the cylinder of damper. Furthermore, vibration response of a three-story model structure equipped with MR grease damper was investigated experimentally, and it was shown that MR grease damper worked effectively as a semi-active damper.

关键词： vibration control damper smart material Magneto-Rheological (MR) grease MR fluid

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燃油喷雾形态主动控制的可能性 Review

Masataka Arai

《工程（英文）》 2019年第5卷第3期页码 519-534 doi: 10.1016/j.eng.2019.04.010

摘要：

内燃机（ICE）对于汽车是有吸引力的动力源，具有良好的可储存性、可运输性，同时需要供应高能量密度的液体燃料。具有高性能和低环境危害的紧凑型内燃机是内燃机发展趋势。未来必须把燃油喷雾智能主动控制的燃烧作为解决传统内燃机相关重大问题（如排放）的突破性技术。已发展出在喷雾期间形成预期的燃料喷射速率和喷射模式的技术，并且传统内燃机可以在一定程度上控制燃烧。但是在燃烧范围内，燃料在空间上的扩散并未取得预期进展。因此，对于燃烧的智能控制，新且有效的燃油喷雾主动控制技术是非常必要的。空化、闪蒸、喷雾- 喷雾相互作用、喷雾-壁面相互作用和空气流动是有可能实现燃油喷雾形态主动控制的基础。本文使用文献中的论据来讨论未来喷雾燃烧的智能紧凑内燃机中喷雾形态主动控制技术的可能性。

关键词：内燃机，燃料喷雾，喷雾控制，喷雾形态，喷油器

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Deformation control criterion of shield tunnel under lateral relaxation of soft soil

《结构与土木工程前沿（英文）》 2023年第17卷第5期页码 780-795 doi: 10.1007/s11709-023-0944-3

摘要： Metro shield tunnels under the lateral relaxation of soil (LRS) are susceptible to significant lateral deformations, which jeopardizes the structural safety and waterproofing. However, deformation control standards for such situations have not been clearly defined. Therefore, based on a specific case, a model test is conducted to realize the LRS of a shield tunnel in a sandy stratum to reveal its effect on segment liners. Subsequently, a deformation control criterion is established. The LRS is simulated by linearly reducing the loads applied to the lateral sides of the segment structure. During lateral unloading, the lateral earth pressure coefficient on the segment decreases almost exponentially, and the structural deformation is characterized by horizontal expansion at the arch haunches and vertical shrinkage at the arch vault and arch bottom. Based on the mechanical pattern of the segment structure and the acoustic emission, the deformation response of a segment can be classified into three stages: elastic and quasi-elastic, damage, and rapid deformation development. For a shield tunnel with a diameter of approximately 6 m and under the lateral relaxation of sandy soil, when the ellipticity of the segment is less than 2.71%, reinforcement measures are not required. However, the segment deformation must be controlled when the ellipticity is 2.71% to 3.12%; in this regard, an ellipticity of 3% can be used as a benchmark in similar engineering projects.

关键词： shield tunnel lateral relaxation of soil deformation control criterion of segment structure model test

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Improving existing “reaching law” for better discrete control of seismically-excited building structures

Zhijun LI, Zichen DENG

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 111-116 doi: 10.1007/s11709-009-0022-5

摘要： In this paper, a novel “composite reaching law” was explained in details: 1) the equation of discrete motion for a control system; 2) the design of discrete-time variable structure control. In addition, the model of a three-storey shear-type building structure was used to verify the effectiveness of the discrete variable structure control method. The results of numerical example analysis of the model show that the control law can effectively reduce the peak value of seismic response of the building structure and the chattering effect of the control system.

关键词： discrete-time variable structure control composite reaching law chattering effect saturated control law

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Simplified theoretical analysis and numerical study on the dynamic behavior of FCP under blast loads

Chunfeng ZHAO, Xin YE, Avinash GAUTAM, Xin LU, Y. L. MO

《结构与土木工程前沿（英文）》 2020年第14卷第4期页码 983-997 doi: 10.1007/s11709-020-0633-4

摘要： Precast concrete structures have developed rapidly in the last decades due to the advantages of better quality, non-pollution and fast construction with respect to conventional cast-in-place structures. In the present study, a theoretical model and nonlinear 3D model are developed and established to assess the dynamic behavior of precast concrete slabs under blast load. At first, the 3D model is validated by an experiment performed by other researchers. The verified model is adopted to investigate the blast performance of fabricated concrete panels (FCPs) in terms of parameters of the explosive charge, panel thickness, and reinforcement ratio. Finally, a simplified theoretical model of the FCP under blast load is developed to predict the maximum deflection. It is indicated that the theoretical model can precisely predict the maximum displacement of FCP under blast loads. The results show that the failure modes of the panels varied from bending failure to shear failure with the mass of TNT increasing. The thickness of the panel, reinforcement ratio, and explosive charges have significant effects on the anti-blast capacity of the FCPs.

关键词： precast structure fabricated concrete panel blast resistance theory model empirical equation

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Behavior of compacted clay-concrete interface

R. R .SHAKIR, Jungao ZHU

《结构与土木工程前沿（英文）》 2009年第3卷第1期页码 85-92 doi: 10.1007/s11709-009-0013-6

摘要： Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared. Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface roughness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

关键词： soil structure interaction simple shear test interface friction compacted clay interface modeling

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Semi-active vibration control using piezoelectric actuators in smart structures

Jinhao QIU, Hongli JI, Kongjun ZHU

《机械工程前沿（英文）》 2009年第4卷第3期页码 242-251 doi: 10.1007/s11465-009-0068-z

摘要： The piezoelectric materials, as the most widely used functional materials in smart structures, have many outstanding advantages for sensors and actuators, especially in vibration control, because of their excellent mechanical-electrical coupling characteristics and frequency response characteristics. Semi-active vibration control based on state switching and pulse switching has been receiving much attention over the past decade because of several advantages. Compared with standard passive piezoelectric damping, these new semi-passive techniques offer higher robustness. Compared with active damping systems, their implementation does not require any sophisticated signal processing systems or any bulky power amplifier. In this review article, the principles of the semi-active control methods based on switched shunt circuit, including state-switched method, synchronized switch damping techniques, and active control theory-based switching techniques, and their recent developments are introduced. Moreover, the future directions of research in semi-active control are also summarized.

关键词： smart structure semi-active method vibration control piezoelectric actuator