Table of Content

30 June 2014, Volume 48 Issue 06 Previous Issue    Next Issue

Energy and Power Engineering

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Experimental Study of NOx Storage/Reduction Performance Using the Mixture of Stream Reforming of DME as Reducer ZHANG Wugao,CHEN Xiaoling,WU MinChao 2014, 48 (06):  741-745.  Abstract ( 710 )   Save Dimethyl ether(DME) steam reforming (SR) could provide excellent reducing agent of H2 for NOx storage and reduction (NSR) technology to remove nitrogen oxide (NOx) emissions from DME engine. This paper studied the influence of DME reforming gas on the performance of NSR by using Pt/Co-BaO/Al2O3 as NSR catalyst and CNZ-1/HZSM-5/Ga2O3 as the catalyst of DME steam reforming. The experimental result shows that the NSR performance is improved evidently by using the DME reforming gas as reductant. The conversion efficiency could be raised by 11%. Although the water vapor has some inhibition effect on the NOx adsorption, it participates in DME reforming and could produce evident promotion on the NOx conversion rate of NSR. References | Related Articles | Metrics

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Influence of Humidity on a Double-Swirled Non-Premixed Syngas Burner GE Bing1,TIAN Yinshen1,XIE Yuesheng2,ZANG Shusheng1 2014, 48 (06):  746-749.  Abstract ( 700 )   Save Experiments were performed to investigate the influence of humidity on a doubleswirlded nonpremixed syngas burner. Planar laserinduced fluorescence (PLIF) of OH radical measurement was adopted to identify main reaction zones and burnt gas regions as well. Together with the temperature and emission measurements during the exhaust section, some important characteristics of the syngas flame were investigated in detail. The results indicate that fluorescent signal strength of OH radicals pronounce weakening, and the flame gradually show a W type distribution with the increase of humidification amount. CO missions in combustor change little when φ is in the range of 0 to 30%, but increase quickly when φ is over 40%. NOx missions in combustor reduce continuously with the humidity of air increaseing. However, the slope of NOx descending decreases when φ is over 20%. References | Related Articles | Metrics

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Life Cycle Analysis of Microalgal Biodiesel in China ZHANG Tingting,XIE Xiaomin,HUANG Zhen 2014, 48 (06):  750-755.  Abstract ( 1169 )   Save This paper presents the impact of energy consumption and greenhouse gas (GHG) emissions of microalgal biodiesel compared with the conventional petroleum based diesel via life cycle assessment (LCA). The results indicated that the fossil energy consumption of upstream stage for microalgal biodiesel was higher than that of petroleum based diesel, except for petroleum consumption and GHG emissions. The growth of microalgae was the most energyintensive stage during its life cycle, followed by oil extraction stage. From the perspective of the full life cycle, microalgal biodiesel (BD100) can reduce the life cycle petroleum consumption and GHG emissions. At present, the use of BD20 can decrease the life cycle fossil energy consumption and GHG emissions.   References | Related Articles | Metrics

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A Numerical Study of Thermal Performance and Pressure Loss in a Cooling Channel with Detached Pin Fins LI Lin,RAO Yu,WAN Chaoyi 2014, 48 (06):  756-760.  Abstract ( 805 )   Save This paper investigated the influence of the width of detached space on the thermal performance and flow resistance in a cooling channel over the Reynolds number range from 8 200 to 52 500. The threedimensional steadystate simulation was conducted to investigate heat transfer and pressure loss characteristics of detached pin fin arrays with different widths in cooling channels. The numerical results are tested by three grid strategies, and the numerical method was validated by experimental data. Numerical results show that in the researched Re number range, the width of detached pin fin has a great influence on the cooling ability while the width of the detached pin fin has an optimal value to make the best cooling performance. Key words： detached pin fin; turbine blade cooling; width of pin fin; flow and heat transfer References | Related Articles | Metrics

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NOx Removal Performance on Self-Propagating High-Temperature Synthesis Prepared TiCe0.2W0.2Ox Catalyst YANG Yang,LIN He,CHEN Ting,HUANG Zhen 2014, 48 (06):  761-766.  Abstract ( 871 )   Save In order to broaden the temperature window of nitrogen oxide removal efficiency of selective catalytic reduction （SCR） catalyst, the research of Ti-Ce-W mixed oxide catalysts was conducted. Among a series of Ti-Ce-W mixed oxide catalysts prepared by SHS (self-propagating high-temperature synthesis) method, catalyst with n(W)∶n(Ti)=0.2(n is the amount of substance) showed a 100% NO removal efficiency from 200 to 440 ℃ and 100% N2 selectivity below 400 ℃. The SCR characteristic of TiC0.2W0.2Ox was also tested under high GHSV( gas hourly space velocity) of 11 400 h-1. Besides by directly deposit the catalyst on cordierite carrier, a 95% NO removal efficiency and a 100% N2 selectivity from 250 to  450 ℃ were obtained.   References | Related Articles | Metrics

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Flame Height Characteristics of Fire Whirls in a Vertical Channel with Gaps HUO Yan，ZOU Gaowan，LI Shusheng，GAO Ye 2014, 48 (06):  767-771.  Abstract ( 826 )   Save In order to study the height characteristics of fire whirls in a vertical channel, experiments of fire whirls induced by ethanol and Nheptane in different diameter fuel pans were performed in a vertical channel with a dimension of 32 cm (length) ×32 cm (width) ×200 cm (height) and corner gaps, opposite gaps, respectively. In the experiments, the flame height reached its maximal stage after a relativelyshort primary stage. The later height of stronger fire whirls induced by Nheptane dropped rapidly, but for ethanol, there existed a buffer stage. For stronger fire whirls induced by N-heptane, both buoyancy and violent rotating had an obvious effect on flame height. The dimensionless expression for flame height was revised based on the results of experiments.   References | Related Articles | Metrics

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Static Stability Analysis of Air-Conditioning Chilled Water System for Variable Differential Pressure Control Considering Bypass Loop Regulation Characteristics   LIU Xuefeng,LIU Jinping,CHEN Xinglong,LUO Wenhai 2014, 48 (06):  772-777.  Abstract ( 1013 )   Save The terminal cooling load distribution and pipe network structure of the air-conditioning system are the key factors that influence its control stability and reliability. An exact mathematical model of pipe network hydraulic characteristics was built in this paper based on a directreturn chilled water system, in which the regulation characteristics of bypass loop was considered in detail. The influence of pipe network hydraulic characteristics and energy consumption characteristics on pressure difference setting value of bypass loop were studied in detail, and the hydraulic characteristics in different running conditions were also studied. This paper focused on the influence of static stability and control quality on variable pressure difference control system by checkpoint of pressure difference feedback signal. The research shows that reasonable adjustment in control target value and setting value of bypass control valve are the key factors to achieve efficiency and stable operation. References | Related Articles | Metrics

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Experimental Research of an All-Glass Evacuated Tubular Solar Water Vapor Generator LI Shuangshuang,LIU Zhenhua 2014, 48 (06):  778-781.  Abstract ( 710 )   Save A new-type all-glass evacuated tubular solar water vapor generator was designed and tested to provide flowing high temperature water vapor. The experimental apparatus consists of 60 linked collecting units, each mainly includes a simplified CPC, an allglass evacuated collecting tube and a heat transfer annular pipe amounted in the evacuated collecting tube. A special solidliquid mixed medium with high thermal conduction is filled between allglass evacuated tube and annular tube. The collecting performance of the apparatus was investigated for understanding the effect of weather condition conditions and collecting unit design on the vapor temperature, collecting power and system efficiency. Experimental results show that the vapor temperature in the outlet of the collector can reach 200 ℃, while the collector efficiency is above 0.332, which manifests excellent solar collecting performance. The present new solar water vapor generator demonstrates industrial potentiality and provides a good technology support for solar high temperature collecting system. References | Related Articles | Metrics

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Experimental Study of Flow and Heat Transfer in Cooling Channels with Pin Fin Arrays and Detached Pin Fin Arrays RAO Yu,LI Lin 2014, 48 (06):  782-787.  Abstract ( 805 )   Save  Pin fin array is a commonly used cooling structure in a gas turbine blade. Based upon the conventional pin fin cooling structure, this paper proposed a novel cooling structure with detached pin fin arrays. In the Reynolds number range of 8 200 to 50  500, a comparative experimental study was conducted to obtain the pressure loss and heat transfer characteristics in the cooling channels with detached pin fin arrays and with conventional pin fin arrays respectively. The results indicated that, compared to the counterpart of the pin fin channel, the detached pin fin channel has higher average Nusselt numbers and significantly reduced pressure loss over the studied Reynolds number range. Moreover, threedimensional conjugate computations were carried out for similar experimental conditions, and the computations showed the detailed characteristics in the distribution of the velocity and turbulence level in the flow, which revealed the underlying mechanisms for the associated pressure loss reduction and heat transfer enhancements in the channels with detached pinfin arrays.   References | Related Articles | Metrics

General Industrial Technology

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Simulation and Experimental Validation of Two-Phase Flow Distribution in Plate Heat Exchanger ZHANG Ruxu1，HU Haitao2，ZHUANG Dawei2，DING Guoliang2， 2014, 48 (06):  788-792.  Abstract ( 928 )   Save A mathematic model was developed in this paper to predict the two-phase flow distribution characteristics in a plate heat exchanger. The submodels of the pressure drops in both the channel and the distributor were established based on pressure balance equations. The submodels of both the phase split in distributor and the liquid film distribution in the inlet of distributor were established based on phase separation equations. The algorithm of the mathematical model was developed by interatively solving the pressure drop balance equations and the phase separation equations respectively. The predictions of the model were compared with the experimental data. The relative errors of pressure drop between mathematic model and experimental data are within ±20%. The relative errors of two-phase region height between mathematic model and experimental data are within ±13%. References | Related Articles | Metrics

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Stability Analysis of Layered Seabed Under Wave and Current Loading WEN Feng, WANG Jian-hua 2014, 48 (06):  793-797,803.  doi: 10.16183/j.cnki.jsjtu.2014.06.011 Abstract ( 751 )   HTML ( 123 )   PDF (355KB) ( 612 )   Save The stability of layered seabed subjected to combined wave and current loading was studied by numerical model based on Biot's consolidation theory. The numerical results reveal that the existence of following current not only aggravates the possibility of liquefaction, but also increases the depth of shear failure. As a treatment, higher permeable soils layered upon seabed composed of low permeable soil will decrease the potential possibility of liquefaction as well as help to prevent original seabed from shear failure. Figures and Tables | References | Related Articles | Metrics

Architechural Science

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Correlation Analysis of Residents’ Health and Dwelling Environment in Shanghai ZHANG Xiaojing，DAI Changzhi，LAN Li，LIAN Zhiwei 2014, 48 (06):  798-803.  Abstract ( 93 )   Save Shanghai was selected for a questionnaire investigation to explore the correlation between residents’ health and dwelling environment in SouthEast China. The results indicated that the prevalence of noninfectious chronic diseases in the elderly was as high as 70%, the most prevalent diseases in the middleaged were respiratory tract diseases and gastrointestinal diseases, and 45% of the children suffered from rhinitis in the last 12 months prior to the study. The results also showed that nearly 50% of the residential area had such problems as light pollution, longterm noise, dust, cooking fumes and unpleasant odor. Moreover, 90% of the residents had a strong wish to inspect the air quality in their bedrooms. The logistic regression analysis indicated good health habits would significantly reduce the diseases prevalence among residents while indoor smoking, cooking fumes, dampness and unpleasant odor could significantly increase residents’ health risk. References | Related Articles | Metrics

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Analysis of Wind-Induced Vibration and Fatigue Effects of a Typical Tower Crane MA Jin,WANG Zitong,ZHOU Dai,LIAO Linheng,HUANG Zhen 2014, 48 (06):  804-808.  Abstract ( 129 )   Save Combining the weighted amplitude wave superposition method and the autoregression method, a novel mixture simulation technique that can simulate the time histories of 3D wind velocity series was produced. The wind velocity time series were converted to the time series of 3D wind loadings. For a typical tower crane tower, the parametric mechanical model was established. The analysis of wind-induced vibration responses was conducted by Newmarkβ approach. After obtaining the time histories of the stresses for structural hotspots, the method of S-N curve was used to study the effects of structural fatigue damage. The results show that the time history curves of structural windinduced displacement, velocity and acceleration of each node on the tower are stable respectively and structural wind-induced displacement has certain periodicity. The deformation and fatigue damage on both ends of the boom and the top of the tower are relatively greater. These results are expected to provide reference for the windresistant design of tower structures.   References | Related Articles | Metrics

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Mathematical Model and Performance Analysis with Variable Condition of Enthalpy Recovery Wheel FANG Jihua，GU Bo，ZHANG Jie 2014, 48 (06):  809-815.  Abstract ( 125 )   Save The mathematical model of enthalpy recovery wheel was built and verified by comparison with existing literatures, based on which, the effects of air velocity, proportion of fresh air and exhaust air, fresh air temperature (when humidity ratio is constant or relative humidity is constant), fresh air humidity ratio on the heat recovery efficiency of enthalpy recovery wheel were investigated. The results show that the sensible heat efficiency, latent heat efficiency and total heat efficiency of enthalpy recovery wheel decrease with increasing of air velocity; when proportion of fresh air and exhaust air increases, or fresh air temperature increases (relative humidity is constant), and the sensible heat efficiency, latent heat efficiency and total heat efficiency increase, too; with increasing of fresh air temperature (humidity ratio is constant ), the sensible heat efficiency increases, while the latent heat efficiency and total heat efficiency decrease; when fresh air humidity ratio increases, the sensible heat efficiency remains constant, while the latent heat efficiency and total heat efficiency increase.   References | Related Articles | Metrics

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Multi-Storey Cable-Stayed Steel Moment Resistant Frame and Its Lateral Force Resisting Performance LAN Shengning,LI Chunxiang 2014, 48 (06):  816-820.  Abstract ( 124 )   Save A new lateral force resisting system (LFRS), referred to as the multi-storey cable-stayed steel moment resistant frame (CSMRF) system, was proposed in this paper. The CSMRF integrates the respective advantages of both the steel moment resistant frame (MRF) and inclined cables, thus effectively promoting the lateral resistant capacity of the original MRF. Likewise, the CSMRF renders both the dual seismic defense line and selfcentering capacity. The composition and working mechanism of the CSMRF were introduced. The floor displacement (relative to the ground) approximation formula was developed for the CSMRF under the lateral loading. The numerical analysis was made of the CSMRF with resorting to the developed approximation formula. The results show that the interstory drift and the floor displacement were significantly reduced with respect to the original steel MRF. The approximate calculation formula of elastic floor displacements for multi-storey CSMRF system can provide a theoretical basis for the preliminary design of its components.   References | Related Articles | Metrics

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Analysis of Influencing Factors on Performance of the L.D.A.C. System Based on the Concept of Ideal Dehumidification Efficiency YANG Zili,LIAN Zhiwei 2014, 48 (06):  821-826.  Abstract ( 124 )   Save A new concept called “ideal dehumidification efficiency” was proposed to evaluate the performance of the liquid dehumidification system based on the laws of conversation of mass and conversation of energy. The effects of mass flow rate, inlet temperature and inlet quality concentration/humidity of both humid air and lithium chloride solution were analyzed in detail. It was found that although the increase in solution mass flow rate or decrease in air mass flow rate can increase the dehumidification efficiency, the regularities were different. The relationships between dehumidification efficiency and air inlet humidity were also studied at five different liquid-air ratios. Compared to the existing research, the results obtained in this paper were much more reasonable and precise. References | Related Articles | Metrics

Mechanical instrumentation engineering

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Normal Stiffness of Tunnel Surface Contacting with Thrusting Boots of TBM with Various Surface Characteristics HAO Pei,YU Haidong，ZHAO Yong 2014, 48 (06):  827-832.  Abstract ( 93 )   Save The rock surfaces of tunnel excavated by the Tunnel Boring Machine (TBM) have various rough characteristics, which is closely related to the load transmission, the direction of excavation, and the wear of cutterhead when the boots of TBM is put on it directly. In this paper, the description on the 3D isotropic fractal rough surfaces of tunnel was calculated by using the modified W-M function. The normal contact stiffness models were established considering the failure of rocks when it underwent compressive loads applied by the boots of shield machines. The normal contact stiffness behavior was investigated considering the variable loads, mechanical behavior of rocks, and the surface roughness. The results show the normal contact stiffness is dependent on the failure of rocks. When the load remains unchanged, the contact stiffness of the parts of failure rocks supporting loads is smaller than those. It  decreases when rock failure occures on the contacting surface. The contact stiffness decreases with the increase of the surface roughness. When elastic modulus remains unchanged, the contact stiffness increases as the hardness increases. When the hardness remains unchanged, the contact stiffness increases as the elastic modulus decreases.   References | Related Articles | Metrics

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Influence of Intermediate Principle Stress on Embedded π Plane Crack Propagation WANG Deyong，ZHANG Zhennan，GE Xiurun 2014, 48 (06):  833-837.  Abstract ( 160 )   Save To explore the influence of the intermediate principle stress on embedded crack propagation, the simplified Augment Virtual Internal Bond (AVIB) model in conjunction with the threedimensional element partition method was used to simulate the propagation process of an embedded π plane crack subjected to true triaxial stress. The simulation results suggest that the fracture first initiates at the tip of the preexisting planar crack and then propagates in wrapping mode along the maximum principle stress. With the increase in intermediate principle stress, the “wrapped” extended crack rotates to the direction of the intermediate principle stress. The triaxial compressive strength of rock is also related to the intermediate principal stress. When the intermediate stress is smaller than a certain value (approximately 0.5σc), the triaxial compressive strength almost grows linearly with the intermediate principal stress. After the t intermediate principal stress exceeds a certain value (approximately 0.8σc), the triaxial strength decreases with intermediate stress increasing. The simulated results provide valuable reference for the analysis of embedded planar crack propagation in rock under high compressive insitu stress. Key words： References | Related Articles | Metrics

Communication and Transportation

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Reasonable Support Pressure for Shield Tunneling by Discrete Element Method LIAO Shaominga,b,SHI Zhenhaoa，WU Juna 2014, 48 (06):  838-844.  Abstract ( 142 )   Save Using the discrete element method (DEM), the particle flow of dry sand with friction angle of 37 degree and progressive failure in a tunnel workface under three cover depths were simulated to examine the limit support pressure of workface and ground turbulence in sandy ground. These simulations resulted in three main findings. First, under different cover depths, the support pressures evolve to limit values when workface displacement reaches 6%D (D is the diameter of the tunnel), and the corresponding limit support ratio is 10% to 20%; the softening effect of sand after peak strength enlarges the final limit support pressure. Second, severe ground disturbance is triggered when the support ratio is reduced to 40% to 50%, and the disturbance degree and range are sensitive to cover depth: the disturbance range and degree triples and doubles, respectively, when cover drops to 0.5D from 2D. Significant ground settlements occur when the support ratio drops to 40% to 50%. Third, based on deformation control, the support ratio is 40% to 50%, which is much smaller than that basedon limit failure; by taking into consideration both tunneling efficiency and cutters’ wear, it is rational to drop the support ratio to 40% to 50%. Key words： References | Related Articles | Metrics

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Development of a Gasoline Engine Controller Based on MotoTron ZHANG Hu,WANG Cunlei,ZHANG Jianlong,YIN Chengliang 2014, 48 (06):  845-849.  Abstract ( 170 )   Save The popular V-model development process, which is characterized by high efficiency and excellent performance, has been widely applied in controller development process. The rapid prototyping acts as a part of the V-model process. The control strategy can be realized and validated conveniently. The cost and development risk can be reduced simultaneously. In this paper, a gasoline engine controller was developed based on MotoTron rapid prototyping platform. First, the control system frame was established under MotoHawk toolkit and the basic software and system I/Os were configured. Then the engine control strategy was developed with Matlab/Simulink, including electronic throttle control, air control, fuel injection control, ignition control and accessory control. Finally, an engine start test was conducted on bench to validate the engine control functions. The test results show that the engine starts quickly and reliably. The engine state transitions are smooth. The air-fuel ratio of each engine start stage is well controlled. The fundamental functions of gasoline engine controller have been realized.   References | Related Articles | Metrics

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A Mass Source Method for Numerically Generating Internal Solitary Waves in Two-Layer Fluid WANG Xu1,LIN Zhongyi2,YOU Yunxiang1 2014, 48 (06):  850-855.  Abstract ( 130 )   Save According to the applicability conditions for three type of internal solitary wave theories including KdV, eKdV and MCC, and integrating with fully nonlinear Euler equations, a numerical wave-generating method for internal solitary waves in two-layer fluid was proposed by adding mass sources  to continuity equation. Series of numerical simulations were presented to analyze the generation mechanism for the internal solitary wave in the process where mass sources release and absorb fluids. Besides, the variation characteristics of the waveform, amplitude, and flow field induced by the internal solitary wave were discussed. The results show that the waveform remains stable and the amplitude decays much weakly during the propagation of the internal solitary wave generated by the present method, and its waveform and amplitude are in good agreements with the experimental and theoretical results. References | Related Articles | Metrics

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Fretting Characteristics of the Rubber O-Ring for a Mechanical Seal ZHENG Jinpeng，SHEN Mingxue，MENG Xiangkai，LI Gan，PENG Xudong 2014, 48 (06):  856-862.  Abstract ( 147 )   Save The fretting characteristics of the nitrile rubber O-ring for a mechanical seal were successfully simulated by axisymmetric finite element analysis, using the MooneyRivlin model with highorder terms. The effects of the displacement amplitude, medium pressure, precompression ratio and friction coefficient were investigated. The results show that three contact states for the fretting characteristics of rubber O-ring can be determined, i.e. stick state, mixed stickslip state and slip state with the increase of the displacement amplitude．The fretting running behavior of rubber Oring was strongly dependent upon the medium pressure, precompression ratio and friction coefficient. In mixed stick-slip state, the strong fluctuations of frictional force on the sealing interface would weaken the floatability of floating ring. In slip state, the high Von Mises stress may lead to shear failure and severe surface wear. However, Oring possessed the optimum comprehensive performance when working in stick condition. In a word, to mitigate shear failure and surface wear of Oring and meet the floatability and tracking property of the seal ring, the mixed stickslip state should be avoided and a compression of appoximately 10% and a lower coefficient would be preferred. References | Related Articles | Metrics

General Industrial Technology

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Free Vibration Analysis of Orthogonally Rib-Stiffened Composite Sandwich Plate YANG Kun,MEI Zhiyuan,LI Huadong 2014, 48 (06):  863-869.  Abstract ( 96 )   Save The continuity of orthogonally rib-stiffened homogeneous core material was described using δ function basing its deformation on the firstorder shear theory. Composite panels were considered as Kirchhoff thin plate, taking the in-plane displacements of the face panels and the transverse displacement of the whole structure as variables, and the kinetics equations of the orthogonally rib-stiffened composite sandwich plate were derived using Hamilton’s principle. The approximate solution of free vibration of the orthogonally rib-stiffened composite sandwich plate with simply supported boundary was obtained by using the series solution form. The natural frequency results were validated comparing to the FEM simulation. Considering the damping of the composite panels, the effects of some geometrical parameters of the sandwich plates including panel thickness, rib-stiffened web thickness, web height and web spacing on the nature frequency and structural lossfactor were discussed.The results show that there is an optimal value of the panel thickness making the structural lossfactor max; when the areal density is identical, altering web thickness or web spacing have no effect on the natural frequency of the sandwich plate.   References | Related Articles | Metrics

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Dynamical Saint-Venant’s Principle Solution for Rotor System with Shallow Crack LI Ming,LI Fucai,LI Hongguang,MENG Guang 2014, 48 (06):  870-876.  Abstract ( 56 )   Save This paper is dedicated to the solution of rotor system with common fault shallow crack based on dynamical Saint-Venant’s principle and gives the interpretation of the fact that shallow crack is not detectable via the signal processing method. Analysis and proof are implemented on two prerequisites of dynamical SaintVenant’s principle: dynamical resultant of external load equal to zero and the influence of stress wave produced by external load to distal end equal to zero via breath function and elastodynamics respectively. The criterion for  whether rotor system with shallow crack yields to dynamical SaintVenant’s principle is also proposed. It concludes that most practical rotor systems with shallow crack yield to dynamical Saint-Venant’s principle and it is difficult to detect characteristics of the crack by signal processing method. Other means of shallow crack prognosis should be adopted for regular testing or online monitoring of the rotor system. References | Related Articles | Metrics

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Progressive Damage Analysis of Double-Sided Adhesively Bonding Repaired Structures of Composite Laminates LI Zhenkai,YU Yin,WANG Hai 2014, 48 (06):  877-882.  Abstract ( 112 )   Save A method for predicting and analyzing the ultimate load of the double-sided repaired structures of composite laminates subjected to tensile load was proposed. A three dimensional FEA model was established to analyze the damage process. The adhesive layer was modeled with the isotropic constitutive. A square criterion based on three direction shear strains to predict the occurrence of the damage of the adhesive layer, and a degradation function associated with the stress and strain was defined to degenerate the stiffness of the damaged material. The composite laminates was modeled with the orthotropic constitutive, and the occurrence of damage was predicted by 3D Hashin’s initiation criterion and Ye criterion. Damage variables was introduced to characterize the damage extension. The ultimate load obtained from the numerical prediction agreed well with the experimental results. It is verified that the method and model can predict the tensile ultimate strength of the double-sided repaired composite laminate structures effectively.   References | Related Articles | Metrics

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A Hyperelastic Constitutive Model for Membrane and Its Application in Air Cushion CHEN Ming1,PENG Xiongqi1，SHI Shaoqing2,YANG Huazheng3 2014, 48 (06):  883-887.  Abstract ( 200 )   Save In order to accurately describe the mechanical behavior of air cushion in finite element analysis，a constitutive model for polymer membrane was developed and applied to study the cushioning properties of air cushion. Based on uniaxial tensile tests of the polymer film, a compressible hyperelastic constitutive model was proposed. Material parameters were obtained by curve fitting. The model was validated by implementing numerical simulations on compression test of one column of the air cushion. Comparisons between simulation results and experimental data show that the proposed hyperelastic model can effectively characterize the nonlinear material behavior of the polymer membrane. The model was further applied to analyze the influence of inflation pressure on the performance of the air cushion. The development of the hyperelastic constitutive model is critical to the numerical simulation and design optimization of air cushion packaging. References | Related Articles | Metrics

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A Novel Contact Detection Procedure for Blocks and Its Application in Discontinuous Deformation Analysis CHEN Libiao1，2,LIU Quansheng1,CHE Ailan3 2014, 48 (06):  888-892.  Abstract ( 107 )   Save Linked lists were used for expressing discrete blocks based on the procedure of bounding volume and the implicit grids of space decomposition. And an equivalent loop mode, in which the inner processing depended neither on the horizontal number nor on the vertical number of implicit grids, was obtained from the loop of all discrete blocks. Then, it depended neither on the size of the finite space of discrete mass distribution nor on the number of the discrete blocks. So, the CPU time for contact detection was in direct proportion to the number of blocks. The main results obtained from some examples and numerical tests indicate that the CPU time for contact detection is only in direct proportion to the number of blocks and that the CPU time for contact detection is less with respect to conventional methods.   References | Related Articles | Metrics