bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of the Vibration and Structure-Borne Noise of the Viaduct
Authors: Li Jing , Zhang Nan
Published: November 2012

Based on the combination of finite element software ANSYS and acoustics software LMS Virtual.Lab Acoustics, this paper makes an analysis of the Vibration and sound radiation of the viaduct of urban rail transit. First of all, transient dynamic analysis of three-dimensional model of box girder was made in ANSYS, with train passing bridge simulated as a moving load or a moving mass-spring system. Then vibration displacement response obtained is taken as boundary condition of outer sound field, which can achieve accurate acoustic response in Virtual.Lab Acoustics. According to comparing the results of the two different models, we can draw that the noise pressure with the moving mass-spring system is higher than the other, and the noise pressure range is from 70 to 95 in decibels. Using the transient boundary element module of LMS Virtual.Lab Acoustics can solve engineering problems in time domain, with simulating the vibration properly.
Noise Decreasing Methods of Gearing Vibration for a Idling Construction Machine
Authors: Mu Cun Yuan , Gao Cong Min , Ge Zhen
Published: November 2012

This paper analyzes the gearing noise of a reinforcing bar straightening cutting machine, according to the test of the machine around six positions under the background noise of 49dB(A). The test result shows highest noise is in the position 4 and position 6. The noise is arrived at 1026 dB(A). By frequency spectrum analysis before noise reduction and after noise reduction, Identify the source of main noise, points out relative elements gears 26/54, and presents some methods to decrease the noise: the methods of gear correction, improving the vibration resistance of mechanism, reducing noise in the view of process and control noise transmission. The best methods is gear correction and the test improves that it can reduce noise 0.5-2 dB(A). It can be a reference to the designers and manufactures.
Free Vibration of Damaged Beam Structure with a Notch Defect
Authors: Chen Jiang Yi , Fan Li Ge , Qin Dong Chen
Published: November 2012

In this paper, we derive the universal expression of the modal parameters for a damaged beam under arbitrary boundary conditions. The delta function is first employed to describe a notch damage in the beam and consequently to derive the governing equation for the damaged beam. Second, by virtue of the perturbation method, the eigenvalues and the corresponding mode shapes are obtained for the damaged beam. Finally, numerical examples are given for an elastically supported beam. It is believed that the proposed approach could provide the necessary theoretical background for damage identification in beam structures.
Dynamics of A Single Elastic Bodies under Large Rigid Rotation
Authors: Liu Zhan Fang , Yan Shi Jun
Published: November 2012

The generalized elasticity is presented where a modified constitutive relation for the couple stress is proposed. A rigid-flexible coupled model is set up where three types of additional inertia forces along with their increments are elucidated in the model. The finite element formulation is developed with the use of the constrained variational principle. As an example, a dynamic analysis on a rotating cantilever is numerically carried out. The dynamical responses of the displacement and rotational angle at the free end, the stress and couple stress at the fixed end of cantilever are presented. An idea of critical angular velocities is proposed to insure system stability. The displacement trajectory of the free end of cantilever is approached and the dynamic stiffening problem is discussed.
Fluid-Structure Interaction Analysis of Flexible Marine Propellers
Authors: Sun Hai Tao , Xiong Ying
Published: November 2012

The present paper focuses on the fluid-structure interaction of flexible marine propellers. The aim is to develop a simulation method to predict the hydro-elastic performance. To compare with the experimental results, the geometry of propeller DTMB4119 is used. The solution procedure first computes the hydrodynamic pressures due to rigid-blade rotation via the BEM (Boundary Element Methods, BEM). The hydrodynamic pressures are then applied as external normal surface traction for the FEM (Finite Element Methods, FEM) solid model to obtain the deformed geometry. The commercial FEM code is then used to solve the equation of motion in the rotating blade-fixed coordinate system. User-defined subroutines are developed to generate FEM models using 8-node linear solid volumetric elements. Iterations are implemented between BEM and FEM solvers until the solution converges. This study shows that the simulation method developed in this paper is reasonable.
Elimination of Support Effects in Modal Testing
Authors: Ren Jun , Bi Shu Sheng , Wang Wei , Zong Guang Hua
Published: November 2012

In modal testing, the measured Frequency Response Functions (FRFs) are often inaccurate due to the adverse mechanical effects, such as mass-loading effects of transducers, shaker-structure interaction and the support effects. This paper deals with the elimination of the support effects from measured FRFs using dynamic substructure method. Both stiffness and damping are considered in the support effects. The validity of the method is proved in a simulated modal test. It is shown that with the given support conditions the affected FRFs can be corrected provided that some additional FRFs concerned with the support point are also measured. Finally, performance of this method is assessed with noisy measured data. Simulation shows that 1% white noise is acceptable in the proposed correction method.
Bifurcation Induced by Mass Variation in Piecewise Linear System
Authors: Li Yue Hua , Chen Shi Dong
Published: November 2012

This paper investigates the bifurcations of the periodic solutions in the piecewise linear systems. Firstly the equation about amplitude-frequency response is deduced by the averaging method. Then the bifurcation classification is conducted by applying the singularity theory. The effects of the two parameters, the mass and the excitation amplitude, are discussed. The balance position will be changed when the quality changed, So the system is divided into two kinds of state. The results show that the parameter plane is divided into thirteen regions where bifurcation types are different. At last, discussing the amplitude- frequency response of different regions. this paper provides some theoretical guidance for system of considering load variation, and it is significant to help research the change in amplitude-frequency characteristic of piecewise linear system.
The Study of Reliability in MDO of Aircraft
Authors: Xia Qing , Li Man , Cao Zong Jie , Wang Hong Wei
Published: November 2012

MDO and reliability design are independently processed in the traditional aircraft design. The designs process is thus consuming compute intensive, so that integrated design of MDO and reliability is required. To achieve the integration, there are two problems needed to be solved. First, a reliability function needs to be expressed by performance design parameters in a probability form. Second, the reliability function needs to be imported into MDO arithmetic. For the first one, stress-strength interference theory is useful. According to the theory, performance design parameters are described in the formulas which calculate probability of reliability. For the second, the reliability function is considered as a part of optimization objective functions or as a constraint function. The simulation of aircraft design shows that the above method is useful and effective to the actual project.
The Research of Strain Rate of Common Bolt Materials
Authors: Gao Xiao Han , Wang Yu , Du Jian Ye
Published: November 2012

In this article, quasi-static tensile and dynamic tensile tests of three common bolt materials (three kinds of steels) were conducted, and their stress-strain curves at various strain rates were obtained. By this means, the mechanical properties of three common bolt materials were analyzed. Based on the John-Cook model, author established the constitutive relation models of three materials which could describe their strain rate dependence, and used these models in the numerical simulation. The research show us that bolt material strain rate effect not only could affect the bolt impact strength, but also could not be ignored in the study of impact strength of equipments connected by bolts. The research has great significance to the study of impact resistance strength of equipments and bolts.
Dynamic Analysis of the Rotor System with a Semi-Elliptical Fronted Crack on the Shaft
Authors: Di Yuan , Liu Chang Li , Zhang Qi Di , Cheng Wei , Zhou Shao Ping
Published: November 2012

Dynamic behaviors of a rotor with a transverse fatigue surface crack have been studied a lot in the past. In the present study the rotor containing a transverse crack with semi-elliptical fronted edge is considered since the crack grows in an elliptical path when the rotor is subjected to long time cyclic loads through fatigue experiments and realistic cases. Using the finite element method, the stiffness of the shaft with the semi-elliptical fronted transverse crack is calculated. Then, the vibration responses and the coupling mechanism of bending and torsional vibrations of the rotor with and without torsional excitation are analyzed. The result shows that there are slight differences between the dynamic responses of the straight fronted cracked rotor and the semi-elliptical fronted rotor in common frequency fields and high frequency fields. The similar contrast is obtained when the rotor system is applied by torsional excitation.
The Discretization Methods of a Rotating Flexible Cantilever Beam
Authors: Fan Ji Hua , Zhang Ding Guo
Published: November 2012

The dynamics of a rotating flexible cantilever beam is investigated by using assumed mode method, finite element method and Bezier curve interpolation method in this paper. The longitudinal deformation and the transverse deformation of the flexible beam are considered and the coupling term of the deformation which is caused by transverse deformation is included in the expression of longitudinal deformation. The assumed mode, finite element and Bezier interpolation are used to discretize the deformation of the flexible beam, and then the dynamics equations are built by Lagrange equation, and a software package for the dynamic simulation of the rotating cantilever beam is developed. Two cases are considered in the simulations. One is the dynamics study which the external rotating torque is known, another one is that a rotating fixed axis flexible beam falls with gravity. According to the simulation results, assumed mode, finite element and Bezier interpolation method can be well used for discretizing the deformation of the flexible beam; the computational efficiency of finite element method is the lowest, and Bezier interpolation method is the highest; the calculation accuracy of the assumed mode method is lower than the Bezier interpolation method.
Mechanical Analysis on Destruction of Coal Cutters Guide Shoes
Authors: Yang Zhi Jun , Zhang Wei Na
Published: November 2012

Some key components’ failure often occurs in the process of the use of large-scale mining coal machine, and seriously affects the production of the enterprise. So it is necessary that analysis on the failure mechanical reason of guide shoes with the coal-winning machine by the modern mechanics analysis method. The stress diagram of guide shoes could be got by static analysis with MATLAB, and the dangerous parts of the finite element model with guide shoes appeared after loading. Finally, analysis on the fatigue strength and fatigue life of components under various complex condition, which provide some reference theory basis for the future related product designing, Manufacturing and maintenance.
Time-Accurate Simulation of Longitudinal Flight Mechanics with Control by CFD/RBD Coupling
Authors: Guo Dong , Xu Min , Chen Shi Lu
Published: November 2012

This paper describes a multidisciplinary computational study undertaken to compute the flight trajectories and simultaneously predict the unsteady free flight aerodynamics of aircraft in time domain using an advanced coupled computational fluid dynamics (CFD)/rigid body dynamics (RBD) technique. This incorporation of the flight mechanics equations and controller into the CFD solver loop and the treatment of the mesh, which must move with both the control surface deflections and the rigid motion of the aircraft, are illustrated. This work is a contribution to a wider effort towards the simulation of aeroelastic and flight stability in regions where nonlinear aerodynamics, and hence potentially CFD, can play a key role. Results demonstrating the coupled solution are presented.
The Comparison of Two Processing Methods of Sliding Bearing in Impact Dynamics Analysis of Finite Element Software
Authors: Gao Xiao Han , Wang Yu , Du Jian Ye , Gao Xiao Peng
Published: November 2012

In this article, author studied the application of two models of "single point damping-spring" model and "contact" model in the process of impact dynamic analysis. Research shows that the load and force could be transmitted smoothly in all these methods. But there still have limitations in two methods, we could not study the impact response of bearing itself and the shaft neck contacted with bearing in the "single point damping-spring" model, on the other hand, the penetration of contact parts could not be avoided completely in the "contact" model, sometimes, the numerical calculation even could not be converged if the parameters were not be set properly in this method. Of course, this two methods also have their own advantages, we could select different model according to different circumstances.
On the Basis of Double Fuzzy Control of Honing Machine Reciprocating Motion
Authors: Hu Chi Bing , Wang Ya Zhou , Chen Shan Shan , Zhao Jia Li , Gong Jun
Published: November 2012

This paper mainly researches the control system of honing machine spindle reciprocating motion. On the basis of brief introduction to the processing of honing machines, its mathematic models were established, and design the double control system on the base of fuzzy control .Two fuzzy controllers were used separately according to actual error signal of the system output to improve the system rapidity and overshot .so that make the designed control system of honing machines spindle reciprocating motion can satisfy the design requirements better. Finally the control system was conducted by using the tool of MATLAB. The simulation result showed that the double fuzzy controller can effectively reduce steady-state error of the system and overshoots can well satisfied the system performance index, and has some quick response ability.
CPG-Based Movement Control for Bionic Flapping-Wing Mechanism
Authors: Hou Yu , Wang Fang
Published: November 2012

Flapping-wing flying is a kind of rhythmic movement with symmetry of time and space essentially, and this movement is generated and controlled by Central Pattern Generator (CPG). A 2-DOF flapping mechanism was designed according to the flapping-wing flying principle of insects, and the flapping-wing flying CPG model was constructed by nonlinear oscillators. The system responses were studied, and the influences of the model parameters to the system characteristics were analyzed. Through the engineering simulation of flapping-wing flying control model, the first modal vibration of the system was selected, and the different flying modes of bionic aircraft were realized by adjusting system parameters. This kind of bionic control strategy promoted the movement and control ability of flapping-wing flying, and provided a new method to the generation and control of flapping-wing rhythmic movement.
Research on the Damage of Warship Structure Subjected to Mixed Explosion Load
Authors: Wang Huan Jun , Wang Chao , Yue Yong Wei , Sun Deng Cheng
Published: November 2012

In order to calculate the damage effect of the surface warships subjected to modern anti-ship missile precisely, the solid modeling technology is applied firstly to simulating the penetration explosion of the anti-ship missile in this paper and initial detonation parameter of typical anti-ship weapon is solved based on mixed explosion theory for typical warhead and the explosion load is simulated by corrected sphere-feeding method. On that basis, material model and physical equation referred to numerical simulation of warship structure damage with the whole circuit described in detail and specifically. Also presented is typical computational example calculated by the general finite element procedure LS-DYNA which indicates qualitative coincidence from the impact effect to response tend between the numerical simulation results and experimental data and the method can be applied to the engineering calculation to analysis the damage characteristic subjected to penetration load which provides the basis for the research of ship blast-resistant.
Lessons Learnt from Seismic Damage Induced by the 2008 Wenchuan Earthquake
Authors: Guo De Ping , Hamada Masanori
Published: November 2012

The 2008 Wenchuan earthquake with a surface wave magnitude of 8.0 induced numerous infrastructure damages. The typical seismic damages of 61 bridges, 18 tunnels and slope reinforcements are presented. The results show longitudinal or transverse displacement was the most widespread bridge seismic damage and resulted in girder dropping, shear key failure, joint expansion and support damage. Pillar was sheared off or crushed failure due to strong motions and lack of sufficient hoop steels. Tunnel damage was mainly observed at portal, which was mostly caused by slope failure. Strong ground shaking caused multi-direction cracks in the lining, shear failure of lining resulted from serious surrounding rock relative displacement. Investigation of slope reinforcements suggests anchor cable and frame beam had good anti-seismic property. Furthermore, some suggestions about resistant countermeasures to future earthquake are proposed.
Influence Analysis of Layout of Braces on Structural Dynamic Properties of Large Space Multi-Storey Buildings
Authors: Yu Jin Zhu , Cao Ping Zhou , Wu Kai , Min Ming Bao
Published: November 2012

Taking a six-storey steel frame construction as the research object, parameters under study are the horizontal space of braces’ nodes and the layout of vertical braces. Based on the analysis of the structural period, layer displacement and angles of storey drift, research on the influence of layout of braces on structural dynamic properties of large space buildings is conducted. The results show that when column spacing is larger, braces-setting contributes to significantly improve the structure’s lateral stiffness and reduce the section size of columns, and that the section size of braces can be reduced by shortening the horizontal space of braces’ nodes. Braces should be set between the columns as full as possible. It is better to set the vertical braces positioned in the center instead of on the side between the columns. The lateral stiffness is higher when braces are set concentratedly than dispersedly. It’s more economical to set the inclined braces uniformly.
Tunnel Surrounding Rock Classification Forecast Based on the Geological Advanced Prediction System in Seismic Area
Authors: Ren Tao , Jiang De Yi , Chen Jie , Guo Wei , Ren Song
Published: November 2012

The global earthquake disaster happened frequently in recent years, how to guide the construction correctly in seismic area becoming a problem to be solved, while the study on the tunnel geological advanced prediction system in seismic area is limited. This paper established an integrated prediction system which was combined with engineering geology analysis and geophysical method combined with the analysis of the characters and reasons of tunnel disaster in seismic area. And then, based on the forecast results, the interval of the groundwater correction factor K1, main strike-dip of structural surfaces correction factor K2, the initial stress state influence correction factor K3, which affected basic quality indicator of surrounding rock BQ were divided. At last, the dynamic division of tunnel surrounding rock classification was made by using of comprehensive evaluation method of surrounding rock classification. Construction feedback information showed that the forecast results were accurate and it played a good role to guide the tunnel construction.
Alignment Method for FOG Single-Axis Rotation-Modulation SINS
Authors: Liu Fang , Wang Wei , Li Kui , Wang Lei
Published: November 2012

Aircrafts with common attitude maneuverability (e.g. helicopter) are in more and more urgent need of low cost and high precision inertial navigation system (INS). To meet this demand, a scheme of fiber-optic gyroscope (FOG) strapdown inertial navigation system (SINS) with single-axis to and fro rotation-modulation method is adopted. A short-time alignment method bases on open-loop mathematic platform misalignment model is studied. The test results from the actual system show that this method has characteristic of high accuracy and simple, reliable operation. The estimate accuracy of azimuth error and is less than 2’. And the estimate error of north drift achieves 0.001º/h. Simultaneously, the input-axis accelerometer bias and gyroscope drift are estimated exactly.
An Automatic Measurement for Pipeline Thickness Detection Using Ultrasonic Method
Authors: Dai Bo , Ma Ming Lu
Published: November 2012

The measurement of wall thickness of pipelines is an important procedure of pipeline corrosion inspection. This procedure can be done automatically in a computer by processing data acquired from ultrasound probe, forming C-scan image, and running thickness detection algorithms. This paper presents in detail the comparison of three ways of processing, which are FFT algorithm, twice FFT algorithm, and improved twice FFT algorithm. The final results show that improved twice FFT algorithm has the best precision compared with the other two algorithms. It has higher accuracy than FFT algorithm and less decision error than twice FFT algorithm. Using this method, defects of a pipeline can be identified and measured effectively using ultrasonic wave.
Experimental and Numerical Investigation of CO2 Injection into Water-Saturated Porous Media: Effect of Capillary Pressure on Displacement Efficiency
Authors: Zhao Ming Long , Wang Da Yong , Ma Xiao Jing , Xu Hu Shan
Published: November 2012

CO2 sequestration in deep saline aquifers is regard as the most promising option among all the CO2 storage technologies. Capillary pressure can influence the CO2 storage efficiency in the aquifers. The core-scale experimental and numerical simulation studies are usually used to understand the mechanism and degree of such influence. Based on both magnetic resonance imaging (MRI) technique and numerical simulation method, this study investigates the effect of capillary pressure on the CO2 displacement efficiency in water-saturated porous media especially in quantitative form. Our results indicate: (1) the magnitude of capillary pressure may significantly affect the CO2-water displacement efficiency, and the displacement efficiency declines with increasing capillary pressure; (2) Sensitivity of the numerical model to capillary pressure becomes more unobvious with increasing capillary pressure. Thus, an accurate capillary pressure parameter is particularly required for improving the reliability of the model predictions in the case of the high permeability porous media.
Design of Double Delta-Doped Al0.22Ga0.78As/In0.22Ga 0.78As Pseudomorphic HEMTs
Authors: Wang Zhi Ming , Mou Jin Chao , Yu Wei Hua , Lv Xin
Published: November 2012

In this study, performances of double delta-doped AlGaAs/InGaAspseudomorphic high electron mobility transistors are investigated. Simulation results demonstrate good performance for this structure. Form simulation, the structure demonstrates a maximum current gain cutoff frequency of 145GHz for 100nm gate length, a peak extrinsic transconductance of 526mS/mm, and a maximum saturation current density of 350mA/mm.
Hardware-in-the-Loop Simulation for Automatic Rack and Pinion Steering System
Authors: Nasir Mohd Zakaria Mohammad , Dwijotomo Abdurahman , Abdullah Mohd Azman , Hassan Muhammad Zahir , Hudha Khisbullah
Published: November 2012

As new features for driver assistance and active safety system are going rapidly in vehicle, the interface between hardware and simulation model within a virtual and real environment has become necessity. In this paper, a Hardware-in-the-loop Simulations (HILS) test rig has been develop using actual rack and pinion steering mechanism with controller in Matlab xPC Target environment, LVDT and rotary encoder sensors installed for data measurement at various steering angle. It can manipulate the steering mechanism with various control structure, decrease time with real experiment and trial risk as well as improve development efficiency. Results from HILS experimental model demonstrate a linear pattern occurred from maximum lock-to-lock steering wheel angle with acceptable error.
Fuzzy Comprehensive Evaluation for IT Project Risk Management
Authors: Tang Xing Yan , Jiang Yong Nian , Jian Jie
Published: November 2012

In order to improve project management ability, prevent communication accident, and identify 21 concrete risk factors in IT engineering construction, this paper has set up an evaluation index system with five risk factors for one class index such as design, the personnel, technical force, management, project implementation, and security measures. Then, this paper has used the method of fuzzy comprehensive evaluation to assess the overall risk for CDMA core network expansion project in Xinjiang telecommunication, and put forward the relative solutions for risk.
A Review on the Mechanical and Physical Properties of Natural Fiber Composites
Authors: Zaleha M. , Shahruddin M. , Idris Maizlinda Izwana
Published: November 2012

Research on the use of natural fibers as replacement to man-made fibre in fiber reinforced composites have received more interest and opened up further industrial possibilities. Natural fibre presents many advantages compared to synthetic fibers which make them attractive as reinforcements in composite material. They come from abundant and renewable resources, which ensures a continuous fibre supply and a significant material cost saving to the plastics, automotive and packaging industries. The paper reviews the previous and current research works published in the field of natural fiber reinforced composite material with special reference in mechanical properties of the natural fiber reinforced composite.
Design Optimization of a Dual Function Piezoelectric Actuator
Authors: Bai Yang , Tuncdemir Safakcan , Wang Jian , Guo Ji Feng , Uchino Kenji
Published: November 2012

An optimization algorithm on the stator design of a dual function piezoelectric actuator was described in this paper. Four different sets of motors were investigated using various geometric parameters to determine the best design. The predicted prototype characteristics were in good agreement with the experimental results as well as the ANSYS simulation analyses. This optimization method can be used to enhance the motor output characteristics and efficiency.
Compressive Strength Changing Law of Oil Well Cement Paste under Corporate Corrosion of HCO3- and SO42-
Authors: Wang Yu , Chen Yu Feng , Lu Yan , Zhang Hui Fang , Sun Zhi Guo
Published: November 2012

On the basis of analyzing the oil well cement corrosion mechanism by SO42- and HCO3-, the corrosion products, microstructure and compressive strength of cement stone were measured and the changing regularity and influence factors of compressive strength were analyzed under different experimental conditions. The following conclusions can be drawn. Under the interactive corrosion effect of SO42- and HCO3-, Ca(OH)2 in cement stone was dissolved out and consumed, the calcium silicate hydrate was decomposed, ettringite, gypsum, calcite and thaumasite were produced which destroyed the structure and components of cement stone primary products and led the compressive strength of corrosion cement stone decline. With the increases of ion concentration of corrosive solution, temperature and corrosive time, the compressive strength was decreased gradually, even collapsed completely.
Evaluation of Delamination in Drilling Rice Husk Reinforced Polyester Composites
Authors: Azuan S.A. Syed , Juraidi J.M. , Muhamad Wan Mansor Wan
Published: November 2012

Delamination is recognized as one of the most critical defects that can result from the machining composites. Delamination has been a major form of failure in drilled composite materials due to the composites lack of strength in the drilling direction, which results in poor surface finish, reduction in bearing strength, reduction in structural integrity and ultimately poor performance of the composite. Currently, most of the major research reported delamination address specific of machining fiber glass, graphite fiber or carbon fiber reinforced polymer composites. It is not yet clear how different drilling parameters affect the machinability of natural fiber reinforced polymer composite materials and quality of drilled holes. This paper report the investigation in drilling holes on natural fibre reinforced polyester composites and evaluate its hole quality by measuring delamination. Three different type of drill: twist 118o drill, brad drill and end mill were used. Drilling process is carried out for three spindle speed (1500 rpm, 2000 rpm and 2500 rpm) and three feed rate (0.1 mm/rev, 0.15 mm/rev and 0.2 mm/rev). Brad drill experienced higher delamination values compared to twist and end mill. Increasing of feed rate and spindle speed also caused a relevant increase in the delamination values. It is found that Rice husk reinforced polyester composites delamination value is lower when compared to the glass fiber reinforced polymer.
The Element Free Galerkin Method for Fully Developed, Open-Channel Magnetohydrodynamic Flow
Authors: Cai Xing Hui , Ji Guo Xun , Xu Peng , Zhu Man Lin , Lu Jiang Ren
Published: November 2012

In this paper, an element-free Galerkin method is presented to simulate the liquid metal flow in an open channel under external magnetic field. The global weak form of governing equations is obtained for the case of same size of the height of the liquid film and width of the open channel. Numerical simulations are carried out for some cases of liquid metal flow in an open channel. Results show that the element-free Galerkin method may steadily compute this kind of problem in some cases.
Dynamic Response of an Electro-Rheological Sandwich Beam with Different Elastic Layers Subjected to Simultaneous Impact Loads
Authors: Sepehrinour M. , Nezami M.
Published: November 2012

Dynamic response of an electro-rheological sandwich beam subjected to simultaneous Impact loads will be considered. Analytical solution will be used to draw FRF diagram of the beam for different electric field. Upper and lower layers of the beam have different material properties. Coupled governing equations derived from Hamilton Principle will be solved in frequency domain to find transverse vibration of the beam.
Biomechanical Study of Lumbar Spinal Fixation Device
Authors: Manek Filip , Marcián Petr , Florian Zdeněk , Valášek Jiří , Ebringerová Veronika
Published: November 2012

This article is focused on computational modeling of an interaction of malleable lumbar spine fixation device with ambient bone tissue focusing on solving problems of clinical practise. It describes creation of computational model including model of geometry, materials, loads and constraints. There is a comparative stress strain analysis of spinal segment after fixation device application with its physiological state. Computations are performed with use of FEM method. To simulate natural way of loading we used the compression of motional spinal segment. Results show the difference between the system including intervertebral disc in between vertebras and the system with applied lumbar spinal fixation device.
Microstructures and Various Properties of Hot-Extruded Mg-Zr-Ca Alloys for Biomedical Applications
Authors: Zhou Ying Long , Luo Dong Mei , Li Yun Cang , Wen Cui'e , Hodgson Peter
Published: November 2012

The microstructures, mechanical properties, corrosion behavior, and biocompatibility of hot-extruded Mg-Zr-Ca alloys have been investigated for potential use in orthopedic applications. The microstructures of the alloys are examined by X-ray diffraction analysis and optical microscopy. The mechanical properties of Mg-Zr-Ca alloys are determined from compressive tests, the corrosion behavior is studied using immersion tests, and biocompatibility is evaluated by cell growth factor using osteoblast-like SaOS2 cell. The experimental results indicate that the hot-extruded alloys have much higher compressive strength than the as-cast alloys and the human bone, and can offer good mechanical properties for orthopedic applications. The hot-extrusion significantly enhances corrosion resistance of the alloys. Among the alloys, the hot-extruded Mg-0.5Zr-1Ca and Mg-1Zr-1Ca alloys possess good combination of mechanical properties, corrosion resistance, and biocompatibility, suggesting that they have a great potential to be good candidates for orthopedic applications.
Effect of Nose Tip on Wing Rock of Slender Delta Wing
Authors: Bakaul Saifur Rahman , Wang Yan Kui , Wu Guang Xing , Humayun Qureshi
Published: November 2012

The root cause of wing rock is investigated by examining two slender delta wings (700 and 850 sweep back angle) in wind tunnel using force measurement, pressure measurement and PIV techniques. The results show presence of asymmetric flow at 200 angle of attack and initiation of wing rock at the same point for 850 model while there is neither asymmetric flow nor wing rock for 700 model suggesting close relation of flow asymmetry with wing rock. Investigation with three apparently identical nose sections reveals that the asymmetry comes from the area very close to the wing tip. This asymmetric flow causes the vortices to interact in a complex way resulting in wing rock when the vortices are in close proximity (such as for 850 model), which is not the case when the vortices are ‘comparatively away’ (such as 700 model) from each other.
Hypothesis of Local Zones with Dependent Fatigue Damages Accumulation
Authors: Urbahs Alexanders , Banov Mukharbiy , Turko Vladislav
Published: November 2012

It is set on results the conducted experiments, that the appearance of multiple of fatigue cracks on specimens and design units with numerous concentrators takes place stochastically dependently. This stochastic relationship, both positive and negative, is observed in some zone, with certain dimensions. Positive cross-correlation relationship supposes that before there the fatigue crack will have been originated, the early the subsequent crack will be found out in direction perpendicular to the applied force. Such sequence of fatigue cracks’ originations assumes a mode as a propagation of the first crack, converting it to the only main spread out one. Such zone can be examined as a separate specimen or desigh element with probabilistic descriptions of endurance, fatigue strenght and other characteristics of reliability, that determines reliability of whole system. A physical proof of such zones existence and the description of reliability characteristics are shown as mathematical models.
Influence of Tip Clearance on the Turbulent Aerodynamics of Axial Flow Fan under off Design Conditions
Authors: Akula Praveen Kumar , Singh Balbir , Manikandan M. , Srinivas G.
Published: November 2012

Compressor is a dynamic machine with complicated 3d aerodynamics. Dynamics creates an uncertain environment and induces the flow with instabilities, resulting in reduced performance. Motion being circumferential, flow is also subjected to rotational accelerations. Added to these complications are the tip gap and related vortex aerodynamics in the tip region, which also influence the passage flow of the rotor and thus complicates the flow field. The result of these implications is the generation of the turbulence in the flow field. Turbulence is a fluctuating characteristic of the flow, which extracts its energy from the mean flow field. Energy consumed by the turbulent nature of flow is a waste. Therefore it is very much important to understand about the influence of the turbulence and related kinetic energy compressor aerodynamics. In this paper work is presented to understand about the turbulence under such varying geometry conditions of flow, as well as blade. Results of nature of the turbulence and its growth are discussed for varying mass flow rates and different tip gaps of acceptable range.
Experimental Research on Acoustic Emission of Granite under Uniaxial Compression and Splitting Tensile
Authors: Li Zong Zhan , Tao Jun Lin , Li Yi
Published: November 2012

This paper makes the acoustic emission of granite under uniaxial compression and splitting tensile test by electro-hydraulic testing machine and AE .We studied the relationship of uniaxial compressive strength and splitting tensile strength with the loading rate and AE characteristics of granite .The results show that uniaxial compressive strength and peak strain raise with loading rate, the AE energy gradually increases and get maximum in the 30% of the peak stress in the process of uniaxial compression test, and in the splitting tensile AE energy generates in the initial loading and gets maximum when the granite brittle fracture.
Numerical Wind Tunnel Simulation of Wind Loads on a Solar Photovoltaic Power Generation Station
Authors: Xu Shi Min , Huang Hua Gui , Yu Si Qiang , Wang Peng
Published: November 2012

Aiming at the wind load evaluation in the mechanical structure design of solar photovoltaic power generation station with sun tracking, a numerical wind tunnel model was established based on the computational fluid dynamics theory and finite element method. The 8-level wind velocity was applied in the model considering the mal-condition of reef islands and Gobi desert where the solar photovoltaic power generation station usually installed. From the numerical simulation results, the influence of elevation angle of the solar cells on the wind load was presented. To decrease the maximum wind load on the power station, the gap between solar cells was proposed as air vent in this paper, which has been adopted in a prototype machine, and more than 20% of the equipment weight has been reduced.
Flow Velocity Investigation by Particle Image Velocimetry in Supersonic Air Ejector
Authors: Bouhanguel Ala , Desevaux Philippe , Bailly Yannick , Girardot Laurent
Published: November 2012

Ejectors are devices usually made of two convergent/divergent coaxial nozzles which are used to convert pressure energy into kinetic energy. These devices involve very complex phenomena which strongly affect their performance. Flow visualization methods are often used to provide precious information as for the nature of the flow within the ejectors and the comprehension of the physical phenomena encountered. Unfortunately, the visualization methods used successfully until now in these systems are primarily qualitative techniques. Some attempts at quantitative flow visualization by Particle Image Velocimetry have been carried out in quite specific applications but with mitigated results due to the complicated conditions of investigation. The objective of this paper is to present an attempt at PIV measurements in a supersonic air ejector. Several ejector operating conditions and flow seeding methods are taken into consideration. The velocity fields obtained are compared with CFD simulations of the flow and allow the rigorous validation of numerical models.
A Two-Phase Flow Model with VOF for Free Surface Flow Problems
Authors: Zhang Wei , Tang You Hong , Zhao Cheng Bi , Zhang Cheng
Published: November 2012

A numerical model based on the two-phase flow model for incompressible viscous fluid with a complex free surface has been developed in this study. The two-step projection method is employed to solve the Navier–Stokes equations in the numerical solutions, and finite difference method on a staggered grid is used throughout the computation. The two-order accurate volume of fluid (VOF) method is used to track the distorted and broken free surfaces. The two-phase model is first validated by simulating the dam break over a dry bed, in which the numerical results and experimental data agree well. Then 2-D fluid sloshing in a horizontally excited rectangular tank at different excitation frequencies is simulated using this two-phase model. The results of this study show that the two-phase flow model with VOF method is a potential tool for the simulation of nonlinear fluid sloshing. These studies demonstrate the capability of the two-phase model to simulate free surface flow problems with considering air movement effects.
Capillary Force in the Particle-Particle-Substrate System
Authors: Yang Li , Hu Jun Hui , Sheng Nan , Kong Ling Jiang
Published: November 2012

The prediction and the control of the magnitude of the capillary force are essential for the micromanipulation techniques. It is generally considered that the capillary force is an effective and reliable scheme for micromanipulation. In this paper, a very complicated calculation process for the theoretical capillary force is reviewed, and a practical approximate formula for the calculation of the total capillary force in the particle-particle-substrate system is proposed. Comparison is made between the approximation and theoretical results and good agreement is found. It is suggesting that the approximate formula can be applicable for the evaluation of the capillary force in the micromanipulation.
Research of Pipeline Fault Diagnosis for Liquid Rocket Propulsion System
Authors: Li Yan Jun , Peng Xiao Hui , Cheng Yu Qiang , Wu Jian Jun
Published: November 2012

The applications of healthy monitoring and fault diagnosis's system can enhance the reliability and safety of the whole vehicle, which has significance to detect and isolate fault as early as possible and that tragedy can be avoided. In this paper, pipeline fault simulation analysis and fault diagnosis for LRE is studied as direct-inverse problem. Firstly, the failure model was constituted for pipeline to analysis the necessary condition for fault isolation. Then the conclusion that strategy of fault diagnosis was build by analysis the simulation result based on AMESim. Finally, the fault diagnosis algorithm was validated by test data. The results indicate that the fault diagnosis algorithm can detect fault exactly and effectively. There are no false alarm to normal test data and no false alarm to other components fault. Consequently the fault isolation result could be reached.
Advanced Space Launching Mechanism
Authors: Chowdhuri Rajdeep , Prakash Pate Sweety , Shakya Ravi Kumar
Published: November 2012

Improving the standards of the launch mechanisms and cutting down the launching costs is the prime objective here.
Studies on Gravity Influence on Solid Propellant Burn Rate
Authors: Vasudevan Hariprasad , Sankar P. , Shivahari P. , Kumar V.R. Sanal
Published: November 2012

Experimental studies have been carried out using the in-house developed propellant samples at the atmospheric conditions to examine the influence of propellant surface orientation / attitude on burn rate. A series of burning tests are conducted with different grain orientations, viz., vertical, inverted and horizontal. We have observed 5 % burn rate augmentation on end-burning grains when the burning surface evolution was against the earth gravity compared to the normal vertical candle burning condition. We conjectured that the coupled effects of the instantaneous variations of the propellant burning surface attitude and the flight acceleration during the mission could alter the flame structure due to the local gravitational influence, which in turn alter the burn rate. This paper throws light for developing a suitable gravitational force dependant burn rate model for improving the performance prediction of solid rocket motors for aerospace applications.
Design Algorithm for Upper Stage’s Attitude Control System
Authors: Delalat Meysam , Nosratollahi Mehran , Adami Amirhossein
Published: November 2012

Inserting a satellite into different orbit of injection orbit require an orbital maneuver. In addition, the orbit maneuver needs a suitable control of upper stage. Providing required angles is the duty of this control and it must be able to come over disturbances. This paper, with looking over Attitude Control Systems (ACS) used in upper stages, introduces an algorithm for design and sizing of upper stage`s ACS considering requirements and constraints. The algorithm derives required ACS propellant mass, tanks value, feeding pressure, amount of thrust, combustion chamber pressure and total mass of ACS. Presented algorithm needs minimum inputs and estimates the outputs using accuracy experimental functions and scientific theorems. Finally the algorithm is validated by some real cases.
A New Method for Precision of a Serpentine Snake-Like Robot
Authors: Sarrafan Siavash , Akbarzadeh Alireza
Published: November 2012

In this paper, a planar snake-like robot travelling in serpentine locomotion is considered. A method is presented where structural and gait control parameters are used to obtain the minimum snake-robot positional error, geometrical error. Two structural parameters, length and mass of each link as well as two control parameters, initial winding angle (α0) and arc length (s) are considered. Each of the four input parameters is examined at five different levels. The method uses Taguchi experimental techniques and analyzes effects of uncertainties by means of adding noise to the robot parameters. Significance of the input parameters is also determined using Analysis of Variance.
Localization and Identification of Vibroacoustic Sources of Gear Transmission Mechanism by Inverse Frequency Response Function
Authors: Derouiche Abbassia , Hamzaoui Nacer , Boukharouba Taoufik
Published: November 2012

Our contribution in this work is to detect, localize and quantify the noise sources radiated by a spur gear transmission mechanism. The imaging technique is used; it is based on the acoustic inverse frequency response function (IFRF). The IFRF is based on the inversion of the transfer matrix built between the source points represented by their complex source strengths and listening points represented by the complex pressures measured by the hologram. The measurements were performed in a semi-anechoic room where the floor is concrete and the walls are covered with glass wool. The complex acoustic pressures are measured by an antenna with microphones regularly spaced; it is placed above the noisy mechanism. The reconstruction problem is therefore an inverse problem and is said ill-posed; thus, regularizations are needed to stabilize and to find the best solutions. As regularization technique, the Tikhonov method is applied and the regularization parameters are chosen according to the L-curve method. The goal is to reconstruct as accurately as possible the acoustic field radiated by the transmission mechanism on a fictive and tangent plane to the noisy mechanism considered open and sometimes closed. The results obtained showed that the sources were located with good approximation. The IFRF method is able to reconstruct the sound sources responsible for the noise radiated by the mechanism without any a priori information of the sources distribution, and the visualization of spatial acoustic fields facilitate the understanding of the complex phenomena of radiation.