bluuebunny/crossref_metadata_2025 huggingface dataset:
Special Issue on Structural Impact and Crashworthiness: Part II - Preface
Authors: Hadavinia Homayoun , Elmarakbi Ahmed
Published: July 2014

This issue is the Part 2 of papers submitted to a call by International Journal of Vehicle Structures and Systems on Structural Impact and Crashworthiness. The division of the papers between the two parts was only due to the editorial and refereeing matters and there is no priority among the papers. As mentioned before the goal of these Special Issues is to provide a broad, but by no means comprehensive cross-section of some of the current research in the field of Structural Impact and Crashworthiness. Papers presented in this issue describe advances in research and application in the related area. They reflect enormous research effort of all the participants and substantial research funding commitments from various government bodies in different countries and the wider community.
Dynamic Performance of Electro-hydraulic Steering System for Off-road Vehicles
Authors: Emam Mohamed Ali , Tayee Mohamed Said Baywme Mohamed , El-Demerdash S.M. , Rabie Mahmoud Galal
Published: July 2014

The dynamic characteristics of an Electro-hydraulic (EH) steering system plays an important role in realizing an accurate steering control for an automatically guided vehicles. In this paper, a mathematical model has been developed for EH steering system that includes EH servo valve with mechanical feedback, steering actuation cylinders and associated steering linkages. A proportional-integral controller has been designed to improve the dynamic performance of EH steering system for off-road vehicles. The simulated system models using SIMULINK were validated using experimental tests. The control of steering angle using the proposed proportional-integral controller has been demonstrated for different soil conditions.
Single Interrupt Control and Regenerative Braking of PMBLDC Motor for Electric Vehicles
Authors: Shah Varsha A. , Mistry Divyesh , Kundu Prasanta , Maheshwari Ranjan
Published: July 2014

Permanent Magnet Brushless DC Motors (PMBLDC) have been widely used in electrical vehicles as they provide high torque in starting and acceleration modes. Hall sensors are used for recognition of rotor position and 3-leg metal oxide semiconductor field effect transistor bridge inverters are used for electronic commutation of the stator winding. In addition, when a microcontroller controls the PMBLDC motor, the hall sensors firing the appropriate switching devices need continuous monitoring. This demand puts a strain on the controller required for other tasks such as pulse width modulation management, speed control, direction command, measurement of speed, and simultaneous display of various performance parameters. To overcome these difficulties, a single interrupt-based commutation is proposed to generate an external interrupt for every hall sequence transition. In order to drive the bridge inverter efficiently, a new driver circuit has been designed with a TLP250 driver integrated circuit. Also, regenerative braking is proposed to extend the travelling range of the electric vehicle. The proposed regenerative braking is achieved by using either a hysteresis current controlled buck converter or an inverter with boost mode. The results obtained from the hardware setup of the proposed system are discussed.
Improved Cable type Accelerator Control System with Slider Mechanism for Commercial Vehicles
Authors: Biswas Sanjoy , Bardhan Abhisek , Pandey Ajay , Sharma Sanjay
Published: July 2014

This paper details the design and validation of an improved cable-type accelerator control system for left hand drive (LHD) army vehicles. A slider mechanism is used for the pedal control unit. The design is verified by kinematic analysis using ADAMS simulation. The vehicle performance and verification of ergonomic parameters are tested using a prototype vehicle. Improvements in the ergonomics, system reliability and packaging/installation in comparison with the existing accelerator control system are demonstrated.
Preventing Disc Brake Squeal using a Thin Plate Shim
Authors: Abu Bakar Abd Rahim , Zainudin Muhammad Amir
Published: July 2014

Squealing from car disc brakes is a source of considerable discomfort and leads to customer dissatisfaction. The high frequency squeal noise above 1 kHz is very annoying and difficult to eliminate. Good braking performance against noise is considered to be a big market advantage. Reduction of brake squeal in the design stage is a formidable challenge that is faced by the automotive engineers. This paper attempts to provide a solution of eliminating disc brake squeal up to 10 kHz using a thin plate shim. First squeal occurrences in a disc brake assembly without thin plate shim are investigated for various operating conditions using a drag type brake dynamometer. Having identified the dominant squeal frequencies several shapes of thin plate shim are proposed and tested. The aim of using thin plate shims is to modify contact pressure distribution on the brake pads. A good shim should be able to effectively suppress and prevent those squeal frequencies generated in a disc brake system.
Proportional Integral Derivative Control of Hydro-Gas Suspension Unit for Tracked Vehicles
Authors: Srinivasan G. , Bashaa A.M. Junaid , Kumar M. Senthil , Anbudurai K.
Published: July 2014

High-speed tracked vehicles traversing off-road terrains are subjected to ride vibrations of low frequency and large amplitude. This causes bodily discomfort to the operator and limits the mobility and performance of the vehicle. The damping of the terrain vibrations is achieved by a Hydro-Gas Suspension Unit (HGSU) with inbuilt damper and hydraulic actuator piston mechanism. The present studies have been carried out to develop a quarter-car dynamic model of passive and active suspensions for improving the HGSU characteristics using proportional integral derivative controller. Performance of the active suspension system has been compared with the passive suspension system through simulations using MATLAB/SIMULINK software.
Fatigue Crack Growth Arrestor for High Speed Flexible Coupling of Fighter Aircraft Transmission Systems
Authors: Nagesh S. , Bashaa A.M. Junaid , Abilash S.
Published: July 2014

A lightweight High Speed Flexible Coupling (HSFC) is used to connect the engine gear box (EGB) with an accessory gear box (AGB) for fighter aircrafts. The HSFC transmits the power at high speeds ranging from 10000 to 18000 rpm from the EGB to AGB. The HSFC also accommodates larger angular and axial misalignments resulting from differential thermal expansion of the aircraft engine and mounting arrangement. The HSFC utilizes series of metallic contoured annular thin flexible plates. These flexible plates are susceptible to fatigue failures in the presence of minuscule surface defects. The present work describes the analysis carried out on a typical HSFC with incipient flaw for various kinds of imposed misalignments. Based on the sensitivity study of the flaw on the stress levels, a Fatigue Crack Growth Arrestor (FCGA) is designed. In order to contain the crack propagation, drilling a hole at the tip of the crack on the flexible plate as a FCGA is adapted. The fatigue life of the flexible plates is improved by finding appropriate size and location of FCGA through finite element analysis and simulations.
Improved Air Intake System Louvers for Armour Fighting Vehicles
Authors: Krishnakumar S. , Singaravelu N. , Kumaravelu C. , Suresh S.
Published: July 2014

This paper details the air flow characteristics of the louvers of air intake system in armour fighting vehicles. An attempt is made to optimize the louver configuration to meet the requirements of protection and Airflow characteristics without increasing the vehicle volume and with modifications wherever possible. Pressure drop tests on S type of louvers were undertaken in the existing air intake system of Armour Fighting Vehicles for various configurations.
Performance of Electromagnetic based Suspension System for Automobiles
Authors: Prabu K. , Jancirani J.
Published: July 2014

This paper is concerned with studying the response of a hybrid magnetic vehicle suspension system. The objective of this work is to produce vehicle body isolation by reducing the sprung mass acceleration and minimize the suspension travel, to produce good road holding ability. Two degrees of freedom quarter car model of a passive suspension system with a cylindrical type hybrid magnet is considered for the analysis. Analytical modelling, simulations and laboratory scale experiments are conducted. The performance of active suspension systems from simulations using MATLAB and experiments are compared with the passive suspension system. The amplitude of vibration of the sprung mass using active suspension is considerably reduced from that of passive system.
Experimental Investigation of Failure Mechanisms in GFRP Lap Joint using Acoustic Emission
Authors: Asokan R. , Dinesh M. , Santosh R. , Arumugam V. , Stanley Joseph A.
Published: July 2014

In this paper, Acoustic Emission (AE) based damage mode identification of Glass Fibre Reinforced Plastic (GFRP) lap joints is detailed using laboratory scale experiments. Bonded single lap joint specimens are fabricated from GFRP laminates. These specimens are subjected to tensile test with on-line AE monitoring. The study of failure mechanisms is facilitated by the choice of different oriented lap joint specimens in which one or two such mechanisms predominate. Range of peak frequencies in each orientation is investigated using frequency analysis. Fast Fourier Transforms enabled calculating the frequency content of each damage mechanism. Parametric plots are used to discriminate the different stages of occurrence of failure mechanism in lap joints. Results have shown that predominate of failure modes in each orientation is used as a key in the study of discrimination of failure modes from AE data in lap joints.
Recent Advances in Railway Vehicle Dynamics
Authors: Sharma Rakesh Chandmal
Published: July 2014

In this paper, the state of the art of railway vehicle dynamics is presented. Much of the attention is paid to the performance characteristics such as lateral stability, curving, multibody simulation, wheel to track interaction, ride quality and comfort. The scope and limitations of linear and nonlinear analyses for vehicle dynamics are reviewed. Two and three dimensional theories for wheel-to-track interaction are discussed. Detailed analysis of ride quality and comfort evaluation methods is presented. Some concluding remarks are discussed along with further directions of research in the railway vehicle dynamics.
Comparative Study of Steering Mechanisms for Large Wheelbase Vehicles
Authors: Pramanik S. , Ingle R.B. , Latey A.A.
Published: July 2014

This paper presents an optimum synthesis of Ackermann, rack and pinion and centre lever steering mechanisms using Hookes and Jeeves optimization. The objective function of the optimisation comprises of steering error. The length of the steering arm has been assumed as one-fifth of the wheel track for all cases. The steering error, transmission angle and mechanical advantages of these steering mechanisms have been compared. It has been found that the rack and pinion steering mechanism produces the least steering error. The transmission angle and mechanical advantage of the centre lever steering mechanism are most favourable. A suggestion has been made to replace the existing Ackermann steering mechanism for long wheelbase vehicles by a central outrigger type leading rack and pinion steering mechanism.
Energy and Cost Analysis of Weight Reduction using Composite Brake Rotor
Authors: Maleque M.A. , Adebisi A.A. , Shah Q.H.
Published: July 2014

This paper attempts to predict the effect of weight reduction on energy consumption and cost savings using an aluminium matrix composite automotive brake rotor. Mathematical models are established to evaluate the influence of weight reduction on material consumption, cost and energy savings. The study showed that a 50% weight reduction due to AMC brake rotor replacement compensates for 19% of energy savings against cast iron brake rotor.
Special Issue on Composites and SHM - Editorial Forward
Authors: Dattaguru B. , Gopalakrishnan S.
Published: July 2014

The Indian Institute of Science, Bangalore along with North Carolina State University, Greensboro, NC, USA and Indian Society for Advancement of Materials and Processes Engineering (ISAMPE) conducted an International Conference on Composites for 21st Century: Current and Future Trends during Jan 4-7, 2011. The conference was attended by several distinguished Scientists from India and from many countries outside India. As recognition of the high standard set by the conference, the International Journal for Vehicle Structures and Systems (IJVSS) has proposed to bring out a special issue of select papers from the conference.
Structural Health Monitoring of Composite Structures - Issues and Challenges
Authors: Sundaram Ramesh , Kamath G.M. , Gupta Nitesh
Published: July 2014

Composite materials are increasingly being used in aircraft structures due to their superior properties. Although composites have a higher ability than metals to withstand fatigue loading, they have a lower resistance to impact. Moreover, unlike in metals where impact results in a visible dent or damage, impact on composite structures results in internal defects, which cannot be detected through a regular visual inspection. Thus composites necessitate more sophisticated methods of non-destructive inspection resulting in higher maintenance costs. One of the ways to bring down this cost is Structural Health Monitoring (SHM). SHM technologies would lead to a ‘condition-based maintenance’ or ‘maintenance-on-demand’ paradigm that would increase inspection intervals, leading to lower maintenance costs. Apart from the diagnostic role that SHM would play, an equally important aspect is prognostics, wherein the damage/defect growth rates can be predicted or estimated. The key to an effective SHM system for aircraft structures is not only the appropriate sensor selection but also the processing of the sensor data to predict the flight load and the damages, if any, in the structure. However, structural failure along with sensor malfunction during flight can pose a serious challenge and can lead to erroneous load estimation or inaccurate damage quantification which is extremely critical as far as a robust health monitoring scheme is considered. This paper discusses the issues and challenges in realizing a fully online SHM system.
Innovative Material Systems for Composite Vehicle Structures
Authors: Potluri Prasad , Jetavat Dhaval , Hogg Paul
Published: July 2014

Prepreg-based materials currently used in high-end applications as well as SMC/BMC-based materials used in automotive body panels are not likely to lead the future growth in the application of fibre-reinforced composites in primary as well as secondary vehicle structures. Out-of-autoclave techniques based on rapid fibre preforming and part consolidation will drive the structural composites applications in aerospace and automotive sectors. Fibre preforming has been identified as a key bottleneck in the composites supply chain, considering recent growth predictions in civil airframe and automotive markets. Automated Tape Laying machines have modest deposition rates, and global autoclave capacity is not likely to cope with projected growth rates in composites. This paper investigates the potential for near-net preforming using conventional textile technology as well as robotic approaches. Robotic or multi-axial machines have been shown to extend the preforming capability of weaving, braiding and stitching concepts. A multi-axial weaving machine, equipped with automated trimming of non-interlaced tows, can create 3D woven preforms tapered in width as well as length directions. 3D preforms with through-thickness reinforcement have been created with a robotic system equipped with dry fibre lay-up and tufting capability. A 9-axis complex winding machine in conjunction with braiding has been demonstrated for preforming over complex mandrels.
Advanced Reinforced Thermoplastic Composites for Mass Transit and Heavy Truck Applications
Authors: Vaidya U.K. , Pillay Selvum Brian , Balaji Thattai K. , Ning Haibin
Published: July 2014

The objective of the research effort is to develop cost-effective high performance thermoplastic composite materials and product forms and manufacturing of structural components for mass transit, heavy truck and military transport applications. Thermoplastic composites technologies possess the potential to provide structures with lower cost, lighter weight, and improved performance. This paper discusses an integrated processing and product development approach for select components such as seats, floor segments, and roof cover doors generic to mass transit, heavy transit and military transport. Long fiber thermoplastic (LFT) and continuous thermoplastic fiber forms have been used in processes ranging from extrusion-compression to vacuum thermoforming. About 40-60% weight savings with equivalent or enhanced performance have been achieved in these applications. Process modeling such as fiber/polymer melt flow in the LFT process has also been discussed in this paper.
Aircraft Composite Skin Stacking Sequence Generation using Genetic Algorithms
Authors: Sathyanarayana K. , Sandeep V. , Pradeep K.R. , Sujib D. , Ravindra K. , Ravi Kumar G.V.V.
Published: July 2014

Composites structures are widely used both in military and commercial aircraft industries. Design of tapered composite skins is quite laborious and time consuming. Optimization of these composite skins is essential for realizing the full benefits offered by composites. Composite skins are optimized in two stages. In the first stage, thicknesses of various zones of composite skin along with the percentage of fiber orientations is computed using gradient based algorithms. In the second stage, the stacking sequence generation is performed mostly using knowledge based engineering approaches using rules and heuristics. The stacking sequence generation is a combinatorial problem and is quite complex. Such combinatorial problems can be solved elegantly by genetic algorithms. The available genetic algorithm based stacking sequence approaches are mostly theoretical and are demonstrated mainly as research and academic problem for laminates of constant thickness with few constraints. In this paper a genetic algorithm based approach for stacking sequence generation of tapered composite skins with multiple zones is presented. This approach is scalable and can solve large size composite skin generation problems with reasonably good number of constraints. The paper also demonstrates the usefulness of the current approach by solving few large scale stacking sequence generation problems in real life aircraft industry.
Propagation of the Fundamental Symmetric Lamb Mode in a Symmetrically Delaminated Composite Laminate
Authors: Ramadas C. , Padiyar Janardhan , Balasubramaniam Krishnan , Joshi Makarand
Published: July 2014

In this paper, a study on the propagation of the fundamental symmetric Lamb mode (So) in a symmetrically delaminated glass/epoxy composite laminate is presented. It was found that when So mode is incident at the front and rear edges of a symmetric delamination, it generates Ao mode. This mode is exclusively confined to the sub-laminates. It was also observed that, during the interaction of the generated Ao mode with the edges of delamination, it, in turn generates So mode. Thus, So mode and mode converted Lamb modes undergo multiple mode conversions in the sub-laminates. The only mode that propagates in the main laminate is So. A signal-processing scheme based on the time-frequency spectrographic analysis was utilized to identify the wave groups propagating in the main and sub-laminates.
Computed Tomography based Process Control of Composite Structures for In-service Defects
Authors: Ramesh Babu G. , Srinivasa Reddy B.N. , Murari Krishna
Published: July 2014

In this study, Computed Tomography (CT) is employed to characterize service defects in polymer composites, paying particular attention to the influence of density and the effects of inclusion waviness and its distribution to the effective stiffnessof composites. Laminated composites, fabricated with varying densities and varying thicknesses, are subjected to low loading damage at various energy levels. X Ray CT is used to observe in plane matrix distribution and overall dark line indication propagation. CT is exploited to examine the through thickness matrix distribution and 3D dark line indication damage pattern. It is revealed that less fiber volume ratio act as crack initiation zones due to the presence of weak resin-rich pockets around fibers. Denser and unevenly distributed fiber volume ratio has shown more dark line indication (delamination) for various loading at different service hours. An appropriate density mapping using CT number and attenuation distributions are obtained from the fatigue test of specimen and flight test data of rotary wing blade to assess their safety and structural reliability.
Study on Finite Element Modeling Aspects of Delaminated Honeycomb Sandwich Beams
Authors: Pradeep K.R. , Srinivasan S.M. , Nageswara Rao B. , Balasubramaniam K.
Published: July 2014

The simulation of damaged honeycomb sandwich structures is an important aspect in the structural health monitoring and prognosis. This paper studies finite element modeling aspects of delaminated honeycomb sandwich structure. The models proposed are 3-D model of the honeycomb sandwich construction using isotropic shell elements and a layered shell element model, both with contact elements defined in between the delaminated skin and core. Case study is conducted on damaged and undamaged metallic sandwich beam with 3-D shell element modeling and layered element modelling. The models are validated using three point bending test of damaged and undamaged beams. Results are compared with the experimental, theoretical and finite element results. The results show that the layered element modeling simulates the stiffness and gives the similar results to that of 3D model in the global responses and is computationally efficient.
Special Issue on First Brazilian Conference on Composite Materials – Editorial Forward
Authors: Cimini Jr. Carlos A. , Melo Jose D.D. , Marinucci Gerson , Neto Flaminio L. , Arakaki Francisco K.
Published: July 2014

In the wake of Brazil becoming a member nation in the International Committee on Composite Materials at ICCM-17 in Edinburgh, Scotland (2009), the Brazilian composites community decided it was time for Brazil to organize the first conference in the area. Research and development in composites have been successfully conducted in Brazil long enough and scientists usually communicated their work in international conferences overseas or in limited seminars within local conferences. However, the maturity and high quality of the research conducted and the increasing importance of the composites industry demanded a conference in Brazil.
Analysis of Low Energy Impact on Filament-wound Composite Cylinders
Authors: Ribeiro Marcelo L. , Martins Tulio , Sartorato Murilo , Ferreira Gregorio F.O. , Tita Volnei , Vandepitte Dirk
Published: July 2014

Composite materials are very attractive for structural applications due to its inherent mechanical properties and low density. However, during their service life, composite structures can be damaged by impact such as tool drop during assembly or maintenance. Several studies have been developed for impact on composite plates, but there are only few scientific investigations about impact on composite cylinders. This study presents experimental analyses of low energy impact on filament-wound cylinders. Three different lay-ups were evaluated for 9J and 31J impact levels. Bidirectional strain gauges, one accelerometer sensor, force and displacement sensors were used for data acquisition from the results The influence of the lay up on the behaviour of the filament-wound cylinder was discussed.
Prediction of Failures in Single Lap Bonded Composite Joint Subjected to Low Energy Impact Loading
Authors: Capasciutti de Oliveira Sergio A. , Donadon Mauricio V. , Tarpani Jose R.
Published: July 2014

The purpose of this work is to predict the failure modes of single lap composite bonded joints subjected to low energy impact loading using finite element analysis. Experimental data were collected during mechanical tests by impacting the specimen using a drop test tower. Maximum impact induced force and dissipated energy for each specimen were measured. Finite element simulations were carried out in Abaqus/Explicit using two damage models. The first damage model accounts for delamination failure modes by using a de-cohesive contact logic. The second damage model accounts for in-plane failure modes using maximum stress criteria and continuum damage mechanics. These models enable the prediction of inter and intra-laminar failure modes. The predicted impact force, displacement and damage pattern were found to be in good correlation with tests and thermographic inspections.
Sensitivity of Automated Fibre Placement Parameters on Manufacturing Defects in Laminated Composites
Authors: Bottene Alex C. , Nunes de Mello Wellington L. , Hemerly de Almeida Rynaldo Z.
Published: July 2014

Composites are being continuously used to fulfil the demands for lighter and high performance components. Automated Fibre Placement is used as a technique to achieve best results to manufacture complex composite parts. However, this process induces some defects such as gaps, overlaps and tow drops in the manufactured laminate. This paper presents the influence of the manufacturing parameters such as feed rate, tow temperature, tow tension, and compaction pressure on the manufacturing induced defects in the laminate. Test results have revealed that it is possible to control these manufacturing parameters to minimize or avoid such defects for manufacturing high quality laminates.
Representative Volume Element based Transverse Shear Characterisation of Laminated Composites
Authors: Sartorato Murilo , De Medeiros Ricardo , Ribeiro Marcelo L. , Tita Volnei
Published: July 2014

This paper presents a methodology to calculate the shear correction factors for composite plates using a representative volume element approach and finite element analyses. The results are obtained for two case studies: a carbon-epoxy laminate made of UD layers and a glass-epoxy laminate made of BD layers. The results have been compared with other calculations obtained by models provided in the literature. Finally, a finite element model of a cantilever beam is developed using ABAQUS for undertaking modal analysis. The finite element analysis results compared the dynamic characteristics of a beam using both the shear correction factors calculated via the proposed methodology and without the shear correction factors. The finite element analysis results, provided by the shear correction factors calculated via proposed methodology, are compared to the results obtained for a model without shear correction factors. It is possible to observe that the natural frequencies can change by more than 10% due to the effect of transverse shear.
Numerical and Experimental Dynamic Analyses via Smart Composites
Authors: De Medeiros Ricardo , Ribeiro Marcelo L. , Ferreira Gregorio F. O. , Marques Flavio D. , Tita Volnei
Published: July 2014

This paper consists of evaluating a methodology based on a representative volume element and finite element analyses, using numerical and experimental modal analyses via smart composites. Vibration tests and finite element models are developed for aluminium cantilever beam with and without piezoelectric patches. The effective properties of the smart composites are calculated by applying the proposed methodology. Numerical predictions and experimental results are compared, showing that the relative differences between these dynamic analyses via piezoelectric patches are within 2.0%. The dynamic behaviour of the structure can be reasonably changed for a variation in the effective coefficients of the piezoelectric patches.
Thermal Expansion Behaviour of Magnesium Boron Fibrous Composites
Authors: Soares Alexandre R. , Marinkovic Bojan A. , Prisco Luciana P. , D’Almeida José R.M.
Published: July 2014

Magnesium boron fibrous composites have been used in the aeronautical/aerospace due to their resistance/weight properties. The focus of the study was to collect detailed behaviour of thermal expansion for controlled rates of heating and thermal cycles through experiments. The results were compared with Schapery model and rule of mixtures for a range of temperatures and fibre orientations. The measured valuesof coefficient of thermal expansion values were in good agreement with the theoretical calculations for the considered 0 and 60 degrees fibre orientations. The behaviour for 90 degrees orientation was dominated by the thermal expansion of magnesium matrix as expected.
Parametric Analysis of Puck-Matzenmiller Theory based Damage Model for Composite Structures
Authors: Angelo Marcus V. , Galucio Ana-Cristina , Tita Volnei
Published: July 2014

This work aims to provide a computational tool to calculate composite aeronautical structures such as fuselage and rotor blade, considering large damage capabilities. The computational tool developed was based on the theories proposed by Puck and Matzenmiller. The damage propagation is carried out by progressive failure analysis via a phenomenological approach. The material model separates the mechanisms concerning the fibre and the matrix and addresses them under different perspectives. Some parameters related to the material model were obtained from standardized experimental tests, while the identification of others required the development of special procedures. The material model was implemented as subroutines in FORTRAN language, which were linked to ABAQUS by UMAT/URDFIL. A non-local criterion was used to provide spatial regularization, avoiding numerical convergence problems. In order to perform an automatic identification of the parameters related to the material model, another computational tool was developed. After the identification process, a parametric sensitivity study was carried out using a composite plate with a circular hole. The investigated parameters - finite element mesh size, load step and characteristic radius were selected considering that their influences were supposed to be material independent. Finally, a damage analysis of the same composite plate under a specific loading condition was carried out using the “optimal” values for the investigated parameters. Based on the convergence between the numerical results and experimental data, it can be concluded that the theories and methods applied in this work consisted a good strategy to simulate composite structures in the industry environment.
Real-Time Automated SHM for Systems in Interplanetary Subsurface Exploration
Authors: Statham S. , Hanagud S. , Glass B.J.
Published: July 2014

This paper presents a real-time automated structural health monitoring system (SHM) for a drill system. The drill system is for obtaining subsurface samples during interplanetary exploration. Such an SHM has stringent specifications including a fast-response of the health of the system before the faults or defects have the potential to stop the drilling operation, use of drill motor as the internal actuator, a need for non-contact sensors, automation of the complete SHM system, real-time capability and a reliability of monitored health of the structure. The paper presents the formulation, development and validation of such an SHM through a combination of analysis, laboratory tests and field tests on a selected test vehicle.
Stability and Eigenvalue Analysis of an Indian Railway General Sleeper Coach using Lagrangian Dynamics
Authors: Sharma Rakesh C.
Published: July 2014

This research paper determines the eigenvalues of main rigid bodies i.e. car body, bolsters, bogie frames and wheel axles of a 37 DoF coupled vertical-lateral model of a General Sleeper ICF coach of Indian Railway formulated using Lagrangian dynamics. The primary and secondary hunting speeds of the railway vehicle are determined to investigate the dynamic stability. Critical parameters which influence the railway vehicle dynamic stability are analysed.
Thermo-mechanical Stress Analysis of Disc Brake Rotor
Authors: Belhocine Ali , Bouchetara Mostefa
Published: July 2014

This paper presents a thermo-mechanical analysis of dry contact between the brake disc and pads during the braking phase. The simulation strategy is based on computer code ANSYS. The modeling of transient temperature in the disc is used to identify the influence of geometric design of the disc to install the ventilation system in vehicles. A thermo-structural analysis is then used to determine the deformation, Von Mises stresses in the disc and the contact pressure distribution in the pads. The results are satisfactory compared to those found in the literature.
Rack and Pinion Steering System Control using Electronic Side-stick
Authors: Albatlan Saeed A.A.
Published: July 2014

The objective of this research is to electronically control the steering in a vehicle with power steering system using a side-stick. To achieve this goal an electronically controlled module is implemented on a rack and pinion steering system. This module is operated using a side-stick. Necessary sensors and actuators replaced the conventional steering wheel. An embedded controller is used as a control unit. Required interfacing circuits are designed and implemented. For investigation of the proposed steering control system, a mathematical model is developed. The test rig of the control system showed a great benefit in modifying a conventional steering system to be electronically controlled. The simulation results agree well with the test results.
Vibration Based Prediction of Noise in Passenger Car Gearbox Structures
Authors: Abouel-seoud Shawki S. , Mohamed Eid S. , Abouel-yazid Ahmed A. , Abdalkkah Ahmed S.
Published: July 2014

In this paper, a method for predicting the contributions to noise radiated by a vehicle gearbox structure using measured vibration responses is presented. The gearbox structure is idealised as a set of flat plates. The radiation efficiency is calculated from the physical properties and edge constraints of each plate and the measured vibration response of the gearbox structure surfaces. These data were used in a simple acoustical power theory to determine 1/3-octave band sound pressure level under free field conditions for the whole and individual noise sources. The predicted individual noise sources are then used to pinpoint the exact problem area in the gearbox structure with a view to noise reduction.
Effect of Natural Frequency in a Low Mass Flexible Vertical Slender Beams
Authors: Jalwadi Sudhindra N.
Published: July 2014

In this paper thermal-structural behaviour of an internally heated vertical low mass cantilever beam was analyzed by a mathematical model and finite element analysis. The obtained results are verified with experimental results. The analysis shows that when natural frequency of the beam is in the range of 0.788 to 1.051Hz thermally induced vibrations occur. This indicates that determining natural frequency of the beam is more important than the heating rate. Outside the range of 0.788 to 1.051 Hz, thermally induced vibrations are absent since thermal moment developed due to temperature difference is insufficient to drive the beam.
Finite Element Methodology for Flexible Track Models in Railway Dynamics Applications
Authors: Pombo J. , Almeida T. , MagalhÃ£es H. , Antunes P. , AmbrÃ³sio J.
Published: July 2014

The dynamic analysis of railway vehicles involves the independent construction of models representing vehicle, track and wheel-rail contact. In this work, a multibody formulation with Cartesian coordinates is used to describe the kinematics of the rigid bodies and joints in the vehicle model. In order to create detailed three-dimensional track finite element models, a methodology that includes the flexibility of rails and substructure is proposed. Finite element methodology is used to model the rails as beams supported in a discrete manner by spring-damper systems that represent the flexibility of pads, sleepers, ballast and substructure. The inclusion of flexible track models is very important to study the dynamic behaviour of railway vehicles in realistic operation scenarios. The proposed wheel-rail contact formulation outputs, the contact points location in real time during the dynamic analysis, for the most general three-dimensional motion of the wheelsets with respect to the track. The proposed methodology to build flexible track models is validated by comparing the results obtained with this new approach with the ones obtained using ANSYS. The methodology is demonstrated by studying the dynamic behaviour of the Alfa Pendular railway vehicle.
Prediction of Residual Stress Distribution in Flash Butt Welded Rails using Electro-Thermo-Mechanical Simulation
Authors: Haibatollahi Seiied P. , Tehrani Parisa H.
Published: July 2014

Flash butt welding is commonly used in the manufacture of continuously welded rails. It is a resistance welding method, often performed in stationary plants, which consists of electrical heating and hydraulic forging of the rail ends. This method introduces a residual stress field in the foot, web and head of the rail. This investigation performs an electro-thermo-mechanical analysis using finite element techniques to analyze the residual stress in two continuously welded rails. The residual stress results are compared with ASTM E837-99 standard test data.
Effects of Axle box Lateral Clearance and Friction Coefficient on Dynamic Stability and Wear of 3-Piece Bogies
Authors: Rezvani M.A. , Mazraeh Amin
Published: July 2014

Three piece bogies are commonly used in worldwide as freight wagons. Manufacturing and maintaining expenses are noticeably less than other types of freight wagons. Therefore many investigators have focused on optimization of these bogies in order to improve their performance. These bogies have been reported to have bad performance both in curved and straight pads. High number of wear in both contact points has been observed. In this investigation, a freight wagon equipped with a pair of three piece bogies is simulated in Universal Mechanism software to observe its hunting and wear behaviour. Parameters of lateral clearance and coefficient of friction are investigated to see their effects on vehicle behaviour. The results show that as the lateral clearance or coefficient of friction increase, the nonlinear critical speed would decrease and this would lead to encounter different nonlinear critical speeds for rear and front bogies. The lateral clearance has little effects on decreasing friction work in both contact points in transient section of curves due to the considered wheel-rail profiles.
Optimisation of Anti-Resonance Vehicle Configuration for Vibration Attenuation of Railway Bridges
Authors: Vesali Farzad , Kolagar Mina , Rezvani M.A.
Published: July 2014

Movements of the wheel loads and their sequential entry onto the bridges are known as the two root causes for the vibrations of the railway bridges. It is possible to reduce the levels of the unwanted bridge deck oscillations by introducing one or more size adjusted wagon(s) in the train configuration. The added wagon(s) are of different size(s) compared with the other cars in the train configuration. This can disturb the periodicity in the wheel loading. Consequently, it can interfere with the resonance phenomena and prevent the bridge from excessive vibrations. The purpose of this research is to calculate proper sizes for the anti-resonance rail vehicles. Such vehicles need to fulfil the requirements for the controlled excitation of the bridge dynamic response. The bridge is subjected to series of moving loads. A computer aided analytical method is used to calculate the dynamic response of the bridge. Time matrix method is used to facilitate the calculation procedures. A criterion that can be used for the assessment of the dynamic response of all railway bridges is arrived. It is also attempted to manage the levels of the bridge vibrations by simultaneously working on the size of the anti-resonance vehicle, the vehicle axle load and the placement and the distribution of the loads throughout the train. Variety of the train speed of travel is considered. Eventually, the optimized sizes for the anti-resonance vehicle are obtained and their effectiveness in reducing the levels of the bridge vibrations is demonstrated.
Numerical Analysis of Aerodynamic Performance of Regional Passenger Train under Crosswind Conditions
Authors: Mohebbi Masoud , Rezvani M.A.
Published: July 2014

This paper presents the numerical analysis of unsteady aerodynamic performance of a regional train for crosswind stability. Results of numerical investigations of airflows past a train under different yaw conditions are summarized. Variations of occurrence flow angle from parallel to normal with respect to the direction of forward train motion resulted in the development distinguish different flow pattern. Numerical simulation addresses the ability to resolve the flow field around the train subjected to relatively yaw angles with three-dimensional Reynolds-averaged Navier-Stokes equations and turbulence model were solved on a multi-block structured grid using a finite volume method. The massively separated flow for the higher yaw angles on the leeward side of the train justifies the use of RANS, where the numerical results show good agreement with test results.
Sensitivity of Train Velocity and Track Curvature on Wear in Closed Loop Wheel-Rail Profiles
Authors: Molatefi Habibollah , Shadfar Morad
Published: July 2014

In this paper an open wagon equipped with three pieces bogies has been simulated as multi body dynamics model with non-linear effects of wedges and structural clearances using Universal Mechanism software. Analyses have been performed on closed loop track with tangent and curved sections considering random irregularities in the vertical and lateral directions of the track. Simulation results are used to calculate the friction work, wheel wear depth and worn wheel profiles for different velocities and radii of curvature. â€œSpechtâ€ model based on â€œArchard's Theoryâ€ is used for wear calculations. The wear depth of outer wheels is assessed to determine the effect of velocity, track curvature and Pivot friction of bogie on the wear pattern of wheels. The results show that Pivot friction has a great effect on the non-uniform wear of wheels even in short distances and the friction work is found to be dependent on the velocity.
Extraction and quantification of pigments in aerobic anoxygenic phototrophic bacteria
Authors: Ruivo Mickael , Cartaxana Paulo , Cardoso Maria Inês , Tenreiro Ana , Tenreiro Rogério , Jesus Bruno
Published: July 2014

Using a 15‐min High Performance Liquid Chromatography (HPLC) elution program, the current study compared pigment extraction efficiencies in aerobic anoxygenic phototrophic bacteria (AAPB; Dinoroseobacter shibae, Roseobacter denitrificans, Erythrobacter longus, and a strain of Rhodovulum sp. isolated from Tagus estuarine intertidal sediments — SPS1025T) using four extraction times (15, 30, 60, and 120 min) and three solvents (acetone, acetone/methanol, and methanol). Overall, increasing extraction time showed no significant effect on bacteriochlorophyll a (BChl a) and carotenoid extraction efficiencies in all strains. BChl a extraction efficiency was significantly higher in the mixture acetone/methanol and methanol, but methanol induced significantly higher BChl a degradation for all strains. Carotenoid extraction efficiencies were dependent on solvent and pigment polarity. Non‐polar carotenoids were better extracted with acetone and polar carotenoids with methanol. We suggest the application of the used HPLC procedure for the quantification of photosynthetic pigments in AAPB due to its high sample throughput and peak resolution. We also recommend the use acetone/methanol for extraction of AAPB photosynthetic pigments with extraction periods of 15 min to achieve higher BChl a extraction yields and minimize carotenoid degradation.
Relationship between wind speed and gas exchange over the ocean revisited
Authors: Wanninkhof Rik
Published: July 2014

The relationship between gas exchange and wind speed is used extensively for estimating bulk fluxes of atmospheric gases across the air‐sea interface. Here, I provide an update on the frequently used method of Wanninkhof (1992). The update of the methodology reflects advances that have occurred over the past two decades in quantifying the input parameters. The general principle of obtaining a relationship constrained by the globally integrated bomb‐14CO2 flux into the ocean remains unchanged. The improved relationship is created using revised global ocean 14C inventories and improved wind speed products. Empirical relationships of the Schmidt number, which are necessary to determine the fluxes, are extended to 40°C to facilitate their use in the models. The focus is on the gas exchange of carbon dioxide, but the suggested functionality can be extended to other gases at intermediate winds (≈4−15 m s−1). The updated relationship, expressed as k = 0.251  (Sc/660)−0.5 where k is the gas transfer velocity,  is the average squared wind speed, and Sc is the Schmidt number, has a 20% uncertainty. The relationship is in close agreement with recent parameterizations based on results from gas exchange process studies over the ocean.
Design, development, and implementation of recirculating aquaria for maintenance and experimentation of deep‐sea corals and associated fauna
Authors: Lunden Jay J. , Turner Jeffrey M. , McNicholl Conall G. , Glynn Chloe K. , Cordes Erik E.
Published: July 2014

Here, the development and construction of recirculating aquaria for the long‐term maintenance and study of deep‐water corals in the laboratory is described. This system may be applied to the maintenance and experimentation on marine organisms in the absence of a natural seawater supply. Since 2009, numerous colonies of Lophelia pertusa as well as several species of associated invertebrates from the Gulf of Mexico have been maintained in the described systems. The behavior of some of these species, including L. pertusa, the corallivorous snail Coralliophila sp., the polychaete Eunice sp., and the galetheoid crab Eumunida picta in the laboratory is described. Additionally, these systems were used for the manipulation of pH and dissolved oxygen for short‐term experiments using L. pertusa. The detailed manipulation of carbonate chemistry in artificial seawater is described for use in ocean acidification experiments.