114 research outputs found
USM AND PROTON ESTABLISH COLLABORATION IN AUTOMOTIVE ENGINEERING
No full textNIBONG TEBAL, 18 January 2016 – Universiti Sains Malaysia (USM) Engineering Campus received
an 11member
delegation visit from PROTON headed by its Professor, Dr. Shuhaimi Mansor here
recently
Superaugmented pitching motion of UTM CAMAR UAV using advanced flying handling qualities
No full textThis paper focused of a robust flight control system (FCS) for a small UAV. The main
objective of this design is to ensure the small UAV can fly safely in severe gusty
conditions. The Superaugmentation FCS consisted of Stability Augmentation System
(SAS) and Command Stability Augmentation System (CSAS) was developed in UTMLST
to improve the dynamic characteristics of the longitudinal stability of UAVi.e
UTM Camar. A combination of the variable stability technique along with advanced
flying and handling qualities (FHQ) requirements are used to reduce the gust effect
on the aircraft or UAV. The results obtained from the simulation studies showed that
the superaugmented aircraft can be operated in severe gust environments than
augmented aircraft. The result from here has reduced strain on the elevator activity
in both extreme and calm weather conditions. Moreover, the superaugmentation FCS
in the longitudinal axis meets the requirements of the level 1 handling qualities
specification in flight phase
An analysis on second generation intact stability criteria
No full textLe Sous-comité de la conception et de la construction navale de l'Organisation maritime internationale (OMI) a entrepris l'élaboration de critères de stabilité intacts de deuxième génération (SGISC). Le SGISC est une règle supplémentaire qui complète les règles actuelles.En outre, ces critères sont structurés en trois niveaux, à savoir le premier niveau, le deuxième niveau et l'évaluation directe. Les procédures d'évaluation directe pour chaque échec de stabilité sont développées avec la technologie de pointe la plus avancée disponible soit par analyse numérique, soit par travail expérimental pour une analyse quantitative. Dans cette thèse, on présente une implémentation des niveaux 1 et 2 du SGISC dans le solveur hydrostatique, une approche expérimentale pour le navire en détresse dans une tempête et des simulations RANS du même critère. En conclusion, il est possible de mettre en oeuvre les critères de stabilité du navire intact de deuxième génération dans le code de stabilité GHS ©, un code couramment utilisé par les industriels dans le domaine. Cinq navires ont été considérés pour vérifier cette mise en oeuvre. Une méthode expérimentale utilisant une grande soufflerie et une méthode de calcul CFD simplifiée ont été appliquées sur deux modèles. Dans les deux cas, les résultats montrent que l'angle de roulis maximal atteint par les deux navires étudiés est inférieur à celui donné par le calcul réglementaire. La méthode expérimentale est certainement plus proche de la réalité et le calcul CFD reste conservateur sans être aussi contraignant que la réglementation. En conclusion les méthodes expérimentale et numérique développées et utilisées dans ce travail de thèse peuvent être proposées pour l’évaluation directe du critère.The Sub-Committee of Ship Design and Construction of International Maritime Organisation (IMO) has undertaken the development of Second Generation Intact Stability Criteria (SGISC). The GISC is an additional rule that complement present rules. Five failure modes will be address in SGISC are excessive roll in dead ship condition, pure loss of stability, broaching, parametric roll, and excessive acceleration. Moreover, these criteria are structured in three levels namely, first level, second level and direct assessment. Direct assessment procedures for every stability failure are developed with the most advanced state-of-the art technology available either by numerical analysis or experimental work for quantitative analysis. In this thesis, implementations of Level 1 and Level 2 of the SGISC in the hydrostatic solver, experimental approached for dead ship condition and RANS simulation are presented.In conclusion, it was possible to implement the stability criteria of the intact second-generation vessel in the GHS © code of stability, a code commonly used by industrialists in the field. Five vessels were considered to verify this implementation. An experimental wind tunnel method and a simplified CFD calculation method were used on two different models. In both cases, the results show that the maximum roll angle reached by the two vessels studied is lower than the one given by the regulatory calculation. The experimental method is certainly closer to reality and the calculation CFD remains conservative without being as binding as the regulation.Therefore, the two approaches, numerical and experimental can be proposed to be used for Direct Assessment of the criterion
Estimation of bluff body transient aerodynamic loads using an oscillating model rig
No full textA method for the estimation of transient aerodynamic data from dynamic wind tunnel tests has been developed and employed in the study of the unsteady response of simple automotive type bodies. The experimental setup consists of the test model mounted to the oscillating model facility such that it is constrained to oscillate with a single degree of freedom of pure yawing motion. The yaw position is recorded from a potentiometer and the time response provides the primary measurement. Analysis of the wind-off and wind-on response allows the transient aerodynamic loads to be estimated. The frequency of oscillation, (synonymous with the frequency of disturbing wind input) is modified by altering the mechanical stiffness of the facility. The effects of Reynolds number and oscillation frequency are considered and the model is shown to exhibit damped, self-sustained and self-excited behaviour. The transient results are compared with a quasi-steady prediction based on conventional tunnel balance data and presented in the form of aerodynamic magnification factor. The facility and analysis techniques employed are presented and the results of a parametric study of model rear slant angle and of the influence of C-pillar strakes is reported. The results are strongly dependent on shape but for almost all rear slant angles tested the results show that the transient response exceeds that predicted from steady state data. The level of unsteadiness is also significantly influenced by the rear slant angles. The addition of C-pillar strakes is shown to stabilise the flow with even small strakes yielding responses below that of steady state. From the simulation results the self-sustained oscillation is shown to occur when the aerodynamic damping cancels the mechanical damping. The unsteadiness in the oscillation can be simulated by adding band-limited white noise with an intensity close to that of the turbulence intensity found in the wake. From vehicle crosswind simulation results the aerodynamic yaw moment derivative and its magnification factor are shown to be the important parameters influencing the crosswind sensitivity and path deviation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Analisis kestabilan statik membujur pesawat terbang ringan
No full textSebuah pesawat terbang ringan telah direka bentuk oleh kumpulan penyelidik Aeronautik, Fakulti Kejuruteraan Mekanikal, Universiti Teknologi Malaysia. Tujuan kertas kerja ini adalah untuk membentangkan hasil analisis kestabilan statik membujur pesawat terbang setelah beberapa pengubahsuaian dilakukan terhadap spesifikasi asal pesawat semasa pembinaan. Analisis ini akan memberikan maklumat berkenaan ciri-ciri kestabilan statik membujur seperti titik neutral, jidar statik, sudut penaik dan sudut serang pesawat semasa dalam keseimbangan. Ciri-ciri kestabilan statik membujur pesawat telah dinilai untuk keadaan trim yang berbeza seperti pada kedudukan pusat graviti dan kelajuan yang berlainan. Analisis telah dilakukan menggunakan perisian MathCAD untuk menyelesaikan persamaan serentak bagi mendapatkan parameter-parameter yang diperlukan. Hasil analisis dibentangkan dan graf-graf yang berkaitan juga diplotkan beserta kesimpulan dan perbincangan
Measurement of a bluff body aerodynamic yaw moment magnification and damping using a dynamic wind tunnel facility
No full textThis paper describes a technique for determining the dynamic aerodynamic yaw moment derivative based on the time response data using an oscillating model rig. The aerodynamic yaw moment derivatives are initially estimated using oscillation frequency and amplitude decay. The results from the dynamic measurement are compared with conventional static test and presented in the form of aerodynamic magnification. The yaw moment derivative exceeds that determined statically across reduced frequency range measured. The yaw damping derivative was found to be a function of freestream speed; at low velocities it is negative but progressively increases to a positive value. With further increases in speed, a self-sustained oscillation is observed with almost constant frequency and amplitude. This result is attributed to coupling between the model wake and the model stability; however, the exact behavior of the interaction is not fully understood; this phenomenon is under further investigation
Development of a flight Dynamics Engineering Simulator (FDES) at Universiti Teknologi Malaysia : an overview
No full textA synthesis of an aircraft approach, landing & overrun
No full textAll conventional aircraft flights start at a point of departure with a take-off and end at the destination with a landing. During this phase, the aircraft is transferred from the airborne state to the ground-borne state and brought to a halt. Although landing an aircraft looks simple but in reality it is difficult to predict the performance during this phase due to its very dynamic nature, a high sensitivity to piloting technique and uncertainties in aerodynamics. As this critical manoeuvre (beside takeoff) takes place in close proximity to the ground, and at a low airspeed (‘dirty’), there is a relatively a high risk to the safety of the aircraft and its occupants. A significant number of incidents and accidents occur during this crucial phase in which the aircraft could not be stopped on the runway during landing-known as overruns. Although it has been a problem for quite a long time, unfortunately, not much has been learned. This paper presents some important and interesting facts regarding runway overruns and the crucial aspects during the penultimate stages of the landing process together with the airworthiness and regulatory requirements
Finite element modelling to predict equivalent stiffness of 3D space frame structural joint using circular beam element
No full textIn automotive industry, thin walled beam is widely used to build vehicles structure. Vehicle structure is built by joining thin walled beams using various welding techniques. The usage of thin walled structure in automotive is important to improve vehicle performance by offering better strength-to-weight ratio. However the application of thin walled structure will cause few drawbacks to vehicle structure. When thin walled beam or structure is loaded with compression load, at certain limit it will undergo local or global buckling. Another problem is when thin walled beam is joined to other thin walled beams, it will show unexpected deformation which called joint flexibility. Both phenomena will cause numerical and analytical model to predict stiffness of structure tend to deviate from experimental result. In vehicle structure fabrication 3D space frame is used a lot. As a case study for this application, area around car bulkhead where cross member, side sill and A pillar are connected to each other at right angle is studied. The intention of this research work is to produce validated finite element model to predict equivalent stiffness of 3D space frame structural joint. Finite element, shell element is most common technique used to model the joined structure. However it is known that shell model cannot produce good result. In this result work, modelling of equivalent stiffness for 3D space frame structural joint is presented. The result shows, using this model the accuracy is about 65%. New modelling technique is proposed to increase the accuracy based on solid model. By introducing circular beam elements at welding area, it is found that accuracy improves up to 90%. © (2013) Trans Tech Publications, Switzerland
Influence of rear-roof spoiler on the aerodynamic performance of hatchback vehicle
No full textRear-roof spoiler is commonly used for improving the aerodynamic performance of road vehicles. This study aims to investigate the effect of strip-type rear-roof spoiler on the aerodynamic performance of hatchback vehicles. The main parameter of study was the inclination angle of the spoiler. A computational fluid dynamics (CFD) method was used. The numerically obtained results were compared to the experimental data for validation of the CFD method. The spoiler effectively reduced the aerodynamic lift at positive inclination angle by causing the surface pressure near the roof-spoiler junction to increase. However, its effect is unfavourable when configured at negative angle due to the downward accelerating flow that causes the surface pressure around the roof-spoiler junction to drop. Although the aerodynamic lift was found to decrease with the spoiler angle, this was accompanied by drag increment
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