Arc fusion welding predominates in the welding industry as a reliable joining method and has been the subject of investigations by researchers for decades. To ensure in-service structural integrity, optimization of weld-induced... more
Arc fusion welding predominates in the welding industry as a reliable joining method and has been the subject of investigations by researchers for decades. To ensure in-service structural integrity, optimization of weld-induced imperfections such as welding deformations and residual stresses is critically desirable in circumferentially welded thin-walled cylinders owing to their wide applications in aerospace and aeronautical structures, pressure vessels, and nuclear engineering fields. In this research, computational methodologies for sequentially coupled non-linear transient thermomechanical analysis of the complex arc welding of thin-walled cylinders of stainless steel (AISI 304) are presented. Detailed three-dimensional finite element (FE) simulations with a single V butt-weld joint configuration of 150 mm outer diameter and 3 mm wall thickness cylinders are carried out to investigate the effects of varying structural boundary conditions (mechanical constraints) on weld-induced ...
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Aerial imaging systems are mounted on two axis serial robotic manipulators with high powered pan and tilt actuations, known as a Gimbal. The angular displacement of the gimbal is measured through very high precision sensors, typically... more
Aerial imaging systems are mounted on two axis serial robotic manipulators with high powered pan and tilt actuations, known as a Gimbal. The angular displacement of the gimbal is measured through very high precision sensors, typically shaft encoders with high PPR specifications. The purpose of the gimbal is to keep the orientation of the payload towards the target irrespective of the displacement of the UAV (unmanned aerial vehicle) and any other vibrations/disturbances that might be introduced into the system. Because of 2-DOF (degrees of freedom) dynamical model of the gimbal, frictional force, noise, cable restraint, disturbances from the external environment along with the motions of the vehicle’s body (as a result of manoeuvring or vibration), the spotting and tracking accuracy of the gimbal platform system may significantly degrade. The nature of these redundant disturbances is mostly of nonlinear nature and their modelling is a difficult task as they keep on changing. In orde...
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In this paper, a kinematic model for the platform pitch angle of a shrimp rover is presented with in-built passive adaptability and ability to move in unstructured environments. With the rhombus configuration of the shrimp rover, platform... more
In this paper, a kinematic model for the platform pitch angle of a shrimp rover is presented with in-built passive adaptability and ability to move in unstructured environments. With the rhombus configuration of the shrimp rover, platform pitch angle was determined over different types of terrains. The kinematic model of the shrimp rover was established and the rotation angles and the Pitch angle for the Platform of the Front Fork, Boogies and rear Wheel were analyzed. The Kinematic analysis and the Simulations were performed using MATLAB, Solid Works.
Research Interests: Kinematics and Terrain
Research Interests: Engineering, Computer Science, Motion control, Stability, Control Systems, and 15 moreControl system, MIMO, Mobile Robots, Computer Simulation, Hardware, Inverted Pendulum, Pid, System performance, PID control, Digital System Testing, Control Algorithm, Proportional Integral Derivative, Benchmark Testing, System testing, and Pendulums
Multi-grade diesel lubricants exhibit viscoelastic characteristics, which affect journal bearing lubrication of a high torque engine at a low speed. During engine operation the main end of the crankshaft journal is most vulnerable to the... more
Multi-grade diesel lubricants exhibit viscoelastic characteristics, which affect journal bearing lubrication of a high torque engine at a low speed. During engine operation the main end of the crankshaft journal is most vulnerable to the cyclic combustion loads and must be protected against adhesive wear. This research models the Newtonian behavior of a lubricant by solving the 2-D Reynolds equation and determining the film thickness between the bearing and the crankshaft. It is followed by solving the continuity and Navier-Stokes equations to ensure conservation of mass and momentum of the lubricant flows. The constitutive equations exhibiting viscoelastic characteristics are coupled with the momentum conservation equations to generate simulation results for non-Newtonian lubricant response. The steady state wedging and transient squeeze effects are studied for a viscoelastic engine lubricant at low speed. The simulation results for Newtonian and viscoelastic engine lubricants are analyzed separately and then compared for definite conclusions. The results show that at a low initial speed the Newtonian lubricant is not affective against the cyclic loads to prevent physical contact and wear of interacting surfaces. The viscoelastic characteristics of the lubricant visibly contribute towards improving the pressure and film thickness profiles of a high-torque low-speed engine. It reduces the chances of breakdown of lubricant film and enhances the life of crankshaft by preventing adhesive wear.
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Evolution of virtual prototype technology has a paramount importance in advance mechanical system development and exploration. In this paper skid steered RVAS (Robotic Vehicle with Articulated Suspension) virtual prototype model was... more
Evolution of virtual prototype technology has a paramount importance in advance mechanical system development and exploration. In this paper skid steered RVAS (Robotic Vehicle with Articulated Suspension) virtual prototype model was designed and co-simulation method was presented to integrate dynamic system model with a designed velocity tracking controller. The vehicle modelling was carried out in ADAMS/View. In addition, PID (Proportional Integral and Derivative) control strategy was employed to achieve desired velocity response along with efficient PID tuning technique in MATLAB/SIMULINK. It was observed that cosimulation was performed successfully and desired longitudinal velocity was achieved by the controller in an effective way.
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This paper presents a mathematical model for multi-axle steering vehicles operating on level ground. For transporting heavy loads vehicles with multiple axles are required. Apart from added complexity steering of multiple axle for turning... more
This paper presents a mathematical model for multi-axle steering vehicles operating on level ground. For transporting heavy loads vehicles with multiple axles are required. Apart from added complexity steering of multiple axle for turning is a big challenge. Due to type of load being carried a single unit vehicle is sometimes preferred. The mathematical model of a six axle vehicle with 4-axle steering system is developed. Simulations at various track radii, vehicle speeds and steering ratios (ratio between the first, second, fifth and sixth steering axle) are performed. Axle steering angles and wheel slip angles are evaluated. The steering ratio requirements vary with vehicle speed and turn radius. A configuration is selected for better performance for a wider range. The resulting steering ratios show good vehicle maneuverability, stability and steering efficiency.
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Research Interests:
Rotary diesel fuel injection pump is a vital subassembly and its failure ultimately leads to failure of diesel engine. The radial clearance between the surfaces is generally in the range of 2 to 3 microns for effective fuel injection. Of... more
Rotary diesel fuel injection pump is a vital subassembly and its failure ultimately leads to failure of diesel engine. The radial clearance between the surfaces is generally in the range of 2 to 3 microns for effective fuel injection. Of late it has revealed that there is an unprecedented high failure rate of rotary type diesel fuel injection pumps. This study, therefore, is aimed at developing mathematical model and simulation based on fundamental principles for hydrodynamic lubrication regime between the plunger and sleeve of hydraulic head in a rotary diesel fuel injection pump. Finite Difference Method is used for computational purpose. The effects of shear stresses, dimensionless film thickness, dimensionless pressure and load are studied and analyzed by varying radial clearances between the plunger and the hydraulic head of rotary diesel fuel injection pump. Comparative analysis is carried out based on hydrodynamic lubrication in a rotary mechanism.
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Journal bearings of high torque diesel engines are used to cater for high combustion loads which are applied intermittently. A lubrication layer is provided between journal (crankshaft) and bearing to avoid contact between them. The... more
Journal bearings of high torque diesel engines are used to cater for high combustion loads which are applied intermittently. A lubrication layer is provided between journal (crankshaft) and bearing to avoid contact between them. The relative velocity between crankshaft and journal bearing results in viscous shear heating among the different layers of lubricating oil. The shear heating reduces the viscosity of the lubricant that ultimately reduces the load carrying ability of the journal bearing. It offers a physical contact and reduces the designed life of crankshaft. In this study the 2-D transient numerical lubrication model is developed by employing the Reynolds equation to calculate the pressure and film thickness profiles as a function of crankshaft speed. The shear heating effects are determined by coupling the energy equation with lubrication model. The finite difference method is used and an appropriate numerical scheme is employed to simulate the conduction and convection b...
In this paper, a kinematic model for the platform pitch angle of a shrimp rover is presented with in-built passive adaptability and ability to move in unstructured environments. With the rhombus configuration of the shrimp rover, platform... more
In this paper, a kinematic model for the platform pitch angle of a shrimp rover is presented with in-built passive adaptability and ability to move in unstructured environments. With the rhombus configuration of the shrimp rover, platform pitch angle was determined over different types of terrains. The kinematic model of the shrimp rover was established and the rotation angles and the Pitch angle for the Platform of the Front Fork, Boogies and rear Wheel were analyzed. The Kinematic analysis and the Simulations were performed using MATLAB, Solid Works.
This research work is an investigation of active and passive methods to reduce rollover tendency of a three wheeled platform. This configuration is common in small to medium aircraft landing gears, mobile robots, and fuel efficient... more
This research work is an investigation of active and passive methods to reduce rollover tendency of a three wheeled platform. This configuration is common in small to medium aircraft landing gears, mobile robots, and fuel efficient futuristic concept vehicles. In developing countries three wheeled vehicles (TWV) have a significant share in point to point public transport. Such vehicles have a higher rollover risk resulting in significant single vehicle fatal crashes, and thus are the main focus of the current research. In Delta configuration the front single wheel offers no roll resistance, hence no lateral load transfer takes place during cornering at the front axle. The effect on directional behaviour is evaluated for this unique lateral load transfer setup. Dynamics of the vehicle are studied in the state space spanned by the yaw rate and side slip angle. These states encompass the directional behaviour of the vehicle fairly well. The effect on roll over and directional behaviour...
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Purpose The purpose of this study is to provide the full-state mathematical model and devise a nonlinear controller for a balloon-supported unmanned aerial vehicle (BUAV). Design/methodology/approach Newtonian mechanics is used to... more
Purpose The purpose of this study is to provide the full-state mathematical model and devise a nonlinear controller for a balloon-supported unmanned aerial vehicle (BUAV). Design/methodology/approach Newtonian mechanics is used to establish the nonlinear mathematical model of the proposed vehicle assembly which incorporates the dynamics of both balloon and quadrotor UAV. A controllable form of the nine degrees of freedom model is derived. Backstepping control is designed for the proposed model and simulations are performed to assess the tracking performance of the proposed control. Findings The results show that the proposed methodology works well for smooth trajectories in presence of wind gusts. Moreover, the final mathematical model is affine and various nonlinear control techniques can be used in the future for improved system performance. Originality/value Multi-rotor unmanned aerial vehicles (MUAVs) are equipped with controllers but are constrained by smaller flight endurance ...
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Abstract: In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or struc-tural loads) are becoming more stringent,... more
Abstract: In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or struc-tural loads) are becoming more stringent, putting immense pressure on welding ...
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Pan-tilt platform (PTP) is a complex electromechanical assembly and its motion is characterized by coupled non-linear behaviour. Control design and validation for PTP needs system models with different levels of abstraction and fidelity.... more
Pan-tilt platform (PTP) is a complex electromechanical assembly and its motion is characterized by coupled non-linear behaviour. Control design and validation for PTP needs system models with different levels of abstraction and fidelity. The study is an attempt to build a multi-bond graph (MBG) model of an ideal PTP using object oriented modeling (OOM) approach. Joint friction, backlash and detailed actuator dynamics can be incorporated in modular manner. One of the mechanical imperfection; mass imbalance in tilt axis is also presented. The multi-bond graph model is created using 20-sim and results are compared with a general purpose multi-body dynamics software.
Three wheeled vehicles (TWV) are a common low cost mode of transport in the Asian Subcontinent, Africa and South America. It is very prone to rollover in turns even at moderate speeds. Recently anti-roll bars (ARB) have been installed... more
Three wheeled vehicles (TWV) are a common low cost mode of transport in the Asian Subcontinent, Africa and South America. It is very prone to rollover in turns even at moderate speeds. Recently anti-roll bars (ARB) have been installed claiming increase in rollover thresholds for (one front two rear) 1F2R wheel configuration. Roll moment is resisted at the rear axle only. Rear Axle installed ARB typically increases over-steer tendency. In the current study a Six degrees of freedom model is used to investigate the effect of ARB stiffness on the rollover threshold.
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This work presents the design and optimization of out of plane electrothermal MEMS actuators. The proposed concept is capable of generating large out of plane displacement at low driving power and a low actuation temperature. The... more
This work presents the design and optimization of out of plane electrothermal MEMS actuators. The proposed concept is capable of generating large out of plane displacement at low driving power and a low actuation temperature. The performance of this actuator is evaluated and simulated in ANSYS. The out of plane displacement of 291µm at a temperature increase of 135°C from ambient has been achieved with the applied power of 2.7mW(0.7V). Moreover, a thermal time constant of 5.6ms and a frequency of 85Hz is accomplished for this actuator.
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... Modeling and simulation of hydrodynamic lubrication of rotary diesel fuel injection pump. Auteur(s) / Author(s). AFZAAL MALIK M. (1) ; RASHID Badar (1) ; KHUSHNOOD Shahab (1) ; RAJA AMER AZIM (1) ; Affiliation(s) du ou des auteurs /... more
... Modeling and simulation of hydrodynamic lubrication of rotary diesel fuel injection pump. Auteur(s) / Author(s). AFZAAL MALIK M. (1) ; RASHID Badar (1) ; KHUSHNOOD Shahab (1) ; RAJA AMER AZIM (1) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). ...
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This paper presents inverted pendulum with moving reference for the testing of stabilizing control algorithms. The proposed system extends classical inverted pendulum by incorporating two moving masses. The motion of the two masses, that... more
This paper presents inverted pendulum with moving reference for the testing of stabilizing control algorithms. The proposed system extends classical inverted pendulum by incorporating two moving masses. The motion of the two masses, that slide along the horizontal plane, is controllable for the purpose of platform stabilization. The usefulness of the idea presented is demonstrated using computer simulations by employing
Research Interests: Motion control, Stability, Control Systems, Control system, MIMO, and 13 moreMobile Robots, Computer Simulation, Hardware, Inverted Pendulum, Pid, System performance, PID control, Digital System Testing, Control Algorithm, Proportional Integral Derivative, Benchmark Testing, System testing, and Pendulums
This paper presents inverted pendulum with moving reference for the testing of stabilizing control algorithms. The proposed system extends classical inverted pendulum by incorporating two moving masses. The motion of the two masses, that... more
This paper presents inverted pendulum with moving reference for the testing of stabilizing control algorithms. The proposed system extends classical inverted pendulum by incorporating two moving masses. The motion of the two masses, that slide along the horizontal plane, is controllable for the purpose of platform stabilization. The usefulness of the idea presented is demonstrated using computer simulations by employing
Research Interests: Motion control, Stability, Control Systems, Control system, MIMO, and 13 moreMobile Robots, Computer Simulation, Hardware, Inverted Pendulum, Pid, System performance, PID control, Digital System Testing, Control Algorithm, Proportional Integral Derivative, Benchmark Testing, System testing, and Pendulums
ABSTRACT Three wheeled vehicles (TWV) are a common low cost mode of transport in the Asian Subcontinent, Africa and South America. It is very prone to rollover in turns even at moderate speeds. Recently anti-roll bars (ARB) have been... more
ABSTRACT Three wheeled vehicles (TWV) are a common low cost mode of transport in the Asian Subcontinent, Africa and South America. It is very prone to rollover in turns even at moderate speeds. Recently anti-roll bars (ARB) have been installed claiming increase in rollover thresholds for (one front two rear) 1F2R wheel configuration. Roll moment is resisted at the rear axle only. Rear Axle installed ARB typically increases over-steer tendency. In the current study a Six degrees of freedom model is used to investigate the effect of ARB stiffness on the rollover threshold.
Research Interests:
ABSTRACT Pan-tilt platform (PTP) is a complex electromechanical assembly and its motion is characterized by coupled non-linear behaviour. Control design and validation for PTP needs system models with different levels of abstraction and... more
ABSTRACT Pan-tilt platform (PTP) is a complex electromechanical assembly and its motion is characterized by coupled non-linear behaviour. Control design and validation for PTP needs system models with different levels of abstraction and fidelity. The study is an attempt to build a multi-bond graph (MBG) model of an ideal PTP using object oriented modeling (OOM) approach. Joint friction, backlash and detailed actuator dynamics can be incorporated in modular manner. One of the mechanical imperfection; mass imbalance in tilt axis is also presented. The multi-bond graph model is created using 20-sim and results are compared with a general purpose multi-body dynamics software.
ABSTRACT The wear between the plunger and plunger sleeve of rotary diesel fuel injection pump causes considerable decrease in injection pressure and the quantity of fuel to combustion chamber of an engine, which ultimately leads to... more
ABSTRACT The wear between the plunger and plunger sleeve of rotary diesel fuel injection pump causes considerable decrease in injection pressure and the quantity of fuel to combustion chamber of an engine, which ultimately leads to failure of engine assembly. This research investigates the cause of failure particularly focusing on surface roughness effects to hydrodynamic lubrication and scuffing failure due to abrasive contaminant. The surface roughness of plunger and plunger sleeve were measured and incorporated in Reynolds equation to analyze roughness effects on hydrodynamic lubrication. The critical particle size of the dust normally present in the diesel fuel is evaluated to determine which test dust sample could cause systems to fail. Based on this information, scuffing failure of pumps due to an abrasive contaminant partially penetrated in the plunger sleeve is analyzed. The abrasive contaminant is modeled as a spherical shaped rigid particle. Excessive temperature rise between the particle-plunger interface is used as an indication of whether scuffing would take place. Experiments were conducted to determine parameters such as particle size of dust samples, surface roughness of plunger and plunger sleeve, specific heat of diesel fuel, diesel fuel density, quantity of fuel flow and radial clearance. These experimentally determined parameters are then used as input in our computer program to lend more confidence to our predicted results.