An Experimental Study of Odometer as a Navigation aid for Land Vehicle Application

Strap-down inertial navigation system (SINS) shall provide position, velocity, and orientation information with reference to a pre-defined reference frame. The SINS shall have excellent accuracy over a short duration and is highly self-contained. However, the errors in navigation solutions build up exponentially with time and make the system output very unstable. In order to mitigate these errors, there is a need for a damping mechanism through external aiding sensors. In this article, one such approach is proposed to improve navigation accuracy for land vehicles in the GNSS (Global Navigation Satellite Systems) denied environment. The design and implementation of an odometer are carried out with the use of inductive proximity sensors and a mounting assembly to attach the odometer to one of the non-steering wheels of a vehicle. The odometer gives the pulse-high and pulse-low output with reference to the rotation of the wheel to which it is attached. Vehicle ground velocity is derived through sensed output pulses processed through quadrature decoder circuitry. Odometer measurements along with non-holonomic constraints (NHC) are used for minimizing velocity and position errors in SINS using an extended Kalman Filter (EKF) technique. Field trials are carried out to validate the proposed scheme of hybrid navigation with odometer design and experimental results are presented with a positioning accuracy of 0.05 % of distance travelled (DT)

Effect of Porosity on the Free Vibration Analysis of a Rotating Pretwisted Sandwich Blade with a Functionally Graded Core in the Thermal Environment

This work deals with the investigation of the effect of porosity on the natural frequencies of the rotating pretwisted sandwich blade with a functionally graded core in the thermal environment. The top metallic and the bottom ceramic surfaces are exposed to ambient temperature and high inlet temperature, respectively. A finite element approach using a layerwise theory is developed. Two different porosity distributions are assumed here. The effect of the volume fraction index, rotational velocity, porosity model and temperature gradient on the natural frequencies of the pretwisted sandwich blade is studied

The Investigation of KH560 Coupling Agent with Carbon Fiber One Step Dipping Method Compared with Functionalized Multi Walled Carbon Nanotubes

Interlaminar and interfacial properties of composites are important parameters for any application, extensive research has been out bursting to enhance the above properties using nanotubes (NTs) as an alternate solution to minimize delamination of laminates. This research focused on significance of functionalized engineering materials for better efficiency in industries, especially stealth technology. Silane-coupling agent “3-glycidyletheroxypropyl-tri methoxy silane, KH-560” is one module among five modules designed in this work. Five modules are considered as (M1, M2, M3, M4 & M5) with (0.5wt% of AMINE, CARBOXYL, multi wall carbon nano tubes (MWCNTs), 5% KH-560 treated carbon laminate and finally with base carbon fiber). PAN-based 12k carbon fiber as base fiber with functionalized and non-functionalized nanocomposite are incorporated as fillers in the epoxy laminates fabricated using vacuum bagging technique. Findings indicated 5% KH-560 silane treated carbon fiber (module M5) showed best results such as properties with 39%,55% and 20% in “tensile, flexural and interlaminar shear strength (ILSS)” respectively. FESEM analysis is conducted to understand morphology of the laminates

Selected Papers from 4th National Aerospace Propulsion Conference NAPC 2022

The National Aerospace Propulsion Conference (NAPC) is a national conference dedicated to aerospace propulsion technologies. Two erstwhile popular conference series, the National Propulsion Conference (NPC) and the National Conference on Air-Breathing Engines (NCABE) were merged to result in NAPC. This biennial conference is intended to bring together the entire propulsion community spanning the industry, academia and the research labs nationwide. The aerospace propulsion-centred conference is considered an ideal opportunity to showcase one’s research activities with peers and foster future collaborations through networking. The 4th edition of the conference, NAPC-2022, comprised a keynote lecture, several topical invited lectures and presentations of contributed papers in parallel sessions. This special issue contains eight manuscripts selected based on peer-reviews of selected papers presented during the conference. The manuscripts broadly cover several aspects pertaining to aerospace propulsion that includes airbreathing engine components such as intakes, compressors, combustors and nozzles. From the rocket propulsion (non-airbreathing), there are papers that investigate the rocket motor grain port alignment and another paper on the heat transfer characteristics of a supersonic rocket nozzle

Terramechanics Models for Tracked Vehicle Terrain Interaction Analysis A Review

Efficient manoeuvrability of off-road tracked vehicles such as military tanks and rovers is essential in ensuring the success of military/extra-terrestrial operations. To achieve this, in-depth research on vehicle-terrain interaction is crucial. This manuscript deals with reviewing the ways to study terramechanics viz. theoretical, empirical, and field tests, and proposing the merits and demerits of each method. Under the theoretical approach, empirical, numerical, and semi-empirical methods are discussed. Under the empirical approach, the method based onthe vehicle cone index for tracked and wheeled vehicles is discussed. Under the numerical approach, advantages and disadvantages of Finite Element Method (FEM) and Discrete Element Method (DEM) are discussed. Semi-empirical method, based upon a combination of the best features of numerical and empirical approaches discusses terrain response to normal repetitive loads and shear repetitive loads for tracked as well as wheeled vehicles. Pressure sinkage relationship for terrains at various loading conditions and shear stress displacement relationship for different terrains obtained through penetration and shear tests are discussed to determine the vehicle’s mobility parameters under a semi-empirical approach. Further, the Super element model, multi-body simulation model, and ride and cornering vibration model are discussed under computer simulation models. A detailed review of various models customized towards tracked vehicle-terrain interaction discussed in this manuscript helps the authors set up a laboratory for terramechanics at DIAT. Preliminary analysis along with conceptual design of the experimental setup is also discussed. In a nutshell, this paper attempts to summarize the research that has been carried out in the field of tracked vehicle-terrain inter action comprising of VCI, MMP, FEM, DEM, Super element model, Multibody technique, and Semi-empirical methods helping the authors to establish a laboratory of terramechanics for their M. Tech. program on Armament and Combat Vehicles at DIAT Pune

Unveiling the Impact of Extreme Learning Machine in the Defence and Military Sector

Among the most well-known machine learning algorithms, Extreme Learning Machine (ELM) has seen widespread use across a variety of fields, including the defence and military industries. For problems like sluggish technique and iteratively altering the hidden layer’s parameters to optimise the efficiency of the gradient descent approach, a cutting-edge machine learning algorithm known as the ELM has been developed. Depending on the specific objective and circumstance, the Extreme Learning Machine (ELM) may be more appropriate than Deep Neural Network (DNN) techniques. The models constructed in this manner perform quite well in generalisation. The following three goals are emphasised in its unconventional structure: 1) A great degree of accuracy in learning 2) less need for direct human involvement 3) an extremely rapid rate of learning, and moreover, it provides an optimal response for the whole world. As a result of its quick training, flexibility, and resilience, the Extreme Learning Machine (ELM) has several uses in this field, including target detection and tracking, image and signal processing, cybersecurity and intrusion detection, decision support systems, pattern recognition and classification, etc. According to our findings, the ELM approach was used with low training time and the testing accuracy is excellent. Also, this study presents the contribution of the revolutionary machine learning algorithm ELM to the defence and military sectors

Influence of Resin Viscosity on Physical Properties of a Composite Shell Wound on a Low Density Material Mandrel

This study is made to improve the structural performance of composite shells/ vessels meant for aerospace vehicles. The effect of resin viscosity on the physical properties of carbon/ epoxy composite shell wound on polyurethane (PU) foam-based mandrel is studied and presented in this paper. Cylindrical shells were manufactured through the filament winding process at different resin viscosities. The physical properties of the composite shell are found to be improved significantly with a reduction in resin viscosity. Resin pick-up in impregnated fibers is found to be lower by 4.5 %, whereas mass and thickness of the shells are recorded to be lower by 3 % and 5.4 % respectively at resin viscosity range of 600 -760 mPa.s compared to the viscosity range of 1380 – 2080 mPa.s. Fiber volume fraction and density of composite shell are found to be higher by 6.3 % and 2.8 % at the same resin viscosity range. This trend reverses/stabilizes after further heating and corresponding lowered resin viscosity. Experiment and their result indicate an optimal viscosity range of 600 – 760 mPa.s. for filament winding of efficient carbon/ epoxy composite shel

Comparison of Response Surface Based Preliminary Design Methodologies for a Gas Turbine Combustor

Preliminary design of gas turbine combustor is a multi-objective optimization problem. The methodology to be used at the preliminary design stage depends on the freedom of design choices available. In this article, we explore three preliminary design methodologies for gas turbine combustor - M1: combustion liner design for a given casing; M2: combustion liner design without the casing and M3: coupled design of combustion liner and casing. A workflow for the automated design space exploration of gas turbine combustor using response surface methodology is presented. Computational fluid dynamics studies along with central composite design for design of experiments and genetic aggregation for response surface generation are used to quantify the combustor performance in design space. Comparison of three different design methodologies (M1, M2 and M3) is made to show how the choice of design methodology changes the available design space and limits/expands combustor performance. Candidate optimal designs and associated trade-offs from the optimization study are also presented. This study can aid combustor design engineers choose the most suitable preliminary design methodology for their specific use case

Impact of Blowing Location on the Aerodynamic Characteristics Over the Delta Wing

The performance of an aircraft can be enhanced by altering the flow field favourably by adopting flow control techniques. The present study deals with the application of the active flow control methods on a sharp-edged delta wing with a wing sweep of 65°. The concept of blowing was employed as an active flow control technique. The blowing technique is applied on the suction surface of the delta wing by varying its location. The various identified locations of the blowing holes are 1.62 %, 3.24 % and 4.86 % of root chord from the leading edge to the centre of the blowing holes. The computation is performed using the commercial software ANSYS Fluent. An unsteady, incompressible Reynolds-averaged Navier–Stokes equation and the shear-stress transport k-ω turbulence model are employed. The angles of attack varied in the range of 0°<α<35° and Reynolds number is 2.64×106 and the jet momentum coefficient is fixed at 0.05. The blowing of air from the injection region enhances the strength of the leading-edge vortices, resulting in a delay in the vortex breakdown. The performance of the delta wing is greatly improved while using the blowing method specifically for the blowing holes located at 3.24 % of root chord from the leading edge compared to without the blowing method

Studying the Interaction of Waves to Determine the Impact Response of a Layered Elastic Medium

When an impactor strikes a layered target, both the impactor and the target experience waves. The waves produced travel and engage in interactions with other waves as well as the interfaces in the impactor-target system. For the impact problems on a layered medium with periodic properties and layered elastic media of Goupillaud-type (each layer has the same wave travel time), researchers have presented an analytical solution for stress variation with position and time within the target. However, the solution for an elastic media not satisfying the above conditions is not available in the literature. The present study fills this gap and finds the behaviour of a generalized layered medium to an impact problem. The response of the material at any position inside the layered medium is found by solving the interaction between waves, interfaces, and boundaries. The mass, momentum balance and constitutive relationship are solved to get the exact analytical expressions for particle velocity and stress for each possible wave interaction happening in the impactor and the layered medium. The expressions are utilized in a computer program to study the impact behaviour of a layered media. The code tracks each wave as it travels through the system and identifies those interactions that occur in the shortest time, uses the stress and velocity expression for that interaction, and updates the state of the material. When stress produced at the impact surface is tensile in nature, the impactor and target can be separated. The work can be applied to both finite and semi-infinite impactors and targets, and the layered medium does not necessarily have to be a periodic layered media or a Goupillaud-type medium