National Aerospace Laboratories Institutional Repository

    Hybrid Composites for Morphing Applications

    Get PDF
    This work is directed towards realizing large scale shape changes of wing like structures. It is relevant to discuss the work carried out in this area so far. AMR BAZ (ref l) details the work in which SMA is embedded in sleeves located at the neutral planes and arranged parallel to the longitudinal axis of the composite beam. Here emphasis is placed on describing quasi-static theory of shape control and implementation of this theory to composites incorporated with SMA. Emphasis has been placed on full utilization of shape memory effect without compromising on structural stiffness of the composite beam. Koryo Miura et a1 (ref.2) explain about adaptive structures and their use in aerospace applications. Here a variable geometry (VG) truss concept is presented. Comparison is made between tetrahedral and octahedral truss elements. Since octahedral is richer in symmetry, it is considered to be adequate for adaptive structures. DC motor is used as an actuator. It is shown that VG truss is the basic form of adaptive structures. The basic formulations for its geometrical as well as vibrational properties are established. Some applications such as second generation manipulator arm, support architecture for a space station and others are discussed here. Deepak.S. Ramrakhyani et a1 (ref.3) explains about the use of compliant cellular truss where tendons are used as active elements. This tendon actuated elements can be used for local or global shape changes. Here an octahedral unit cell is developed for bending deformations and compliant joints are made of cylindrical elements of superelastic shape memory alloys. Several concepts of morphing skin were also presented. Tendon actuators are presently under development. The tendons could be actuated locally or combined from a remote location such as the root of the wing. Since we are looking for large deflection of thin beams we have deliberately embedded the SMA wires off the neutral axis of the beam. In the literatures there is hardly any material that deals with this type of an approach. In this the effect of embedding the thermal SMA wires off the neutral plane of thin beams was studied. These wires were prestrained and embedded off the neutral axis to produce high amount of recovery forces when electrically energized. Superelastic SMA (SESMA) wires were used on the other side of the beam so as to increase the spring back effect of the beam when de-energized. Thus we were able to obtain large deflection together with faster return back to original position when de-energized

    Studies on Fire Protection Scheme for Engine Bulkhead of HANSA-3 Prototype Aircraft

    Get PDF
    The firewall used in Hansa - 3 Prototype I1 is a stainless steel of 0.4 mm thickness. JARVLA requirement on the firewall is that a stainless steel be atleast of 0.38mm thickness. Behind this firewall there is an engine bulkhead made of plywood of 8mm thickness and of fire resistant quality, covered on either side by 2 layers of bidirectional glass cloth with epoxy resin system of aircrafk quality. It is essential to demonstate that the engine bulk head is not adversely affected by a flame temperature of 1 1 OO°C for 15 minutes

    Advanced Research Areas for the Development of Autonomous Micro Air vehicles : An overview

    Get PDF
    For the past one decade great impetus is given to the development of Micro Air Vehicles (MAV). It is an autonomous flying vehicle capable of carrying a payload. The maximum linear dimension of this machine is 150 to 300mm and its weight can vary from 100 to 300 grams. The flight speed is around 10m/s and it operates at Reynolds number in the range of 5x104 to 2x105. MAV flies in the low Re regime and hence there is a marked deterioration of Lift at most operating conditions. This calls for the use of some lift enhancing techniques. Another important criteria is the control aspect of this type tiny vehicles. All these demands can be met only by choosing an appropriate structure/power plant. Flight testing and fabrication of these machines also pose many difficulties and it is tough challenge to design and fly a MAV in the autonomous mode . MAVs can carry various special sensors as payload to support such civil and military missions as traffic monitoring, weather observation, anti terrorists operations and enemy surveillance

    Effect of temperature and soaking time on the synthesis of Mo(Al,Si)2

    Get PDF
    Mo(Al,Si)2 has been prepared by hot pressing elemental powders of Mo, Al and Si, at 1200-1700xB0;C and 22 MPa. Mo5Si3 or Mo5Si3C have been observed as minor phases in all the samples with 1300xB0;C being the best processing temperature for synthesizing Mo(AlSi)2: with minimum amount of impurities. As the soaking time increases, the amount of impurity phases also increases. xA9; 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved

    Quality Control and Characterisation of Epoxy Resin and Ahesive System Used in HANSA-3 Prototype II Aircraft Fabrication

    Get PDF
    As a part of material qualificatio~lr equirements for HANSA 3 composite component fabrication program the quality control parameters identified earlier (Epoxy'content,Viscosity and Gel time) of epoxy resins are checked as and when they are received

    Finite Element Analysis of Inter Spar Ribs of Composite Wing of Light Transport Aircraft against Brazier Load

    Get PDF
    Inter spar ribs of wing of a transport aircraft is ubjected to various types of loads. One of the loads that poses stability problem to the interspar ribs of a wing is brazier load, which arises due to flexure of the wing. This paper describes about the finite element analysis of inter spar ribs of a wing at local level against brazier load. This study has been taken place while converting metal wing in to composite wing. The objective of this study is to reduce the weight penalty to the maximum possible extent by removing material wherever feasible. This paper is limited to discuss about the linear buckling analysis of ribs against brazier load. The buckling factor of ribs under consideration are reported in terms of square root times the eigenvalue obtained from finite element analysis, which represent the nonlinear effect of bending moment on brazier load. This study has helped to reconfigure/redesign the interspar ribs of wing. This has led to substantial weight saving of 2.85 Kg which accpunts 15.77% reductions of total mass of inter spar ribs

    3D Finite Element Vibrational Analysis of T385 Turbine Rotor BLISK Using SAFE Diagram

    No full text
    Integrally bladed rotors (BLISK) are most stressed part of aircraft engines due to high rotational speeds, elevated temperatures and pressures. Turbine blades fail mainly due to fatigue under alternating stresses resulting from vibration of rotor systems. Non-uniform pressure field is experienced by turbine BLISK due to interaction of stator and rotor blades which acts as a source of excitation during turbine operation. The number of stator blades dictates the occurrence of resonance in the rotor BLISK during steady-state operation. Therefore, it is necessary to design a mechanically feasible rotor with respect to stator and verify its modal and harmonic response to ensure its resonance-free operation. Design and development of T385 turbine stage for 1 kN small gas turbine engine are carried out in Propulsion Division, CSIR-NAL. The dynamic behaviour of T385 turbine rotor BLISK is evaluated for vibration reliability. This paper presents vibrational analysis of the T385 turbine rotor BLISK using finite element technique to evaluate critical nodal diameter, critical frequencies and response in engine environment. The turbine speed is 50,500 rpm at the engine design point based on the inlet temperature. Detailed vibration analysis of T385 turbine is carried out using FEA to plot Campbell and SAFE diagrams. The critical nodal diameter extracted from plotted SAFE diagram is 19, which is very well agreeing with Bertini analytical formulae. The Campbell diagram is plotted for T385 turbine at critical nodal diameter of 19. The obtained critical speed from this Campbell diagram is 33,000 rpm, which ensures the rotor is safe in the operating conditions

    Density measurements using the Background Oriented13; Schlieren technique

    Get PDF
    This paper describes the implementation of a13; novel technique called Background Oriented Schlieren that13; can produce quantitative visualization of density in a flow.13; This technique uses only a digital still camera, a structured13; background, and inverse tomographic algorithms which13; can extract two-dimensional slices from a three-dimensional13; flow. This has been applied to obtain the density13; field for an axisymmetric supersonic flow over a conecylinder13; model. Comparisons with cone tables show13; excellent agreement

    Aircraft parameter estimation, control and simulation (APECS) computer: Evaluation of final offers

    Get PDF
    Details of the final evaluation of four proposals of APECS Computer System from the vendors are presented in this repor

    Robustness Analysis Of Flight Control Systems : Part 1 Based On Singular Values/Eigenvalues

    Get PDF
    In This Report, Development Of Computer Aided Stability Robustness Analysis (CASRA) Software, Implemented In PC MATLAB Is Described . Some Results Of Application To Several Flight Control Systems Are Also Given
    National Aerospace Laboratories Institutional Repositoryis based in IN
    Access Repository Dashboard
    Do you manage National Aerospace Laboratories Institutional Repository? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! CORE Repository Dashboard!