Development of Closed Loop Temperature Control System for Composite Repair in LabVIEW Environment

This report deals with the design and development of a closed loop temperature controller for the resin system used in composite repair. This process involves two steps, bonding an annular rin g using SMA based repair device and bonding a flush patch taking its support. Controller has been developed to control the temperature in the bonding region. Simulation based analysis of the controller has been done using MATLAB Simulink. Initially, the real time implementation of the controller was done using 'C' language in Visual C++ environment. Later to provide real time graphical representation it was implemented using LabVlEW and the experimental results were obtained. The experimental results have shown a degree of convergence with simulation result

Vacuum induction melting of NiTi shape memory alloys in graphite crucible

Vacuum induction melting (VIM) is the most widely used process for the commercial production of NiTi alloys. But, the major drawback in VIM is the carbon contamination of the ingot from the graphite crucible. During melting, carbon reacts with Ti and forms TiC. This alters the Ni/Ti ratio in the alloy and thereby changes the transformation temperatures drastically. Also, the TiC particles in the matrix hinder the workability of the alloy as well as the memory properties of the products. The present experimental study deals with the VIM of NiTi alloys melted in graphite crucible wherein it has been shown that the carbon pick up in the melt can be reduced significantly when Ni and Ti are placed in the graphite crucible by a novel method of charging. The cast ingots (weighing 7x2013;8 kg each) were subjected to various secondary metal processing operations viz., forging, rolling and wire drawing. The properties of the wire products were evaluated

Fuzzy Logic and Bayesian Networks Based SAS in Air-to-Air Combat Scenarios

Situation Assessment System (SAS) is implemented using Fuzzy logic and Bayesian network (BN) hybrid technique to find out the exact situation in an air-to-air combat scenario, which helps the pilot to take correct and quick decision. The capability of SAS has been demonstrated by simulating a typical air-to-air combat scenario. It is observed that the BN based on several agents were able to accomplish the job assigned with fairly good amount of precision. However, further improvement of SAS performance is envisaged by fine-tuning of entries of Conditional Probability Tables corresponding to different agents with the help of experienced pilots for typical combat scenario

Compression behavior of NbC under nonhydrostatic conditions to 57 GPa 13; 13;

The analysis of the diffraction data under nonhydrostatic stress condition created in a diamond anvil cell suggests that the compressive strength of NbC crystallites is at least 24 xB1; 4 GPa at a confining pressure of 57 xB1; 0.5 GPa. When using Al as a pressure transmitting medium in the diamond anvil cell pressure conditions become nearly hydrostatic. The bulk modulus derived from the compression data under quasi-hydrostatic pressure condition gives K0 = 274 xB1; 3 GPa when fixing . This value agrees well with the value obtained from the first-principles numerical calculation

Unsteady flow computations for flow past multiple moving boundaries using LSKUM

We present the latest developments in the least squares kinetic upwind method (LSKUM), a kinetic theory based grid free approach for the solution of Euler equations. A single step higher order scheme through modified CIR splitting is presented. A new weighted least squares method has been used in the present work which simplifies the 2-D formulae to an equivalent 1-D form. This is achieved through diagonalisation of the least squares matrix through suitable choices of the weights. All these developments have been extended to problems with moving nodes and boundaries. A 2-D unsteady Euler code has been developed incorporating all the above ideas along with the well known dual time stepping procedure. The code has been verified and validated for the standard test case AGARD CT(5) which corresponds to unsteady flow past oscillating NACA0012 airfoil pitching about quarter chord. Good comparisons with the experimental values have been obtained. In order to demonstrate the ability of the method to handle multiple moving bodies we have computed unsteady flow past two oscillating NACA0012 airfoils one behind the other. Some interesting results are presented for this case.13; 13

Dynamic aeroelastic subsonic discrete gust response analysis of lifting surfaces in time domain using Newark's method.

The Dynamic gust response analysis of lifting surfaces of aerospace structures requires attention to two main factors, namely, the character of the gust and the aeroelastic effects. In the present work,the Dynamic aeroelastic response of subsonic airplane in discrete gusts is determined using Newmark's direct integration method.The adopted time domain method is a departure from the usual modal analysis and the frequency domain approach.The aerodynamic strip theory is assumed,but compressibility and aspect ratio corrections may be included,if desired.The method has been validated by performing discrete gust response analysis of an airfoil model of the elastic wing flying through sharp-edged gust.The unsteady aerodynamic forces on the wing are calculated from the theory of two-dimensional thin airfoils in non-uniform motion.The theory takes proper account of 'unsteadiness' by using the kussner's and Wagner's unsteady lift functions for calculating the aerodynamic forces.The pitching motion and tail effects are neglected.For validating the present work,the responses obtained from Newmark's method is compared with those reported in literature using Laplace method.It is found that the results are in close agreement with reported in the literature

Cycle counting using rainflow algorithm for fatigue analysis

Rainflow algorithm is one of the widely accepted techniques of cycle counting in fatigue analysis for damage assessment in engineering components and structures. In this paper a brief summary of Rainflow cycle counting technique has been outlined. To demonstrate the efficacy of the developed Rainflow algorithm in a computer is being validated by numerous standard set of test problems simple sequences are described. An attempt has been made to illustrate the algorithm accuracy by demonstrating a number of simple examples. The examples that are included are (i) Available literature sequences, (ii) Decreasing amplitude sequence (iii) Increasing amplitude sequence and (iv) Constant amplitude sequence. Finally the results from analyzing a service load spectrum of a fighter aircraft is provided in this paper