B. Nageswara Rao

Bio: B. Nageswara Rao is an academic researcher from K L University. The author has contributed to research in topics: Ultimate tensile strength & Composite laminates. The author has an hindex of 27, co-authored 236 publications receiving 2810 citations. Previous affiliations of B. Nageswara Rao include Indian Space Research Organisation & Vikram Sarabhai Space Centre.

On the development of instability criteria during hotworking with reference to IN 718

Abstract: A simple instability condition based on the Ziegler’s continuum principles as applied to large plastic flow, is developed for delineating the regions of unstable metal flow during hot deformation. It can be used for any type of the flow stress versus strain rate curve. This criterion has been validated using the flow stress data of IN 718 with microstructural observations. The optimum hot working conditions for the superalloy IN 718 are suggested based on the instability map.

Instability criteria for hot deformation of materials

Abstract: Forming and forging processes are among the oldest and most important materials related technologies. New materials technologies centre on the development and widespread use of thermomechan...

Effect of drilling induced damage on notched tensile and pin bearing strengths of woven GFR-epoxy composites

Abstract: Analytical and experimental studies were made to evaluate the notched tensile and pin bearing strengths of the woven glass fiber reinforced (GFR)-epoxy composite laminates. The symmetric glass/epoxy woven mat cross-ply laminates containing 16 woven mats were prepared using hand lay-up technique with 45% of volume fraction. The laminates were cut into specimens as per ASTM standards. The experiments were done at three different feed rates, spindle speeds and hole diameters to examine the influence of drilling parameters on the notched tensile strength and bearing strengths of the laminates. The design of experiments and analysis of variance (ANOVA) techniques of Taguchi, were utilized to study the statistical influence of the drilling parameters on the extension of delamination. The fracture data of center-hole tensile specimens were correlated using a modification in one of the stress fracture criteria viz., the point stress criterion (PSC). The bearing strength was correlated with notched and un-notched tensile strengths of the woven fabric composite laminates.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Processing Maps: A Status Report

Abstract: In the last two decades, processing maps have been developed on a wide variety of materials including metals and alloys, metal matrix composites, and aluminides, and applied to optimizing hot workability of materials and for process design in bulk metal working. Processing maps consist of a superimposition of efficiency of power dissipation and the instability maps, the former revealing the "safe" domain for processing and the latter setting the limits for avoiding undesirable microstructures. The dynamic materials model, which forms the basis for processing maps, is discussed in relation to other materials models. The application of dynamical systems principles to understanding of deterministic chaos in the system will help in achieving a greater degree of microstructural control during processing. The patterns in the hot working behavior as revealed by the processing maps of several classes of alloys relevant to technology are reviewed briefly. Processing maps have also been applied to analyze several industrial problems including process optimization, product property control, and defect avoidance, and a few examples are listed. With the processing maps reaching a matured stage as an effective tool for optimizing materials workability, expert systems and artificial neural network models are being developed to aid and prompt novice engineers to design and optimize metal processing without the immediate availability of a domain expert, and the directions of research in this area are outlined.

The Statistical Analysis, of Experimental Data: A Fresh Approach Employing a Graphical Method for Investigating Non‐Normal Frequency Distributions

Abstract: WHILE the introduction of statistical methods into the analysis of aeronautical experimental data, whether for quality control in production, for the interpretation of the results of structural and aerodynamic laboratory experiments, or for airline operation, has been brought about only in recent years, it may by now be fair to assert that their advantages and even their indispensability are no longer in dispute. Hitherto, investigations on these lines have usually involved, explicitly or implicitly, only the ‘normal curve of error’ and allied considerations; owing, it may be thought, to the controllability of the various manufacturing or laboratory techniques, but also perhaps to the scarcity of data hitherto available. It may well be, however, that with the accumulation of information arising out of investigations planned with particular reference to the statistical analysis of their results the whole range of the apparatus for statistical analysis, usually confined to such fields as those of biology or economics, will be called into full play.

The mechanical behavior of GLARE laminates for aircraft structures

Abstract: GLARE (glass-reinforced aluminum laminate) is a new class of fiber metal laminates for advanced aerospace structural applications. It consists of thin aluminum sheets bonded together with unidirectional or biaxially reinforced adhesive prepreg of high-strength glass fibers. GLARE laminates offer a unique combination of properties such as outstanding fatigue resistance, high specific static properties, excellent impact resistance, good residual and blunt notch strength, flame resistance and corrosion properties, and ease of manufacture and repair. GLARE laminates can be tailored to suit a wide variety of applications by varying the fiber/resin system, the alloy type and thickness, stacking sequence, fiber orientation, surface pretreatment technique, etc. This article presents a comprehensive overview of the mechanical properties of various GLARE laminates under different loading conditions.