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

The Design and Analysis of Experiments

Data Mining Practical Machine Learning Tools and Techniques

This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

Adaptive Control

A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

Effect of Temperature

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In this paper, we present a method to accelerate incremental bulk metal-forming simulations by using different mesh discretisations in two depending meshes. This multimesh method is preventing a loss of local resolution by using a special data transfer. Two example processes show the working of this method and the archieved acceleration.

Modelling and optimisation of incremental bulk metal-forming processes for near net shape components

Superplastic forming (SPF) is a well-known and widely used sheet metal forming process especially useful for the production of very complex and light thin sheet metal components. The superplastic behavior of a material is highly dependent on the temperature and occurs only at a narrow range of strain rates with an optimum value that is unique for each material. Within the aeronautic industry, this process is mainly used to form complex sheet metal parts made of the titanium alloy Ti6Al4V in heat affected areas and areas where corrosion resistance plays an important role. Even though the process times of SPF are often in the range of hours and therefore recurring costs are very high, the process is sometimes still the only choice when it comes to the forming of Ti6Al4V sheet metal parts for aeronautic or aerospace applications. To overcome the problem of long process times and high costs, in recent years, a lot of research did happen with the goal of temperature reduction during forming or forming at higher strain rates. Especially the change in the aeronautic industry towards high volume production is increasing the competition between suitable forming technologies and the SPF technology can only persist if both goals, reduction of process time and recurring costs are reachable. In this paper we will address those goals and show highly useful numerical procedures to make the SPF process ready for the next generation of aerospace manufacturing.

Optimization of Superplastic Forming Processes for High Volume Production in Aeronautics

Gearing components are an example for widely used machining parts in engines. Nowadays the development and optimization of materials and process chains are driven towards a concurrent improvement of final product properties and production efficiency. Excellent mechanical properties needed for gearing components e.g. high load capacity and high fatigue resistance depend on a fine homogeneous microstructure in the final product. Efficiency in gear manufacturing can be optimized by increasing the temperature during processing, which allows for lower forging loads and lower die stresses, thus improving die life in terms of mechanical fatigue. Additionally, increasing the temperature during case hardening reduces the process duration significantly. Hence process efficiency also increases. To meet the need of a fine homogenous microstructure, dynamic recrystallization has to be initiated during hot forging and grain growth has to be avoided during dwell times and case hardening. This grain size control can be achieved by applying micro-alloying concepts. Recently, an Nb-Ti-based alloying concept for case hardening steels was introduced, which increases fine grain stability and therefore potentially allows for higher forging and case hardening temperatures, leading to improved process efficiency [1]. In this paper a 25MoCr4-Nb-Ti steel grade is characterized in terms of flow resistance and microstructure evolution by hot compression tests and annealing experiments. The processing limits of this material in terms of abnormal grain growth are determined and a JMAK-based microstructure model considering these limits is presented and implemented in the FE-Software DEFORM 3dTM. The model is used in a case study to design a laboratory scale forging process for lowest possible die stresses and finest possible grain sizes. Experimentally measured grain sizes and forging loads from forgings at the laboratory scale are used to evaluate the process design. It is shown that considering microstructure evolution in process design is absolutely necessary to jointly optimize for process efficiency and final properties. The application of the Nb-Ti-based micro-alloying concepts allows for lower die stresses and thus seems to reduce mechanical fatigue of the dies compared to conventional case-hardening steels. [1] S. Konovalov et. al.: Testcase gearing component. In: G. J. Schmitz, U. Prahl (Ed.): Integrative Computational Materials Engineering, Wiley-VCH Verlag GmbH & Co. KGaA, 2012, ISBN 978-3-527-33081-2

Die and Process Design for Hot Forging of a Gear Wheel – A Case Study

Modern hot sheet metal forming processes offer the opportunity, especially in the automotive sector, to meet current demands for ultra-lightweight design. Due to the increased formability at the high process temperatures, high-strength aluminium alloys are increasingly coming into the focus of the industry. However, the complex thermo-mechanical interactions within these processes can lead to undesirable microstructural changes that could have a negative impact on the final mechanical properties. The purpose of this work is therefore to investigate the microstructural evolution of age-hardenable EN AW 6010-S alloy in the course of a modern gas-based sheet metal forming process and to quantify its influence on the resulting mechanical T6 properties. For this purpose, two different components were first formed at laboratory scale and the areas of microstructural interest were identified. Metallographic examinations and EBSD measurements were performed to visualize the influence of process temperature and deformation on the microstructure. EDX analysis helped to identify non-metallic phases. In the next step, artificial aging of the components was performed to increase the mechanical properties. Tensile tests and hardness measurements showed that the deformation and temperature have no negative influence on the final mechanical properties of the alloy.

Investigation on evolution of microstructure and mechanical properties of heat-treatable 6010-S aluminium alloy during gas-based hot sheet metal forming process

Gerhard Hirt

Papers

Modelling and optimisation of incremental bulk metal-forming processes for near net shape components

Optimization of Superplastic Forming Processes for High Volume Production in Aeronautics

Die and Process Design for Hot Forging of a Gear Wheel – A Case Study

Investigation on evolution of microstructure and mechanical properties of heat-treatable 6010-S aluminium alloy during gas-based hot sheet metal forming process

Model-based Control of the Strip Roughness in Cold Rolling