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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The motivation of this study is to investigate micro warm coining of metals with high strength (e.g. austenitic steels) in the field of fabricating micro functional surface structures. The current micro cold coining technology, which uses punches made out of steel, is limited to soft metals, such as Al and Cu. Conducting micro cold coining on steels, leads to high tool wear and bad form filling. The approach of this study is integrating electric conductive heating into a micro coining system to realize micro warm coining of stainless steel. This paper presents the experimental and numerical analysis of micro warm coining technology using the material stainless steel 1.4401. A coupled thermal-mechanical model in the commercial Finite-Element-code ABAQUS is used to help analyzing the micro warm coining process. The results are summarized as follows: (1) Open die micro warm coining has been realized. The form filling achieved was 56%, which was three times larger than the form filling of cold micro coining on the same material. (2) Both the experiments and simulations showed that faster processing, by increasing the punch velocity, resulted in a slightly improved form filling (5% from 5 mm/s to 100 mm/s). (3) Surface chilling hindered the filling of thin ribs.

Micro Warm Coining of Stainless Steel Sheets Using Electric Conductive Heating

The electric wheel hub engine is a promising technology for the development of future urban electric mobility and offers different advantages. Conical shaped copper coils offer the potential for a better exploitation of the available coil assembly space, causing a higher power density of the electric engine. The production of these copper coils using casting technology is possible, but expensive. Thus, an economical serial production process for such coils using metal forming technology is highly desirable. In this paper, different manufacturing approaches for the production of conical shaped copper coils are presented and compared. In total, four approaches for the production of these copper coils were investigated. The basis for all approaches are pre-bended ETP-copper coils, which are further compressed to a conical shape. The investigated processes are: a single-stage upsetting process with a constant geometry constraint on the outer side of the coil, a multi-stage upsetting process with adjustable geometry constraints on the outer side of the coil in each stage, an upsetting process with a steel coil as an additional forming tool and an upsetting process using an additional counter punch. The most homogeneous wire cross section was achieved by the upsetting process with a steel coil as an additional tool. However, the extraction of the copper coil from the steel coil after forming is difficult. Thus, the multi-stage process, which could enable greater productivity, and the process using the additional steel coil will both be considered in future work.

Comparison of Different Upsetting Processes for the Production of Copper Coils for Wheel Hub Engines

Thixoextrusion could become one possibility to enlarge the complexity of extruded profiles made of steel. Accordingly semi‐solid extrusion experiments of X210CrW12 tool steel using round dies of approximately 15 mm diameter were performed in order to achieve first information concerning possible process windows and process limits. For liquid fractions between 38% and 10%, extrusion press velocities from 10 mm/s to 50 mm/s and dies with novel PVD‐coatings no complete solidification during extrusion was achieved. However the collected pieces of the extruded bars showed a fine and evenly distributed globular microstructure.

Influence Of Tool Geometry, Tool Coating And Process Parameters In Thixoextrusion Of Steel

The non-proportional loading path describes a strain-dependent development of stress triaxiality and Lode parameter during metal forming processes. Existing studies suggest a strong dependence of damage evolution on the non-proportional loading path. This work focuses on investigating the influence of non-proportional loading paths observed in hot caliber rolling of the case-hardening steel 16MnCrS5 using laboratory scale experiments. The applied torsion plastometer is highly flexible as it can apply combined loading types (tension, compression and torsion) on notched round specimen and enables deformation at elevated temperature. In this study, two characteristic non-proportional loading paths in caliber rolling and the maximal achievable non-proportional loading path variation were recreated in the torsion plastometer based on both FE simulations and experiments. After deformation, the specimen were further analyzed using Scanning Electron Microscopy (SEM) to quantify the damage. The results indicate an influence of the non-proportional loading path on damage evolution. Furthermore, fatigue tests were employed to characterize the fatigue performance of the deformed specimens. In the torsion plastometer trials carried out no clear correlation of performance and damage was observed. This is most likely due to differences in residual dislocation density after static recrystallization and deviations in the microstructure after hot working. Thus, the superposition of microstructure evolution and damage needs to be considered carefully when testing at elevated temperature.

/pdf/torsion-plastometer-trials-to-investigate-the-effect-of-non-5biy2hzwlq.pdf

Torsion plastometer trials to investigate the effect of non-proportional loading paths in caliber rolling on damage and performance of metal parts

To reduce the failure of dies by abrasive wear, mechanical fatigue and thermal fatigue in closed-die forging usually measures like nitriding, deposition of ceramic layers by Physical Vapour Deposition (PVD), Chemical Vapour Deposition (CVD) or deposition welding are used. However, after some time wear appears and the dies have to be replaced. A new concept implements sheet metal die covers, which are placed on the die engraving during forging and will absorb abrasive wear, thermal and mechanical load. The inexpensive cover will be replaced quickly by a new one after it is worn-out. This concept is regarded in a first numerical and experimental study by comparing a covered die (C) and an uncovered die (U) for the production of the same part. A one-time use of the die cover showed a reduction of the peak temperature by 140 K and of the temperature amplitude by 37 %. The temperature reduction and the increase of inner radii of the engraving to fit the 1mm thick die cover doubled the expected die life time. The experiment showed that the soft deep drawing steel DC04 is not suitable in the current case for a die cover and a higher strength sheet metal should be applied.

Gerhard Hirt

Papers

Micro Warm Coining of Stainless Steel Sheets Using Electric Conductive Heating

Comparison of Different Upsetting Processes for the Production of Copper Coils for Wheel Hub Engines

Influence Of Tool Geometry, Tool Coating And Process Parameters In Thixoextrusion Of Steel

Torsion plastometer trials to investigate the effect of non-proportional loading paths in caliber rolling on damage and performance of metal parts

First Experimental and Numerical Study on the Use of Sheet Metal Die Covers for Wear Protection in Closed-Die Forging