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

After twenty years of partly quiet and ten years of partly enthusiastic research into lead-free piezoceramics there are now clear prospects for transfer into applications in some areas. This mimics prior research into eliminating lead from other technologies that resulted in restricted lead use in batteries and dwindling use in other applications. A figure of merit analysis for key devices is presented and used to contrast lead-containing and lead-free piezoceramics. A number of existing applications emerge, where the usage of lead-free piezoceramics may be envisaged in the near future. A sufficient transition period to ensure reliability, however, is required. The use of lead-free piezoceramics for demanding applications with high reliability, displacements and frequency as well as a wide temperature range appears to remain in the distant future. New devices are outlined, where the figure of merit suggests skipping lead-containing piezoceramics altogether. Suggestions for the next pertinent research requirements are provided.

Transferring lead-free piezoelectric ceramics into application

The aim of the present chapter is to provide an in-depth survey of arbitrary Lagrangian–Eulerian (ALE) methods, including both conceptual aspects of the mixed kinematical description and numerical implementation details. Applications are discussed in fluid dynamics, nonlinear solid mechanics and coupled problems describing fluid–structure interaction. The need for an adequate mesh-update strategy is underlined, and various automatic mesh-displacement prescription algorithms are reviewed. This includes mesh-regularization methods essentially based on geometrical concepts, as well as mesh-adaptation techniques aimed at optimizing the computational mesh according to some error indicator. Emphasis is then placed on particular issues related to the modeling of compressible and incompressible flow and nonlinear solid mechanics problems. This includes the treatment of convective terms in the conservation equations for mass, momentum, and energy, as well as a discussion of stress-update procedures for materials with history-dependent constitutive behavior.


Keywords:

ALE description;
convective transport;
finite elements;
stabilization techniques;
mesh regularization and adaptation;
fluid dynamics;
nonlinear solid mechanics;
stress-update procedures;
fluid–structure interaction

https://onlinelibrary.wiley.com/doi/pdf/10.1002/0470091355.ecm009

Arbitrary Lagrangian–Eulerian Methods

In response to the current environmental regulations against the use of lead in daily electronic devices, a number of investigations have been performed worldwide in search for alternative piezoelectric ceramics that can replace the market-dominating lead-based ones, representatively Pb(Zr
 x
 Ti1-x
 )O3 (PZT)-based solid solutions. Selected systems of potential importance such as chemically modified and/or crystallographically textured (K, Na)NbO3 and (Bi1/2Na1/2)TiO3-based solid solutions have been developed. Nevertheless, only few achievements have so far been introduced to the marketplace. A recent discovery has greatly extended our tool box for material design by furnishing (Bi1/2Na1/2)TiO3-based ceramics with a reversible phase transition between an ergodic relaxor state and a ferroelectric with the application of electric field. This paired the piezoelectric effect with a strain-generating phase transition and extended opportunities for actuator applications in a completely new manner. In this contribution, we will present the status and perspectives of this new class of actuator ceramics, aiming at covering a wide spectrum of topics, i.e., from fundamentals to practice.

Giant electric-field-induced strains in lead-free ceramics for actuator applications – status and perspective

Recent advances in modelling of metal machining processes

Simulation of the orthogonal metal cutting process using an arbitrary Lagrangian–Eulerian finite-element method

Roller bearing acoustic signature extraction by wavelet packet transform, applications in fault detection and size estimation

The spinal cord may be injured through various spinal column injury patterns (e.g., burst fracture, fracture dislocation); however, the relationship between column injury pattern and cord damage is not well understood. A three-dimensional finite element model of a human cervical spine and spinal cord segment was developed, verified using published experimental data, and used to investigate differences in cord strain distributions during various column injury patterns. For a transverse contusion injury, as would occur in a burst fracture, a 33% canal occlusion resulted in two peaks of strain between the indentor and opposing vertebral body and intermediate peak strain values. For a distraction injury, relevant to column distortion injuries, a 2.6 mm axial displacement to the cord resulted in more uniform strains throughout the cord and low peak strain values. For a dislocation injury, as would occur in a fracture dislocation, an anterior displacement of C5 corresponding to 30% of the sagittal dimension of the vertebral body resulted in high peak strain values adjacent to the shearing vertebrae and increased strains in the lateral columns compared to contusion. This model includes more anatomical details compared to previous studies and provides a baseline for mechanical comparisons in spinal cord injury.

A Three-Dimensional Finite Element Model of the Cervical Spine with Spinal Cord: An Investigation of Three Injury Mechanisms

Multilayer piezoelectric actuators are used in fuel injectors due to their quick response, high efficiency, accuracy, low power consumption, and excellent repeatability. Experimental results for soft lead zirconate titanate (PZT) stack actuators have shown that a significant amount of heat is generated when they are driven under high frequency and/or high electric-field magnitudes, both of which occur in fuel injectors. Self-heat generation in these actuators, mainly caused by losses, can significantly affect their reliability and piezoelectric properties, and may also limit their application. Other studies have demonstrated that at large unipolar electric-field magnitudes, displacement–electric-field loss (displacement hysteresis) shows a direct relation with polarization–electric-field loss (dielectric hysteresis). In this paper, a simplified analytical self-heating model is presented. The model directly relates self-heating in multilayer piezoelectric actuators to displacement–electric-field loss (displacement hysteresis). The model developed is based on the first law of thermodynamics, and accounts for different parameters such as geometry, magnitude and frequency of applied electric field, duty cycle percentage, fuel type, and environmental properties. The model shows reasonable agreement with experimental results at low and high electric-field magnitudes.

https://iopscience.iop.org/article/10.1088/0964-1726/18/4/045008/pdf

Self-heat generation in piezoelectric stack actuators used in fuel injectors

In high speed machining of hard materials, tools with chamfered edge and materials resistant to diffusion wear are commonly used. In this paper, the influence of cutting edge geometry on the chip removal process is studied through numerical simulation of cutting with sharp, chamfered or blunt edges and with carbide and CBN tools. The analysis is based on the use of ALE finite element method for continuous chip formation process. Simulations include cutting with tools of different chamfer angles and cutting speeds. The study shows that a region of trapped material zone is formed under the chamfer and acts as the effective cutting edge of the tool, in accordance with experimental observations. While the chip formation process is not significantly affected by the presence of the chamfer, the cutting forces are increased. The effect of cutting speed on the process is also studied.

Mohamed S. Gadala

Papers

Simulation of the orthogonal metal cutting process using an arbitrary Lagrangian–Eulerian finite-element method

Roller bearing acoustic signature extraction by wavelet packet transform, applications in fault detection and size estimation

A Three-Dimensional Finite Element Model of the Cervical Spine with Spinal Cord: An Investigation of Three Injury Mechanisms

Self-heat generation in piezoelectric stack actuators used in fuel injectors

Numerical Analysis of Metal Cutting With Chamfered and Blunt Tools