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

Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201707035

Soft Robotic Grippers.

Structural systems often show nonlinear behavior under severe excitations generated by natural hazards. In that condition, the restoring force becomes highly nonlinear showing significant hysteresis. The hereditary nature of this nonlinear restoring force indicates that the force cannot be described as a function of the instantaneous displacement and velocity. Accordingly, many hysteretic restoring force models were developed to include the time dependent nature using a set of differential equations. This survey contains a review of the past, recent developments and implementations of the Bouc-Wen model which is used extensively in modeling the hysteresis phenomenon in the dynamically excited nonlinear structures.

The Hysteresis Bouc-Wen Model, a Survey

Topology optimization has become an effective tool for least-weight and performance design, especially in aeronautics and aerospace engineering. The purpose of this paper is to survey recent advances of topology optimization techniques applied in aircraft and aerospace structures design. This paper firstly reviews several existing applications: (1) standard material layout design for airframe structures, (2) layout design of stiffener ribs for aircraft panels, (3) multi-component layout design for aerospace structural systems, (4) multi-fasteners design for assembled aircraft structures. Secondly, potential applications of topology optimization in dynamic responses design, shape preserving design, smart structures design, structural features design and additive manufacturing are introduced to provide a forward-looking perspective.

Topology Optimization in Aircraft and Aerospace Structures Design

Advantages and Challenges of Relaxor-PbTiO3 Ferroelectric Crystals for Electroacoustic Transducers- A Review.

The Distributed Tuned Mass Damper system, which is defined as the multiple Tuned Mass Damper design based on one specific vibration mode of the main structure, is investigated in this study. As those for single TMD design cases, the challenge work in this area is to attain the best vibration suppression performance through an optimally designed DTMD system. In the traditional DTMD or TMD design, the general approach is to focus on the attached spring(s) and damper(s). In this study, a novel DTMD design methodology will be proposed, in which the design parameters are the attached masses in the DTMD system under assumed constant spring(s) and damper(s). The presented method provides a simple and straight-forward way to design the DTMD system, and may provide a more cost-efficient approach in manufacturing, installation and also maintenance than the traditional design. The numerical examples will be presented to illustrate the validity and effectiveness of the proposed DTMD design approach.

A novel distributed tuned mass damper design approach

Development of hard landing diagnosis system based on acceleration sensing using mems

Centrifugal Pendulum Vibration Absorber (CPVA) has been effectively used inrotating and reciprocating machines to control torsional vibrations passively Thisresearch presents results from analytical investigation of rotor systems integratedwith CPVA The system under investigation is modeled as a rotating disk attachedwith CPVA in which the disk is subjected to an external simple harmonic torqueMathematical model of a rotor fitted with a CPVA has been formulated and theequations of motion are derived using Lagrange principle The effect of gravity due toCPVA operating in a vertical plane with a horizontal shaft has been considered in theformulation The results are also compared with those based on CPVA operating in ahorizontal plane in which the effect of gravity has been neglected Moreover,softening nonlinear behavior of the pendulum and its effect on the natural frequencyof the system has been investigated

https://amme.journals.ekb.eg/article_35490_ce2de4a7d90b46e2b19c05da1f584c13.pdf

Analytical investigations of the gravity effect on the dynamics and performance of centrifugal pendulum vibration absorber

Small-scale magnetoactive soft robots (MSRs) with multimodal locomotion and wireless actuation capabilities have emerged in recent years for various highly sensitive and precise biomedical tasks such as targeted drug delivery and minimally invasive therapies. MSRs comprise magnetoactive elastomers consisting of micron-sized hard magnetic particles, such as neodymium-iron-boron (NdFeB), suspended or arranged into an elastomeric matrix. These robots generally exhibit large deformation under an applied magnetics stimulus, which is considered favorable for the aforementioned applications. Only limited efforts, however, have been reported on characterization of such robots. This is likely due to their nonlinear dynamics, especially under large deformations and hysteretic stress-strain characteristics, which strongly depend on the magnitude and frequency of the external magnetic stimuli. This study experimentally investigated and analyzed the real-time nonlinear and hysteretic responses of a MSR fabricated in the form of a cantilever beam made of a magnetoactive elastomer. An experiment was designed to characterize dynamic responses of the MSR under different magnetic stimuli at relatively higher frequencies to evaluate the rate-dependent hysteresis effect. A hardware-in-the-loop technique in conjunction with a PID controller was implemented, which permitted the generation of a precise and uniform magnetic field. The MSR was subjected to uniform magnetic loading perpendicular to the robot’s length leading to large amplitudes and rates of harmonic movements of the MSR. The experiments were performed under different intensities, ranging from 2 to 30 mT, at frequencies up to 3 Hz. The measured data were analyzed to obtain response time-histories and frequency response characteristics of the MSR, apart from the motion snapshots.

An experimental investigation of dynamic motions of a small-scale magnetoactive soft robot undergoing large nonlinear movements

In this study, limit load analysis of thin geometrically nonlinear structures is performed using a new shell element. The element is developed by combining the discrete kirchhofi triangle (DKT) plate bending element, and the optimal membrane triangle (OPT). Inconsistent stress stifiness matrix is formulated using appropriate approximations for displacements. Using co-rotational approach combined with arc-length method, nonlinear analysis is performed and the limit load is found for shallow thin shells. The results are compared with those found by other membrane elements combined with the same plate bending element. It is shown that analysis using other membrane elements may overestimate the stifiness and consequently the limit load of the structure signiflcantly.

Ramin Sedaghati

Papers

A novel distributed tuned mass damper design approach

Development of hard landing diagnosis system based on acceleration sensing using mems

Analytical investigations of the gravity effect on the dynamics and performance of centrifugal pendulum vibration absorber

An experimental investigation of dynamic motions of a small-scale magnetoactive soft robot undergoing large nonlinear movements

Limit Load Analysis of Thin Geometrically Nonlinear Structures Using a New Shell Element