Vadim V. Silberschmidt

Bio: Vadim V. Silberschmidt is an academic researcher from Loughborough University. The author has contributed to research in topics: Machining & Materials science. The author has an hindex of 44, co-authored 543 publications receiving 8619 citations. Previous affiliations of Vadim V. Silberschmidt include University of Rhode Island & Universities UK.

Effect of Machining on Shear-Zone Microstructure in Ti-15V-3Cr-3Al-3Sn: Conventional and Ultrasonically Assisted Turning

Abstract: This work systematically studied morphology of nano- and microstructures in primary and secondary shear zones of machining chips produced with two different machining methods: conventional and ultrasonically assisted turning. Electron backscatter diffraction and transmission electron microscopy showed that chips had similar microstructures for both machining techniques. The nanostructure in secondary shear zones was less homogeneous than that in primary shear zones. In addition, a heavily deformed layer was formed in a subsurface of Ti-15V-3Cr-3Al-3Sn work-pieces, replicating the microstructure of secondary shear zones of the machining chips, and elongated nanocrystalline grains in this layer were aligned with a tangential direction of turning.

Dynamics and Scaling Characteristics of Shear Crack Propagation

Abstract: A model for a description of a shear crack (fault) propagation is proposed on the basis of the unification of continuum damage and fracture mechanics with ideas of fracture models for random media. Energy release linked with local failures of elements as a result of evolution of fracture processes at lower scale levels (stimulated by the stress concentration in the vicinity of the fault) is treated as a seismicity source. 2d simulations are performed for analysis of the effect of the size of pre-existing fault on characteristic features of rupture evolution. Scaling (including multifractal) character of crack propagation and of respective energy release is shown.

Interfacial failure under thermal fatigue loading in multilayered MEMS structures

Abstract: The reliability of MEMS, and in particular of RF MEMS switches, might be increased by the use of a Physics of Failure (PoF) methodology. A numerical study, based on the finite element method (FEM) and on the representative volume element (RVE) approach was performed to examine the effects of temperature dependent materials properties, temperature variations on failure (e.g. yielding of metals) and to predict interfacial damage in multilayered MEMS structures. The effect of residual stresses, due to electroplating processes of the metal layers was considered in these studies to investigate their effects on MEMS reliability. Numerical results have shown that interfacial damage is mainly concentrated at the plating-base/substrate interface and it is strongly influenced by the temperature dependent material properties and by the presence of residual stresses.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

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

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

Effect of Temperature

Abstract: 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.