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.

Crystallographic Structure and Mechanical Behaviour of SnAgCu Solder Interconnects under a Constant Loading Rate

Abstract: With the continuing increase of the integration density in electronics, dimensions of interconnections for electronic components have been miniaturized to a scale that is comparable to those of their crystallographic structure. For instance, a SnAgCu solder joint in the flip chip package can contain only one or a few grains. In this case, the mechanical behaviour of the micro-joint is expected to shift from a polycrystalline-based to single-crystal one. Considering the further miniaturization, both the crystallographic structure and mechanics of each component (Ag3Sn, Cu6Sn5 and beta-Sn matrix) within a grain and the adjacent SnCu interface will play an important role in the reliability of the micro-joint due to their size comparable with that of a grain, irregular geometry, their heterogeneous distribution and considerably different properties. In addition, at such a small scale, the non-local effect on deformation of beta-Sn should be taken into account to interpret mechanical interactions between components. In this paper, a shearing test, in which it is possible to apply a constant loading to a SnAgCu joint is deigned to investigate mechanics of substructure within a SnAgCu grain and near the SnCu interface.

Intermetallics formation and evolution in pure indium joint for cryogenic application

Abstract: Intermetallic compounds (IMCs) properties play a significant role in determining the reliability of solder joints in service. IMCs and their evolution become more important for devices with micro- or nano-scale joints used in cryogenic applications. In this study, the interfacial reactions of In/Cu and In/Ni/Cu due to low-temperature cycling are investigated. The results illustrate that the character of IMCs is linked to thickness of indium joints exposed to low-temperature cycling. The formation of Cu-In IMCs and Ni-In IMCs are diffusion-controlled, and low-temperature cycling results in brittle IMCs.

Crystal-Plasticity Simulation of Micromachining of Single-Crystal Metal: Methodology and Analysis

Abstract: A crystal-plasticity modelling framework was implemented to simulate micromachining of a single-crystal metal. A new shear strain-based criterion was proposed to control material removal. This criterion was implemented in three different modelling techniques: element deletion, arbitrary Lagrangian–Eulerian (ALE) adaptive remeshing and smooth particle hydrodynamics (SPH) in a general-purpose finite-element software package ABAQUS. The three different modelling approaches were compared in terms of their computational accuracy and efficiency. Based on these studies, an optimized modelling strategy was proposed to simulate microscratching of single-crystal copper. The validity of the suggested methodology was corroborated through comparison between FE simulations and experimental data in terms of cutting forces, chip morphology and pile-up patterns in the work-piece.

Estimation of cutting forces in conventional and ultrasonic-vibration assisted turning using inverse modelling

Abstract: In this work, cutting forces in conventional and ultrasonic-vibration assisted turning are estimated using an inverse method to evaluate the velocity-dependent friction and fracture toughness based on a few tests in conventional turning. The inverse methodology requires the data on cutting and feed forces at two specified cutting speeds. Analytical expressions are employed to estimate the cutting forces in conventional as well as ultrasonic-vibration assisted turning. The suggested method was verified with experimental data. The validation of the direct model with the finite-element results available in the literature was also carried out. A sensitivity analysis revealed a significant effect of friction on cutting forces. Thanks to its simplicity, the proposed procedure may find a good application in industrial practice.

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.