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.

Hybrid-hybrid machining of SiC-reinforced aluminium metal matrix composite

Abstract: A hybrid-hybrid (ultrasonic-assisted + laser-assisted) turning study of silicon carbide reinforced aluminium metal matrix composite is presented. The results show a significant reduction of average cutting force with an improved surface finish of machined components compared to conventional machining, implying that this new and novel paradigm is a viable machining process.

Modelling the dynamic behaviour of hard-to-cut alloys under conditions of vibro-impact cutting

Abstract: Industrial applications of titanium alloys have grown significantly over the years primarily due to their high strength, light weight as well as good fatigue and corrosion-resistance properties. Since these alloys are hard-to-machine, there is an obvious demand to develop simulation tools in order to analyse the material's behaviour during machining and, thus, optimise the entire cutting process. Deformation processes in the machining of Ti alloys are typically characterized by high strains, strain rates and temperatures; the material behaviour under such conditions was derived from split Hopkinson pressure-bar (SHPB) tests. In the current study, a computational three-dimensional finite element model of the SHPB test is developed to assess the material's behaviour at high-strain, strain-rate and temperature regimes. The material behaviour derived for high strain rates was used in three-dimensional finite-element modelling of conventional turning and ultrasonically assisted turning of Ti-15333 alloy. A parametric analysis of the studied alloy was carried out using the developed model. Comparisons of simulations with experimental results demonstrate their predictive capability.

High-impact exercise stimulated localised adaptation of microarchitecture across distal tibia in postmenopausal women

Abstract: We provided evidence that a 6-month regular hopping exercise intervention can increase trabecular number and possibly trabecular volume fraction of the distal tibia. Our novel localised analysis demonstrated region-specific changes, predominantly in the anterior region, in postmenopausal women. The localisation of bone remodelling and microarchitectural adaptation to exercise loading has not been demonstrated previously in vivo in humans. The aim of this study is to assess the feasibility of using 3D image registration and high-resolution peripheral quantitative computed tomography (HR-pQCT) to investigate the effect of high-impact exercise on human trabecular bone variables and remodelling rate across the distal tibia. Ten postmenopausal women were recruited for 6-month unilateral hopping exercises, with HR-pQCT scans taken of both exercise leg (EL) and control leg (CL) for each participant before and after the intervention. A 3D image registration was used to ensure measurements were taken at the same region. Short-term reproducibility tests were conducted prior to the assessment using identical setup. The results were assessed comparing CL and EL, and interaction (time × leg) using a two-way repeated measures analysis of variance (RM-ANOVA). Across the whole tibia, we observed significant increases in trabecular number (Tb.N) (+ 4.4%) and trabecular bone formation rate (tBFR) (3.3%), and a non-significant increase in trabecular bone volume fraction (BV/TV) (+ 1%) in the EL. Regional resorption was higher in the CL than the EL, with this difference being statistically significant at the lateral tibia. In the EL, tBFR was significantly higher in the anterior region than the medial but a trabecular bone resorption rate (tBRR) showed no significant regional variation. Conversely in the CL, both tBFR and tBRR were significantly higher in the anterior and lateral than the medial region. We demonstrated that it was possible to detect exercise-related bone adaptation with 3D registration of HR-pQCT scan data. Regular hopping exercise increased Tb.N and possibly BV/TV across the whole distal tibia. A novel finding of the study was that tBFR and tBRR responses to loading were localised: changes were achieved by formation rate exceeding resorption rate in the exercise leg, both globally and at the anterior region where turnover was greatest. clinicaltrials.gov : NCT03225703

Propagation of delamination zones in bonded joints

Abstract: Delamination is one of the main failure mechanisms in bonded composite joints. Owing to a considerable spatial scatte r in adhesion over the interface in such joints, initiation of a delamination zone and propagation of its front are highly random processes. The main delamina- tion front is rather tortuous, and many small delamination spots are formed in its immediate vicinity. These processes can be additionally complicated in the case of loading types such as fatigue and/or multiple impacting. This paper deals with experimental methods of analysing delamination zones at various stages of their ev olution. X-radiographs of delamination zones are digitalized and scaling analyses based on fractal a nd multifractal approaches are performed in order to quantify the morphology as well as the damage distribution in the immediate vicinity of delamination fronts.

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.