Influence of material distribution and damping on the dynamic stability of Bernoulli-Euler beams

The study analyzed the influence of materials and different types of damping on the dynamic stability of the Bernoulli-Euler beam. Using the mode summation method and applying an orthogonal condition of eigenfunctions and describing the analyzed system with the Mathieu equation, the problem of dynamic stability was solved. By examining the influence of internal and external damping and damping in the beam supports, their influence on the regions of stability and instability of the solution to the Mathieu equation was determined

Constitutive modeling and hot deformation processing map of a new biomaterial Ti–14Cr alloy

A new biomaterial Ti–14Cr alloy was designed for biomedical applications. The manufacturing process of Ti alloys through hot deformation is crucial for controlling the grain structure and the mechanical performance of the alloy. In the present study, several compression tests at elevated temperatures (1123–1273 K) and strain rate ranges of 0.01–10 s−1 were conducted using a Gleeble-3800 thermomechanical simulator. A processing map of the studied alloy was constructed using the principles of the dynamic material model to evaluate the hot workability and deformation mechanisms at different ranges of temperature and strain rate. The resulting grain structure was correlated with the processing map. The processing map showed that adiabatic shear bands are expected to form at low temperatures (1123–1223 K) and moderate to high strain rates (1–10 s−1), whereas the nucleation of wedge cracks is likely to develop at the grain boundary at high temperatures and low strain rates (1248–1273/0.01 s−1). Consequently, a deterministic domain in the temperature and strain rate ranges of 1148–1273 K and 0.01–0.1 s−1, respectively, was identified as the domain of dynamic recrystallization with a peak efficiency of the order of ∼70% at 1173 K/0.01 s−1, and these were considered to be the optimum parameters for hot deformation. The constitutive flow behavior was modeled based on the hyperbolic–sinusoidal Arrhenius-type equations, and a mathematical relation was used to elucidate the influence of true strain on material constants.publishedVersionPeer reviewe

Study of Grain Boundary Character

This book contains eight chapters with original and innovative research studies in the field of grain boundaries. The results presented in the chapters of this book are very interesting and inspiring. This book will be very valuable to all researchers who are interested in the influence of grain boundaries on the structure and different kinds of properties of engineering materials. This book is also addressed to students and professional engineers working in the industry as well as to specialists who pay attention to all aspects related to grain boundaries and their impact on the various properties of innovative materials. The chapters of this book were developed by respected and well-known researchers from different countries

Influence of Surface Roughness on the Cavitation Wear of P265GH and X2CrNi18-9 Steel Cavitation Generators

The aim of this paper was to determine the effect of surface roughness of cavitation generators made from two different materials: P265GH steel, with a ferritic-pearlitic structure, and X2CrNi18-9 (304L) steel with an austenitic structure on the mass loss and cavitation wear. Cavitation generators were tested in the conditions of cavitation wear environment continuously for 500 PMHs in a specially designed and constructed author's stream and flow device. Based on the carried out experiments was confirmed that the highest mass loss - 0.1752 g is seen for a sample of P265GH steel wet sanded with paper with the grain size of 1000. The smallest mass loss was recorded for the cavitation generator made of X2CrNi18-9 (304L) steel, sanded with sandpaper with the grain size of 2500. Certainly, the smallest number of cavitation wear effects was found for a cavitation generator made of austenitic steel X2CrNi18-9 (304L). Few places were identified based on macroscopic photographs, especially near the edges of the straight-through openings, but their number was much smaller than for the ferritic-pearlitic steel, which is associated most of all with the properties of austenitic chromium - nickel steel

Cavitation - Selected Issues

Cavitation erosion is one of the most popular phenomena of the destruction of engineering materials working in water conditions and various kinds of liquids. The cavitation effect is defined as a physical effect, induced by a variable field of liquid pressures, where bubbles or other voids (caverns) - containing steams of a given liquid, gas, or a steam-gas mixture - are formed, expanded, and disappear. A better understanding of all aspects related to cavitation wear will allow for more thoughtful analysis in the selection of innovative engineering materials additionally protected by various technologies or techniques in the field of surface engineering, and optimization of the design of constructional elements used in the cavitation environment. The novelty of this book is the presentation of extensive knowledge related to cavitation, erosion, and how to protect engineering materials against this phenomenon supported by the results of thorough research by the authors

Magnesium Alloys - Selected Issue

Classical magnesium alloys are a combination of aluminium, magnesium, manganese and zinc. Magnesium combined with lithium forms ultralight alloys that have many uses. Since it is a reasonable material, it offers great possibilities and is constantly tested at various angles of applications and properties. Magnesium, previously used for military purposes, seems to fit perfectly to the requirements of the currently prevailing technology. Low density with appropriate mechanical properties (strength, high operating temperature), good foundry properties (high castability and low shrinkage), vibration damping ability and cost-effectiveness of recycling seem to be an ideal response to market needs. All things considered, magnesium alloys are the perfect material used in various industries starting from the automotive industry, through sport, electronics up to the space industry and defence. This book is written by experts in various areas of magnesium science and technology. It gives a general idea of modern advancements in theory and practical purposes of magnesium alloys. The book reports fundamental aspects of corrosion types and details about magnesium alloys designed to work in elevated temperatures and superplastic behaviour. Fundamentals, broad experience, theory as well as complex technological aspects make this work helpful for engineers and scientists from all over the world

Austenitic Stainless Steels - New Aspects

Stainless steel is still one of the fastest growing materials. Today, the austenitic stainless steel with the classic composition of 18% Cr and 8% Ni (grade 304L) is still the most widely used by far in the world. The unique characteristic of stainless steel arises from three main factors. The versatility results from high corrosion resistance, excellent low- and high-temperature properties, high toughness, formability, and weldability. The long life of stainless steels has been proven in service in a wide range of environments, together with low maintenance costs compared to other highly alloyed metallic materials. The retained value of stainless steel results from the high intrinsic value and easy recycling. Stainless steel, especially of austenitic microstructure, plays a crucial role in achieving sustainable development nowadays, so it is also important for further generations