A review of multiaxial fatigue of weldments: experimental results, design code and critical plane approaches

A survey of biaxial (bending or tension and torsion) constant amplitude fatigue of welded connections is presented. Re-analysis of 233 experimental results from eight different studies has been performed based on hot spot stresses and three potential damage parameters: maximum principal stress range; maximum shear stress range; and a modified critical plane model for welds. Of the three methods, the critical plane model was most successful in resolving the data to a single S – N line. The design curve for all toe failures based on the critical plane model was FAT 97 with a slope of 3. By excluding butt welds and including only fillet welds that failed at the weld toe, the design curve was increased to FAT 114 with a slope of 3. However, observed scatter was 70–100% larger than that observed in uniaxial loaded specimens analysed using the hot spot approach.     

Flash pyrolysis of biomass: a review of recent advances

Clean Technologies and Environmental Policy - To assuage global consumer demand for energy, there is a need for increased biofuel production. Flash pyrolysis is an important technique for biomass...     

Recent advances on understanding the origin of superhardness in nanocomposite coatings: A critical review

The remarkable mechanical properties of nanocomposite coatings, such as superhardness, high elastic modulus and recovery, excellent resistance against cracking, low wear rate, and high thermal stability, are due to their unique structures and deformation mechanisms at the nanometer scale. In this paper, recent advances are reviewed mainly with respect to the understanding of the origin of superhardness in nanocomposite coatings. A few controversial issues relevant to the identification of superhard coatings are mentioned. Also discussed are several models, based on analyses and simulations at different levels from continuum to atomistic scales, to elucidate likely superhardening mechanisms. Finally, some open problems and continuing challenges are highlighted.     

Recent advances in computational materials design: methods,applications, algorithms,and informatics

Journal of Materials Science -     

Fundamental aspects and recent advances in transition metal nitrides as electrocatalysts for hydrogen evolution reaction: A review

With increasing human population, sustainable energy production has become one of the most persistent and significant problems of the current century. Hydrogen is considered to be the best clean fuel for future energy requirements. As a substitute of fossil fuels, hydrogen is readily provided by an electrocatalytic hydrogen evolution reaction that splits water molecules. Conventional electrocatalysts based on noble metals are scarce and considerably expensive for large-scale hydrogen production, necessitating the search for low-cost earth abundant alternatives. In this context, transition metal nitrides have gained considerable attention as competent electrocatalytic materials for water splitting. This review presents recent advancements and progress on transition metal nitrides as efficient and cost-effective electrocatalysts for hydrogen production. After overviewing the fundamental aspects of the hydrogen evolution reaction (HER), the review discusses various synthetic strategies for developing transition metal nitrides. Discussed herein are titanium nitrides, vanadium nitrides, iron nitrides, nickel nitrides, molybdenum nitrides, tungsten nitrides, and their composite electrocatalysts employed in HER applications. Some design viewpoints for improving the electrocatalytic activity are systematically proposed. Finally, the review discusses challenges and future perspectives for the advancement of non-noble metal-based electrocatalysts.     

Plated-wire technology: A critical review

Electrodeposited cylindrical magnetic film memory technology is reviewed. Extensive references are made to previous work. New data is given in areas not previously reported. Special emphasis is given to the following items: 1) Applications: Plated-wire applications cover the spectrum from 100 to 1000 ns cycle time NDRO memories of 10⁵to 10⁷bits capacity in commercial and military markets. 2) Processing: Substrate preparation and electrochemical processing, as well as alternative magnetic plating solutions, and the control of pH, temperature, flow rate, Ni-Fe ratio, and other variables necessary for high yield plating are reviewed. 3) Aging: The conditions that stabilize the film and the test methods that predict a 10- to 100-year life are reviewed. 4) Testing: A practical approach to continuous production line testing is reviewed. 5) Bit Packing Density: Calculations on magnetization distribution along the wire are compared to experience. Although memory plane geometry is important, the wire characteristics dominate the achievable bit density. Wire diameter, film thickness Hk, and other factors are included in graphs useful for design purposes. 6) Memory Plane Construction: The relative advantages of several different forms are compared. The need for magnetic keepers and their advantages are reviewed. 7) Interactions: New data is presented on some of the effects of variations in word strap alignment and spacing as well as the sensitivity to variation in plated-wire spacing and bending.     

Review of silicon photonics: history and recent advances

Silicon photonics has attracted tremendous attention and research effort as a promising technology in optoelectronic integration for computing, communications, sensing, and solar harvesting. Mainly due to the combination of its excellent material properties and the complementary metal–oxide semiconductor (CMOS) fabrication processing technology, silicon has becoming the material choice for photonic and optoelectronic circuits with low cost, ultra-compact device footprint, and high-density integration. This review paper provides an overview on silicon photonics, by highlighting the early work from the mid-1980s on the fundamental building blocks such as silicon platforms and waveguides, and the main milestones that have been achieved so far in the field. A summary of reported work on functional elements in both passive and active devices, as well as the applications of the technology in interconnect, sensing, and solar cells, is identified.     

Experimental and computational composite textile reinforcement forming: A review

Preforming is an important step in the manufacturing of textile-reinforced composites with resin infusion processes. It is important to control the fiber orientation to avoid fiber misalignments and wrinkles, which would reduce the mechanical properties of the composite part. The objective of the present paper is to give an overview of the literature dedicated to the textile reinforcement forming process. Therefore, experimental tests for the determination of the basic fabric properties, the experimental characterization of the forming and the numerical approaches for the modeling of the textile forming are reviewed. A great part of the literature has been devoted to the characterization of the shear behavior since it is the most important property for textile reinforcement forming processes. The bending behavior was initially neglected in mechanical models but was found to be important for the simulation of wrinkles.     

Recursive annealing: A computational model for machine design

We propose a model for optimally directed conceptual design of machines in which the transformation of function to form occurs iteratively along an abstraction continuum. An algorithm called FFREADA is introduced as a computational implementation of the model. FFREADA is a grammar-based optimizing design algorithm that uses recursive simulated annealing to generate optimally directed designs. During FFREADA's design process, the mapping of function to form is accomplished using an abstraction grammar production system and a predefined library of function and form entities. FFREADA also has a random design generation mode that can be used to record data to characterize the space of design solutions. FFREADA is demonstrated by designing an idealized power supply using a variety of performance objectives. Results show the algorithm able to explore and record information about a tractably infinite design space before converging to the optimal design.     

A survey of recent advances in magnetic recording materials

Magnetic recording coatings are still made predominantly of iron oxide particles but the newer particles are significantly better in magnetic properties, dispersibility and orientability than the particles used, say, ten years ago. Chromium dioxide particles show excellent recording performance (particularly at densities above 1000 flux changes per millimeter) but they are presently being challenged by the new cobalt-modified iron oxides. These are formed by diffusing cobalt into the surface of acicular iron oxide particles and it is claimed that the particles prepared in this way are much more stable with respect to temperature and stress than the older cobalt-substituted iron oxides. Metal particles, by virtue of their high moment density and high coercivity, would be ideal for high density recording if they could be passivated permanently. The paper reviews improvements which have been made within the last nine years in the properties of particles for magnetic recording applications and discusses how the improvements were effected.     

Science and design methodology: A review

Design methodology has always seemed to have a problematic relationship with science. The design methods movement started out with intentions of making design more scientific, but the more mature field of design methodology has resulted in clarifying the differences between design and science. This paper reviews the relatively short history of design methodology and its relationship with science, maps out some of the major themes that have sustained it, and tries to establish some agreed understanding for the concepts of scientific design, design science and the science of design.     

CD-ROMs for publication of patents: A critical review

The disadvantages of CD-ROMs for use by small firms and patent agents are discussed. These include cost of the hardware, unsuitability of the information provided on many CD-ROMs, total cost of printing specifications from the disks, and incompatibility of the various CD-ROM products.     

Throughput analysis of production systems: recent advances and future topics

Throughput analysis is important for the design, operation and management of production systems. A substantial amount of research has been devoted to developing analytical methods to estimate the throughput of production systems with unreliable machines and finite buffers. In this paper we summarise the recent studies in this area. In addition to the performance evaluation of serial lines, approximation methods for more complex systems, such as assembly/disassembly systems, parallel lines, split and merge, closed-loop systems, etc., are discussed. Moreover, we propose future research topics from the automotive manufacturing systems perspective.     

Conceptual and computational advances in multiple-scattering electronic-structure calculations

A physically transparent transformation of the Korringa-Kohn-Rostoker (KKR or multiple-scattering) method into a tightbinding form is described. The transformation replaces the complicated, slowly decaying, traditional KKR structure constants by exponentially decaying “tight-binding” parameters. The main computational effort consists in the inversion of sparse matrices and scales for surfaces and interfaces, i.e. for systems with two-dimensional periodicity, linearly with the number of layers. This gives the opportunity to treat high-indexed surfaces as an approximation for almost isolated surface steps. Additional adatoms on surfaces and at steps can also be treated and it is discussed that reliable atomic forces and geometric arrangements can be obtained.     

Inorganic solid state optical materials:: Major recent advances

Major advances have recently been made concerning the optical properties of solid-state materials. Four notable areas of research are: upconversion and downconversion luminescence, new high-efficiency scintillator materials, and photonic band gap materials or photonic crystals. Each of these research fields has contributed greatly to our basic understanding of solid-state optical materials as well as contributing to applied research.     

A computational method for optimal structural design II: Continuous problems

A method for solving structural design problems that allows a continuous distribution of material along structural elements is presented. The method is an extension of the generalized steepest descent method presented in Reference 1. Inequality constraints on design variables, displacement, natural frequency, and buckling are explicitly treated and a minimum weight cost function is employed. A steepest descent method for boundary-value state equations is developed and a computational algorithm is given. Several example problems in minimum weight structural design are solved and compared with results obtained by discretization techniques.