There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Dual-phase (DP) steel is the flagship of advanced high-strength steels, which were the first among various candidate alloy systems to find application in weight-reduced automotive components. On the one hand, this is a metallurgical success story: Lean alloying and simple thermomechanical treatment enable use of less material to accomplish more performance while complying with demanding environmental and economic constraints. On the other hand, the enormous literature on DP steels demonstrates the immense complexity of microstructure physics in multiphase alloys: Roughly 50 years after the first reports on ferrite-martensite steels, there are still various open scientific questions. Fortunately, the last decades witnessed enormous advances in the development of enabling experimental and simulation techniques, significantly improving the understanding of DP steels. This review provides a detailed account of these improvements, focusing specifically on (a) microstructure evolution during processing, (b) exp...

An Overview of Dual-Phase Steels: Advances in Microstructure-Oriented Processing and Micromechanically Guided Design

Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsky bar systems, which include both split Hopkinson pressure bar (SHPB) and split Hopkinson tension bar (SHTB) systems. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system. This review aims to fully describe and critically assess the detailed procedures and principles of techniques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined, followed by the key loading techniques that are useful for dynamic rock tests with SHPB (i.e. pulse shaping, momentum-trap and multi-axial loading techniques). Various measurement techniques for rock tests in SHPB (i.e. X-ray micro computed tomography (CT), laser gap gauge (LGG), digital image correlation (DIC), Moire method, caustics method, photoelastic coating method, dynamic infrared thermography) are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements (i.e. dynamic compression, tension, bending and shear tests), dynamic fracture measurements (i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity), and dynamic techniques for studying the influences of temperature and pore water.

https://cyberleninka.org/article/n/236168.pdf

Dynamic rock tests using split Hopkinson (Kolsky) bar system – A review

Thermomechanical processing of advanced high strength steels

Metallographic Methods for Revealing the Multiphase Microstructure of TRIP-Assisted Steels - some applications for steels

Design and Thermodynamics Analysis of Marine Dual Fuel Low Speed Engine with Methane Reforming Integrated High Pressure Exhaust Gas Recirculation System

The high-speed deformation behavior of a dual phase steel was studied by means of dynamic Hopkinson bar shear punch testing, with an emphasis on the influence of microstructure. Dual phase microstructures with different fractions of martensite were obtained by changing heat treatment parameters during intercritical annealing. The effects of low temperature tempering (170°C, 235°C, and 300°C) and bake hardening treatment (5% pre-strain followed by holding at 170°C for 20min) were also investigated for two selected microstructures containing 22% and 61% martensite, respectively. Quasi-static shear punch property was also measured by a MTS hydraulic machine and compared with dynamic results. Additionally, quasi-static tensile tests for some specimens were also conducted for validating the shear punch data.

Effect of microstructure on static and dynamic mechanical property of a dual phase steel studied by shear punch testing

The high-speed deformation behavior of a commercially available dual phase steel composition was studied by means of split Hopkinson bar testing in shear punch mode. The as-received cold-rolled material was subjected to a variety of heat treatment conditions to produce several different microstructures, namely ferrite plus pearlite, ferrite plus bainite and/or acicular ferrite, ferrite plus bainite and martensite, and ferrite plus different fractions of martensite. A strong effect of microstructure on both static and dynamic properties and on the dynamic factor (ratio of dynamic to static strength) was observed. According to the variation of dynamic factor with static strength, three groups of microstructures with three distinct behaviors were identified. Under the same static strength level, the classic dual phase microstructure was found to have the highest value of dynamic factor and therefore can absorb more dynamic energy than other microstructures.

Effect of microstructure on the dynamic deformation behavior of dual phase steel

The high strain rate properties of high strength steels with various microstructures and static strength levels were studied by means of split Hopkinson bar apparatus in shear punch mode. The as received cold rolled sheet steels were subjected to a variety of heat treatment conditions to produce several different microstructures, namely ferrite plus pearlite (F+P), ferrite plus bainite (F+B), ferrite plus martensite (F+M) and ferrite plus bainite and retained austenite (F+B+RA). According to the variation of dynamic factor (ratio of dynamic to static strength) with static strength, two groups of microstructures with two distinct behaviours were identified, i.e. classic dual phase (ferrite plus martensite) and multiphase (including ferrite–pearlite, ferrite–bainite, etc.). It was also observed that the general dependence of microstructure on the dynamic factor was strongly influenced by chemical composition in the case of ferrite plus martensite microstructures.

Effect of microstructure and chemical composition on dynamic factor of high strength steels

This paper presents a review of system design and analysis, control strategy, optimization and heat and mass integration of integrated solid oxide fuel cell (SOFC) and reciprocating internal combustion engine (ICE) system. Facing the future power-fuel-power path, both SOFC and ICE can adapt to a variety of fuels, which is one evidence that ICE is amenable to integration with SOFC, while SOFC is more efficient, cleaner, and quieter than ICE. Different system topologies are classified, whose dynamic performances are also analyzed. In addition, the heat and mass integration of system is discussed. Moreover, the combustion modes of ICE, which can be applied to steady combustion, high efficiency and low emissions, are analyzed and compared. Meanwhile, the potential and methods of system waste heat recovery are discussed. The exergy analysis, energy density and techno-economy are discussed. Finally, the results are discussed in the last section with the final conclusion that SOFC-ICE systems are very suitable for long-distance transportation such as maritime and aviation, which can also solve problems of the carbon and pollutant emissions with the background of engine cannot be replaced in maritime, while the system can adapt a variety of alternative fuels. 

Progress and prospect of the novel integrated SOFC-ICE hybrid power system: System design, mass and heat integration, system optimization and techno-economic analysis

Jinbo Qu

Papers

Design and Thermodynamics Analysis of Marine Dual Fuel Low Speed Engine with Methane Reforming Integrated High Pressure Exhaust Gas Recirculation System

Effect of microstructure on static and dynamic mechanical property of a dual phase steel studied by shear punch testing

Effect of microstructure on the dynamic deformation behavior of dual phase steel

Effect of microstructure and chemical composition on dynamic factor of high strength steels

Progress and prospect of the novel integrated SOFC-ICE hybrid power system: System design, mass and heat integration, system optimization and techno-economic analysis