Novel Electrical Joints Using Deformation Machining Technology—Part II: Experimental Verification
This is the second part of the paper related to the exploration of deformation machining technology (DMT), originally developed at Bauman Moscow State Technical University, as it may apply to making electrical joints and comparing their performance to bolted and welded electrical joints. The DMT process is used to generate tooth-like profiles on two opposing surfaces that make the electrical joints which are later joined by applying a mechanical load. Part I contained a more detailed explanation of the DMT process and the description of the results of computer modeling of DMT joints in copper and aluminum. This paper provides the experimental results of the mechanical and electrical performance of copper and aluminum DMT joints which were compared to bolted and welded electrical joints of identical geometries. Measurements of tensile strength and electrical resistance, after thermal cycling and short-circuit testing, show equivalent or better performance of copper DMT joints compared with copper bolted and welded joints. In addition, it is observed that copper DMT joints have superior performance when compared with aluminum DMT joints, this was attributed to lesser gap filling and the springback effect that occurs after the mechanical load for making the joint is removed. The computer modeling results reported in Part I of this paper support these observations.
Surface Hardening by Turning without Chip Formation
The present study describes the basic principles, specific features in the implementation and technological capabilities of a new method of quench surface turning without separation of chip. The underlying process of this method is process of Deformational Cutting (DC) which is based on undercutting and deformation of the surface layers that remain on the workpiece. The energy released in the area of deformational cutting is used to heat the undercut layer up to the temperatures of structural and phase changes of the material being processed. As a result of processing, a hardened structure is formed on the surface which consists of inclined, thin undercut layers tightly fitted to each other. Options are available where the undercut layer is fully hardened in its thickness or only partially hardened. Options are presented which show structures generated on steels. Samples hardened by DC method showed a higher wear resistance compared to samples with volumetric hardening. © 2017 Jordan Journal of Mechanical and Industrial Engineering. All rights reserved
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.