Assessment of Deformation Field during High Strain Rate Tensile Tests of RAFM Steel Using DIC Technique

AbstractNnnnTowards developing a constitutive model for describing the flow and fracture behaviour of engineering materials under higher strain rates, studying the deformation fields in uniform and localized deformation regime using the high strain rate tensile tests is of technical importance. To this end, high strain rate tensile tests have been carried out on flat tensile specimen of reduced activation ferritic-martensitic (RAFM) steel at different loading rates varying from 5 m/s to 14 m/s. The strain fields at uniform and localized deformation regime have been mapped by Digital Image Correlation (DIC) technique. For carrying out the DIC, high speed images of the specimen surface have been captured in-situ by high speed camera, synchronized with the load-displacement data acquisition system. The stress-strain fields thus obtained in this study would be an appropriate input to numerical analysis to characterize the flow and fracture behaviour of RAFM steels

Water use and grain yield response of rainfed soybean to tillage-mulch practices in southeastern Nigeria

Despite the agronomic, economic and food values of soybean (Glycine max L. Merrill), there is still dearth of information on the tillage need and the implications of surface mulch for the crop in the eastern part of the forest-savanna transition zone of Nigeria. This study was therefore carried out on a sandy loam Ultisol at Nsukka with a sub-humid climate, during 2006 and 2007 cropping seasons. Our objective was to devise an appropriate tillage method for the crop from evaluated effects of no-till (NT), conventional tillage (CT) and mulch on selected key agronomic indices. Each of the NT and the CT was either unmulched (U) or mulched (M) in a split-plot, giving four treatments/tillage methods (NTU, NTM, CTU and CTM) randomized in four blocks. Rainfall was more favorable in the first than in the second season. The mean seasonal soil water storage (range, 99-109 mm) within 0.5-m soil layer differed among the treatments (NTU < CTU < NTM = CTM). However, for the first and second seasons, both water use (582-616 and 667-709 mm respectively) and grain yield (0.71-0.81 and 1.22-1.91 Mg ha-1 respectively) were not different. Mulch lowered the crop water use but had no influence on grain yield. Water use efficiency was enhanced with mulch only in the second season. Although either of the two mulch treatments (NTM/CTM) would be suitable for growing soybean especially in years of unfavorably distributed rainfall, NTM is a more rational choice than CTM. Rainfall adequacy at the critical reproductive stage of the crop showed to be a more important yield factor than the tested tillage methods

A Formula for Assessing Yields of Clean Coal for any Desired Ash Percentage for Shampur-Chatabar Coal of Raniganj Coalfield

A parabolic relationship has been established between the percentage of sinks for every one per cent reduction in ash for different levels of cleans and the respective ash per cent in cleans of Shampur-Chatabar coals (size ½ in – 36 B.S.) and it is expressed by an equation Y = 4.075 + X (0.368 – 0.019 X), where Y is the weight percentage of sinks for every one per cent reduction in ash of cleans and X is the ash per cent in clean coal. Further, from the calculated value of Y, weight per cent W of clean coal can be calculated by the equation W = 100 – RY, where R denotes total reduction of ash

Some Methods for Calculating Hardgrove Grindability Index of Coals

From a study of large number of determined values of Hardgrove Grindability Index (H.G.I.) of all major types of Indian coals in has been found that H.G.I. of coals is mainly dependent on two factors: (i) rank of the coal and (ii) the amount of ash in it. It has been established that volatile matter together with the moisture of coals (both reported at 60% R. H. and at 40º C) is very closely associated with the carbon content (d.m.f.) which is one of the parameters for measuring the degree of coalification of coals. An equation has been evolved for estimating H.G.I. of coal from a knowledge of their volatile matter plus moisture ® and ash (A) contents (moisture, ash and volatile matter percentages being reported at 60% R.H. and at 40º C basis). The formula HGI=105-R(1.16+0.002R) 00.4 A, may be used for estimating H.G.I. for preliminary selection of coals for pulverized fuel fired furnaces. Further, by an algebraic simplification of the original Hardgrove Equation, a formula has been deduced for calculating H.G.I. of coals from the weight of the coal particles above 200 ASTM sieve, left after the specified Hardgrove test (and which is actually weighed), instead of from the weight of the coal particles below 200 ASTM sieve, estimated indirectly. This has also lead to the construction of a standard table which almost eliminates the calculation part of the H.G.I. determination

Natural Coke (Jhama), its Properties and Possible Utilization

It has been estimated that about 400 million tones of natural coke (Jhana) exists in the Jharia coalfield. Apart from difficulties of mining this hard material, its utilization is the biggest stumbling block in its winning. The paper makes a study of the different properties of natural coke from different sources of the Jharia coalfield with a view to studying the potentialities of its use. Some of the important observations are – the very low melting point of the ash and very good combustion characteristics when the material is crushed to a particular size. The first property suggests the possibility of its utilization in furnaces where a molten ash is desirable for ease of removal and the second property suggests its possible utilization as a domestic fuel. The formation of the natural coke must have taken place at a temperature of above 600ºC but not exceeding 900ºC. the composition of ash indicates reaction of the intrusive material with coal during the formation of natural coke

On Some Aspects of Heat Transfer in a Continuous Vertical Retort for the Production of Smokeless Fuel

Some aspects of heat transfer in the F.F.R.I. narrow continuous vertical retorts have been dealt with in this paper. The down moving charge in the continuous vertical retort receives heat from the combustion chamber on both the sides in the following three manners: (i) transfer of heat from the flame and the hot products of combustion to the retort walls mostly by radiation, (ii) transmission of heat through the retort walls mostly by conduction, and (iii) flow of heat from the hot inner face of retort walls to the charge mostly by convection. The heat received by the charge in the first two ways have been computed. The influence of the operating variables and other associated factors on the thermal performance of the retort have also been discussed in the article. The mechanism of heat transfer from the inner face of retort walls to the charge is rather complicated as the process is continuous, the movements of the charge and steam/gas are counter-current and the physical state inside the retort is not in equilibrium. The heat transfer in this way has not been worked out but studies for the same have been initiate

The Planning of a Central Coal Washery at Bhojudih

In order to meet TISCO’S demand of additional coking coal at the end of the second Five Year Plan it has been decided to install a central washery at Bhojudih, which would receive its raw coal supply from the collieries dispatching coal through Bhojudih railway marshalling yard. Depending on the present output from the different collieries located in this region, the normal capacity of the washery has been rated initially at 250 t.p.h. with due provision for future expansion to 500 t.p.h by incorporating some additional units and/or sections. Since the supplies are to be drawn from seams with comparatively superior wahsability characteristics, it has been possible to plan a fairly simple layout with no provision for recovery of middling. The design takes into consideration any possible size variation in the feed coal and also some reasonable fluctuation in the yield of washed products. The present paper relates to the washing scheme to be followed and the general description and specification of some of the major sections of the washery, such as raw coal handling: storage and pre-treatment: washing ; slurry treatment; products loading; medium preparation, recovery and control; centralized control; buildings; control laboratory; etc. indication the relative advantages of some of the units wherever possible. Some idea of the extent of the coast involved in the various sections of the washery is also given

Industrial minerals and their prospects in north western Kutch, Gujarat

The north western part of kutch district of Gujarat is a potential source of many minerals, viz. limestone, clay, bauxite, siderite, gypsum etc. yet the industrial development has not taken place mainly for the acute shortage of power rendering thereby the whole area industrially backward. Exploration and development of the lignite resources of this region may, however, solve this power crisis and increase thereby the viability of industrialization utilizing the locally available minerals. For instance, limestone can be used in the cement industry, clay deposits in the ceramic industry, red ochre deposits in the dyes and pigment industry, siderite for hydrogen production and gypsum for calcium sulphide production. The present paper deals primarily with the evaluation studies of the mineral resources occurring in panandhro and its adjoining area