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"2.1. General Considerations and Properties2.1.1. IntroductionOur present knowledge of the platinum-group elements (POE) is extensive, the reason being two-fold. The elements have many uses and, moreover, they exhibit extremely varied chemical behaviour, depending on their state of oxidation and chemical environment. The present chapter reviews a selected body of material which is of particular relevance to mineralogy and geochemistry.Comprehensive treatises on the POE include those by Mellor (1956-1957), Gmelin (1938-1957) and Pascal (1958). The inorganic chemistry, particularly coordination chemistry, has been dealt with in works by Griffith (1967), Hartley (1973) and Livingstone (1975), and the analytical chemistry by Walsh and Hausman (1963), Beamish (1966) and Beamish and Van Loon (1972, 1977). Darling (1973) and Savitsky (1978) have reviewed the metallurgical properties and applications of the metals. Goldberg and Helper (1968) have reviewed the thermochemistry and oxidation potentials of POE systems, and Wagman et at. (1969) have also provided selected values of their thermodynamic properties. The geochemistry of the POE has been reviewed by Yushko-Zakharova et at. (1967), Cousins (1973), Cabri (1974), and Naldrett and Duke (1980).Platinum was used briefly as a coinage metal in ImperialRussia. Otherwise, the principal early use for platinum and its alloys was in the fabrication of chemically resistant apparatus. Subsequently, a large part of platinum production was utilized for catalysts in the sulphuric acid and ammonia industries. Platinum has been replaced by vanadium pentoxide in the manufacture of sulphuric acid, but, in recent times, catalytic upgrading of petroleum and emission control systems for automobiles have opened further huge markets for the metal. All of the POE find uses either as reagents or catalysts in the synthesis of organic compounds, e.g., in the Wacker process, which uses palladium chloride to catalyze the production of acetaldehyde from ethylene. There are, of course, a large number of specialized uses for the elements, particularly in alloys, temperature measurement devices, cancer therapy and so on."

Jan 1, 1979

By B. R. Bowerman, W. J. Thoburn, M. J. Humphris

"Nickel granules are produced for carbonylation by pouring a molten stream into a path of high pressure water. Granules and water are separated in dewatering bins. The overflow, which contains up to 0.1 weight percent solids, was initially cooled and recycled to the granulating step. However, the rate of buildup of these solids in the handling system was intolerable. A lamella thickener was installed to solve the problem by removing solids from the dewatering bin overflow. Its description, application and performance to date are discussed.The lamella thickener treats a slurry containing about 0.1% solids of which about 30 weight percent is less than 325 mesh. It recovers 80 to 90 percent of the input solids in an underflow slurry containing 90 weight percent solids. Since its installation the frequency of cleanout of the recycle water handling system has dropped from about once per month to about once or twice per-year."

Jan 1, 1977

By J. D. Wright

This paper describes current milling practice at Endako Mines Ltd., a molybdenum producer in central British Columbia. The various steps in the crushing, grinding and flotation of the ore are outlined, with emphasis on the metallurgy of the latter operation. Tailings disposal and concentrate assaying methods are also described.

Jan 1, 1969

By John Knox

The object of this paper is to present an analysis of the major problems encountered both in the design and application of downhole drills. Particular reference is made to design features governed by: physical size limitations; metallurgical material standards; physical operating environment; range of commercial materials to be drilled; high power output required, coupled with simplicity from the operating and maintenance viewpoint; and bit design. The history of attempts to develop downhole drills is discussed, and representative mechanical configurations are illustrated. The general design and application aspects of the different types are commented on. The application of this drill type in various commercial fields, such as (a) oil-well drilling, (b) open-pit mining and (c) underground mining, is discussed, along with the limitations presently imposed by the commercial state of the art in the manufacture of accessory equipment; e.g., drill rods, air compressors, mountings, etc. Suggestions on the possible future direction of the development and application of this tool are put forth.

Jan 1, 1965

By Dean L. Millar

Measures taken by mining companies around the world to reduce their carbon footprints are becoming increasingly important in the sector securing its social licence to operate. The options for measures reduce to three categories of activity: i) demand reduction by avoiding unnecessary waste of supplied energy, ii) improving the utilization of energy that does have to be consumed and iii) adopting low carbon energy production options?including renewable energy. As well as the environmental imperative, as the prices of electricity, gas and liquid fuels increase, so the economic case for activities i) to iii) gains higher priority, especially in such an energy intensive industry. The specific energy consumption for certain upstream minerals industry operations in Canada is reported to be as follows: underground mining: 99.5 kWh/tonne mined; surface mining: 11.7 kWh/tonne mined; base metal processing: 81.4 kWh/tonne milled; gold processing: 99.6 kWh/tonne milled. Around 508 kWh/tonne (slag) of heat is reported to be available in cooling slag from 1500°C to 25°C; an amount that is simply indicative of the energy intensity of downstream smelting and refining operations. Low carbon, energy saving technology options that are available to mining industry companies lead to projects with return rates that must compete alongside other capital intensive projects considered by mining company boards. Energy projects frequently involve longer payback periods and lower rates of return than those of competing bids for capital, such as those for development of new mineral properties. For energy services companies (ESCOs) that specialize in the financing, construction, and the efficient operation and maintenance of energy projects, the same returns and payback periods may be considered acceptable or even attractive. For the ESCO, the key commercial risk mitigating factor is a securing a long term contract for the supply of energy.

May 1, 2011

By D. Stone, N. J. Aslin, W. Webb

In today's modem copper electro-refineries, increasingly higher average current densities are being employed. With these increases many refineries are approaching their limiting current density. The nearness of the average operating current density to the limiting current density has placed increasing emphasis on the need to maintain an even current distribution. This paper explores the importance of maintaining even current density and discusses the factors, processes and practices that are necessary to achieve and maintain high quality production at high operational intensity.

Jan 1, 2005

By K. Chattopadhyay

Fluid flows in metallurgical reactors play a vital role on liquid metal cleanliness for both ferrous and non-ferrous metallurgy. Thus, it is absolutely critical to understand different fluid flow mechanisms, and the use of computational methods to model the complex non-isothermal, turbulent, single- and multiphase-flows, has to be appreciated. The present case study emphasizes on controlling the flow of liquid steel in a tundish and enhancing liquid metal cleanliness. CFD modeling was used to build a robust mathematical model, and effects of flow control furniture and non-isothermal conditions were analyzed. The mathematical model was validated against water model experiments. Parameters that were conducive for inclusion removal were identified and implemented in the plant. Some flow control devices could increase inclusion removal to a great extent compared to the existing configurations. In cases, where a hot ladle was poured into a relatively cooler tundish, inclusion removal was better, whereas results were catastrophic in cases where colder liquid was poured from ladle to the tundish. Similar techniques can be applied for other liquid metals including light metals and non-ferrous metals.

Jan 1, 2015

By M. Aljarrah

The phase equilibria in the Mg-Al-Ca system was investigated experimentally by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques similarly the Mg-Al-Sr system has been studied using DSC and XRD as well as scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) and quantitative electron probe micro-analysis (EPMA). A new ternary solid solution MgxAl4,xSr was confirmed in Mg-Al-Sr system, which is a substitutional solid solution of Mg atoms in Al4Sr. Maximum solubilities of 21.3 at.% Al in Mg17Sr2 and 11.4 at.% Al in Mg were observed. It was also noticed that Mg38Sr9 dissolved 12.5 at.% Al. In the Mg-Al-Ca ternary system, one of the invariant transformations predicted by thermodynamic modeling was verified experimentally and found to occur at 512°C with composition close to 10.8 at.% Ca, 79.5 at.% Mg and 9.7 at.% Al. A ternary solid solution (Mg,Al)2Ca was confirmed where large solid solubility of Al in Mg2Ca was observed.

Jan 1, 2006

By John Kostuik

AT the Sladen-Malartic mine, a number of orebodies have been mined, some by shrinkage and others by open sub-level scopes, from which the ore is handled either through a grizzly system or by mechanical loaders. This paper deals with the comparative costs and relative merits of the two handling arrangements. The facts brought out in this comparison have a bearing on the selection of a proper handling method. The mine is in Fourniere township, northwestern Quebec, about forty miles east of the town of Rouyn. It is served by the Rouyn-Senneterre branch of the Canadian National railways. Two vertical three-compartment shafts give access to the present workings. No. 1 shaft, at which the plant is centralized, is the main hoisting shaft, with five levels to 950 feet. No. 2 shaft, 2,400 feet east of No. 1, is under development, with four levels to 725 feet. At the main shaft, the ore is hand-trammed in 1 1/2 tons cars from the scopes to the stations o:i each level and hoisted in cages to surface at a rope speed of 900 feet per minute. Air-operated tipples are used to dump the ore through grizzlies of 14-inch openings into a surface bin of 150 tons capacity. The ore hoisted at No. 2 shaft is trucked from the headframe bin to the mill. Milling commenced in January, 1938, ar a daily rate of 250 tons. Within two months this rate was increased to the unit's maximum capacity of 325 tons. A second unit to treat a further 325 tons daily was installed in April, 1939. The orebodies mined at No. 1 shaft are parts of a silicified zone at the contact between syenite porphyry and greywacke. The zone is ten co sixty feet wide, strikes easterly, and dips to the south at 55 to 85 degrees. The hanging-wall of the zone is marked, though not precisely, by a strong gouge fault. Locally, the boundary of silicification may be as much as twenty feet either above or below the fault, but for practical mining purposes the fault is the hanging-wall of the ore-zone. The footwall roughly parallels the fault, but as an assay wall it is usually irregular in detail. The ore is dense and hard, a siliceous replacement of both porphyry and greywacke, mineralized with fine disseminated pyrite.

Jan 1, 1941

By D. Campbell Mackenzie

THIS paper is submitted primarily to put on record the results of a number of experiments carried out at the Wingdam mine of Consolidated Gold Alluvials of B.C., Ltd., with the object of establishing a reliable method of concentration of 'wash' and a maximum recovery of gold from the concentrate. It will be generally admitted that, during the last two decades, a tremendous amount of research work has been carried out, both by private companies and Government departments, with a view to improving the technique of the recovery of gold .from quartz veins or lodes. So thorough have been these investigations that milling practice at a modern quartz gold mine is almost an exact science, carried out with meticulous accuracy. In placer mining, on the other hand, very little departure from old traditional methods can be noted, with the exception perhaps of the more modern gold dredges. This may be due to the fact that the concentration of placer gravels, up to a certain point, is comparatively easy. Only a simple equipment of sluice box and riffies seems necessary where the gold is coarse and the gravel free from clay. In the early days of placer mining, when claims were rich and fairly 5hallow, nobody worried very much about fine gold; and, if clay was present, an enlarged dump box was constructed in which the gravel was subjected to a rather desultory puddling. That large quantities of gold are lost in normal placer practice is generally admitted. Some 26 years ago, I had inspectorial charge of many bucket dredges on the Ovens river, in Australia. Occasionally it was necessary for a dredge to work through its own tailing to reach a new section, and almost without exception enough gold was recovered from these tailings to defray the total cost of moving the dredge. Since those days, the technique of gold recovery in dredging has been considerably improved and it is still receiving close attention. Outside of dredge mining, most placer operations, deep or otherwise, are as they were-notorious gold losers, paying little attention to the recovery of fine gold and taking an absurd amount of time over each clean-up. In the Cariboo district of British Columbia, the alluvial gold is usual y associated with varying quantities of black sand (magnetic) and grey sand (non-magnetic); and it can be taken as axiomatic that, if you save all the black sand and grey sand, you save practically all the gold. It is on this hypothesis that we have carried out our research work and brought our recovery system up to its present highly satisfactory standard.

Jan 1, 1937

By PAULL. BROUGHTON

Commercial deposits of sodium sulphate are harvested from alkaline lakes that are widespread throughout semi-arid southern Saskatchewan and adjacent southeastern A lberta. Concentration of sodium sulphate occurs in undrained basins under semi-arid conditions. Precipitation runoff from land adjacen1 to 1hese basins leaches 1he mineral from the soils and carries it in solu1ion 10 the basins. The process may be largely subsurface, wherein spring seeps feed basins associated with buried (preg/acial) river valleys. Evapora1ion during summer concentrates salts in the brines, and chilling of water below sa/Uration poin1 during win1er resu//s in deposi1ion of sodium sulpha1e (mirabili1e) crystals on lake bo//oms. Sodium su/pha1e, commercially known as sa/1 cake, ranks second only 10 po1ash in cen1ral-wes1ern Canada's nonme1allic mineral production. // is recovered from su,face brines, directly from intermittenl salt beds, and, until recently, by solution mining of shallow subswface deposits. Sodium sulphate is extrac1ed from seven alkaline lakes and sail f/a1s in Saska1chewan and one in Alberta. Annual produc1ion is approxima1e/y a halfmillion tonnes. Manufacture of kraft paper is the mos1 significanl marke1 for salt cake, but addi1ional quantifies are used in the glass and detergent manufac1uring indus1ries.

Jan 1, 1984

By M. D. Scott

"Highland Valley Copper recently installed a semi-mobile in-pit crushing and conveyor system designed to feed both the Bethlehem and Lornex concentrators with a feed averaging 120000 tonnes per day. The system installed with a rated capacity of 12000 tonnes per hour is the highest capacity hard rock semi-mobile crushing and conveying system currently in existence.The system is designed in a manner that the crushers can be moved easily as the pit is developed in depth with conveyors extending deeper into the pit, and conveyors being moved radially from a surge pile located at the rim of the ultimate pit as the pit increases in size laterally.The system consists of two 6000 tph, 60 by 89 Krupp semimobile crushers feeding two moveable 4500 hp, 60 in. conveyors, 1.25 km long feeding a 7500 tonne live storage surge pile. Two 96 in. belt feeders installed in reclaim tunnels under the pile feed two parallel 4500 hp, 60 in. conveyors, 1.25 km long on a 12 per cent uphill grade to the two existing Lornex plant feed conveyors. A third 96 in. belt feeder, under the pile, feeds a 60 in. conveyor, loading trucks hauling crushed ore to the Bethlehem mill.A description will be given: (1) of the system's design features in which climatic extremes, operating, and maintenance characteristics were of primary importance; (2) of the way the system was constructed from components purchased internationally on an extremely tight construction schedule; and (3) of the way the system has operated during the first few months in operation during which time it demonstrated that it has met various design criteria."

Jan 1, 1988

By S. Kivrak

The firms in construction industry could not sufficiently adapt the rapidly emerging information technologies in recent years into their corporate structures. Therefore, in an effort to further exploit the benefits of information technology (IT), integration of the experiences and backgrounds of construction industry and the advantages of IT, is one of the most open-ended fields for improvement in this industry. Utilization of IT in the construction sites will positively affect the efficiency, productivity, quality and health & safety issues in the construction sites thus the cost and completion time of the projects. Within this context, augmented reality technology, which brings a new perspective into IT, can be put into the service of construction industry. Augmented reality which has been designed to improve the services in many application domains such as school education, military warfare, military trainings, industrial maintenance, retail and medical, can be defined in the simplest form as augmenting the real world with information from the virtual world. The main aim of this study, which presents an overview of an ongoing project, is to develop an innovative method by making a construction worker, foreman, equipment operator or a site engineer watch a very comprehensive and informative animation which will enable the said staff to perform or supervise all the phases of the activity he or she is in charge for in a more efficient, productive, safer and qualified manner by means of smart glasses using augmented reality systems. In this respect, training material related with the activities in the construction sites will be prepared and with a well-fictionalized scenario, animations exhibiting all the phases and details regarding the related activity (e.g. masonry, formwork and rebar works etc.), method of statement, correct and incorrect applications in comparison-wise manner, will be produced. Therefore, the user will be able to reach the training material, method statements etc. in the animations about the activity he or she is in charge for, enabling him or her to figure out the work as prescribed in the specifications. Basic trainings about the system will be given to target group, i.e. construction workers, foremen, operators, site engineers and managers working in the construction sites to apply the system on sites after all the system was tested. After the testings, to determine the effectiveness of this system, semi-structured interviews and survey questionnaires will be conducted among the mentioned target group. Therefore, the potential benefits of this system to the construction industry can be determined. The main target of this study is to implement an efficient, thorough construction management by orienting the staff in the construction sites to perform efficient, safe and qualified works by means of smart glasses that use augmented reality. There are relatively few studies about the implementations of augmented reality technology in construction. The outputs to be attained in the end of the study have the potential of improvement of time, cost, quality and safety parameters by ensuring a qualified, safe, efficient and productive construction management via augmented reality technology in the construction industry.

Aug 1, 2013

By Su-Ping Peng

Three dimensional (3D) seismic exploration has been carried out since the 1980s in the mining district of China, where it has been playing an indispensable role in the high yield and efficiency of coal mining. Unlike oil exploration, this technique uses high density seismic acquisition technology. In recent years, it has focused on wide azimuth 3D seismic acquisition. Evaluation of geometry moved away from depending on folds, azimuth and offset, toward being based upon a focus-ray beam. Conventionally, coalfield 3D seismic interpretation focused on time domain and was based on kinematics information, which is only suitable for less complex geological conditions. To achieve high-resolution processing for the complex topography and structure in coalfields, data processing shifted from poststack to prestack. The means to improve the accuracy of interpretation for complex geological conditions are 1) integration of multiple attributes and multiple disciplines, 2) combination of seismic and geological data, and 3) comprehensive combination of time domain and depth domain data. With the demand for lithological exploration, high-resolution data processing must also take into account the requirements of preserving amplitude in seismic data. Seismic attributes technology, seismic inversion technology, and dynamic tracking interpretation are key techniques in 3D seismic exploration. They greatly improve interpretation accuracy, produce better results in the goaf space description of the coal-bearing strata and coal seam structure, and effectively reduce exploration costs under complicated geological conditions. Therefore, these techniques will be the primary means employed in the future to deal with coalfield complex structure and lithological exploration.

Aug 1, 2013

By Lionel A. York

This paper outlines the type of water-bearing formations encountered in the Prairie Sediments and describes a method for effectively sealing these zones in order that shaft-sinking operations may be carried out with safety. Details are given of the procedure for carrying probe holes ahead of the shaft bottom. These probe or grout holes are employed for establishing a series of overlapping grout covers around the proposed shaft excavation to safeguard against large inflows of water during sinking. The pattern and length of grout covers cannot be standardized, and each cover needs to be specially designed to suit the varying ground conditions. In order to provide effective protection through the Prairie Sediments, the number of holes in any one cover would not be less than 8, and possibly as many as 64 would be required in certain zones. The length of covers would vary from 100 ft. to 250 ft. Emphasis is placed on the need for obtaining accurate geological and water information from exploratory holes, drilled in the shaft vicinity, in order to effectively plan all grout covers.

Jan 1, 1964

By Peter F. Pullen

The need to apply the latest available technology to develop better tools and methods to meet problems in the mining industry was recognized by six of Canada's leading mining companies. As a result, MIROC (Mining Industry Research Organization of Canada) was chartered to identify problem areas in Canadian mining and to have research carried out to develop the tools and equipment to meet these perceived needs. The initial activity of MIROC has been in the environmental field, with improved clothing and protective devices being developed by contractors. Work clothing for miners is now being field tested. Respiratory protection and a new personal light source combined in a new "space-age" helmet are about to be issued for testing. Further developmental work is being carried on to offer these units and probably other personal protective devices on an individual basis as well as in a combined package.

Jan 1, 1979

By Baki Özüm

Early evaluations of Pasquia Hills kerogen shale deposits by Geological Survey of Canada, Saskatchewan Geological Survey, Manitoba Energy and Mines and Sun Oil Company, using modified Fischer Assay, Rock-Eval and other techniques, estimated recoverable reserves of about 2.6x109 barrels of oil in areas favorable for strip-mining; each metric ton of ore was determined to yield about 30 L to 50 L of shale oil remarkably high in aromatic compounds. Western Petrochemical Corp. (WPC) is holding two Oil Shale Exploration Permits covering about 76,635 hectares in the Pasquia Hills Region of eastern Saskatchewan and conducting a 15-corehole drilling program to determine stratigraphic correlation on both first and second white specks kerogen shale. In this program, correlation will be established between oil yield and oil quality, using different retort techniques, including modified Fischer Assay, steam retort and Rock-Eval. Results will lead to further resource evaluation and to a preliminary engineering design for a shale processing plant, including selection of retort process, upgrading of shale oil to petrochemical feedstock, hydrogen management, energy balance and evaluation of environmental impact.

May 1, 2002

By F. W. Gray

Ideal utilization of the heat energy in coal should theoretically be secured by supplying each atom of combustible material present with the exact quantity of oxygen necessary for complete combination. An intimate and equal admixture of the fuel particles with air is therefore to be sought. Coal, or the combustible substances of which coal is composed, may be used in solid or liquid or gaseous form. The use of coal in small particles intimately mixed with air is, in effect, a specification of coal in pulverized or dust form. There has been much important development of this manner of using coal, which may be instanced as the outstanding advance in the use of coal as a solid. The completeness and efficiency of combustion in a properly designed dust-fired furnace permits the use of locally available coals of inferior quality, and enables them to be used commercially instead of imported coals of better quality. That is to say, some grades of coal of low calorific value, that are not economically useable in lump form on grates, are useable in pulverised form, because of the more complete combustion thereby obtained, and the consequent more efficient results. In the case of coals that are unsuitable for steam-raising in grate-fired furnaces, because of clinker troubles, (arising usually from a combination of high sulphur content and low-temperature fusibility of the ash content) use in pulverised form has obvious advantages, and in addition gives the benefit of any heat units that are contributed by free sulphur in the coal.

Jan 1, 1924

The dynamic breakage process of rocks by the impact of a hydraulic hammer is more complex than one normally assumes. It is even more difficult when one has to conduct the breakage under water. In such cases one does not know exactly what the surface topography and composition are at the bottom of the sea or river and, hence, it is more difficult to select the best position of the hammer before starting the hammering. Typically, an industrial hammer has a diameter of about 250 mm, a length of about 1.25 to 1.75 m and a mass of several tons. The hammer frequency can be up to 50 impacts per minute. The general principles of rock hammering can be easily summarized, but this knowledge is not sufficient to adapt adequately the method for less common rock conditions (e.g. less brittle rock, presence of vertical and subvertical fractures, etc.). That is the reason why we initiated a research project, whereby a scale model has been developed to conduct experiments in the laboratory and whereby discrete element simulations are being conducted. Both aim at a better understanding of the basic mechanisms of rock hammering. The scaled experimental model allows varying the impact energy and the static weight independently. Within the experiment, the hammer is in contact with the rock specimen under a certain confining pressure and with a certain contact pressure due to the static weight. A weight falls on the hammer, creating the dynamic action or impact; the height over which the weight falls can be varied. The penetration is recorded after each impact. After a certain penetration the test is stopped and the internal crack patterns are described. Some simulations have been conducted, allowing the modeling of individual fracture initiation and growth during the penetration of the hammer by either a constant displacement rate (using the UDEC-code) or by introducing the dynamic process (using the PFC-code). Some of the observed features in the laboratory experiments can be visualized in the simulations. However, further research is needed to allow the simulations being an adequate tool to well understand the dynamic process in laboratory experiments, as well as the in-situ behavior.

Aug 1, 2013

By Zhenyu Han, Dion Weatherley, Ruslan Puscasu

"This study aims to demonstrate the capacity of the Discrete Element Method (DEM) to model and simulate fracture in brittle rock, capture the crack propagation process and determine crack propagation rates for various levels of external loading. In the numerical experiments reported here, a macroscopically homogeneous body of brittle rock, containing a single pre-existing crack, was subjected to tensile stress loading. Simulations concerned with model I crack growth process in 3D were carried out. The process of fracture has been observed under various steady state and dynamic conditions. The numerical results obtained reproduce qualitatively and quantitatively a variety of observed fracture phenomena. Specifically, this study examined the onset of cracks, single dominant cracks that grow across the specimen, crack bifurcations and branching. The density of fractures that can be nucleated and grow to a significant size with and without arresting each other, crack growth speed and stress distribution, all have been consistently and systematically analyzed. Suggestions on potential future developments are made and discussed.INTRODUCTIONFracture and failure mechanics are very important in mining, manufacturing, materials processing, mineral processing, civil and mechanical engineering, and many other disciplines of science and engineering. Yet, due to the complexity of fracture phenomena, no theoretical models of broad applicability are currently available (Bieniawski 1967). The simulation of crack propagation is therefore considered an open question in numerical rock mechanics. Although, a significant body of experimental research on fracture of materials was carried out since the early days of fracture mechanics (circa 1940s) (Poncelet 1946, Mott 1948), often in parallel with the development of fracture mechanics theories as well as with the development of experimental and observational techniques themselves, the experimental results were often done on particular classes of material such as glasses and other very brittle materials. Indeed, a number of specific experimental observations on the behavior of growing cracks in brittle materials were made in the 1940s for which generally accepted explanations based on physical principles are still lacking. Likewise, quantitative numerical modeling, based on both continuum and discrete methods, as a basis for understanding dynamic crack growth is still in a preliminary stage."

Jan 1, 2015