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The word "engineering" should not be considered as all-inclusive. Perhaps it should be redefined at this time. Various fields of learning that are indispensable to the locating, beneficiating, processing and using of minerals cannot be classified properly as engineering. For example, in locating deposits, the sciences of paleontology, stratigraphy, mineralogy, petrology, petrography, geo- chemistry, economic geography, and mineral economics might be involved. Beneficiating, processing, and using go beyond the normal scope of engineering to include fuel technology, physical and organic chemistry, physical and atomic metallurgy, and ceramics. Fifty-eight institutions of higher learning in the United States offer curricula in one or more subject-matter fields of the mineral arts and sciences. Thirty-four curricula are offered in mining; 42 in metallurgy; 17 in petroleum and natural gas; 13 in ceramics; 1 in fuel technology; 23 in geological engineering; 8 in geology; 4 in geophysics; 2 in mineral preparation; and l in mineral economics.1 Under given conditions, some of these curricula probably could be eliminated without the slightest retardation in the rate of advancement of knowledge concerning the science of mineral discovery, extraction and utilization, but it is no credit to mineral industries colleges that five departments of mining per-

Jan 1, 1950

CHARLES G. ROEBLING Charles Gustavus Roebling, president of the John A. Roebling's Sons' Co., of Trenton and Roebling, N. J., and of the New Jersey Wire Cloth Co., of Trenton, and vice-president of the John A. Roebling's Sons' Co., of New York, died at his home, No. 333 West State Street, Trenton, on Oct. 5, 1918. Mr. Roebling, who was born in Trenton, was a son of the John A. Roebling who finished the plans for the Brooklyn Bridge just before he died. The bridge was completed by his sons, Charles G. Roebling and Col. Washington A. Roebling. Upon graduation from the Rensselaer Polytechnic Institute in 1871, Charles Roebling became associated with the Roebling company as a mechanical engineer. He was engineer and builder of the suspension

Jan 12, 1918

Organization Place Date 1917 American Society of Sanitary Engineers Grand Rapids, Mich. Aug. 1-3 National Association of Stationary Engineers... Evansville, Ind. Sept. 10-15 National Safety Council New York City. Sept. 10-15 National Exposition of Safety and Sanitation. New York City Sept. 10-15 American Iron, Steel & Electrical Engineers..:. Philadelphia, Pa. Sept. 10-14 American Institute of Metals Boston, Mass. Sept. 24-29 American Foundrymen's Association Boston, Mass. Sept. 24-29 Chemical Industries, Third National Exhibition. New York City Sept. 24-29

Jan 8, 1917

Meeting of Apr. 23, 1915.-The Iron and Steel Committee was authorized in its discretion to defer the date of acceptance of papers for the Hadfield Research Prize to Nov. 1, 1916. The sum of $250 was appropriated as a guarantee fund to establish a Library Research Bureau in co-operation with the other Founder Societies. The sum of $50 was appropriated to the Puget Sound Section. The sum of $250 was appropriated to the San Francisco Section. The sum of $125 was appropriated to the St. Louis Section. The matter of memorializing the New York State Constitutional Convention was referred to the New York Section of the Institute with authority to act as a Section only. Upon recommendation of the Committee on Membership, 50 Mem¬bers, 1 Associate, and 6 Junior Members were elected.

Jan 6, 1915

By AIME

Generally speaking, the mining industry had a good year in 1948 with most mineral products being produced in record quantities for peacetime standards. The big boys-iron and steel, coal, and petroleum-indicated the industry-wide trend by surpassing 1947 production figures. Although exploration and expansion are being pushed aggressively in all branches of the industry, there is a pronounced trend to engineering and research directed at cutting production costs, improving the product, and finding new markets. These improvement campaigns are making headway; in the bituminous coal industry, 5.43 tons per man employed is the new production record; 83 million tons of iron ore were unloaded at lower Lake ports, breaking another peacetime record; magnesium, due to improvement in manufacturing techniques, now competes on the market with aluminum.

Jan 1, 1949

By J. J. Thomas

THIS investigation was undertaken to determine, if possible, the relation between static and dynamic tensile tests as measured by the work required to break test specimens slowly, in a tensile testing machine, and rapidly, by means of a falling weight. It was hoped that the investigation would throw some light on the role played by ductility under different rates of application of load. FIG. 1.-STRESS-STRAIN DIAGRAM. In problems of design, it is usually assumed that the moduli of elasticity of all steels are equal; viz., about 30,000,000. The stress-strain diagram within the elastic limit is a straight line, as shown in Fig. 1, where OA is the curve of a hard steel and OB that of a soft steel. If the modulus of elasticity is constant, as assumed, the slope of the line OC

Jan 2, 1921

By John V. Beall

It is difficult to understand why they did it. It was a demonstration of total commitment which sent chills of mixed admiration and fear up and down your spine. The scene was the bodega in Section A, 2660 Level on the 12 to 8 shift. The jefe was patiently waiting for the tea leaves to settle in a large metal cup. His attention was distracted by the appearance of a miner who had a problem. The long and short of it was that the miner believed the branch raise he was driving was unsafe and he wanted the jefe to come and see it. After lunch the jefe went around. First cautiously shining his light to peer up the raise from outside the chute, he then scrambled inside and swiftly climbed the cribs to the face. No question, it was hairy; about 4 crib sets were needed to catch up to the face. The unsupported raise was slabbing. It didn't take the jefe more than a few seconds to ascertain this situation and to slide back down. As he came out of the chute, a small avalanche arrived on his heels and provided a sort of exclamation point to his order; "cerrado!" In other words, shut 'er down.

Jan 1, 1970

By R. L. Watts

Successful mining of taconite has required the solution of a series of difficult problems, including more efficient magnetic separation. Progress in this field is evidenced by reductions in operating and capital costs made possible by the advances in permanent magnetic materials and in new circuits for better utilization of these materials. The advent of the flux control circuit appears to be one of the more important breakthroughs in permanent magnet drum design circuitry and has contributed greatly to the economics and metallurgical requirements of the modern day taconite concentrators. High strength permanent magnetic separators are now replacing electro types in many applications requiring field strengths of 900 - 1000 gauss measured at 2 in. This is made possible by the new circuits having gauss readings at 2 in. previously attained only by electromagnets.

Jan 12, 1967

Pursuant to notice duly given in accordance with law and the constitution, a special business meeting of the members of the Institute was held at the office of the Institute on June 27, 1919, at 8.30 P.M., 1573 members were present in person or by proxy. On resolution duly made and seconded, the change of name to American Institute of Mining and Metallurgical Engineers, Incorporated, was authorized and the officers of the corporation were instructed to take the necessary steps to accomplish this result. The votes were 1565 in favor of the resolution and 7 against. It was then moved and seconded that the certificate of incorporation be amended to define the purposes for which the corporation was formed as follows: "To promote the arts and sciences connected with the economic production of the useful minerals and metals, and the welfare of those employed in the industries by all lawful means, " etc., etc.-the remainder of the article reading the same. The purpose of this change was to allow the Institute to take any legal means it desires to accomplish the objects mentioned above instead of restricting it within narrow limits. The vote was 1573 in favor of the resolution and none against.

Jan 8, 1919

By R. S. Shoemaker, F. W. McQuiston

EMPEROR GOLD MINES Vatukoula, Fiji 1974 Operating Data to July 1 ORE DESCRIPTION: Ore bodies occur in basalt and associated ash beds overlain by andesite tuffs and sediments. The basalt in much of the ore mined is weathered with alteration of olivine to serpentine and iron oxides, and augite to chorite. The most important host minerals for gold are the tellurides sylvanite and hessite. Next in importance the sulphide s, pyrite, marcasite and arseno-pyrite. A small amount of free gold also occurs. Chalcopyrite, sphalerite, tetrahedrite, bornite, galena and native tellurium are present in small quantities. TYPE OF MINE: Underground and open pit ORE HAULAGE TO MILL: 3.5 ton bottom dump skips from underground. 7 ton trucks from open pit. CAPACITY IN TONS/24 HRS: 1345 short tons ASSAY HEADS (1973): 0.232 oz Au per ton, 0.357 oz Te per ton PRODUCTS: Gold Bullion (400 oz bars) Metallic Tellurium (1 2 lb bars ) RECOVERIES: AU 86.2% Te 88.0% ORE GRINDABILITY: 9.25 Kwh/T TOTAL POWER: 25.7 Kwh/T WATER: Pumped 112 mile to a 318, 000 gallon head tank. Consumption: 2 140 gal per ton, no reclaimed water used. TAILINGS: Pumped 2 /3 mile through 8" pipe. Uphill sections are steel. Downhill sections are fibro asbestos.

Jan 1, 1975

By Thomas Read

AMONG the large number of deep mines in the world there are several which do not differ much in depth. The St. John del Rey mine, in Brazil, has reached a vertical depth of 6726 ft. below the top of its shaft; miners enter it, however, through an adit which intersects the shaft 324 ft. below its top, wherefore it might be said that the mine is really only 6400 ft. deep. In the Kolar gold field of India there are a number of deep shafts, one of which reaches to a vertical depth of 6140 ft. below surface. In South Africa also there are a number of deep shafts, the Village Deep being 6100 ft. early in 1921. The City Deep, Ltd., proposes to sink to a depth of 7000 ft. but pre-sumably by the time it does so the St. John del Rey will be deeper than that, since it has been increasing in depth at an average rate of about 150 ft. per year. The deepest shaft in the United States, the Tamarack No. 5, although it is only 5308 ft. deep, actually approaches nearer to the center of the earth (4100 ft. below sea level, as against 3958 ft. , at St. John del Rey). The deepest workings in the Calumet & Hecla go down to 4600 ft. below sea level. The St. John del Rey is not only the deepest, mine in the world, but it also is worked by the oldest registered English mining company, which was organ-ized in 1830 to work a mine at a considerable dis-tance from this one. That mine proved unprofitable, and in 1837 operations were transferred to the. deposit now under discussion, where operations have been prac-tically continuous ever since.

Jan 6, 1923

By C. C. Hatch, C. R. Larsen, A. L. Mular

INTRODUCTION As part of a general project to simulate a concentrator, the Brenda Mines Limited secondary crushing plant, located near Peachland, B. C., was sampled during the summer/winter of 1975 and during the summer of 1978 to develop a digital crushing plant simulator specific to the Brenda operation. The purpose of this simulator was to study the influence of manipulable process variables on important responses, to permit study of alternative circuit configurations if desired and to perform off-line optimization. This chapter describes the methodology employed to develop the simulator (1,2) along with typical applications thereof. SECONDARY CRUSHING PLANT FLOWSHEET Figure 1 is a schematic diagram of the Brenda Mines Ltd. secondary crushing plant circuit. The 41,000 tonne coarse ore stockpile(a) is -17.8 cm oversize (3B belt) from two 2.4 m x 6.1 m double deck vibrating screens (not shown). The screens are fed by 2 conveyor belts operated in series with two 198 cm apron feeders that handle discharge from a 152 cm x 226 cm primary gyratory crusher(520 KW). The primary crusher (not shown) treats up to 2725 tonne/hr of run of mine ore. Minus 1.9 cm undersize from the primary screens (#19 belt), referred to as the primary fines, joins secondary screen undersize (#18 belt) for conveyance to fine ore bins (not shown). Feed from the coarse ore stockpile is transferred by means of vibrating feeders and two 120 cm conveyors (#6 and #7) to transfer belts #8 and #9 (Figure 1). The belts feed two secondary 2.1 m standard heavy duty cone crushers (bl and b2). Each crusher is equipped with a modified coarse mantle liner and a standard coarse bowl liner. Mantle throw is 9.2 cm; nominal close side set is 3.2 cm. Crusher .countershafts (443 rpm) are driven by single 260 KW synchronous motors (710 rpm). Discharge from the secondary cone crushers joins discharge from four 2.1 m tertiary heavy duty shorthead cone crushers (fl, f2, f3 and f4). With the exception of the cavity (modified medium mantle liner and standard coarse bowl liner; close side set is nominal .84 cm) and motor (224 KW), these machines are similar to the secondary crushers. The combined discharge is transferred from a 183 cm conveyor to #14 belt which empties into a 1452 tonne secondary screen surge bin (c). Vibrating feeders beneath the bins feed five 2.4 m x 6.1 m double deck vibrating screens (dl, d2, d3, d4 and d5) sloped at 200 from the horizontal. The upper decks are punched plates with 2.7 cm x 7.6 cm slots. Lower decks are woven wire (1.27 cm diameter) sections with

Jan 1, 1982

By Ernest Stütz

(New York Meeting, October, 1918.) THE problem of increasing blast: furnace efficiency through diminution of flue-dust production while operating with burdens consisting largely of fine ores has of recent years attracted the attention of metallurgists, whether directly or indirectly interested in the economies of iron smelting, and the various methods evolved from theory or practice have been submitted to wide discussion. After the very thorough and, at that time, exhaustive view of the whole subject, which was afforded to the industry by the meeting of this Institute in February, 1912, the subject was again taken up at the meeting of the Verein deutscher Eisenhüttenleute at Diisseldorf in December, 1912. While American and German conditions are not entirely identical, it may be of interest to give here the words of the gentleman summing up the discussion at the Diisseldorf meeting: ' The chief advantage offered by the use of briquettes lies in the fact that disturbances in the furnace, caused mostly by the presence of fine ores in the burden, are avoided, and that blast pressure can be considerably reduced. The resulting economies cannot be overrated, as, with lower blast consumption per ton of product, the installation will be able to take care of increased production. In consequence of lower pressure and speed of blast, heat is more efficiently utilized, flue gas temperature is lowered, and coke particles are less liable to be carried along with the flue dust, of which considerably less is produced. Finally, by increased regularity of operation and higher . temperature in the lower parts of the furnace, the quality of the product is improved. The question of briquetting iron ores has grown to be one of the most important in the iron industry, and, it is not any more a question of what is the cost of briquetting ton of ore, but what, in using ore briquettes, is the cost of production of a ton of iron.'

Jan 7, 1913

By Carl Thieme

INDUSTRIAL specialization has rapidly created a demand for new and better alloys. A more thorough understanding of the requirements of specific industries and the discovery of processes by which it has been made possible to utilize certain metallic elements in larger quantities, together with greater purity in most virgin metals, has resulted in a great increase in the number and variety of alloys. This increase in the number of elements entering into non-ferrous alloy manufacture has increased the contamination in secondary metals, as received by the smelter. In order to successfully refine scrap of a much more complex nature it has been necessary for the smelter to install new equipment and to constantly search for new methods of refining as well as to improve the methods already in use. In some instances it is largely responsible for specialization in the secondary metal industry. It is usually necessary to remove the contaminating impurities in scrap or eliminate to a degree not objectionable, no matter how introduced. In order to know what metals or elements are of an objectionable nature, the smelter must make a study of the effect of single elements and combinations of elements on many of the physical and mechanical properties, such as strength, ductility, color, hardness, casting soundness, etc. The smelter of secondary metals must be able to utilize scrap materials of all kinds, for, sooner or later, most fabricated metal parts and the waste products formed during the process of manufacture find their way to the smelter. In addition, the smelter, in contracting for salvaged material from the producer, gets some undesirable and unusual materials. The value of secondary metals and the importance of their recovery has increased in recent years and it is no longer sufficient to recover the base metal only, such as copper from copper-bearing material, but it is essential that other elements present be recovered and converted into useful form.

Jan 1, 1928

[PRESIDENT E. DEGOLYER, District 0 NEW YORK, N. Y. PAST PRESIDENTS J. V. W. REYNDERS, District 0 . NEW YORK, N. Y. SAMUEL A. TAYLOR, District 3 PITTSBURGH, PA. FIRST VICE-PRESIDENT GEORGE OTIS SMITH, District 4 .WASHINGTON, D. C.]

Jan 1, 1928

By W. J. Helfrich, R. A. Dodd

Binary aluminum solid-solution alloys containing various amounts of silver, magnesium, and zinc were prepared by careful directional solidification, and the hydrostatic and X-ray densities were compared. With the exception of the Al(Ag) alloys, the X-ray densities were consistently greater than the hydrostatic measurements, in agreement with earlier observations by Ellwood. In contrast to Ell-wood's interpretation in terms of vacant lattice sites associated with Brillouin zone effects, a tentative explanation based on the existence of solidification microshrinkage was favored. This hypothesis was confirmed by an examination of Al(Zn) alloys prepared by vapor diffusion of zinc into aluminum. The hydrostatic and X-ray densities were now in very close agreement, and it was concluded that the filling of Brillouin zones in aluminum solid-solution alloys does not necessarily result in the formation of defect structures containing an excess of vacant lattice sites. ThE existence of defect structures of the vacancy type in alloys in which the excess vacancies have an electronic rather than a thermal or mechanical, and so forth, origin is well recognized. Examples of incomplete lattices of this type are to be found in the Ni-Al,1-3 Fe-Ni-A1,4 c~-Ni-Al,5 Fe-Cu-Al,= and Co-A17 systems. These defect structures are of a special kind in that the intermediate phases possess an ordered atomic arrangement or superlattice, and in some instances the vacancy concentration may be unusually large, e.g., at 45.25 at. pet Ni in NiA1, approximately 8.8 pet of the lattice sites are unoccupied. Ellwood8-10 has reported similar defect structures in the aluminum solid solution alloys of the Al-Zn and A1-Mg systems and in alloys of the Au-Ni system." In Al(Zn) the (apparent) vacancy concentration rose, somewhat irregularly, to a maximum of about 2 pet vacant sites at 25 at. pet Zn, while in Al(Mg) the (apparent) vacancy concentration increased continuously to 1.7 pet at 15 at. pet Mg. An explanation in terms of Brillouin zone overlap was attempted, although Pearson12 has pointed out the difficulty of reconciling the observations with zone theory. However, the possibility of the effect being caused by the Fermi surface just touching a plane of energy discontinuity inside a prominent Brillouin zone has, in general, been accepted. In fact, Massal-ski13 has interpreted Ellwood's8 observations as confirmation of Leigh's14 theoretically predicted zone overlap occurring at approximately 2.67 electrons per atom. Unfortunately, Massalski was apparently unaware that Ellwood9 had revised his earlier results considerably, and the revised data did not confirm Leigh's analysis. Ellwood's clata were reexamined by the present authors who noted a possible correlation between the percentage defects as a function of alloy composition and the temperature interval of solidification measured from the respective equilibrium diagrams. This suggested an explanation in terms of shrinkage porosity rather than vacant lattice sites, and pointed to the desirability of reexamining appropriate alloy systems using: both Ellwood's method of specimen preparation (casting followed by wrought fabrication) and alternativ'e methods, i.e., diffusion, which might be expected to minimize, or even completely obviate, microporosity. ALLOY PREPARATION 1) Cast Allolys and Aluminum Single Crystals. Al(Ag), Al(Mg;l, and Al(Zn) alloys of various compositions up to 20 at. pet silver, 13.5 at. pet mg, and 30 at. pet Zn were prepared by melting under helium and casting into graphite molds. In the first two systems, the maximum alloying addition was quite close to the limit of solid solubility, but the possibility of transformation to a' during quenching somewhat restricted the suitable Al(Zn) composition range. The alloys were prepared from high-purity aluminum, a lot analysis showing 0.002 wt pet Cu, 0.002 wt pet Fe, and 99.996 wt pet A1 by difference. The silver, magnesium, and zinc were of 99.99+, 99.98+, and 99.998 wt pet respectively. Each composition was analyzed chemically. The as-cast ingots measured 7/16 in. diam and 5 in. length. One in. was removed from the top of the ingot, and the bottom 3 in. was machined to 0.275 in. diam; a point was also machined on the smaller diameter end. The remainder of the original ingot served as a top riser during subsequent remelting and controlled solidification. The machined ingots were now remelted using a Bridgman soft-mold technique to ensure directional solidification and, therefore, a minimum of micro-shrinkage. Alumina powder was used as mold material contained in an alundum thimble, and this crucible was placed in a helium-filled Vycor tube. The assembly was lowered through a suitable temperature gradient at approximately 0.5 in. min-l, and the risered portion of the casting was subsequently removed by sawing.

Jan 1, 1962

By E. G. De Coriolis

The development of huge production facilities and of new or improved processes for manufacturing magnesium from its raw sources has been an outstanding achievement of this war. Furthermore, at least one new method has reached a stage of pilot production that offers promise. Its potentialities seem to indicate that a reduction in cost and simplification or elimination of problems incident to the use of at least one of the present processes are quite within the realm of possibility. Although magnesium of very high purity (99.9 per cent and higher) is obtained, and the rate of recovery reasonable (60 to 70 per cent). the ferrosilicon reduction process is open to a serious objection, which at the time its use was proposed was thought to be sufficient to raise some doubts as to its success, at least on a high production basis. The temperature range at which the reaction is carried out—namely, 2100" to 2150°F.—is very close to the failure temperature of the material of which the retort is made. It is so close that for a time it was assumed it might make commercial use of the process an impossibility. However, at the time under discussion, the demand for magnesium was so great that it was felt by those who had to go ahead and produce this essential metal that the emergency warranted their taking a chance on this process. Subsequent developments have fully justified the soundness of their decision. Fortunately for the war effort, when the plants were put into operation it was discovered that although the retorts did collapse in rather short periods of time, as predicted, they could be blown back into operable shape by application of high-pressure air. This practical method of operation so relieved the situation that the problem disappeared. Nevertheless, if the process had not been successful, or the production of magnesium by the electrolytic process had not been able to keep pace with demands, our war program would have been seriously impaired. Fireless Cooker'' Process For this reason a program was set up and assigned for the development of a new method that had been suggested to the War Production Board in 1941. It is believed justifiable in terming the method "new" for several reasons: (I) while utilizing the same (ferrosilicon) process as the Pidgeon, hence involving similar reactions, the type of retort or furnace is essentially different, (2) the method of operation, reaction temperatures, etc., differ materially, and, most important of all, (3) the problems to be overcome in making the process successful were not and could not have been anticipated by anything previously known about the Pidgcon process. As will be shown later, the briquetting process, the condenser, the furnace lining

Jan 1, 1949

By Clinton L. Miller

MINING operations have been carried on in the immediate area of the Elizabeth mine during periods of high copper prices since 1793, when copperas and vermillion were first won from the outcrop. Present operations started in 1942 as a war baby. Since then production has totaled 1.7 million tons of 1.8 pct Cu ore. Elizabeth mining operations are on a pyrrhotite- chalcopyrite orebody contained in a gently plunging amphibolite syncline. The oreshoot varies in width from 10 to 40 ft, and in the area under consideration is about 150 ft in vertical extent, and more than 1000 ft long. Surface pits or cuts have been worked in three areas along the outcrop, with one pit just completed and a second in full production. Present production is 24,000 tons per month, of which 6000 to 7000 tons is trucked from the open pit.

Jan 11, 1954

By J. B. Mudd

Introduction It is difficult to think of any activity on which mankind has been more dependent than mining, and certainly there is much evidence in almost every part of the world of old workings that clearly demonstrate that man from earliest times has dug and toiled to take from the earth precious stones, metals and materials that from time to time have been essential or of value to him. In step with social development and industrial and technological advances the tempo of mining activity, regulated only by the laws of supply and demand, has quickened and in this century has accelerated rapidly in keeping with its dramatic development. Indeed, the rate of change of events has been such that if it were to continue to accelerate as fast as it has over the past decade there is reason to wonder how the insatiable demands for metals and minerals are to be met in the years that lie ahead. Shallow mines containing high-grade ore deposits either have been or are being rapidly mined out and their place can only be taken in general by ore lying at greater depth, or by ore of low grade, situated for the most part in remote and in underdeveloped areas. The cost of exploration and development is rising at an alarming rate, with the result that the expenditure now required to bring a mine to production far exceeds anything previously contemplated. It is estimated that the total capital required to maintain existing operations and develop new ones during the next 5 years will be of the order of $50,000 million and of this, new capital to bring new mines to production will be of the order of $3,000 million. Today no single mining finance company can, from its own resources, find all the money for a major mining development, and as a consequence there has been a strong trend toward joint ventures and to the formation of multinational consortiums. International lending institutions already play an important part in financing many new mining projects and their participation provides the financial umbrella under which other lenders can invest with greater security. There is little doubt that to finance the costly ventures in the future, governments and international lending agencies, banks and finance

Jan 1, 1971

By J. R. Low, M. Gensamer, W. T. Lankford

THE problem of sheet metal formability is one which has received a vast amount of attention during recent years. In spite of the great amount of study and experimental work which has been devoted to this problem, many of its fundamental aspects are still not well understood. No generally satisfactory test has been developed which is capable of providing a reasonably adequate evaluation of sheet metal formability, particularly in borderline cases. Anomalies persistently arise in which a lot of supposedly satisfactory material exhibits excessive breakage when formed. This lack of suitable technological tests greatly hinders the design of new parts and the substitution of new materials in parts of existing design, frequently necessitating considerable costly trial and error experimentation on an actual production basis. When, at the beginning of World War II, it became apparent that mass production methods of forming would be required in the aircraft industry if the large numbers of military aircraft needed were to be supplied, renewed attention was focussed on the problem of sheet metal formability. It was widely recognized that the formability requirements placed on sheet metals had been steadily increasing in severity through the years, especially as greater and greater emphasis was placed on streamlined designs with the resultant freer application of doubly curved surfaces. The recent advent of several new high strength aluminum alloys of more limited formability than some of the older alloys also served to emphasize the need for new approaches to the problem. It seemed evident that progress in the technology of sheet metal forming would depend to a great extent on the development of more reliable criteria for the evaluation of formability. Although the problem is admittedly very complex, the most logical approach appeared to be through studies of the fundamental material properties of sheet metals, especially under complex stress conditions simulating those prevailing in actual forming operations. Most previous investigations have failed to make full use of existing knowledge of fundamental material properties, and in many instances have attempted correlations with properties which are now recognized as being ambiguous in nature. This investigation was undertaken, therefore, with the aim of developing methods for the study of the flow and fracture of sheet metals under combined stresses, and of making use of such methods as might be developed in

Jan 1, 1947