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Abstract

Two new machines for the testing of metals to fracture under repeated dynamic loading in both tension and torsion are described. These machines are of the ‘falling weight’ type, the yield stress (or yield torque) being measured electronically and the total extension (or total twist) during a particular loading cycle being limited to any desired value.

A preliminary series of tests in both dynamic tension and dynamic torsion, using solid cylindrical bar specimens of 3/8 inch diameter, was carried out on a medium-carbon steel, a mild steel, a silico-manganese spring steel, and two aluminium alloys. For tension, the average time from zero stress to the dynamic yield stress was in the range 0·18-1·00 milliseconds and, for torsion, 0·65-2·67 milliseconds from zero torque to the dynamic yield torque.

In straining specimens to fracture under such repeated dynamic loading, the yield point was found to vary in a manner similar to that for static loading, though all dynamic yield points showed a progressive increase in value with reduction in loading time.

For equal loading times, a greater percentage increase in yield point value was noted for the medium-carbon steel and the mild steel under dynamic torsion as compared with dynamic tension, thus indicating a migration of the criterion of failure away from the Mises-Hencky theory towards the theory of maximum principal stress.

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References

Bonny

A. D.

1948 Trans. Inst. Naval Architects, Vol. 90, p. 229, ‘Effect of Non-contact Explosions on Warship Machinery Design’.

Brown

A. F. C.

Edmonds

1948 Proc. I. Mech. E., Vol. 159, p. 11, ‘Dynamic Yield Strength of Steel at an Intermediate Rate of Loading’.

Brown

A. F. C.

Vincent

N. D. G.

1941 Proc. I. Mech. E., Vol. 145, p. 126, ‘Relationship Between Stress and Strain in Tensile Impact Test’.

Calvert

N. G.

1955 Proc. I. Mech. E., Vol. 169, No. 44, ‘Impact Torsion Experiments’ and ‘Experiments on Effect of Rate of Testing on Criterion of Failure of Certain Mild Steels’.

Campbell

J. D.

1953 Acta Metallurgica, Vol. 1, p. 706, ‘Dynamic Yielding of Mild Steel’.

1954 Jl. Mech. and Physics of Solids, Vol. 3, p. 54, ‘Yield of Mild Steel under Impact Loading’.

Clark

D. S.

Dätwyler

1938 Proc. Am. Soc. Testing Materials, Vol. 38, Part 2, p. 98, ‘Stress-Strain Relations under Tension Impact Loading’.

Clark

D. S.

Wood

D. S.

1949 Proc. Am. Soc. Testing Materials, Vol. 49, p. 717, ‘Time Delay for Initiation of Plastic Deformation at Rapidly Applied Constant Stress’.

Gibson

1952–53 Proc. I. Mech. E., Vol. 1B, p. 536, ‘Behaviour of Metals under Tensile Loads of Short Duration’.

10.

Greene

O. V.

Stout

R. D.

1940 Trans. Am. Soc. Metals, Vol. 28, p. 277, ‘Stress-Strain Characteristics of Torsion Impact Test’.

11.

Hendrickson

J. A.

Wood

D. S.

Clark

D. S.

1954 Ninth Technical Report of California Inst. Technology, Pasadena, California (under American Office of Naval Research Contract N. Cont. 24418).

12.

Itihara

1933–36 Technical Reports of Tohoku Imperial University, Vol. 9, p. 16, vol. 11, p. 512, vol. 12, p. 105, ‘Impact Torsion Test’.

13.

Manjoine

M. J.

Nadai

1940 Proc. Am. Soc. Testing Materials, Vol. 40, p. 822, ‘High-speed Tension Tests at Elevated Temperatures, Part 1’.

14.

Mott

N. F.

Nabarro

F. R.

1940 Proc. Phys. Soc., Vol. 52, p. 86, ‘Attempt to Estimate Degree of Precipitation Hardening with Simple Model’.

15.

Nadai

Manjoine

M. J.

1941 Trans. A. S. M. E., Vol. 63, p. A77, ‘High-speed Tension Tests at Elevated Temperatures, Parts 2 and 3’.

16.

Taylor

G. I.

1934 Proc. Roy. Soc. A, Vol. 145, p. 362, ‘Mechanism of Plastic Deformation of Crystals’.

17.

Taylor

D. B. C.

1954 Jl. Mech. and Physics of Solids, Vol. 3, p. 38, ‘Dynamic Straining of Metals having Definite Yield Points’.

18.

Vreeland

Wood

D. S.

Clark

D. S.

1953 Trans. Am. Soc. Metals, Vol. 45, p. 620, ‘Study of Mechanism of Delayed Yield Phenomenon’.

19.

Warnock

F. V.

Brennan

J. B.

1948 Proc. I. Mech. E., Vol. 159, p. 1, ‘Tensile Yield Strength of Certain Steels under Suddenly Applied Loads’.

20.

Warnock

F. V.

Pope

J. A.

1947 Proc. I. Mech. E., Vol. 157, p. 33, ‘Change in Mechanical Properties of Mild Steel under Repeated Impact’.

21.

Warnock

F. V.

Taylor

D. B. C.

1949 Proc. I. Mech. E., Vol. 161, p. 165, ‘Yield Phenomena of a Medium Carbon Steel under Dynamic Loading’.

Tension and Torsion Properties of Some Metals under Repeated Dynamic Loading (Impact)

Abstract

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