THE FREELY EXPANDING RING TEST - A TEST TO DETERMINE MATERIAL STRENGTH AT HIGH STRAIN RATES

R. H. Warnes; R. R. Karpp; P. S. Follansbee

doi:10.1051/jphyscol:1985575

THE FREELY EXPANDING RING TEST - A TEST TO DETERMINE MATERIAL STRENGTH AT HIGH STRAIN RATES

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1985575 ◽

1985 ◽

Vol 46 (C5) ◽

pp. C5-583-C5-590 ◽

Cited By ~ 5

Author(s):

R. H. Warnes ◽

R. R. Karpp ◽

P. S. Follansbee

Keyword(s):

High Strain ◽

Ring Test ◽

Material Strength ◽

Strain Rates ◽

High Strain Rates

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The Freely Expanding Ring Test—A Test to Determine Material Strength at High Strain Rates

Journal of Engineering Materials and Technology ◽

10.1115/1.3225891 ◽

1986 ◽

Vol 108 (4) ◽

pp. 335-339 ◽

Cited By ~ 4

Author(s):

R. H. Warnes ◽

R. R. Karpp ◽

P. S. Follansbee

Keyword(s):

High Strain ◽

Time History ◽

Ring Test ◽

Test Material ◽

Material Strength ◽

Large Strains ◽

Strain Rates ◽

High Strain Rates ◽

Strain Behavior ◽

Thin Ring

The freely expanding ring test (ERT) is a conceptually simple test for determining the stress-strain behavior of materials at large strains and at high strain rates. This test is conducted by placing a thin ring of test material in a state of uniform radial expansion and then measuring its subsequent velocity-time history. The ring is usually propelled by a high explosive driving system. The test has not become popular in the materials property community, however, because there has been some concern about how the launching of the ring sample with an explosively generated shock wave might affect the properties to be measured. To determine the suitability of the ERT for these fundamental investigations, a series of experiments was performed on a carefully controlled material—oxygen-free electronic fully annealed copper. Recovered ring samples were analyzed and the change in hardness determined. Comparisons of the ERT data with that from Hopkinson bar tests at strain rates of about 5 × 103 s−1 indicate that the shock-induced hardness is approximately equivalent to a strain hardening of 5 percent. ERT data on this material at strain rates up to 2.3 × 104 s−1 are presented.

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A Computational Constitutive Model for Glass Subjected to Large Strains, High Strain Rates and High Pressures

Journal of Applied Mechanics ◽

10.1115/1.4004326 ◽

2011 ◽

Vol 78 (5) ◽

Cited By ~ 91

Author(s):

Timothy J. Holmquist ◽

Gordon R. Johnson

Keyword(s):

Constitutive Model ◽

Strain Rate ◽

High Pressures ◽

High Strain ◽

Material Strength ◽

Large Strains ◽

Single Element ◽

Strain Rates ◽

High Strain Rates ◽

Third Invariant

This article presents a computational constitutive model for glass subjected to large strains, high strain rates and high pressures. The model has similarities to a previously developed model for brittle materials by Johnson, Holmquist and Beissel (JHB model), but there are significant differences. This new glass model provides a material strength that is dependent on the location and/or condition of the material. Provisions are made for the strength to be dependent on whether it is in the interior, on the surface (different surface finishes can be accommodated), adjacent to failed material, or if it is failed. The intact and failed strengths are also dependent on the pressure and the strain rate. Thermal softening, damage softening, time-dependent softening, and the effect of the third invariant are also included. The shear modulus can be constant or variable. The pressure-volume relationship includes permanent densification and bulking. Damage is accumulated based on plastic strain, pressure and strain rate. Simple (single-element) examples are presented to illustrate the capabilities of the model. Computed results for more complex ballistic impact configurations are also presented and compared to experimental data.

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