### Abstract

A generalized threshold function for viscoplastic materials, which can also serve as a yield function in rate-independent plasticity, is suggested for materials that exhibit a strength differential and/or a permanent volume change. The motivation for this type of a threshold function is that experiments, at both 25 and 650°C, on the nickel-based alloy Inconel 718 indicate that higher stresses occur in compression than in tension. Similar results have been obtained for martensitic steels and other metallic alloys at 25°C. A general approach for determining the inelastic flow dependence on each of the three stress invariants (I_{1}, J_{2}, and J_{3}) is to follow stress paths where only one invariant is changing. Two classical experiments that do this are hydrostatic pressure and pure torsion, however many others are possible. Unfortunately, these stress paths generally require three-dimensional stress states, which are difficult to obtain in the laboratory. Thus, for experimental expediency, tests involving axial-torsional loading of thin-walled tubes can be used to determine the significance of the first and third stress invariants, I_{1} and J_{3}, respectively.

Original language | English (US) |
---|---|

Pages (from-to) | 321-326 |

Number of pages | 6 |

Journal | Journal of Engineering Materials and Technology, Transactions of the ASME |

Volume | 122 |

Issue number | 3 |

DOIs | |

State | Published - Jan 1 2000 |

### Fingerprint

### All Science Journal Classification (ASJC) codes

- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering

### Cite this

}

*Journal of Engineering Materials and Technology, Transactions of the ASME*, vol. 122, no. 3, pp. 321-326. https://doi.org/10.1115/1.482804

**Inelastic anisotropy of inconel 718 : Experiments and mathematical representation.** / Iyer, Saiganesh K.; Lissenden, III, Clifford Jesse.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Inelastic anisotropy of inconel 718

T2 - Experiments and mathematical representation

AU - Iyer, Saiganesh K.

AU - Lissenden, III, Clifford Jesse

PY - 2000/1/1

Y1 - 2000/1/1

N2 - A generalized threshold function for viscoplastic materials, which can also serve as a yield function in rate-independent plasticity, is suggested for materials that exhibit a strength differential and/or a permanent volume change. The motivation for this type of a threshold function is that experiments, at both 25 and 650°C, on the nickel-based alloy Inconel 718 indicate that higher stresses occur in compression than in tension. Similar results have been obtained for martensitic steels and other metallic alloys at 25°C. A general approach for determining the inelastic flow dependence on each of the three stress invariants (I1, J2, and J3) is to follow stress paths where only one invariant is changing. Two classical experiments that do this are hydrostatic pressure and pure torsion, however many others are possible. Unfortunately, these stress paths generally require three-dimensional stress states, which are difficult to obtain in the laboratory. Thus, for experimental expediency, tests involving axial-torsional loading of thin-walled tubes can be used to determine the significance of the first and third stress invariants, I1 and J3, respectively.

AB - A generalized threshold function for viscoplastic materials, which can also serve as a yield function in rate-independent plasticity, is suggested for materials that exhibit a strength differential and/or a permanent volume change. The motivation for this type of a threshold function is that experiments, at both 25 and 650°C, on the nickel-based alloy Inconel 718 indicate that higher stresses occur in compression than in tension. Similar results have been obtained for martensitic steels and other metallic alloys at 25°C. A general approach for determining the inelastic flow dependence on each of the three stress invariants (I1, J2, and J3) is to follow stress paths where only one invariant is changing. Two classical experiments that do this are hydrostatic pressure and pure torsion, however many others are possible. Unfortunately, these stress paths generally require three-dimensional stress states, which are difficult to obtain in the laboratory. Thus, for experimental expediency, tests involving axial-torsional loading of thin-walled tubes can be used to determine the significance of the first and third stress invariants, I1 and J3, respectively.

UR - http://www.scopus.com/inward/record.url?scp=0000910351&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000910351&partnerID=8YFLogxK

U2 - 10.1115/1.482804

DO - 10.1115/1.482804

M3 - Article

AN - SCOPUS:0000910351

VL - 122

SP - 321

EP - 326

JO - Journal of Engineering Materials and Technology, Transactions of the ASME

JF - Journal of Engineering Materials and Technology, Transactions of the ASME

SN - 0094-4289

IS - 3

ER -