Mechanical Engineering ETDs

Publication Date

6-26-2015

Abstract

Time dependent plastic deformation in metals can occur at high temperatures. Typically the creep test is conducted to characterize the deformation features; however, the conventional uniaxial power-law creep test may be impractical for small scale materials. Accordingly, instrumented indentation techniques are frequently employed. This study concerns the employment of instrumented indentation to characterize the power-law creep response of metallic materials. Indentation derived creep response using constant load-hold and constant indentation strain rate methods were investigated through systematic numerical finite element analysis of conical indentation. The model system of pure tin (Sn) and Sn-based alloy with known uniaxial power-law creep parameters is used for direct comparison between constant indentation strain rate and constant load-hold methods. It was found that each method accurately yielded the corresponding creep stress exponent (n); thus, leading to parallel lines of strain rate versus creep stress on the logarithmic scale. It is evident that the constant indentation strain rate method produced more uniform results. A parametric analysis taking into account a wide range of power-law parameters was conducted for the constant indentation strain rate method. A unique trend of strain rate ratio between the uniaxial creep test and indentation creep test was identified.

Keywords

Instrumented Indentation ; Indentation Derived Creep Response ; Constant Indentation Strain Rate Method ; Constant Load-Hold Method

Degree Name

Mechanical Engineering

Level of Degree

Masters

Department Name

Mechanical Engineering

First Advisor

Shen, Yu-Lin

First Committee Member (Chair)

Tehrani, Mehran

Second Committee Member

Tarefder, Rafiqul A.

Document Type

Thesis

Language

English

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