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 Committee Member (Chair)

Tehrani, Mehran

Second Committee Member

Tarefder, Rafiqul A.

Document Type

Thesis

Language

English

Download

Share

COinS