Author ORCID Identifier

https://orcid.org/0009-0004-1669-3216

Date Available

7-20-2025

Year of Publication

2025

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Engineering

Department/School/Program

Mechanical Engineering

Faculty

Julius Schoop

Faculty

Jonathan Wenk

Abstract

Machining is by no means a new manufacturing process. However, it is separated from other traditional deformation processes by its extreme temperatures and strain rates. The function and life of a multitude of products and mechanical components are dependent on the material properties induced by changing the surface through machining. Furthermore, the tools used within machining are often expensive and material reserves are sparse. The understanding the mechanics of the machining process, especially related to the friction of the tool and workpiece, helps to further the life of tools and parts to minimize economic and environmental impact.

Current friction modeling primarily takes advantage of numerical models that use constitutive models based upon experiments, like Split-Hopkinson bar, that do not fully capture the strain hardening and thermal softening effects from the magnitude of strain in machining. Additionally, they are limited in their complexity due to becoming increasingly computationally expensive with considerations of tool wear, coatings, and fluid application.

The present study shows the relationship between pressure and velocity on friction in machining using open-tribometer experiments and a custom in-situ characterization test bed. High speed imaging along with digital image correlation (DIC) and particle image velocimetry (PIV) are used to correlate the velocity and deformation within the tool-chip interface to the friction measured in the open-tribometer experiments to build a variable friction model for Ti-6Al-4V. Strain rate measurements in a study of the development of built-up-edge in two similar 17-4 PH heat treatments highlights the need for consideration of microstructure in material selection.

It is found that friction and tool stress oscillate within a chip serration cycle leading to tool fracture and comparing modeled and measured feed forces proves the validity of the friction model and experimental technique.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.318

Funding Information

Lexington Herald Leader Fellowship, Spring 2022

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