Mechanical Engineering ETDs

Publication Date

Fall 11-9-2016

Abstract

This thesis presents the development of non-destructive characterization of functional material properties of additively manufactured metals. In particular, this study was focused on the common structural stainless steel alloy, 316L, utilizing a coupon designed specifically for simple modal analysis. Additive manufacturing (AM) has moved to the forefront of the manufacturing world, particularly in aerospace and defense segments because of the potential to produce multi-functional, highly optimized components. The ability to confidently qualify these complex, and thus expensive, components has been lagging behind the advancing technology. The adoption of traditional characterization techniques developed for wrought materials has been most common, and much useful data can be extracted from these methods, but many of these tests are destructive in nature and thus are performed on representative samples. By taking advantage of the Modal Frequency Technique (MFT), the functional bulk properties of an as-printed component can be accurately characterized and the anisotropies inherent to AM can be quantified. Tests were performed using laser Doppler vibrometry and coupled with finite element analysis to show the ability to determine the functional Young’s modulus of AM coupons. These tests also identified a dependence of this bulk Young’s modulus on both the print orientation and the feature thickness. Modal frequencies were determined across a range of material parameters and experimental data was aligned with these values to determine the resultant Young’s modulus for a suite of coupon dimensions printed in to traditional orientations using powder bed direct metal laser sintering (DMLS).

Keywords

Additive Manufacturing, Advanced Manufacturing, Non-Destructive Evaluation, Modal Frequency, Young's Modulus, Material Properties

Degree Name

Mechanical Engineering

Level of Degree

Masters

Department Name

Mechanical Engineering

First Committee Member (Chair)

Yu-Lin Shen

Second Committee Member

John J. Russell

Third Committee Member

Nicholas Leathe

Sponsors

Sandia National Laboratories

Document Type

Thesis

Language

English

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