Date of Award

Summer 2019

Document Type

Open Access Thesis

Department

Mechanical Engineering

First Advisor

Xinyu Huang

Abstract

The SiCf/SiCm composite material is a promising candidate for accident tolerant fuel cladding in light water reactors and for structural elements in high temperature reactors. The material demonstrates exceptional toughness when compared to monolithic ceramics. It is critical to characterize the mechanical behavior, internal damage and ultimate strength of these composites under relevant loading conditions. In this thesis, the author developed and improved several mechanical characterization and non-destructive evaluation methods and applied them to SiCf/SiCm composites. Impulse excitation (IE) analysis of damaged SiCf/SiCm composite disks following controlled impact testing shows a direct relationship between the damage applied to SiCf/SiCm composite disks and changes in the flexural and torsional resonant frequencies of the disks, as well as a proportional relationship between the change in frequencies and energy absorbed. An experimental exploration of the “size effect” of SiCf/SiCm composite tubes shows a relationship between the length of the material and its burst strength. Samples consistently showed a UTS increase of as much as 33% between samples of approximately 15cm lengths and those of 28cm lengths following repeated burst testing, though further testing is required to fully understand the reasons for this reduction. In the context of SiCf/SiCm composites, novel DIC setups are discussed which are improvements over traditional setups and have a higher capability of capturing the full field strain map of tubular objectives. First, a 3D DIC setup using one camera and mirror splitting is tested and compared with a traditional DIC two-camera setup, showing comparable results along with a host of extrinsic benefits. Lastly, the mirror splitting concept is taken a step further in an exploration that uses a six-mirror setup and telecentric lens to realize 360˚ surround views for the purpose of capturing the failure sites.

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