Young Stress Analyst Competition 2015 10 th International Conference on Experimental Mechanics

Competition overview: Entrants to the Young Stress Analyst (YSA) competition were invited to submit 1000 word summaries of their work. The submissions were reviewed by an expert panel and four finalists were selected and invited to attend the 10 th International Conference on Experimental Mechanics. The YSA 2015 finalists will present their papers in a plenary session on Wednesday 2 nd September 2015. The finalists will be giving 10 minute presentations on their work with a further 5 minutes for questions. A panel of judges will mark the presentations on technical content, quality of presentation and response to questions. All conference delegates are invited to attend these presentations and are welcome to ask questions. We look forwards to welcoming you all to this session. Introduction Boron carbide (B4C) is a lightweight ceramic with excellent mechanical properties and is an attractive material for structural applications where superior strength and lightweight are fundamental requirements, e.g., military armor. Reaction bonding is a promising alternative to traditional sintering of B4C, offering reduced processing temperatures and times and the ability to produce complex, near net-shape parts. In reaction bonding, a porous B4C powder-compact is infiltrated with molten silicon (Si). The reaction between Si and C in the compact forms silicon carbide (SiC), bonding the microstructure together. The final ceramic is composed of B4C, SiC, and Si. Thus, evaluating the presence and spatial distribution of residual microstresses originating from coefficient of thermal expansion (CTE) mismatch is crucial to understanding the mechanical properties and failure behavior of these composites. Because Si is the weakest mechanical constituent of the microstructure, it is the focus of this study. Residual stress determination within a material is crucial to the material design process. X-ray diffraction is a popular method for residual stress determination, but due to limited spatial resolution only bulk stress values can be determined. Raman spectroscopy possesses finer resolution and is used to determine the microscale distribution of residual stresses in electronics. In this method, characteristic vibrational frequencies of a material manifest as characteristic peaks in the Raman spectrum for a given (laser) excitation wavelength. When a crystal is deformed, the induced strain changes the equilibrium spacing and force constants 1 between atoms, shifting the characteristic Raman peaks which can be correlated with a tensile or compressive residual stress [1]. Aims The current study employs Raman spectroscopic mapping to assess the magnitude and spatial distribution of residual microstresses due …