Philip Koshy

Flexural Strength of Ceramic and Glass Rods

Flexural testing is the most common method used to measure the uniaxial tensile strength of ceramics and glasses. Although standard test methods have been developed for rectangular specimens, cylindrical rod specimens may be preferred in many cases. This paper summarizes how rods have been tested in the past, identifies key experimental errors and remedies, and serves as the foundation for a new standard test method for ceramics and glasses.

A simple method for the estimation of laser absorptivity using heat-sensitive paints

The emergence of high-power diode laser technology has paved the way for the widespread integration of laser processing into metal-cutting machine tools. Such integration is of significant benefit not just in terms of better logistics and work flow but also enhanced process capability and flexibility, and part quality. This is particularly true in the batch manufacture of high-value components, wherein it is essential to employ mathematical models to formulate and optimize operating parameters. Consequently, there is an industrial need for a simple and inexpensive technique for the rapid estimation of the laser absorptivity of a surface, which is of critical influence in the effective practical application of process models. To this end, this design note proposes a method that involves an analytical model and a novel experimental technique based on temperature-indicating paints, for estimating the absorptivity of a surface.