Myron J. Maurer

Modeling the compressive fracture behavior of foams for energy absorption

Polymeric foams and foams in general have a wide variety of applications ranging from energy absorption, noise and vibration absorption, and thermal insulation. In some segments of transportation applications, foams are used specifically for energy absorption during a vehicle crash. These foams are designed for one-time use to protect vehicle occupants where recoverability of the foam is not prescribed. Recently, it has been identified that a ‘square-wave’ load versus displacement response is desired for these applications. Observations of foam crushing during compression have demonstrated the need for an appropriate phenomenological model for foam failure. Current foam—structure—property models do not go all the way to final failure and can predict the early stage of load—displacement relationship. But, in terms of energy absorption, the model which covers the extensive load—displacement relationship is very important. This article will detail the development of a structure—property model used throughout the development of a new family of lightweight, space efficient, energy absorbing foams.

Computational Fluid Dynamics Modeling of Latent Heat Discharge in a Macro-Encapsulated Phase Change Material Device

The reduction of greenhouse gas emissions is an important aspect of technology development across multiple industries, including transportation. One approach to reduce carbon dioxide and other emissions from an internal combustion engine involves elimination of the cold start condition, which is well established as a source of inefficiency. This paper will detail the development of a novel waste heat recirculation system devised to improve engine warm-up in a hybrid electric vehicle (HEV). A phase change material (PCM) is proposed as a thermal energy storage mechanism that makes use of the latent heat associated with crystal-melt transition. The waste heat carried by the exhaust gas may be captured and used to melt the PCM via direct or indirect contact. The stored energy is then contained in an insulated device and subsequently discharged to the cold engine via flowing coolant to mitigate the cold-start condition. For optimal thermal discharge, a series of transient two-dimensional computational fluid dynamics (CFD) simulations have been performed to model and optimize the macro-encapsulated device geometry. Experimental tests performed with a laboratory scale heat exchanger validate the predictive capability of the model.