News Column

Study Data from University Erlangen-Nurnberg Update Understanding of Computational Engineering

June 25, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- Current study results on Computational Engineering have been published. According to news reporting originating in Erlangen, Germany, by VerticalNews journalists, research stated, "The objective of this contribution is to develop a thermodynamically consistent theory for general imperfect interfaces and to establish a unified computational framework to model all classes of such interfaces using the finite element method. The interface is termed general imperfect in the sense that it allows for a jump of the temperature as well as for a jump of the normal heat flux across the interface."

The news reporters obtained a quote from the research from University Erlangen-Nurnberg, "Conventionally, imperfect interfaces with respect to their thermal behavior are restricted to being either highly-conducting (HC) or lowly-conducting (LC) also known as Kapitza. For a HC interface the temperature is continuous across the interface while the jump of the normal heat flux is admissible. On the contrary, a LC interface does not allow for a jump of the heat flux across the interface but it does allow for a temperature jump. The temperature jump of a LC interface is frequently assumed to be proportional to the average heat flux across the interface. In this contribution we prove that this common assumption is indeed an appropriate condition to (sufficiently and not necessarily) satisfy the second law of thermodynamics. While HC and LC interfaces are generally accepted and well established today, the general imperfect interfaces remain poorly understood. Here we propose a thermodynamically consistent theory of general imperfect interfaces and we show that the dissipative structure of the interface suggests firstly to classify such interfaces as semi-dissipative (SD) and fully-dissipative (FD). Secondly, for a FD interface the interface temperature shall be considered as an independent degree of freedom and a new (constitutive) equation is obtained to calculate the interface temperature using a new interface material parameter i.e. the sensitivity. Furthermore, we show how all types of interfaces are derived from a FD general imperfect interface model. This finding allows us to establish a unified finite element framework to model all classes of interfaces. Full details of the novel numerical scheme are provided. Key features of general imperfect interfaces are then elucidated via a series of three-dimensional numerical examples. In particular, we show that according to the second law the interface temperature may not necessarily be the average of (or even between) the temperatures across the interface."

According to the news reporters, the research concluded: "Finally, we recall since the influence of interfaces on the overall response of a body increases as the scale of the problem decreases, this contribution has certain applications to nano-composites."

For more information on this research see: General imperfect interfaces. Computer Methods in Applied Mechanics and Engineering, 2014;275():76-97. Computer Methods in Applied Mechanics and Engineering can be contacted at: Elsevier Science Sa, PO Box 564, 1001 Lausanne, Switzerland. (Elsevier - www.elsevier.com; Computer Methods in Applied Mechanics and Engineering - www.elsevier.com/wps/product/cws_home/505645)

Our news correspondents report that additional information may be obtained by contacting A. Javili, University of Erlangen Nurnberg, Chair Appl Mech, D-91058 Erlangen, Germany. Additional authors for this research include S. Kaessmair and P. Steinmann.

Keywords for this news article include: Europe, Germany, Erlangen, Computational Engineering

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Source: Journal of Engineering