Abstract

Aim: The article examines the issue of a stationary temperature field distribution for a multi-layered panel, in the presence of both dispersed and concentrated internal heat sources, taking into account imperfect heat transfer conditions between individual layers.

Introduction: Testing of temperature fields for multi-layered structures continues to be a target of interest for many studies, because structures of this type have many applications in the construction industry. High temperatures pose a threat of structural damage associated with the emergence of significant thermal stress during the heating process. It is commonly known, that the computation of this stress is only possible by solving appropriate heat conductivity equations. Many scientific papers are devoted to the determination of temperature fields in multi-layer structures. Majority of these studies do not take into account thermal sources or the application of coupled equation methods. When the number of layers becomes n> 3 the allotted time to, and volume of calculations increases dramatically. Moreover, a procedure for deriving the coefficient for partial-differential equations inevitably leads to the problem of multiplicity in generalised distributions. This study established that such a procedure is not necessary, and can be substituted by applying a quasi-derived concept.

Methodology: At the equation formulation stage, the coefficient of thermal conductivity and intensity of internal sources of heat were recorded as splains using characteristic functions of half-length intervals and inclusion of the intensity of concentrated sources is accomplished by using the Dirac δ-function, which is introduced on the right hand side of the corresponding quasi differential equation (QDE). To such an equation are added known stress conditions and starting position, and further augmented by discretionary two-point boundary conditions. Subsequently, with the aid of the quasi-derived concept, the described equation is linked with the Cauchy equation of equivalence for appropriate arrangement of differential equations concerning impulses.

Conclusions: The study identifies a solution to the equation dealing with the issue of a stationary temperature field distribution for a multi-layered panel, by taking account of dispersed as well as concentrated sources of heat produced in imperfect heat transfer conditions between layers. The paper articulates an example of temperature field calculations for an eight layered panel, which is exposed to different thermal influences between layers as well as simultaneous or non concurrent sources of dispersed and concentrated heat. Based on assumptions from physics, appropriate differential equations were identified for the Cartesian coordinate arrangements. However, the proposed method can be adopted, without difficulty, to similar exercises involving cylindrical or spherical coordinate arrangements.

Keywords: temperature, heat flux, quasi-derived, multi-layer panels, the Cauchy matrix, the Dirac delta function, differential equations concerning impulses

Type of article: original scientific article