Study on Thermal Response of Adhesively Bonded Honeycomb Sandwich Structure in High Temperature
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Study on Thermal Response of Adhesively Bonded Honeycomb Sandwich Structure in High Temperature Rongnan Yuan, Yi Zhang, Yiren Qin* and Shouxiang Lu, State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230027, China Received: 22 April 2020/Accepted: 12 August 2020
Abstract. Thermal response of the honeycomb sandwich structure was evaluated using the steady-state method at different temperatures ranging from 100°C to 400°C. The results showed that effective thermal conductivity decreases when the temperature set is over 300°C, and the critical temperature is about 310°C. As a result, a set of experiments was conducted to observe the inner structure of the sandwich in a quest to understand why the thermal conductivity decreases. A black substance was found, and it adhered to the interfaces between the faces and the core where the adhesive is located. A series of experiments were carried out to study the thermal response of the adhesive. The TG curves showed that the total mass loss of adhesive can reach 90% due to the thermal decomposition, which can absorb a portion of energy. Meanwhile, the black substance was also produced during the TG measurements and its carbon content reached 64.38%. Keywords: Thermal response, Effective thermal conductivity, Honeycomb sandwich structure, Adhesive, Thermal decomposition
1. Introduction Metallic honeycomb sandwich structures as layers in the fire barrier of high-speed trains have many advantages due to light-weight and heat-insulation properties compared with conventional materials of the same function [1, 2]. A primary issue of design, however, is the structural heat insulation at high temperatures [3–5]. Evaluating the thermal response of the structure is essential to support initial design efforts. Many researchers were devoted to studying the mechanical response of metallic honeycomb sandwich structure but seldom focused on the thermal response [6–8]. The thermal response of the structure has a huge effect on mechanical response, especially at high temperatures [9–13]. Some researchers have paid attention to the thermal conductivity of sandwich structures. However, there are some problems. For example, Swann and Pittman [14] used a finite-difference model to calculate * Correspondence should be addressed to: Shouxiang Lu, E-mail: [email protected]
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Fire Technology 2020 the temperature distributions and effective thermal conductivity for honeycombcore sandwich panels. An empirical equation was derived from the functions of the geometric parameters and material properties. Owing to the deficiency, the usual connection method between the core and faces was not considered. Caogen et al. [15] measured the thermal conductivity of a fabricated superalloy honeycomb TPS panel by transient method. The honeycomb core and the honeycomb sandwich were fabricated by brazing. To study the thermal behavior of honeycomb sandwich structure, Fatemi and Lemmen [16] used finite-element analysis and replaced the honeycomb-core sandwich panel with an equivalent lamin
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