Abstract
Based on the theory of Reissner’s sandwich structure bending, a mechanical model of bending stiffness degradation for a soft-honeycomb sandwich structure under continuous wave (CW) laser heating was established by introducing the equivalent debonding coefficient of adhesive and elastic modulus temperature dependence of panels. To verify the rationality of the mechanical model, a real-time bending stiffness measurement system for a soft-honeycomb sandwich structure under CW laser heating was proposed using the overhanging beam three-point bending method. The results show that the mechanical model works good to describe the decreasing trend of the soft-honeycomb sandwich structure under CW laser heating and to predict the residual bending stiffness after CW laser heating, despite the fact that in the early stage of CW laser heating, the bending stiffness of some kind of soft-honeycomb sandwich structure may increase for a short time due to the pyrolysis gas production. However, with the overflowing of pyrolysis gas and the elastic modulus of panel degradation at a high temperature, the bending stiffness of soft-honeycomb sandwich structure declines rapidly and soon fails to withstand any bending load. The research shows that special attention should be paid to the effect of laser heating on the mechanical properties of the soft-honeycomb sandwich structure. It also enlightens the study of mechanical properties and temperature dependence of the honeycomb sandwich structure at a high heating rate.
Highlights
Since the mismatch between the mechanical model results and the experimental results affects the judgment of the rationality of the mechanical model, this part focuses on the bending stiffness enhancement in the initial stage of continuous wave (CW) laser irradiation
The bending stiffness degradation of a softhoneycomb sandwich structure under CW laser heating is studied, and the main conclusions are as follows: (1) Based on the basic assumptions of Reissner’s sandwich structure bending theory, the elastic modulus temperature dependence of the panel and the adhesive debonding coefficient were introduced to build up a mechanical model, which can be used to describe the attenuation trend of bending stiffness under CW laser heating and to predict the residual bending stiffness after laser heating
(2) A real-time bending stiffness measuring system for the softhoneycomb sandwich structure under CW laser heating was established based on the overhanging beam three-point bending method
Summary
Composite materials of this structure have lots of special characteristics, including high specific strength and high specific stiffness.. Since the honeycomb sandwich structure often bears bending moment in engineering applications, many researchers have studied the mechanical properties of this composite material under different conditions.. Since the honeycomb sandwich structure often bears bending moment in engineering applications, many researchers have studied the mechanical properties of this composite material under different conditions.7–12 Since this material is usually used in elevated temperatures, the bending stiffness temperature dependence of this material has been investigated with the three-point bending method in a heating furnace.. Theoretical mechanical model on the basis of experimental research and to predict the residual bending stiffness of the soft-honeycomb sandwich structure after laser heating
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