Research On Compression And Temperature Control Performance Of Thermal Storage Composite Structure

With the increasing integration of electronic devices in spacecraft,the heat flux density generated by these devices is also increasing.The high heat flux density on electronic devices can be mitigate by using structures with thermal storage and temperature control capabilities.In addition,satellites and other spacecraft have strict requirements for the structure’s volume and weight,so there is a more urgent need for lightweight,multifunctional structures with high load-bearing,high thermal conductivity,and excellent thermal storage performance.In order to develop a lightweight sandwich structure with excellent mechanical and thermal properties,this paper carried out the the research work of structural design,fabrication method,mechanical and thermal performance characterization and evaluation of the load-bearing,thermal storage,and temperature control multifunctional structure.This paper designs and fabricates a multifunctional carbon fiber curved honeycomb structure based on material hybrid design concepts.The structure is prepared by molding process and has excellent compression and thermal conductivity performance.For studying the effect of the addition of graphite film on compression performance,theoretical prediction,simulation analysis,and experimental verification are combined to study the compression performance of the structure.Then,a one-dimensional steady-state heat conduction theoretical model is established.And a three-dimensional surface plot of the thermal conductivity performance of the structure is drawn,which is used for investigating the effect of the panel thermal conductivity coefficient,interface thermal resistance,and graphite film content on the thermal conductivity of the structure.The results show that connecting the panel and the core through co-curing process can significantly reduce the interfacial thermal resistance of the structure,and the addition of graphite film significantly improves the thermal conductivity performance of the structure.In addition,to better characterize the heat dissipation performance of the structure,two working conditions were designed to study the temperature response of the structure under point heat source and surface heat source.The study shows that the heat dissipation capacity of the structure can be enhanced only by simultaneously improving the inplane and out-of-plane thermal conductivity performance,when the structure suffers different heat sources.For solving this problem,a lightweight and temperature control multifunctional composite material structure is designed and fabricated using hybrid material design concepts that make full use of the physical properties of carbon fiber composite materials,copper foam,and noctadecane phase-change materials.Based on the Winkler elastic foundation theory,theoretical models of the structure is derived for making compressive strength prediction,and a threedimensional failure mechanism diagram is drawn after experimental and simulation validation.The effect of parameters such as copper foam modulus,copper foam thickness,and carbon fiber composite material plate thickness on the failure mode of the structure is analyzed.The results show that the main failure modes of the structure are buckling failure and crushing failure.The buckling failure is mainly due to the small thickness of the carbon fiber plate,which results in a lower compressive specific strength.To improve the compressive specific strength,highstiffness PMI foam is added to the structure,and a carbon fiber/copper foam/PMI foam sandwich structure is fabricated.The specific strength of the structure is significantly improved,and the failure mechanism map under compression is drawn,showing the effect of PMI foam thickness on the failure mode of the structure.Finally,the temperature control capabilities of the structure are experimentally studied during heating and cooling processes.A method for evaluating the energy storage efficiency of temperature control structures is proposed by defining effective specific energy and specific power.This method was used to better evaluate the thermal storage and temperature control efficiency of the temperature control structure,and thermal rate capability and Ragone plots are drawn to more accurately characterize the thermal storage and temperature control ability of a carbon fiber/copper foam sandwich structure(TMCSS).The results showed that higher thermal loads weakened the thermal storage efficiency of the structure,reduced the utilization rate of phase change materials,and decreased the effective specific energy of the structure.The influence of the main parameters,such as thermal load,thermal conductivity of phase change material,melting point of phase change material,thicknesses of carbon fiber composite plate and copper foam,on the thermal storage and temperature control ability of the structure is analyzed through the above two figures.Subsequently,in order to carry out the integrated design of structural temperature control and load-bearing,a specific strength-specific energy curve was drawn to study the relationship between compression and thermal storage and temperature control ability efficiency.Afterwards,the effects of more structural parameters on the efficiency of thermal storage and temperature control and load-bearing capacity are studied using Ragone/strength diagrams,providing reference for the multifunctional integrated design of lightweight loadbearing and thermal storage and temperature control structures.Finally,a multifunctional composite sandwich structure with high load-bearing,high thermal conductivity,and thermal energy storage and temperature control capabilities was designed by utilizing the advantages of carbon fiber composites,graphite films,PMI foam,and copper foam/paraffin composite phase change materials.The mechanical properties of the lightweight multifunctional structure were studied through a combination of simulation and experiment,and the results indicate that when the thickness of carbon fiber fins in the structure is small,the failure mode is mixed failure.As the thickness increases,the failure mode of the structure changes from mixed failure to crushing failure.It was found that the addition of graphite films did not significantly reduce the mechanical properties of the structure.Through analysis of the thermal rate capability plot,phase change material state diagram,and temperature distribution diagram of the structure under different thermal loads,it was found that the graphite films significantly strengthened the thermal management capabilities of the structure.