Study On Quasi-static Indentation And Residual Compression Properties Of Zirconia Ceramic Sandwich Structures By 3D Printing

The 3D printed ceramic sandwich structure overcomes the disadvantages of the simple shape structure of traditional ceramic,and can maintain the characteristics of high reliability,corrosion resistance and wear resistance under high temperature conditions while ensuring lightweight.It is an important alternative material for the thermal protection structure of aerospace aircraft,and has a good application prospect.However,due to its brittle nature,during production and use,it is easy to be hit by some low-speed objects such as flying stones and birds,and these local loads will cause damage areas of the structure and lead to the decline of the bearing capacity.Therefore,it is of great engineering significance and value to study the influence of foreign objects injury.However,the damage assessment criteria for ceramic materials are very scarce.In this paper,based on ASTM D 6264-07 standard and combined with the application scenario of ceramic sandwich structure,the quasi-static indentation test and residual compression performance test for ceramic sandwich structure are designed and carried out.Since the damage state cannot be obtained at any time during a single loading process,it is necessary to explore the damage impedance of ceramic sandwich structures under quasi-static indentation together with the stepwise loading method.Firstly,the effects of single loading and step loading on the characteristic contact force of ceramic sandwich structures are compared.The results show that it is also feasible to study quasi-static indentation damage by step loading method.The quasi-static indentation load-displacement curve is obtained by a single loading method,which can roughly analyze the damage process of ceramic sandwich structures.The relationship between indentation energy and damage area and damage width was established based on step loading method.The damage modes and failure mechanisms of ceramic sandwich structures under different energies were studied by scanning the fracture of fragments generated during the process of alignment static indentation using SEM technology.On this basis,Brittle Cracking criterion is used to describe the characteristics of ceramics,and a finite element model of quasi-static indentation test is established.The numerical simulation results show that the finite element is in good agreement with the experimental values,which proves that the criterion can simulate ceramic damage well.Secondly,the acoustic emission system is used to monitor the damage process of the ceramic sandwich structure,and the acoustic emission characteristic signal of the quasi-static indentation process is obtained.Based on the principal component analysis method and K-means clustering analysis method,acoustic emission signals were reduced dimension and clustered,which matched the damage characteristics of ceramic sandwich structure.Finally,the residual compressive strength of ceramic sandwich structures with indentation damage was studied by uniaxial loading method,and the influence of different indentation energy on the residual compressive strength was analyzed.In conclusion,this paper establishes a damage assessment method for ceramic sandwich structures,which can provide a certain reference for future research on foreign objects damage of other types of small brittle samples.