Papers by Author: Li Ping Shi

Abstract: To improve the heat absorbed and scattered properties of quartz fiber tile, porous phenolic resin impregnated quartz fiber tile composite for ablator and thermal insulator was prepared by impregnating the quartz fiber tile with ethanol solution of phenolic resin, and then drying and cured. The phenolic resin impregnated quartz fiber tile ablative composite is a new heat protection composite material with lower density, lower heat conductivity and low mass ablation. It can be used as the widespread thermal protection system of the aero craft in the high heat flux, high temperature and extreme condition. The thermal property and ablation property of the composites were studied respectively. The ablation property of PICA was evaluated by the oxyacetylene ablation experiment. The microstructure morphology of specimen before and after ablation was viewed by SEM. The thermogravimetric analysis of the ablator was taken from room temperature to 800°C.

Abstract: In this paper, we will simulation three different structures of the ceramic/metal armor by ansys Ls-dyna, under the condition of the same thickness ceramic. In the paper, every structure was impacted with the flat-ended ballistic with 600m/s velocity. Through calculation we find that the case2 and case3 has the nearly equal residual velocity, lower than the case1, so the case2 and case3 are superior to the case1, but case3 has the smallest damage area, so that the case3 has the most excellent ballistic performance, especially on the performace of multi-hit.

Abstract: In this paper, LS-DYNA software was used to simulate the penetration of metal-ceramic functionally graded material armor made of Aluminum alloy reinforced by ceramic particle. The ceramic particle volume fraction varies from layer to layer along the armor thickness. The armor’s geometry of the calculation model considered was a four-sides-fixed supported square plate whose side length was far out weight its thickness. The penetrator considered was a long rod projectile, and it impacted the plate with three different speeds along the centre line of the plate. Three different armors with the same areal density were investigated. The results show that at relative low impact velocity, the ballistic resistance has very close relation with the gradient distribution of the armor. At relative high impact velocity, the ballistic resistance of functionally graded armors is not sensitive to the ceramic particle distribution. For the same areal density, the ballistic resistance of ceramic particle reinforced functionally graded armors is better than homogeneous aluminum alloy armor at any velocity situation.

Abstract: Microarc oxidation (MAO) is a relatively convenient and effective technique to deposit ceramic coatings on the surfaces of Al, Ti, Mg and their alloys. This technique can introduce various desired elements into titania-based coatings and produce various functional coatings with a porous structure. Microarc oxidized (MAO) TiO2-based coatings on titanium alloy were formed in electrolytes containing aluminate and ZrO2 particles. The phase composition of the samples was analyzed by glance-angle X-ray diffraction and the surface morphologies of the samples were observed by a scanning electron microscopy (SEM). In addition, the element concentrations on the surfaces of the samples were measured by an energy dispersive X-ray spectrometer. The experiment results indicated that: MAO coatings, which are porous structures and exhibit good interfacial bonding to the substrate, may possess specific surface structures such as crystal phase, non-equilibrium solid and complex mixed-compounds since complex plasma physical and chemical reactions.

Abstract: Ti3SiC2 is one of the nano-layered ternary ceramics Mn+1AXn, where M is a transition metal, A is an A-group (mostly IIIA or IVA) element, and X is C or N. With the filler of Ag-Cu-Ti, the brazing of Ti3SiC2 has been conducted at 800°C–950°C for 5-10min under 3.5×103Pa in a vacuum. The phase composition and microstructure of the joints were investigated by XRD, SEM AND EPMA. The diffusion of Cu element in fillers through the reaction zone toward Ti3SiC2 is the main controlling step in the bonding process. Joint strengths were evaluated by three point bending test. The maximum flexural strength of joints reaches is 306±11MPa, which is lower than the bending strength of Ti3SiC2, obtained under the same condition.

Abstract: ARMOR TPS panel is above the whole ARMOR TPS, and the metal honeycomb sandwich structure is the surface of the ARMOR TPS panel. So the metal honeycomb sandwich structure plays an important role in the ARMOR TPS, while it bears the flight dynamic pressure and stands against the flight dynamic calefaction. So the active environment of metal honeycomb sandwich structure is very formidable. We have to discuss any extreme situation, for reason of making sure aerial vehicle is safe. And high-frequency vibration is one of active environment. In this paper we have analyzed high-frequency vibration response of metal honeycomb sandwich structure. We processed high-frequency vibration experiment by simulating true aerial environment. Sequentially we operated high-frequency vibration experiment of metal honeycomb sandwich structure with cracks, notches and holes. Then finite-element analysis was performed by way of validating the experiment results. Haynes214 is a good high temperature alloy material of both face sheet and core at present, so we choose it in this paper.

Abstract: The preparation technologies of thermal barrier coating by the Electron Beam Physical Vapor Deposition (EBPVD) technique were briefly introduced in this paper. And design principal of thermal barrier coating is discussed, at the same time the selection of raw material was also taken into account. On the basis of several assumed perfect conditions, a reasonable Finite Element Analysis (FEA) physical model was built up in order to exactly describe the whole deposition process. Taking the advantage of the large-scale commercial software of FEA, the distribution of residual stress and the possible displacement tendency were obtained. The analysis results show that: with the increasing substrate preheating temperature, the inter-laminar shear stress increases but the axial residual stress decreases. And the probability of cracking after de-bonding tends to enhance as the thickness of deposition coating is increased. Also it is verified that the FE model has produced little numerical error.