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The high-speed ice-ball impact damage research of epoxy resin/carbon fiber 3D four-way braided composites was carried out. Using the air gun impact test system, ice balls with three different impact velocities were used to conduct impact tests. After the test, industrial CT scans were performed on the main damage positions of the test pieces, and the internal damage forms were observed. The composite macro constitutive model based on surface unit-cell and interior unit-cell and a strain rate related material model of the ice were used to establish the finite element model. The simulation model was compared with the test. The results show that the damage of the matrix in the surface unit-cell area is more serious than that in the interior unit-cell area, the damage area of the front surface is generally larger than that of the back surface, the oblique impact angle has an influence on the damage area and damage location. As the impact angle decreases, the damage area of the composite material also decreases. Increasing the thickness of plate can improve the ability to absorb energy and reduce the damage area of the material.

The artificial accelerated cyclic hygrothermal aging test was conducted on T700/TDE86 carbon fiber reinforced resin matrix composites, and the effects of different cyclic hygrothermal aging days on interlaminar fracture toughness of composites with open type (mode Ⅰ) and slip type (mode Ⅱ) were investigated. The results show that the model Ⅰ interlaminar fracture toughness of composite after cyclic hygrothermal aging exists an obvious R curve, the initial extend energy release rate (GIC,init) and the propagational extend energy release rate (GIC,prop) of composite are improved remarkably with the increase of cyclic hygrothermal aging days. The model Ⅱ interlaminar fracture toughness of composite appears a trapezoidal descent with the increase of cyclic hygrothermal aging days, and the decline is the largest at the early stage of cyclic hygrothermal aging and the largest descent is 21.68%.

This study investigates the use of calcium-based slurry for simultaneous removal NO and SO2 from oxy-fuel combustion flue gas, and recovery of the sulfur and nitrogen species in resulting solutions. The experiments were performed in a bubbling reactor in a transient mode under the pressure of 20 bar. The various influencing factors including the CaO amount, carrier gas (N2/CO2), and absorption time on the simultaneous NO and SO2 removal process, and the solution products were studied comprehensively. The results show that the NO2 removal efficiency can be improved by the presence of CO2, and the gas phase HNO2 produces in this process. The addition of CaO has positive effects not only on the NO2 removal efficiency but also on the formation of stable HNO3. With the presence of CO2, CaCO3 is formed in a solution initially. With the decrease of pH, CaCO3 is gradually converted to CaSO4, and in particular CaCO3 can be fully avoided through decreasing the pH of an absorption solution to 1.14. At the same time, the formation of unstable S(IV) and NO2- can be prevented when the solution pH is lower than 1.37. The nitrogen and sulfur compounds in the absorption solution (at pH 1.14) were further separated by the addition of different amounts of CaO. In particular, 95% of SO42- finally can be recovered in the form of CaSO4.2H2O with nitrogen in solution existing as NO3- by controlling the Ca/S ratio at 4.70. The effectiveness of calcium-based slurry on the removal and recovery of SO2 and NO is confirmed.

A comprehensive computational micromechanics has been presented to predict the transverse mechanical properties and failure envelop of bi-axial stress in a 22-33 plane at high temperatures. First, a paraboloidal elasto-plastic damage model considering the temperature effect of epoxy has been employed. Then, in order to rapidly create the random fiber distribution of the representative volume element (RVE), a simple and effective algorithm of fiber placement and an auto modeling and calculating python script have been developed, where the thickness size effect of RVEs has been discussed. Finally, the transverse tension/compression and out-of-plane shear properties and the corresponding failure envelop of RVEs are analyzed systematically by means of finite element simulations. The results show that the in-plane shear strength exists strongly thickness size effect, and high temperature can significantly weaken the transverse strength, especially for transverse compression, and the temperature effect of modulus can be depicted by a specific Gaussian function. In addition, Hashin and Tsai-wu criteria may be more appropriate to predict the bi-axial failure envelop of σ 2 2 − τ 23 at high temperature, and Tsai-Wu criterion is better and more suitable than Hashin and Catalanotti criteria for considering bi-axial compression. [ABSTRACT FROM AUTHOR]

A direct implicit discretization approach is presented for an arbitrary non-conformal interface by using a virtual cell on unstructured meshes. In this study, the virtual cell is supposed to be located at the neighbour of a target cell adjacent to the non-conformal interface. Any computational value on a virtual cell is formulated as a linear combination of values on contribution cells, which are determined by the nearest neighbouring cells or surface intersecting cells. The linear formulation simplifies the process of implementing implicit discretization for the governing equations. The approach is simple and efficient for information transfer through the interface because it avoids mesh stitching or iterations based on explicit discretization for treating topologically inconsistent meshes. Several numerical tests verify that the proposed method is capable and efficient for dealing with the arbitrary non-conformal interface. [ABSTRACT FROM AUTHOR]