Advanced Materials Research Vols. 217-218

Abstract: In order to research the aircraft impact damage, one symbolic fitting method for analyzing and forecasting the damage data is proposed based on genetic programming (GP). The method can be used to forecast the impact damage by recognizing the rule in some groups of actual data including impact parameters and damage hole size. The principle of GP symbolic fitting method is briefly introduced. The fitting model is created with some sample data respectively for training and testing from Sorenson experiential equation. The computation with Matlab program indicates the model has a good performance to fit and forecast the damage data with avoiding the noise. The application of GP symbolic fitting method can help to decrease the times of fire experiments. Since the method can recognize the complicated nonlinear relationship between the impact parameters and damage data, it is more applicable than theoretical analysis and experiential equation to forecast the aircraft impact damage.

Abstract: The multi-grid composite wall-shear wall structure (the hybrid structure discussed in this paper) is a new dual structural system consisting of the multi-grid composite walls and the RC shear walls. Because of the shear deformation of the composite walls subject to arbitrary loads, it is not accurate to calculate the horizontal displacement of the hybrid structure by using the displacement formulations of the frame-shear wall structure. And therefore, a displacement calculation method for the hybrid structure subjected to horizontal loads should be proposed. In this paper, the composite walls are viewed as shear-flexural type cantilever walls and the shear walls as flexural type cantilever walls. Based on the Timoshenko beam theory, the displacement differential equation of the hybrid structure is proposed by the continuum method. The analytical solutions of the displacement equation for the hybrid structure subject to the inverse triangle load are obtained with boundary conditions. The example indicates that the lateral displacement curve of the hybrid structure from the proposed method exhibits a shear-flexural type characteristic in which the shear deformation should not be ignored.

Abstract: As a new structural system with a bright prospect, multi-ribbed composite slab structure has the advantages of ecological materials and seismic performance. In this paper, the formula of vibration period of multi-ribbed composite slab structure is discussed. Based on the analysis of FEM model and the regression analysis of experimental data, an empirical formula was put forward. It has been shown that the calculated results fit well with the test results.

Abstract: A kind of beam-like space deployable truss mast with square batten frames supported by four longerons and two diagonal cables cross laced per face is described. A simple method for deriving mechanics parameters of the mast is presented. Element loads for mast to maintain self-equilibrating structure are calculated. Symbolic equations for the axial, bending, shear, torsional stiffness and bending strength of the mast are derived based on proposed method. Equations derived by simple method are consistent with expressions for the effective continuum mechanics of beam-like truss derived previously based on equivalent continuum method, these equations are helpful for mast preliminary design and mechanics analysis. Influence of mast structural parameters on mast stiffness and strength is analyzed, mast stiffness and strength can been improved by selecting reasonable structural parameters.

Abstract: To provide theoretical basis for metal honeycombs used as buffering and crashworthy structures, the effect of the cell length and foil thickness on compressive properties of metal honeycombs is investigated by numerical simulation. Numerical results are well consistent with the corresponding experimental results. The numerical results show that metal honeycombs have cyclic buckling when loaded in out-of-plane direction. The thicker the foil is or the shorter the cell length is, the higher the plastic collapse stress is and the plastic collapse stress is much sensitive when cell length is short. The numerical simulation used in this paper can well predict the crush behavior. Single and doubled foil portions of cell walls are also accounted in the FE model. The results demonstrate that the method is effective which can be used in optimization design of buffers.

Abstract: With toluene 2, 4-diisocyanate (TDI), polyethylene glycol (PEG) and 2,3-Epoxy-1-prop -anol (glycidol) used as the raw materials, two epoxy terminated polyurethanes (EPU) was synthesized by prepolymerization and closed end. Moreover, EPU with high toughhess is chosen as a coating agent for carbon fiber with three ethylene tetramine (TETA) as curing agen. The influence of the content of crosslinking agent in the coating layer on properties of composites and the mechanism of interface toughness are investigated. The chemical structure and thermal property of the EPU were studied with FTIR, 1HNMR and TGA, respectively. It proves that the thermal stability of EPU is more stable than epoxy coating. The interlaminar shear strength (ILSS) of the sized high modulus carbon fiber/epoxy composites is improved to 71MPa, which increased by 19.4% compared with the composites reinforced by unsized high modulus carbon fiber, and DMTA show that using EPU as a new kind of polymer coating for carbon fiber is a feasible method to improve the interfacial performance of high modulus carbon fiber/epoxy composites.

Abstract: The deterioration of reinforced concrete (RC) structure due to chloride attack plays an important role in the reduction of structure strength. Consequently, the actual condition of structure is an essential investigation for management planning in concrete structure which is attacked by chloride. In this paper, the proposed assessment bases on the risk management and the reliability theory presents in risk index (RI) of structure. The reinforced concrete building under the marine environment was an illustrative example for risk evaluation. It was found that the risk index of structure equaled to 20, it implied that the structural condition encountered with extreme risk due to chloride attack and must be rehabilitated urgently. As analysis results, the risk assessment is relation to the actual condition of structure. This assessment can be used as a guideline tool for structural engineering to assess the concrete structure attacked by chloride.

Abstract: The effect of water-cement ratio and curing age on the strength of recycled concrete was studied by experiment with the combination of the recycled coarse aggregate adding natural sand. The results showed that with the increase of curing age, the greater the water-cement ratio is, the smaller the strength growth rate is; the smaller the water-cement ratio is, the greater the strength growth rate is. There is a relatively larger increase in the growth rate of 90d strength than 28d’, which is significantly higher than that of the ordinary concrete. The linear relationship between water-cement ratio and strength of recycled concrete is worse than that of ordinary concrete. Under the same water-cement ratio and curing age, the strength of recycled concrete is lower than that of ordinary concrete, and the empirical formulas between the strength of 28d and 7d, 90d and 28d were obtained.

Abstract: This paper introduced the different classifications and advantages of the project level thermoplastic polyurethane elastomer ,and according to the injection molding process of raw materials Isoplast 302EZ and thermoplastic polyurethane elastomer, from raw material preparation, injection machine selection, tooling selection, molding conditions, and introduced TPU injection molding process .The filter housing of TPU were briefly discussed from the design goals, technical characteristics, performance analysis. Combination of typical products, we studied the technology of the production of the thermoplastic polyurethane flexible filter housing. The results showed that the material should be pre-dried in a vacuum, and the time, temperature and pressure should be controlled properly. It should be pay attention that the specification of the waste and the raw materials should be the same, when recycling and on the other hand, the quality of the productions should be improved and no pollution should be ensure during the process; to avoid the decomposition temperature and the products aging, we should empty the material or stop the machine during it doesn’t work.

Abstract: Two types of improved multi-grid composite wall called point contact multi-grid composite wall and light-steel skeleton multi-grid composite wall were proposed in this paper. In order to study the mechanical properties of improved multi-grid composite wall, the low-cycle reduplicative loading tests of 1/2 scale improved multi-grid composite wall were carried out. Through the analysis of testing phenomenon and final test results, the main failure patterns and failure processes of the walls were summarized, and the mechanical characteristics of improved multi-grid composite wall were discussed, then the seismic performance including bearing capacity, ductility, and hysteretic characteristics were researched. The experimental foundations were provided for the further theoretical research and application of improved multi-grid composite wall in practical application.