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Based on the code LS-DYNA, the simulation strategy on the quasi-static crushing process of composite tubes is studied by conducting two series of comparison simulations: one is at different virtual loading speeds with the real material density and the other is with different virtual material densities at the given loading speed. The simulation results are summarized as three types, namely mode-varying type (MVT), unstable type (UT) and stable type (ST), depending on the change of the structural failure mode and the occurrence of the load-fluctuating stage in the load-displacement curve. Analysis has shown that the steady load possesses the stability, the peak load has the convergence zone, and the thresholds of energy ratio can be adopted to evaluate the simulation results. In the end, the simulation strategy is proposed to makes it possible to acquire the simulation results with a higher query precision at a lower computing cost.

Adhesive bonding is one of the effective ways to reduce the weight of structures. Researchers have done lots of numerical analysis and finite element analysis taking into account of the complex stress state in the bonded area, as well as the stress singularity occurs at the overlap edges with a view to efficiently predict the strength and rigidity of adhesively bonded joints. As they may suffer shock or impact loads in practice which leads to high strain rate in structures, analysis methods for adhesively bonded joints differ from that at quasi-static condition for two reasons: one is the mechanical properties of materials, including adhesives and substrates are different at high strain rates, the other is the additional consideration of elastic wave propagation in solid body. This article summaries several finite element analysis methods for adhesively bonded joints at high strain rate developed by domestic and foreign scholars and corresponding experimental standards for determining required parameters of each analytical method and raised some questions that need for further study.

Economical and effective oily sludge pyrolysis residue was prepared, characterized with various techniques, and applied in the removal of COD in biologically treated oil-field wastewater. It was found that surface area of oily sludge pyrolysis residue was 223.62 m2 /g. The content of C and Al2O3 was 27.91% and 27.6%, respectively. Oily sludge pyrolysis residue contains carboxyl, hydroxyl, carbonyl and other oxygen-containing acid functional groups. When the adsorption equilibrium time of oily sludge pyrolysis residue was 90min, pH of solution was 4, the best COD adsorption capacity was 59.5 mg/g. Adsorption of oily sludge pyrolysis residue is determined by its structure and composition. The Al2O3 may play a flocculation and sedimentation role in COD removal, which has a synergistic effect on adsorption. The adsorption of COD from biologically treated oil-field wastewater by oily sludge pyrolysis residue follows Langmuir adsorption isotherm.

Glass fiber reinforced plastics (GFRP) rebars / bolts are more and more being applied in construction projects with its superior corrosion resistance. To improve the economical efficiency of their application it is very significant to develop the prestressed GFRP rebars/bolts structure system. Therefore it is very valuable to probe the stress relaxation properties of GFRP rebars/bolts. With an innovation ends anchoring method for stress relaxation specimens of GFRP rebars/bolts, the stress relaxation properties has been tested in this paper. Results show that the relaxation rate of GFRP rebars/bolts increases with the initial stress increasing and with test time prolonging. It is increasing more rapidly at the beginning stage and it becomes slow after 24 hours. The relaxation law of GFRP rebars/bolts is similar to the law of CFRP and AFRP rebars/bolts. The relation between the relaxation rate and the logarithm of test time in hour follows also better linear law. The relaxation rate of GFRP rebars/bolts is bigger than CFRP ones and smaller than AFRP ones. The mechanical properties do not change obviously after 120h relaxation test.