Papers by Author: Xiao Qing Huang

Abstract: Basalt fiber has the advantages of non-pollution and omnipotence, and will be widely used in the 21st Century. Therefore, more and more attention is paid on experimental research on the basalt fiber in the world. First,according to the requirements of the fibers used in the cement-based materials, the contrast testing of the plastic shrinkage between fiber cement mortar and pure mortar was made. The experimental results showed that basalt fiber , polypropylene fiber and polyacrylonitrile fiber can be preliminarily chosen as reinforced fibers in cement-based materials. Finally, taking both characteristics of basalt fiber and the increase of cement-based materials costs into account, it can be drawn that top priority should be given to the basalt fiber rather than to other fibers for cement-based materials.

Abstract: In this paper coupling damage behaviors of Liquid Rubber Based Concrete (LRBC) are studied experimentally. Compressive fatigue and impact alternant loading tests were carried out on cylindrical LRBC specimens. The elastic moduli were recorded before and after fatigue and impact tests. The quasi-static compressive stress-strain curves after fatigue and impact tests were obtained. According to the definition of dissipated energy, the cumulating of dissipated energy was used to define damage. The analysis on impact and fatigue damages during the loading processes show that fatigue and impact loading lead to the formation and development of inner damage. During the alternant loading process, impact and fatigue damages are coupled mutually, with the former affects the evolution of fatigue damage evidently.

Abstract: Flexure behaviors of plain concrete (PC), steel fiber reinforced concrete (SFRC), polymer modified concrete (PMC), steel fiber reinforced and polymer modified concrete (SFRPMC) and hybrid fiber reinforced concrete (HFRC) with steel fiber and polymer fiber are studied in this paper, flexure tests were carried out and flexure strengths of the five different materials with different mixture ratios were measured and compared. Flexure ductility of PC, PMC, SFRC, and SFRPMC were calculated and compared. In addition, considering performance and cost estimation comprehensively, HFRC is recommended, preliminary tests show that HFRC may be one of the potential materials for bridge pavement.

Abstract: Damage behaviors of plain concrete (PC), steel fiber reinforced concrete (SFRC), steel fiber reinforced and polymer modified concrete (SFRPMC) are studied in this paper by use of a Split Hopkinson Pressure Bar (SHPB). Three kinds of concrete materials appear obvious strain rate strengthening effects. SFRPMC appears a better resistance and energy absorption ability. A rate-dependent damage model is suggested to depict the impact damage evolution of three kinds of materials under different impact velocities. The simulation results showed the theoretical model could well describe the dynamic behaviors of the three kinds of materials, and steel fibers attribute more to resist crack develop in early stage, “bridge effect” of steel fibers slow up the damage evolution in SFRC, with the addition of polymer, the internal structures of SFRPMC were modified, SFRPMC gains better ductility, and appears a kind of “softening effect”, which makes the damage in SFRPMC develop more slowly than that in PC and SFRC under impact loading.

Abstract: The constitutive relation for open-celled metal foams with random characteristics of cells was constructed based on the mechanical behavior and the distribution of the cells, which implied the effect of the mesoscopic characteristics of the cells on the macroscopic behavior of the foam. The constitutive relation was able to represent the whole three phases of the stress-strain curve of the open-celled metal foam with merely one expression. Besides, the explicit expressions for the foam’s yield strain and yield stress were supplied. Experimental data was employed to check the constitutive relation. It was found that the constitutive relation was able to represent accurately the whole compression process of the foams, and the calculated yield points had a good agreement with the experimental results.

Abstract: The experimental studies on the static and dynamic mechanical properties of aluminium foam material are presented first. Finite element models of four structures, including circular tube filled and bonded with aluminium foam, circular tube filled but unbonded with aluminium foam, single aluminium foam column and empty aluminium tube, under dynamic transverse compression are established by FEMB code. The dynamic mechanical behaviors of the structures are analyzed using LS-DYNA finite element code. The simulating results at certain cases are compared with experimental measurements and the satisfying consistency confirmed the validity of the model. The further numerical simulations are carried on the dynamic mechanical behaviors of four structures with outer tubes of different wall-thickness. It is found that aluminium foam filling can greatly improve the load-bearing capacity and energy-absorbing efficiency of structures. On the other hand, the effect of the aluminium outer tube on the structure is obvious compared with single aluminium foam column, in spite of the foam core and the tube are bonded together or unbonded. Another result can be seen that the bonding between the foam and outer tube affects the structure weakly for both thinner and thicker tubes. Finally, the simulating results show that the thicker wall of tube can improve the load-bearing capacity and energy-absorbing ability of the structure.

Abstract: Impact tests were carried out by use of a 74-mm-diameter split Hopkinson pressure bar to investigate the impact damage behaviors of plain concrete (PC), steel fiber reinforced concrete (SFRC) and steel fiber reinforced and polymer modified concrete (SFRPMC). The results show that all three kinds of materials appear strain rate strengthening effects, and SFRPMC appears a better impact resistance and energy absorbing ability than PC and SFRC. Based on the analysis of experimental results, a rate-dependent damage model is suggested to depict the dynamic behaviors of SFRC and SFRPMC, which derives the impact damage evolution of the materials. It shows that the damages in SFRPMC develop more slowly than that in SFRC.