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Zhang J.,Taiyuan University of Technology | Guo H.-W.,Harbin Institute of Technology | Liu R.-Q.,Harbin Institute of Technology | Wu J.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | And 2 more authors.
Nonlinear Dynamics | Year: 2015

Both the friction caused by the preload in locked joints and the impact caused by clearance in unlocked joints cause energy dissipation in jointed deployable structures. The energy dissipation of locked joints is studied by analyzing the force on the infinitesimal body of the joint. The jointed beam with an unlocked joint is simplified into an impact mass-spring model with clearance, which considers the coefficient of restitution of impact. The energy dissipations of the joint caused by friction and clearance are transformed into damping ratios by Taylor expansion. Then, the effects of pressure, clearance and the dynamic parameters on the damping of joints are analyzed by utilizing the damping ratio formulation. The damping ratio increases with the preload and the clearance. To validate the damping ratio formulation of joints, experiments on a single jointed beam with preload and double jointed beams with clearance are conducted. Comparison between the experimental results and the model simulation results shows that the friction and impact damping models are accurate for the dynamic calculation of deployable structures. Furthermore, the damping ratio formulations can be directly introduced into the design and dynamic analysis of deployable structures. © 2015, Springer Science+Business Media Dordrecht. Source


Cui G.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | Kou Z.,Taiyuan University of Technology
Journal of Alloys and Compounds | Year: 2014

Bulks of Fe-Cr-B alloys were prepared by using powder metallurgy technology route (P/M), and the microstructure and mechanical properties of iron matrix alloys were investigated in detail. The boron was an effective strengthened element to reinforce mechanical properties of alloys. The Fe-Cr-B alloys were composed of Fe, FeCr and Fe2B phases. Fe phase was rounded by alloy phases in the matrix. The Fe-Cr matrix alloys transferred from the ductile material to the brittle material with the increase of boron content, which showed high hardness in comparison with that of Fe-Cr alloy due to the formation of intermetallic compounds. The specimen containing 7 wt.% boron showed the best properties. The fracture mode of alloys transferred from transgranular cleavage fracture to the intergranular cleavage fracture. © 2013 Elsevier B.V. All rights reserved. Source


Cui G.,Taiyuan University of Technology | Cui G.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | Lu L.,Taiyuan University of Technology | Wu J.,Taiyuan University of Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

A series of Fe-Cr matrix high temperature self-lubricating composites were prepared by powder metallurgy technique (PM). The tribological properties of composites sliding against ceramic Si3N4 ball were studied by using a ball-on-disc high-temperature tribometer at 10 N and 0.19 m/s for 20 min from room temperature to 800 °C. Mo element showed an obvious solid solution strengthening effect on the matrix, and formed the high temperature solid lubricant BaMoO4. The obtained results showed that the tribological properties of specimens greatly depended on the additives. Generally speaking, the specimen containing 8.0 wt.% BaF2, 10.0 wt.% Ag and 8.5 wt.% Mo kept the lowest friction coefficient (0.4) and specific wear rate (1.8-3.7 × 10-4 mm3 N-1 m -1) from room temperature to 800 °C. The high-temperature tribological properties of Fe-Cr based alloy were improved due to the addition of additives. The excellent tribological behavior of specimen was attributed to the synergetic action of solid lubricants and high hardness. The wear mechanism of specimen FM is ploughing and slightly delamination at room temperature and 400 °C. At 800 °C, the specimen FM shows the micro-ploughing characteristics. © 2014 Elsevier B.V. All rights reserved. Source


Liu Q.,Taiyuan University of Technology | Liu Q.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | Kou Z.,Taiyuan University of Technology | Kou Z.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | And 4 more authors.
Experimental Thermal and Fluid Science | Year: 2015

A shear-impact-type atomized dust controller was designed by combining the rotary spray blades and axial flow fan, and the droplet atomizing process included two steps: shear-atomizing and impact-atomizing. The comprehensive operating parameters of this dust controller were studied by measuring different droplet size, airflow velocity, water consumption, nebulization efficiency, and collecting efficiency under different rotating speed, diversion hole-exit diameter, and colliding tooth angle. The relationships among them have been particularly analyzed. Results indicated that the droplet size is greatly influenced by rotating speed; the airflow velocity enhances monotonously with the increase in rotating speed. Excessive rotating speed and diversion hole-exit diameter can cause water waste, and suitable colliding tooth angle θ can improve nebulization efficiency. The optimal operating conditions were obtained with rotating speed 1500-2100. r/min, diversion hole-exit diameter 2-2.5. mm and colliding tooth angle 35-40° by fully considering security, water consumption, nebulization and collecting efficiencies. In this case, the nebulization efficiency exceeds 96.3% and the collecting efficiency tops 98.6%. © 2015 Elsevier Inc. Source


Wu J.,Taiyuan University of Technology | Wu J.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | Cui G.,Taiyuan University of Technology | Cui G.,Shanxi Provincial Engineering Laboratory Research Center for Mine Fluid Control | And 4 more authors.
Tribology Transactions | Year: 2015

The tribological behaviors of Fe-Cr-B alloy and AISI52100 and AISI304 stainless steel sliding against an AISI52100 steel ball were investigated with a ball-on-disk tribotester under distilled water condition. The Fe-Cr-B alloy was successfully prepared by using powder metallurgy technology. In distilled water, the friction coefficient and specific wear rate of Fe-Cr-B alloy were the lowest compared to other specimens. The different alloys showed different wear mechanisms during the sliding process. The wear mechanism of AISI52100 steel was ploughing and severe plastic deformation; the wear mechanism of AISI304 stainless steel was ploughing and plastic deformation. However, Fe-Cr-B alloy was dominated by microploughs and slight delamination under distilled water condition. The Fe-Cr-B alloy showed better wear resistance than that of the other two alloys. © 2015, Copyright © Society of Tribologists and Lubrication Engineers. Source

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