Abstract: The viscosity behaviors and elastic properties of concentrated cellulose 1-allyl-3-methy -limidazolium Chloride solutions were investigated in the concentration from 10 wt% to 25 wt%. Rheological measurement showed that the solution was pesudoplastic fluid. The non-Newtonian behavior was improved and shear-thinning tendency became more pronounced with increasing polymer concentration. The power law index ranged from 0.19 to 0.30. The effects of cellulose concentration to the storage modulus G′ and the loss modulus G″ were analyzed. First normal stress difference (N1) increased with increasing concentration.
Abstract: Joint parameters identification is a key problem in the modeling of complex structures. Aimed to solve the joint problem effectively in finite element analysis (FEA), the joint parameters (stiffness and damping) of a linear rolling guide were identified by measuring frequency response functions (FRFs). Hertz contact theory compared with the frequency domain identify method identified the correction of the experiment results. Modal analysis based FEA method coupled with modal test was used to analysis the dynamic characteristics of the linear rolling guide, which confirms that the proposed method can be successfully applied to evaluate the dynamics characteristics of mechanical systems of various configurations.
Abstract: A novel aromatic ether diamine 1,3-bis(4-aminophenoxy)benzene (TPER) was synthesized. Four kinds of polyimides were prepared with obtained TPER, 4,4’-diaminodiphenyl(ODA), pyromellitic dianhydride (PMDA) and end capped with phthalic anhydride(PA). The imidization process was solution imidization followed by solid-phase thermal imidization. The results of DSC, 1H-NMR and FTIR analysis showed that high purity TPER had been successfully synthesized. FTIR spectras of polyimides indicated the imidization process could reduce the final imidization temperature. The inherent viscosities([η]) showed molecular weight could be controlled via the introduction of flexible diamine and end capping agent. And all polyimides exhibited excellent thermal stability.
Abstract: In order to investigate dynamic performance of flexible multi-link manipulators more exactly, establishing the dynamic model with accounting for link foreshortening and link material damping is needed. In this paper, a new dynamic model for planar flexible multi-link manipulators is established by using Lagrange approach. Both link foreshortening and link material damping are accounted for in this model. As a case simulation, this model is applied to a planar flexible two-link manipulator with a tip mass, and the motion responses of the manipulator are obtained using Gear method.
Abstract: In order to determine the loads acting on the cutterhead of a compound shield, this paper aims at the large-scale and fully coupled system of the excavation face. Firstly, a new model is proposed to calculate the loads acting on a single cutter, in which the earth pressure of the chamber is taken into consideration. Then, by transforming the large-scale nonlinear contact problem into a smaller one, we set up the governing equations only including the penetration depth of cutters in the approach of the sub-structure condensation, to calculate the loads acting on the cutterhead. Finally, the relationship between the penetration per revolution and the total thrust and total torque acting on the cutters of the cutterhead of a compound shield is investigated.
Abstract: The tube-transferring car is a key part of transportation system for deepwater pipe-laying vessels. This paper covers the design of a tube-transferring car for deep sea pipe-laying, especially its lifting mechanism. Kinematics and dynamics analysis of the lifting mechanism is conducted. During dynamic analysis and calculation, the single degree of freedom mechanical system dynamic analysis method is used. The results show that the rotation angle of the lifting system has a direct impact on the lifting speed and driving force. The support reaction force in each kinematic pair which is calculated by choosing the single degree of freedom dynamics provides a theoretical basis for the design of the lifting mechanism, which is finally reflected in the selection of horizontal drive of the feeding machine and the related parameter design．
Abstract: The mechanism and producing condition of instsbility in low velocity of hydraulic clinder was analyzed based on dynamic model and test ,Nonlinear coupled force combined with hydraulic spring and Self-excited vibration were though the key factor that could effect instability in low angular velocity, The mathematic model was established to obtain the change rule of speed & instantaneous acceleration of the hydraulic clinder A simulation analysisis then created for dynamic characteristics of hydraulic clinder with Simulink to analyze the effect of friction torque, leakage and compressibility of oil and liquid on low-speed stability of hydraulic motor, The test shows that fluctuation was the negative characteristics of friction in the self-excited vibration conditions .Some measures were proposed to improve the low-speed stability of hydraulic clinder.
Abstract: In recent years, light sport aircraft, which not only serve the purpose of personal recreation but also act as a means of transportation for medium and short distance travel, have rapidly gained popularity in the general aviation industry worldwide. The FAA established regulations for this new category of airplanes in 2004. However, the crashworthiness requirements for this type of airplane have not been clearly specified. This study used the finite element method to investigate the effect of the impact angle and speed of the LSA fuselage structure on passenger safety during a crash event. We used sink speed defined by NASA AGATE, ASTM and FAR as parameters. The passenger compartment reducing rate defined by MIL-STD-1290A was used for a safety boundary condition. The results show that the maximum cockpit reducing rate of the airplane impact angle is 30o. When the impact angle increases, owing to the engine mount and fire wall’s reinforced structure, this type of airplane can sustain a greater vertical drop speed. When the impact angle is about 80°~90°, the maximum impact speed the fuselage that can be sustained is 33 m/s. This work also completed a simulation of safe and unsafe ranges for light sport aircraft at various impact angles and vertical drop speeds during impact.
Abstract: The rotor of vertical shaft impact crusher was modeled by SolidWorks and imported into EDEM for dynamic simulation. The average speed, maximum speed, average force, maximum force with time were analyzed in rotor, so the true law of particles motion in rotor would be revealed, indicated that the speed of particle field in rotor increased with the rotor radius at the time of rotor work steady, about 80% of the particles were accelerated to the maximum speed, and the change of speed affected significantly the particle interactions.