Advanced Materials Research Vols. 774-776

Abstract: The square of normal surface velocity of a thin plate with a harmonic excitation is minimized by optimizing the topologies of attached passive constrained layer damping (PCLD) treatments. An extended solid isotropic material with penalization model for topology optimization is introduced based on a simple interface finite element modeling for viscoelastic layer of PCLD patch. For the purpose of illustrating the proposed method, a clamped square plate is used in the numerical study. Significant reductions of the objective functions are achieved by the optimal distributions.

Abstract: A low frequency energy harvesting structure was studied, describing the process of its manufacture. The natural frequency was obtained by modal analysis of the structure. It obtained the relationship between the magnitudes of the voltage generated from the piezoelectric energy harvesting device and the size parameters of structure, so that the energy harvesting structure can operate at the resonant frequency in order to obtain the maximum energy.

Abstract: With the combination of stochastic response surface model (SRSM) and Monte Carlo simulation (MCS)-based inverse error propagation method, a computational efficiency stochastic model updating approach has been proposed. The SRSM of original finite element model is determined using the Hermite polynomial chaos expansion and regression-based efficient collocation method. The efficiency of this method is demonstrated as a large number of computational demanding full model simulations are no longer essential, and instead, the updating of parameter mean values and variances is implemented on explicit SRSM. The effectiveness of this approach is validated through a bolt-jointed double-hat structure numerical example. The proposed method can be applied on stochastic uncertainty quantification of complex engineering structures.

Abstract: To evaluate the noise of a diesel engine and provide the basis for the next step for noise reduction, a boundary element model of the diesel engine has been built and finite element software is used to analyze the noise of the engine. Surface vibration velocity distribution, radiation noise spectrum, sound pressure distribution and total noise level are calculated. The calculation results obtained show that the most representative three points of the peak of SPL (sound pressure level) are 500Hz, 1200Hz and 1950Hz; total SPL is 108.99dB; the main sources of the noise of the diesel engine are oil pan, gear chamber cover and flywheel housing, these three parts should be prior; the noise of the lower part and left and right part (the gear chamber cover side and flywheel housing side) of the engine is greater than the upper part and front and rear part; improving the suspension mechanism of the internal combustion engine, optimizing the oil sump, flywheel housing and gear chamber cover and strengthening the rigidity of the skirt of the engine body can be used as the primary means of noise reduction.

Abstract: Finite element (FE) method is used to study the vibration behavior of armchair and zigzag double-walled carbon nanotubes (DWCNTs). In the analysis, nonlinear spring elements and the Lennard-Jones potential function are used to simulate the Van der Waals' force between non-bond atoms of different tube layers. We systematically analyze the effects of aspect ratio, double-atom vacancy defects and Van der Waals' force on the vibration behavior of DWCNTs. The simulation results show that the first order natural frequency decreases with the increase of length-to-diameter ratio (aspect ratio), the existence of Van der Waals' force causes the increase of natural frequency, and double-atom vacancy defects results in the decrease of each order natural frequency.

Abstract: Based on the tandem sealing structure at the end of the shaft,a finite element model of rubber O-rings has been established and the sealing performance of rubber O-ring has been analyzed. There is an un-uniform compression among these O-rings which lead to the sealing failure. Under different friction factors, several groups of the rubber O-rings have been analyzed, finding that the friction factor is the reason of un-uniform compression. The effect of different average compression rate has been investigated, which has been integrated in the sealing criteria for the tandem O-rings, providing a reference for the optimization of tandem sealing structure at the end of the shaft. According to the sealing criteria for a single O-ring, the sealing criteria for the tandem O-rings is built.

Abstract: On the basis of a newly-built mechanical model of rubber mounting and nonlinear mathematical model, the dynamic characteristics of rubber mounts were simulated and contrastively tested in frequency domain by using simulation software.Results indicate that the nonlinear simulation model of rubber mounts built in this paper can apply to the research of the low and high frequency vibration of rubber mounts.This model can also be applied to the design of rubber mounting products, which has certain engineering application value.

Abstract: The dynamic balancing of crank-slider mechanism was achieved with the guidance of the computer aided simulation-based optimization technique. Taking the reaction force of the rotary pair of connecting links and the input torque as optimization objective functions, the design optimization process was carried out with random-direction optimization method after determining the sensitive independent variables and their variation ranges based on the synthetical planning. The modal damping parameter of simulation model was optimized with the guidance of dynamic balancing experiment and the accuracy of simulation was also improved. Finally, by comparing the results from experiment and from optimization simulation, it is shown that optimization simulation could facilitate to instruct and implement the synthetical dynamic balancing for four-bar mechanism.

Abstract: Modal analysis of chisel subsoiling shovel, arrow subsoiling shovel and double-wings subsoiling shovel were made, which was based on the analysis of the vibration characteristics of subsoiler-soil self-excited vibration system and finite element analysis software ANSYS13.0 was used. Natural frequency and the mode of vibration were determined. Then self-excited vibration conditions of the subsoiling system were studied. All these analysis results could provide theoretical references for the self-excited vibration subsoiling system optimization and design.