To improve the ride comfort of the off-road vibratory roller, the cab’s hydraulic mounts were analyzed to prevent vibration sources transmitting to the cab. However, the cab’s low-frequency shaking in the vertical direction and the direction of forward motion is still great. This study proposes an optimal fuzzy-PID control method for semi-active cab’s hydraulic mounts based on an off-road vehicle roller dynamic model to analyze the low-frequency performance of semi-active cab’s hydraulic mounts under the different operating conditions. In order to evaluate the ride comfort of the off-road vibratory roller with semi-active cab’s hydraulic mounts, the power spectral density (PSD) and the weighted root mean square (RMS) of acceleration responses of the vertical driver’s seat, cab’s pitch, and roll vibrations in the low-frequency range are chosen as objective functions. Contrastive analysis of low-frequency vibration characteristics of the off-road vibratory roller with passive cab’s hydraulic mounts, semi-active cab’s hydraulic mounts without optimization, and semi-active cab’s hydraulic mounts with optimization is, respectively, carried out. The research results show that the semi-active cab’s hydraulic mounts with optimization have an obvious effect on mitigating the cab shaking and improving the ride comfort in comparison with passive cab’s hydraulic mounts and semi-active cab’s hydraulic mounts without optimization.
This study proposes a dynamic model of the vibratory roller interacting with the off-road deformed terrain to analyze the lowfrequency performance of three different cab's isolation mounts under the different operating conditions. In order to evaluate the ride comfort of the vibratory roller with the different cab's isolation mounts, a three-dimensional nonlinear dynamic model is established. The power spectral density (PSD) and the weighted root mean square (RMS) of acceleration responses of the vertical driver's seat, cab's pitch, and roll vibrations are chosen as objective functions in the low-frequency range. Contrastive analysis of low-frequency vibration characteristics of the vibratory roller with the traditional rubber mounts, the hydraulic mounts, and the pneumatic mounts is carried out. Experimental investigations are also used to verify the accuracy of models. The research results show that the hydraulic mounts have an obvious effect on mitigating the cab vibration and improving the ride comfort in comparison with the traditional rubber mounts and the pneumatic mounts.
Purpose
To improve the lubrication and tribology performance (LTP) of the crankpin bearing, this paper aims to propose the optimization of the crankpin bearing parameters considering effect of the high-speed dynamic load and micro asperity contact.
Design/methodology/approach
A numerical simulation method combined by the slider-crank-mechanism dynamic and lubrication models is applied to solve the dynamic and lubrication equations of crankpin bearing. These equations are then computed via an algorithm program written in Matlab software. The contact force (Wac) in the asperity contact region, friction force (Ff) and friction coefficient (μ) of crankpin bearing are chosen as objective functions. The original parameters and experimental data of the engine are used for the simulation to enhance the reliability of the research results. The parameters are then optimized to obtain the minimum values of Wac, Ff and μ.
Findings
The research results show that the LTP is significantly improved with optimized parameters. Particularly, the maximum values of Wac and Ff are greatly decreased by 27 and 32%, respectively.
Originality/value
Reducing the width, radius and surface roughness and increasing the radial clearance of crankpin bearing can improve better the LTP.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0072/
This study, based on preeminent characteristics of both the pneumatic and hydraulic isolations, combined hydropneumatic isolations (CHPIs), is proposed for improving the cab ride quality of the vibratory rollers in low-frequency domain. A 3D dynamic model and mathematical model of the cab isolations and the vibratory rollers are established to simulate CHPI’s characteristics under the excitations of the off-road terrain and vibratory drum at 28 Hz and 35 Hz. To enhance the reliability of research results, vehicle’s mathematical models are also verified via the experimental investigation. The effectiveness of CHPIs on ameliorating the cab’s ride quality is then analyzed via two indicators of the power spectral density (PSD) acceleration on the frequency region and root-mean-square (RMS) acceleration on the time domain of the cab and operator seat. It is found that with the combination of the high-elastic stiffness parameter and high nonlinear damping coefficient of CHPIs using for the vehicle’s cab isolations, the results of the cab’s ride quality are greatly improved compared with other cab isolations in the well-known existing works.
Three different models of the steel spring (SS), the roller-spring (RS), and the air spring (AS) in the negative-stiffness-structure (NSS) used for the driver’s seat suspension system are proposed to ameliorate the vehicle’s ride comfort. A vehicle dynamics model with the driver’s seat isolation system added by the SS, RS, and AS is built and simulated under the different operating conditions of the vehicle. The geometric dimensions and the dynamic stiffness coefficients of the SS, RS, and AS in the NSS are optimized by the genetic algorithm to further enhance the vehicle’s ride comfort. The performance of the optimal SS (OSS), the optimal RS (ORS), and the optimal AS (OAS) in the NSS is assessed through the weight Root-Mean-Square value of the deformation of the driver’s seat suspension system ( zwsb) and the driver’s seat acceleration response ([Formula: see text]). The research shows that with the NSS added into the driver’s seat suspension system, the driver’s ride comfort and the deformation of the driver’s seat suspension system are remarkably improved compared to the driver’s seat suspension system without the NSS. Additionally, the design parameters of the SS, RS, and AS in the NSS also significantly influence their isolation performance. With using the OSS, ORS, and OAS in the NSS, the stable result of the non-dimensional restoring force of the OAS at a variable range of the non-dimensional deformation z is smaller than both the OSS and ORS. Therefore, the OAS better improves the driver’s ride comfort compared to both the OSS and ORS. In particular, the zwsb and [Formula: see text] with the OAS are remarkably decreased by 40.05% and 36.28% compared to the OSS; and by 62.57% and 86.66% in comparison without the NSS, respectively. Therefore, the OAS in the NSS should be applied to the driver’s seat suspension system to further ameliorate the vehicle’s ride quality.
The research has proposed three isolation models of the negative-stiffness-element (NSE), the damping-element (DE), and the NSE embedded to the small mass (NSE-SM) that was connected with the seat suspension to ameliorate the ride comfort of the driver. A vibration model of the vehicle and seat built under the random and bumpy excitations has been used for evaluating the isolation performance of the NSE, DE, and NSE-SM. The effect of the NSE, DE, and NSE-SM’s dynamic parameters on their isolation performance is then evaluated via the root-mean-square values of the seat displacement ( z ws) and seat acceleration ( a ws). Based on the genetic algorithm, the NSE, DE, and NSE-SM’s dynamic parameters are optimized to fully reflect their isolation performance. The investigation result indicates that the driver’s ride comfort is slightly affected by the geometric dimension ratios of the NSE, DE, and NSE-SM, while the driver’s ride comfort is greatly affected by the damping and stiffness parameters; and the damping and stiffness ratios of the NSE, DE, and NSE-SM. With the optimized parameters of the NSE, DE, and NSE-SM, the simulation results under the different operating conditions of the vehicle show that the DE slightly improves the driver’s ride comfort. Conversely, both the NSE and NSE-SM greatly improve the driver’s ride comfort, especially the NSE-SM. Therefore, the model of the seat suspension embedded by the NSE-SM should be applied for improving the driver’s ride comfort.
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