Mounting System Research Articles

Analysis of an Isolation System with Vertical Spring-viscous Dampers in Horizontal and Vertical Ground Motion

This paper proposes a new vibration isolation mounting system, with spherical balls and vertical spring dampers, that provides seismic protection from horizontal and vertical ground excitation. To characterize the system, nonlinear governing equations are derived by considering the kinematics and interaction forces of the structures, and the dynamic characteristics of the design parameters are investigated by numerical analysis. The condition of contact stability for sustaining continuous friction of the isolation device is discussed, along with the design parameters. The vibration transfer characteristics are analyzed for the displacement transfer ratio obtained for the design parameters satisfying the sustainable contact condition, when the base is harmonically excited. The results confirm that the relative motion occurrence satisfies the conditional expression, and a jump in which the transfer ratio suddenly increases at a specific frequency is identified. Finally, design variables that are suitable for the horizontal and vertical acceleration of the El Centro earthquake are set, and a simulation confirms the vibration reduction effect in both the horizontal and vertical motions.

Influence of different mounting strategies on the random measurement error in industrial computed tomography

In order to perform measurements in industrial computed tomography (CT), the specimen in question has to be mounted on the kinematic system of the CT device. In principle this applies to all measuring machines, however, it is an especially critical step of a CT measurement as there are no companies providing mounting systems in particular for CT applications that have been tried and tested by many years of usage. As a mounting system for CT applications should not interfere with x-ray beams to ensure an uncorrupted measurement, many users rely on special mountings cut from foam, 3D printed mounts or custom- made parts. However, there has not been a systematic survey on which mounting strategy leads to minimal random error in measurement results. Therefore, this paper aims at determining the influence of different mounting strategies on the random measurement error and image quality of the resulting scans. To this end, measurements of a defined test-object using different mountings are performed and compared with respect to these quality parameters. Finally, a recommendation for the optimal choice of a mounting system based on the results is given.

New hybrid between NSGA-III with multi-objective particle swarm optimization to multi-objective robust optimization design for Powertrain mount system of electric vehicles

In this study, a new methodology, hybrid NSGA-III with multi-objective particle swarm optimization (HNSGA-III&MOPSO), has been developed to design and achieve cost optimization of Powertrain mount system stiffness parameters. This problem is formalized as a multi-objective optimization problem involving six optimization objectives: mean square acceleration and mean square displacement of the Powertrain mount system. A hybrid HNSGA-III&MOPSO is proposed with the integration of multi-objective particle swarm optimization and a genetic algorithm (NSGA-III). Several benchmark functions are tested, and results reveal that the HNSGA-III&MOPSO is more efficient than the typical multi-objective particle swarm optimization, NSGA-III. Powertrain mount system stiffness parameter optimization with HNSGA-III&MOPSO is simulated, respectively. It proved the potential of the HNSGA-III&MOPSO for Powertrain mount system stiffness parameter optimization problem. The amplitude of the acceleration of the vehicle frame decreased by 22.8%, and the amplitude of the displacement of the vehicle frame reduced by 12.4% compared to the normal design case. The calculation time of the algorithm HNSGA-III&MOPSO is less than the algorithm NSGA-III, that is, 5 and 6 h, respectively, compared to the algorithm multi-objective particle swarm optimization.

Topology optimization and finite element analysis of a jet dragster engine mount

In a jet dragster race car, the engine mount is one of the important components of an engine sub-assembly. The mounting system is the primary interface between the jet engine and the vehicle chassi...

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

The technological developments in the field of image based sensing have led to a vast growth in the use of drones in various domains. The drone is usually equipped with an image sensor (camera) which collect images over the target area. These images are then post-processed to extract the important information. Efficiency and accuracy of the image based sensing are largely dependent on the captured image quality. Therefore, it is important to prevent the transmission of the drone vibrations to the camera. Most of the current camera mounting systems use passive rubber mounts for isolation. However, these mounts are effective only in vertical direction and essentially adds damping to the system which degrades the performance of the isolation at high frequency. In this paper, a multi-degree of freedom isolation system, based on a Stewart platform configuration, is proposed for drone camera stabilization. The important features of the proposed isolation system are — (i) high frequency roll-off, (ii) no use of flexible joints, (iii) uses non-contact voice coil actuator thus avoiding spurious resonances of the legs, (iv) adjustable stiffness, (v) 3D printed lightweight parts and (vi) centralized control using a single sensor (inertial measurement unit). A prototype of the proposed system has been manufactured and validated experimentally. The proposed isolation system is found to reduce the response of the isolation system near resonance without compromising performance at high frequency. The application of the isolation system can be easily extended to other fields which require high quality image acquisition.

A fully unprivileged CernVM-FS

The CernVM File System provides the software and container distribution backbone for most High Energy and Nuclear Physics experiments. It is implemented as a file system in user-space (Fuse) module, which permits its execution without any elevated privileges. Yet, mounting the file system in the first place is handled by a privileged suid helper program that is installed by the Fuse package on most systems. The privileged nature of the mount system call is a serious hindrance to running CernVM-FS on opportunistic resource and supercomputers. Fortunately, recent developments in the Linux kernel and in the Fuse user-space libraries enabled fully unprivileged mounting for Fuse file systems (as of RHEL 8), or at least outsourcing the privileged mount system call to a custom, external process. This opens the door to several, very appealing new ways to use CernVM-FS, such as a generally usable “super pilot” consisting of the pilot code bundled with Singularity and CernVM-FS, or the on-demand instantiation of unprivileged, ephemeral containers to publish new CernVM-FS content from anywhere. In this contribution, we discuss the integration of these new Linux features with CernVM-FS and show some of its most promising, new applications.

A new control method based on fuzzy controller, time delay estimation, deep learning, and non-dominated sorting genetic algorithm-III for powertrain mount system

This article presents a new control method based on fuzzy controller, time delay estimation, deep learning, and non-dominated sorting genetic algorithm-III for the nonlinear active mount systems. The proposed method, intelligent adapter fractions proportional–integral–derivative controller, is a smart combination of the time delay estimation control and intelligent fractions proportional–integral–derivative with adaptive control parameters following the speed range of engine rotation via the deep neural network with the optimal non-dominated sorting genetic algorithm-III deep learning algorithm. Besides, we proposed optimal fuzzy logic controller with optimal parameters via particle swarm optimization algorithm to control reciprocal compensation to eliminate errors for intelligent adapter fractions proportional–integral–derivative controller. The control objective is to deal with the classical conflict between minimizing engine vibration impacts on the chassis to increase the ride comfort and keeping the dynamic wheel load small to ensure the ride safety. The results of this control method are compared with that of traditional proportional–integral–derivative controller systems, optimal proportional–integral–derivative controller parameter adjustment using genetic algorithms, linear–quadratic regulator control algorithms, and passive drive system mounts. The results are tested in both time and frequency domains to verify the success of the proposed optimal fuzzy logic controller–intelligent adapter fractions proportional–integral–derivative control system. The results show that the proposed optimal fuzzy logic controller–intelligent adapter fractions proportional–integral–derivative control system of the active engine mount system gives very good results in comfort and softness when riding compared with other controllers.

New hybrid NSGA-III&SPEA/R to multi-object optimization in a half-car dynamic model

In this article, we conducted a new hybrid method between Non-dominated Sorting Genetic Algorithm II (NSGA-III) and SPEA/R (HNSGA-III&SPEA/R). This method is implemented to find the optimal values of the powertrain mount system stiffness parameters. This is the task of finding multi-objective optimization involving six simultaneous optimization goals: mean square acceleration and mean square displacement of the powertrain mount system. A hybrid HNSGA-III&SPEA/R has proposed with the integration of Strength Pareto evolutionary algorithm-based reference direction for Multi-objective (SPEA/R) and Many-objective optimization genetic algorithm (NSGA-III). Several benchmark functions are tested, and results reveal that the HNSGA-III&SPEA/R is more efficient than the typical SPEA/R and NSGA-III. Powertrain mount system stiffness parameters optimization with HNSGA-III&SPEA/R is simulated. It proved the potential of the HNSGA-III&SPEA/R for powertrain mount system stiffness parameter optimization problem.

Optimum design of a 740 mm-long lens mount for a large-area and high-speed line beam proximity exposure

Proximity exposure with line beam scanning can be an alternative to traditional proximity exposure for a fast, high-resolution, large-area patterning. The optical elements used for shaping the line beams have a very large length-to-cross-sectional area ratio, so even small misalignment has a large effect on the optical path. In this study, a lens mount system based on kinematic coupling was established to accurately locate and align the line beam lens. Finite element models of the line beam lens and the mount were constructed, and then static structural simulations were performed. Optical paths concerning lens deformation and misalignment were calculated based on the vector equations for lines, surfaces, and Snell's law. An optimum design process based on the Taguchi method was carried out to minimize the difference between the actual optical arrival location and the target location. The stiffness and clamping force of the clamp part and support positions were selected as design variables, and the geometrical uncertainties of the lens supports was treated as error factors. A cross product array was constructed for each design variable and error factor, and then a total of 36 simulations were performed. Finally, the influence of each design variable on the optical path was analyzed, and the optimum conditions for the design variables, minimizing the error factor, were determined. As a result, the optical path error due to the geometrical uncertainty was reduced by approximately 30% compared to initial design.

Influence of damping coefficient into engine rubber mounting system on vehicle ride comfort

This study presents a method to improve vehicle ride comfort using additional damping coefficient values for an internal combustion engine (ICE) rubber mounting system. To analyze the effect of the adding damping coefficient values into the rubber mounting system on vehicle ride comfort, a full-vehicle vibration model with 10 degrees of freedom is established under the combination of road surface roughness and ICE excitations. The damping coefficient values are added into ICE rubber mounting system which are respectively analyzed and evaluated according to the international standard ISO 2631-1 (1997). The study results do not only evaluate the influence of the adding damping coefficients on vehicle ride comfort but also suggest the optimal design solution for ICE mounting system to improve vehicle ride comfort.

Multi-objective genetic algorithm in reliability-based design optimization with sequential statistical modeling: an application to design of engine mounting

The present study explores reliability-based design optimization (RBDO) using multi-objective genetic algorithm (MOGA) in the context of practical engineering design. The reliability analysis is carried out using a most probable point-based method with first-order sensitivities. As an effective optimization approach, the two methods MOGA and RBDO are integrated to propose a multi-objective reliability-based design optimization (MORBDO). For considering the uncertainty propagation of reliable constraints, sequential statistical modeling is employed to estimate the appropriate distribution of probabilistic design variables. The present study also applies a multiresponse performance index based on the dimension reduction technique with a quality loss function. After verifying the MORBDO results using simulations on numerical problem, these techniques are applied to an automotive engine mounting system in the hierarchically decomposed problem of minimizing both the difference between the torque roll axis and the elastic roll axis and also the vibration transmissibility under mode purity and frequency requirements. The probabilistic design results indicate that the MORBDO results successfully identify more reliable and conservative optimized solutions than the deterministic results for a given reliability, and the failure probability is compared using a Monte Carlo simulation.

Investigation on a semi-active hydraulic damping strut to reduce vehicle in situ shift vibration

In order to reduce the shock and vibration caused by torque disturbance of the gearbox in vehicles equipped with automatic transmission in the process of in situ shift, a novel semi-active hydraulic damping strut is introduced in the powertrain mounting system. The dynamic response evaluation indexes of vehicle in situ shift are put forward, and a 13-degree of freedom vehicle dynamic model including the semi-active hydraulic damping strut is established. The optimized dynamic characteristic parameters are acquired according to the principle of sharing force and the 13-degree of freedom vehicle dynamic model. The dynamic response evaluation indexes with and without the semi-active hydraulic damping strut are calculated using the 13-degree of freedom vehicle dynamic model in the process of in situ shift, and the calculation results show that the vibration of a vehicle can be reduced by the introduction of a semi-active hydraulic damping strut. Experiments are carried out to analyze the vibration response of the vehicle with and without a semi-active hydraulic damping strut, and the results show that the shock and vibration of the vehicle are reduced by introducing the semi-active hydraulic damping strut. The theoretical calculation values of active-side acceleration of the engine mount and torque strut are consistent with the experimental values, which show that the 13-degree of freedom vehicle dynamic model is reasonable.

A robust active control scheme for automotive engine vibration based on disturbance observer

In this paper, a combination of robust active controller and disturbance observer for active engine mounts is proposed as an effective way to improve driver comfort for automotive vehicles. First, a robust controller based on μ-synthesis is designed for the engine mounting system in the presence of parametric uncertainty. The effectiveness of the μ-controller in satisfying robust stability and performance is demonstrated. To further improve the performance of vibration control, an observer is designed where all system states and unknown disturbances are estimated. The estimated disturbance forces are used as control signals to cancel the unwanted effects of these disturbances. The results of the system behavior at different engine speeds clearly demonstrate a significant improvement of the system performance as a result of applying the system observer.

Performance evaluation of a novel intelligent distributed mounting system for marine mechanical equipment

Machinery mounting system is one of the most significant vibration and noise attenuation technology for marine mechanical equipment. A novel intelligent mounting system having distributed intermediate mass light in weight, intelligent in function and small in installation space is presented. The performance of the novel distributed mounting system is analysed using a simplified but efficient theoretical model. The influences of system designing parameters including weight of intermediate mass, stiffness of isolators and mechanical impedance of foundation on vibration isolation efficiency are analysed. A scale experimental prototype was established to verify the accuracy of theoretical analysis. Conclusions of theoretical and experimental analysis reveal that stiffness of isolators should be chosen as small as possible under the premise of stability of system. The intermediate mass should be chosen within a reasonable range based on the index requested on isolation efficiency because substantial increase on intermediate mass will not lead to substantial increase on vibration isolation efficiency which is different from conventional methods to obtain considerable isolation efficiency. And intelligent safety mechanism designed to ensure the ultimate operation safety of equipment was introduced. The novel intelligent mounting system is qualified with the need of practical projects on vibration isolation efficiency and reliability standard, providing a new way for vibration engineer to choose when making mounting plan for marine machinery equipment.

Nonlinear modeling and verification of an electromagnetic actuator with consideration of friction

To acquire a perfect vibration isolating performance in the active controlled mount system, a precise model for the actuator is required. In this study, we introduce a novel nonlinear lumped parameter model of the electromagnetic actuator for the engine’s idling or low-speed condition. The model considers not only the nonlinear characteristics caused by the reluctant force, cogging force, and magnetic saturation but also the friction between the mover and the supporting parts. The LuGre friction model is employed to describe the friction during the mover’s reciprocating motion. Then, the quasi-static actuator force of the electromagnetic actuator under constant currents is measured to identify the nonlinear parameters of the model, so is the nonstationary actuator force measured to identify the parameters of the LuGre friction model. Finally, a specific experimental scheme is proposed for validation, in which a suspended ring-shaped iron is added as the actuator’s load. This configuration limits the displacement of the mover effectively, allowing the actuator operate at a frequency of 20–50 Hz and at a peak actuator force of about 8 N, which is close to the actual working condition of the active controlled mount in the engine’s idling or low-speed condition. The results show that the proposed lumped parameter model is able to predict the dynamic characteristics of the actuator precisely. The root mean square errors of the current and actuator force are relatively 3% and 10%, respectively.

Improving ride comfort for vibratory roller utilizing semi-active hydraulic cab mounts with control optimization

Hydraulic mounts can provide a better vibration attenuation performance than elastomeric mounts especially in the low frequency range. However, it is incapable of providing a response-dependent damper for the mount system to improve the ride comfort. In this study, a semi-active hydraulic cab mount (SHM) with control optimization was designed to improve ride comfort for the heavy vibratory roller. And a 7-DOF non-linear dynamic model of the vehicle was established for evaluation of the performance of hydraulic cab mounts based on different control optimization algorithms. To simulate roughness height the ISO level D road surface and deformed soil model were employed under the compaction work condition. The optimization study for two performance objectives as measured by responses of the vertical driver’s seat and cab pitch angle was carried out. It was shown that the SHM optimized by the fuzzy logic and proportional, integral, derivative controller methods (FLC-PID) giving best optimum values of the objective vector as compare to by multi-objective genetic algorithm (MOGA) and PID controller based on genetic algorithm (GA-PID).

An efficient analysis and optimization method for the powertrain mounting system with hybrid random and interval uncertainties

In the traditional uncertainty-based analyses and optimizations of the automotive powertrain mounting system (PMS), uncertain parameters are usually treated as either random variables or interval variables. In this article, an efficient analysis and optimization method is proposed for PMS designs with hybrid random and interval uncertainties. An efficient analysis method, named the hybrid perturbation–finite difference method (HPFDM), is first derived to calculate the uncertain responses of the natural frequencies (NFs) and the decoupling ratios (DRs) of the PMS. Then, an optimization model of the PMS with hybrid uncertainties is established based on the HPFDM, where the uncertain responses of the relevant NFs and DRs are taken to create optimization constraints and optimization objectives. With the aid of the HPFDM, the nested optimization model can be solved efficiently. Finally, a numerical example is presented to demonstrate the effectiveness of the proposed method.

An efficient analysis and optimization method for powertrain mounting systems involving interval uncertainty

Uncertainty widely exists in the powertrain mounting system of a vehicle. The traditional analysis and optimization methods for powertrain mounting system design are often based on deterministic or random models. In this study, an efficient analysis and optimization method is developed for powertrain mounting system design involving interval uncertainty. In the proposed method, the uncertain parameters of powertrain mounting system are treated as interval variables, and an efficient method called as Chebyshev-Vertex method is developed to fast calculate the lower and upper bounds of the natural frequencies and decoupling ratios of powertrain mounting system. Monte-Carlo method is taken as a reference method to verify the calculation. Then, an optimization model is established based on Chebyshev-Vertex method, in which the interval responses of decoupling ratios are used to build up optimization objective while the interval responses of natural frequencies and decoupling ratios are taken to create optimization constraints. The optimization model of the powertrain mounting system with interval parameters is generally a double-loop nested problem, and it is rather time-consuming on calculation. However, based on Chebyshev-Vertex method, the optimization model can be approximately simplified into a single-loop one and the calculation efficiency is greatly improved. A numerical example is provided to demonstrate the effectiveness of the proposed method on the analysis and optimization design of the powertrain mounting system involving interval uncertainty.

Vibration reduction against modulated excitation using multichannel NLMS algorithm for a structure with three active paths between plates

Electric and hybrid vehicle engines produce a complex spectrum of vibration and noise. Various active mounting techniques have been developed to isolate them. These are designed to continuously control the dynamic characteristics of the mounts and improve the noise, vibration, and harshness (NVH) performance under various operating conditions. Active mounts have attracted attention as replacement for existing mounts by simultaneously realizing static and dynamic stiffness, which is important for supporting an engine. Therefore, this study focuses on the vibration isolation performance of the upper plate and lower plate when the structure, including the active mounting system, is applied to multifrequency excitation. The overall modeling is based on the lumped parameter model, and the input signal is applied to the amplitude modulated and frequency modulated signals. The adaptive filter is applied for control, and the normalization least mean square (NLMS) algorithm, which is commonly used in research, is extended to a multi-NLMS algorithm. It is shown that when multifrequency input is applied, the adaptive filter is effectively applied to the active mounting system to control vibration.

Method for experimental determination of the coefficients of stiffness and damping of rubber insulators

Rubber insulators are used in many dynamic systems to reduce the impact of vibrations. They are located in the mount system of the engine, gearbox, suspension, et cetera. Two of their characteristics are the dynamic coefficients of stiffness and damping. These characteristics are influenced by the frequency of vibration, the preload in the mounts and the hardness of the rubber. The characteristics of the rubber insulators in the suspension elements also influence the handling of the vehicle. In the work are investigated rubber insulators from different suspensions in the frequency range 70 - 220 Hz. This frequency range contains the resonant frequencies of the radial type pneumatic tyre due its interference with the road surface. The purpose of the work is to develop a method for obtaining the dynamic coefficients of stiffness and damping of the rubber insulators.