Friction Clutch Research Articles

Advancing automobile dry clutch fault diagnosis through innovative imaging techniques and Vision transformer integration

The study investigates the significance of clutch condition monitoring in automotive transmissions to preempt mechanical failures, enhance efficiency, and mitigate risks to human safety and maintenance costs. It explores the integration of Vision Transformer (ViT) with imaging techniques, such as scalograms, spectrograms, polar plots, radar plots, and Hilbert-Huang transforms, to diagnose faults in dry friction clutches. By transforming vibration signals into image representations and utilizing ViT for fault classification, the study aims to identify the most effective imaging technique and optimal hyperparameters for accurate fault diagnosis. Experimental studies on a test rig with varying fault conditions demonstrate the effectiveness of ViT in diagnosing clutch faults when coupled with different image conversion techniques. The results highlight the potential of integrating spectrogram image processing with ViT, achieving a 100% accuracy in fault diagnosis for clutch systems, thus advancing the analysis of faults in clutch systems.

The CRITIC-AHP performance degradation staged fusion evaluation of wet clutch friction components

The performance of wet clutches plays a crucial role in the efficiency and durability of mechanical transmission systems. As a vital component of the clutch, the degradation of friction components directly affects its stability and reliability. To investigate the performance degradation of friction components, we establish a multi-indicator evaluation system and conduct an accelerated life test, which is validated by an accelerated model. Next, we build a Random Forest model to classify the friction stage. Criteria Importance through Intercriteria Correlation (CRITIC) and the Analytic Hierarchy Process (AHP) is proposed to assign weights for each degradation indicator during different stages. A Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) scoring method combines indicator weights to construct a CRITIC-AHP staged fusion evaluation model of friction components. Notably, the average relative error of the evaluation results of the model is 9.35%.

An enhanced analytical and numerical thermal model of frictional clutch system using functionally graded materials

Abstract When a component was built from a functionally graded material (FGM), the temperature of contact was determined using an analytical model (FGM). The analytical solution is applied using the concept of equivalent properties. In order to fully examine the dynamic of the equivalent property principle, a numerical analysis was done. The FGM (silicon carbide and aluminum) friction liner was used. It focuses on a few characteristics that have an impact, such as load, velocity, friction material type, and slip time, which appear in dimensionless form. The results show that for loads and velocities, the ratio of the rate of dissipation to the rate of generation of heat transfer is one, whereas the behavior differs for friction material and slip time. Furthermore, this study’s chosen FGM exhibits superior thermal behavior compared to Al and Sic, bolstering its viability as a friction liner in the clutch system.

On Dynamic Analysis and Prevention of Transmission Squawk in Wet Clutches

Abstract The genesis of clutch noise, encompassing squeaks, chatter, shudders, or judders, predominantly arises from friction-induced vibrations. As time progresses, the degradation of the clutch friction lining manifests due to diverse factors, such as the smearing of surface irregularities, elevated transmission fluid temperatures, fluctuating axial pressure, or aggressive shifting. Consequently, the slope of the friction curves tends to assume a negative gradient, giving rise to adverse damping effects like self-excited oscillations or stick-slip oscillations within the clutch pack. A lesser-discussed phenomenon, known as Squawking, occurs through analogous mechanisms discussed in this article. This article delves into investigating the occurrence of squawking noise observed in automatic transmission multi-disc clutches during low-speed up-shifts. The study discerns friction-induced vibrations as the primary contributor to squawk during the inertia phase of the clutch engagement cycle, a facet previously unidentified. During this phase, high-frequency weakly damped oscillating modes become self-excited due to the negative slope of the coefficient of friction versus slip speed curve. The coefficient of friction functions as negative damping during the inertia phase, where the energy dissipation from damping is insufficient to completely halt the oscillations, allowing them to persist at the natural frequency until clutch lock-up. Experimental data validates the proposed model and hypothesis, with results closely aligning with numerical simulations. The paper concludes by offering practical suggestions to prevent and mitigate squawk in automatic transmission wet clutches, with the aim of enhancing overall performance and reducing undesirable noise.

Application of Grey-Taguchi Method Optimizes the Structural Friction Clutch Disc

Application of Grey-Taguchi Method Optimizes the Structural Friction Clutch Disc

Deep learning based fault detection of automobile dry clutch system using spectrogram plots

Dry friction clutches are extremely important in the context of power transmission systems. Continuous exposure to extreme heat and loading makes clutch extremely susceptible to various faults. The timely detection and diagnosis of such faults are of utmost importance to prevent any damage to internal components and also helps in avoiding transmission system failures. In this research study, a novel approach that leverages the power of transfer learning (a famous deep learning technique) is proposed to diagnose multiple types of clutch faults including, worn release fingers, fractured pressure plates, deteriorated pressure plates, loss of friction material and distorted tangential strips using spectrogram plots. To train and validate the diagnostic system, vibration readings were taken from a specially designed test rig with the help of piezoelectric accelerometer while the clutch system was operated under different load conditions of 0 (no load), 5 and 10 kg This procedure of data collection was then repeated to acquire the vibration data for all of the fault conditions by replacing the good with fault components individually. These vibration signals were further processed and transformed into spectrogram plots that serves as the input data for the deep learning models considered. Fine-tuning techniques were applied on pretrained networks to maximise the prediction accuracy of the models to effectively determine and diagnose faults in the clutch system. For this study 12 pre-trained networks were chosen namely, Xception, InceptionResNet, DenseNet, AlexNet, VGG16, GoogLeNet, VGG19, ResNet101, ResNet50, InceptionV3, MobileNetV2 and ShuffleNet. To optimize the performance of deep learning models, a systematic adjustment of hyperparameters such as the train-test split ratio, learning rate, optimizer and batch size for each network model was carried out. Through careful experimentation and analysis, significant improvements in fault classification accuracy were achieved thereby enhancing the reliability and effectiveness of the diagnostic system. From the results it was noted that 100% classification accuracy was displayed by AlexNet (for the no load condition and the 10 kg load condition) and GoogLeNet (for 5 kg load condition) with extremely low computation times.

Finite element analysis of the thermal and thermo-mechanical coupling problems in the dry friction clutches using functionally graded material

Abstract The friction clutch is an important machine part in the torque transmission system, where it is responsible for gently transmitting the power from the engine to the gearbox and damping the tensional vibration. At the beginning of the engagement between the clutch’s elements, a large amount of heat is released due to frictional sliding between the elements of the clutch system, generating very high temperatures. In this work, the two- and three-dimensional finite element models were developed from scratch to explore the clutch disk’s temperature and contact pressure behaviors using an alternative frictional material such as functionally graded material (FGM). The two assumptions for the thermal loads were considered: uniform wear and uniform pressure assumptions. The thermal–structural problem for the new frictional material was solved numerically and then presented as the temperature distributions and the contact pressure at any instant of sliding time. Also, a comparison was made between the clutch system behaviors when using FGM with different frictional materials. The results showed that the FGM has superior results to the other available frictional materials.

Modeling and analysis of bending and torsional coupling vibration response of multi-piece wet friction clutch

Modeling and analysis of bending and torsional coupling vibration response of multi-piece wet friction clutch

ANALYSIS OF UNCONTROLLED WEAR IN THE AREA OFA BELLEVILLE SPRING OF A FRICTION TORSIONAL VIBRATIONDAMPER IN A MOTOR VEHICLE CLUTCH

The article describes the problem of excessive tribological wear of a torsional vibration damper built intoa single-disc friction clutch of a truck vehicle. In contrast to the controlled, design-based wear of damper’sfriction rings, i.e., wear whose kinetics are known and predictable, uncontrolled wear at Belleville springcontact surfaces effects in a premature decrease in the damper’s friction torque and, consequently, loss ofdurability. As a result of the analyses and experimental work, the causes of accelerated wear were identified.Sets of springs and friction rings from the 10 used vibration dampers that worked under similar operatingconditions but with different operating periods were used as the basic research material. The influence ofabrasive wear of Belleville springs on their load-deflection characteristic was identified. A comparativeanalysis of the characteristics of the new spring and the used springs is also presented to illustrate changes inthe axial load in the assemblies of the analyzed dampers.

Characteristics analysis and nonlinear control of a digital hydraulic pressure tracking system for high-speed helicopter wet friction clutch

The reliability and control precision of the engagement and disengagement of wet friction clutch are crucial to the transmission of high-speed helicopters. In contrast to the traditional proportional hydraulic system, the digital hydraulic system provides a viable solution due to the use of several fast switching valves (FSVs). In this research, a digital hydraulic pressure tracking system using two fast switching valve arrays (DHPTS-FSVA) is proposed and its nonlinear model is established. First, the static and dynamic characteristics of the DHPTS-FSVA are deeply analyzed by virtue of the half-bridge resistance theory. Moreover, a novel pressure control strategy is proposed, which consists of nonlinear adaptive control method, differential pulse width modulation (PWM) with pressure compensation, and logic allocation strategy of PWM duty ratio. Finally, comparative simulation and experimental results indicate that the maximum, average, and standard deviation of the errors are reduced by at least 16.1%, 45.1%, and 39.5%, respectively, at the tracking frequencies of 1 and 2 Hz, which proves that the proposed controller exhibits better tracking performance at low frequencies.

Research and construction of an adaptive drive with increased efficiency based on a balancing friction clutch

Presently, there is significant emphasis on researching the automation of processes, systems, and devices across scientific and technical fields. This emphasis extends notably to sectors like aerospace, robotics, and electric transportation technology. One effective approach to tackling the technical and design challenges of automating various technological tools and processes is through the implementation of adaptive systems. Specifically, achieving efficient and reliable power transmission in electric autonomous and mobile vehicles can be realized by employing an adaptive mechanical drive with two degrees of freedom. The adaptability of this two-mobile system is enabled by introducing an innovative continuous multi-speed drive design featuring an additional friction coupling. The primary attribute ensuring the reliability of this self-adjusting mechanical drive lies in its ability to autonomously adapt to external loads. This is made possible by a balancing friction coupling that establishes a connection between the frictional torque and the relative angular velocity.

РАЗРАБОТКА СПЕЧЕННОГО ФРИКЦИОННОГО МАТЕРИАЛА ДЛЯ ГИДРОТРАНСФОРМАТОРА ГМП САМОСВАЛОВ БЕЛАЗ

The torque converter is designed to transmit mechanical energy from the engine through a circulating fluid flow and automatically steplessly changes, within certain limits, the angular speed and transmitted torque depending on the load on the dump truck wheels. The torque converter makes it possible to achieve low speeds of the dump truck with increased traction on the drive wheels, ensures stable engine operation when the load changes, and also helps reduce dynamic loads in the dump truck transmission. The paper presents the results of a study of the effect of iron-chromium alloy powder ПХ30 (PKh30) on increasing the performance properties of sintered friction material for use in the torque converter locking clutch of a hydromechanical transmission. This is achieved due to the high physical and mechanical properties of PKh30, and the Cr23C6 layer formed during the sintering process with a thickness of up to 6 μm. It is established that the introduction of 10–40 vol.% of PKh30 powder helps to increase the friction coefficient from 0.042 to 0.075, with the maximum content being 28 %. Based on the data obtained, the composition of the composite friction material ФМ-15 (FM-15) was developed and patented. The manufactured friction discs, installed and operated in the hydromechanical transmission torque converter of the BELAZ-7555E mining dump truck with a load capacity of 60 tons, showed high performance properties. The developed composition of the friction material is also used in the friction clutches of the loading and hauling machine MoAZ-40751 with a load capacity of 16 tons and the loading and transport mine machine MoAZ-75851 with a load capacity of 50 tons with an electronic-hydraulic automatic control system. The study of tribological properties was carried out on a friction machine ИМ 58 (IM 58). The morphology of the friction surface was studied on a scanning electron microscope MIRA (Czech Republic) with an INCA 350 micro-X-ray spectral attachment from Oxford Instruments (United Kingdom). Phase composition was determined on an Ultima IV X-ray diffractometer of Rigaku Company (Japan) in CuKα radiation at an X-ray tube voltage of 40 kV, anode current of 40 mA.

Experimental Investigation of Thermal Effect on the Frictional Characteristics of HCC Friction Clutch Material

Increasing temperature due to frictional heat from sliding between contacting surfaces leads to increased wear and friction. Therefore, the researchers continue investigations to find the most suitable friction materials with good mechanical and thermal properties for frictional facings of clutch performance under this condition. In this research paper, the behavior and performance of the friction material HCC was studied under different normal load conditions (125, 175, 225, and 275 N) and different working environment temperatures (300 K and 390 K), where the rotation speed was 300 rpm. The results of the coefficient of friction and friction forces variation under different working conditions were analyzed and discussed in detail. XTM 500 tribometer test rig was used to perform the required tests, and the samples were made of the HCC friction material. The obtained results proved that the ambient temperature of the friction system has a significant negative effect on both the coefficient of friction and the force of friction. So, when the friction system's ambient temperature increases, the magnitude of the friction coefficient will decrease, and, thus, the transmitted torque will reduce too.

Dynamic coordinated control strategy of a dual-motor hybrid electric vehicle based on clutch friction torque observer

The hybrid power system with dual motors and multiple clutches experiences significant torque fluctuation during mode switching process due to the different torque response characteristics of the motor and engine. To address this issue, this paper focuses on the estimation of clutch friction torque and the development of dynamic coordinated control strategies for the components. Firstly, based on the dynamic model of the novel dual-motor hybrid electric vehicle, a torque observer based on the Kalman filter algorithm is developed to predict the friction torque generated in the clutch sliding friction stage. Secondly, the control strategies are developed for the mode switching process from single-motor to dual-motor and from dual-motor to parallel drive on a co-simulation platform. Thirdly, a power level Hardware-In-the-Loop test platform is built, and the performance of the designed control strategies is verified by the HIL platform. The results show that for the mode switching process from dual-motor to parallel drive, compared with the control strategy using the engine target speed, the control strategy based on engine idle speed proposed in this paper reduces the clutch sliding friction work and the maximum longitudinal jerk of the vehicle by 42.5% and 25.4%, respectively.

Influence of Groove Type on Friction Coefficient of Wet Friction Clutch Pair

Influence of Groove Type on Friction Coefficient of Wet Friction Clutch Pair

Study of the influence of dynamic loads in power unit mechanisms on the durability of transmission parts

The article considers the phenomena of dynamic loading of automotive transmission parts resulting from uneven operation of the internal combustion engine. Based on the information about the operability and causes of failures of the mechanisms of the power unit and transmission, a method for calculating loads is proposed, taking into account the impact of external and internal power factors. The expediency of differentiated consideration of dynamic loads in the transmission is shown. Keywords vehicle, power unit, friction clutch, torsional vibration damper, transmissions, dynamic load

Failures and methods of ensuring the service life of friction discs of gearboxes

The resource of a complex machine is determined by the resource of its units and components. As a result of the normal operation of energyintensive mobile vehicles of the K-7 series, it was established that the service life of the hydromechanical gearbox does not exceed 3000 engine hours, and the experimental probability of its failure is more than 0.55 of all machine units. The cause of failure of the hydromechanical gearbox is failure of the clutches and drive shaft. Failures of friction clutches are associated with significant overheating of the friction discs, their wear, welding and changes in spatial geometry. In the practice of normal operation of mobile machines, the drive shaft is repaired or replaced with a new one. Failure of friction discs occurs due to changes in spatial geometry (experimental probability of failure - 0.76), wear (experimental probability of failure - 0.63), destruction (experimental probability of failure - 0.38) and welding (experimental probability of failure - 0.34) friction discs. The work examines the use of the method of restoring friction discs by flat dimensional grinding, and conducts comparative life tests of restored friction discs.

Redesign of a Disc-on-Disc Computer Numerical Control Tribometer for a Wide-Range and Shudder-Resistant Operation

The paper presents a redesign of the custom disc-on-disc-type tribometer intended for the experimental characterization of the friction and wear of automotive dry clutch friction lining. The redesign is aimed at expanding the operating range at which the machine is not sensitive to shudder vibrations. This is achieved through a set of hardware and software upgrade measures. First, the natural frequency of the normal load-generation linear axis of the machine is increased by enlarging its bending stiffness and reducing the suspended mass. The former is realized by replacing the single, two-axial force/torque piezoelectric sensor with a set of three three-axial piezoelectric force sensors, adding a set of stiff linear guides, and reducing the lengths of the cantilevers of lateral forces acting on the linear axis guide system. The latter is accomplished by reducing the overall dimensions of the cooling disc and redesigning the thermal insulation components. The shudder sensitivity resistance is further reduced through individual normal force-readings-based adjustment of parallelism between friction contact surfaces and the increase in the stiffness of eccentrically positioned water-cooling pipes. Finally, the stability of the coefficient of friction and, consequently, the wear process are boosted by adjusting the control routines to minimize the circumferential and/or radial temperature gradients. These adjustments include the introduction of a clutch lock-up interval at the end of the clutch closing cycle, a minimum cooling delay inserted between two closing cycles, and maximum normal force demand of the clutch torque controller. The performance gain of the upgraded tribometer is demonstrated through a study of the dry clutch friction plate static wear experimental characterization for a wide range of operating conditions.

Evaluation of the technical and economic efficiency of controlled power distribution in transmissions of all-wheel drive trucks

BACKGROUD: Operating conditions of all-wheel drive trucks determine the probability of motion in conditions of uneven distribution of grip and rolling resistance for driven wheels of various axles and sides, which actualizes torque redistribution from an engine to the driven wheels. Reasonable power distribution between driven axles and wheels is important in order to improve the efficiency of all-wheel drive vehicles. AIMS: Evaluation of technical and economic efficiency of controlled power distribution in transmissions of all-wheel drive trucks with hydraulically controlled friction clutches. METHODS: A series of experiments was carried out on the basis of the KAMAZ-65222 with a differential lock control system with hydraulically driven friction clutches and a measuring and recording facility. The technical efficiency of control on differentials when driving in various road conditions was evaluated by the acceleration duration of the vehicle, the average speed of straight-line movement and when performing a maneuver, the parameters of the ground clearance, fuel efficiency and comparative loading of the wheels drive. RESULTS: The experiment confirmed the effectiveness of the algorithm for automatic control of the differential lock in the vehicle transmission in terms of cross-country abilities, workload and fuel efficiency. An increase up to 16.7% of the average speed in difficult road conditions, a decrease of the specific work of rolling resistance overcoming and a decrease in fuel consumption by 7–8% were recorded. CONCLUSION: Evaluation of efficiency of solutions for control on differentials in transmission of an all-wheel drive truck showed a significant increase in dynamic properties, cross-country abilities and fuel efficiency. Automatic change of the lock degree of differentials in the transmission when driving on a curved path and on uneven surface has a positive effect on transmission reliability and fuel efficiency, ensuring stability and maneuverability to remain stable. The expected economic effect is more than 206.3 thousand rubles. per year for one vehicle.

Research on nonlinear dynamic characteristics of high-speed gear in two-speed transmission system

The working performance and service life of the two-speed transmission system directly affects the performance and service life of helicopters and other equipment. One of the main tasks of the two-speed transmission system research is to improve its dynamic characteristics. For the two-speed transmission system in high-speed gear, a purely torsional nonlinear dynamic differential equation set considering the number of planetary gears, backlash, and clutch dynamic load is established by using the lumped parameter method, and the equations are dimensionless. Then the dimensionless differential equation set is solved by using the variable step-size fourth-order Runge–Kutta method, and the phase diagram and Poincare diagram of high-speed gear are obtained. By changing the dynamic friction coefficient of the friction clutch and the backlash of the gear pair, the influence of parameter change on the nonlinear dynamic characteristics of the system is analyzed. The results show that, with the increase of excitation frequency, the system has experienced single cycle, quasi-cycle, chaos, and double cycle, then changed from double cycle to chaotic motion, and then changed from chaotic motion to double cycle and single cycle motion in turn, and found the path to chaos. In the low-frequency band, reducing the friction coefficient of the friction clutch can reduce vibration amplitude; In the middle-frequency band, reducing the friction coefficient will make the system tend to unstable vibration. In the high-frequency band, it is a single-cycle movement, which is not affected by friction coefficient.