Torsional Suspension Research Articles

Analysing the Effect of Chassis Torsional Flexibility on the Rollover Threshold of a Multi-Purpose Agricultural Vehicle

Multi-purpose agricultural tractors are vehicles that are usually involved in different operations, including road maintenance in small villages and cultivation of small agricultural plots, particularly in mountainous areas. These vehicles typically feature narrow tracks to enhance manoeuvrability, making rollover stability a critical consideration in operational settings. This characteristic arises from the interplay between the suspension and vehicle chassis. This paper introduces a numerical multi-body model designed to replicate the dynamics of a multi-purpose tractor with a torsional chassis. Model parameters were derived through experimental measurements conducted on an actual vehicle. Static measurements were performed to assess tire and suspension stiffness while tilting tests were performed to establish the static rollover limit of the vehicle. Dynamic tests conducted on a four-post test rig characterised the vehicle’s dynamics. The validated model was utilised to explore the vehicle’s stability by reproducing the static rollover tests and simulating the vehicle’s performance under working conditions on a banked road. The vehicle rollover stability was studied by performing a sensitivity analysis that considered both chassis torsional stiffness and suspension stiffness under different loading conditions. The results indicate a trade-off between frame and suspension stiffnesses that enhances overall vehicle stability.

Quantitative research on vehicle energy consumptions based on the longitudinal-vertical dynamics of the tracked vehicle

In this paper, a longitudinal-vertical coupling tracked vehicle dynamic model is established to simultaneously describe the longitudinal, vertical and pitch dynamic responses of the tracked vehicle under off-road conditions. The road wheels are subjected to variable longitudinal-vertical forces due to the terrain unevenness and the excitations are transmitted to the vehicle body through the torsion suspension system. An experiment by means of a scaled-down tracked vehicle was carried out. The comparisons between the field test results and simulation results verified the effectiveness of the coupling dynamic model on predicting the vehicle dynamics. Taking advantage of the coupling tracked vehicle dynamic model, the energy computation formulas are further derived to quantitatively study the vehicle energy consumptions. The energy consumption distributions of the tracked vehicle on uneven road and paved road at different velocities are analysed. The computation results indicate that the developed energy computation method is reliable on predicting the energy generation and dissipation of the tracked vehicle. It has been found that the proportions of damping dissipation energy and road roughness caused energy consumption to total energy consumption are both higher at a greater speed.

The effect of the coupling radii of the elements of membrane MEMS systems on their own oscillations

The regularities of changes in the frequencies and forms of natural oscillations and the stress state of a silicon sensing element of a mechanical MEMS accelerometer system depending on changes in the radii of rounding of structural elements are considered. An increase in the natural frequencies of the system and stresses in torsion suspensions has been established with an increase in the radii of the coupling of the suspension with the frame and the inertial mass. The rounding of the shape of the suspensions in the plan leads to a decrease in natural frequencies and an increase in stresses arising from oscillatory movements. The fact of localization of high-frequency oscillation forms in the inertial mass is confirmed. A set of design solutions is recommended to control the vibration state of the MEMS accelerometer mechanical system.

Modelling and analysis of longitudinal-vertical coupling dynamics for the tracked vehicle on uneven roads

In this paper, a longitudinal-vertical coupling dynamic model of a tracked vehicle under uneven road conditions is established. The torsion suspension forces and torques generated by the torsion bar springs and torsion shock absorbers are considered in the present model. The tracked vehicle’s longitudinal acceleration and velocity change at the same time as the vehicle heaves under the excitation of uneven road terrain. The vehicle’s longitudinal-vertical coupling dynamics are explained elementarily by analysing the longitudinal and vertical dynamics of a road wheel based on the road wheel force model. From the coupling tracked vehicle model, the dynamic responses of the vehicle in the vertical and pitch directions as well as the longitudinal direction are investigated. The vehicle dynamics characteristics are compared with those obtained by Recurdyn simulation. The results indicate that the proposed dynamic model performs well in predicting the dynamic characteristics of the tracked vehicle on uneven roads. By means of the coupling dynamic model, the influences of vehicle speed and road conditions on the vehicle’s longitudinal dynamics are further studied. It has been found that both a higher velocity and a larger roughness coefficient will lead to a negative longitudinal acceleration with larger absolute value.

РАЗРАБОТКА И МОДЕЛИРОВАНИЕ МАГНИТООПТИЧЕСКОГО ДАТЧИКА ГРАДИЕНТА МАГНИТНОГО ПОЛЯ С ТОРСИОННЫМ ПОДВЕСОМ ЧУВСТВИТЕЛЬНОГО ЭЛЕМЕНТА

The work has been done to simulate and search for a design solution for a magneto-optical sensor of a magnetic field gradient with a torsion suspension of a sensitive element. A mathematical model has been developed and simulation in the Wolfram Mathematica software environment has been performed. A comparison of air, liquid and magnetic-induction dampers has been made and a selection of the most effective solution has been carried out. The results of the analysis have shown that the most effective solution is the magnetic-induction damper, which allows changing of transition processes duration without direct affection on the sensitive element. Adjustment of the transient process velocity allowed achieving optimal system reaction time. The object of the study is the sensor of the magnetic field gradient with the torsion suspension of the sensitive element. The subject of research is physical processes with a magnetic field gradient sensor with a sensible torsion suspension when changing the external magnetic field. Research objective: development of basic design solutions, modeling, and analysis of the magneto-optical sensor of the magnetic field gradient with the torsion suspension of the sensitive element.

Research on Vehicle Damping Control Strategy Based on In-Arm Torsional Electromagnetic Active Suspension

This paper proposes a new control strategy based on the In-Arm Torsional Electromagnetic Active Suspension (ITEAS), which can improve the vehicle ride comfort through adjusting the damper in ITEAS to optimize the kinetic characteristics of the vehicle composed by two ITEAS systems. Firstly, the structure and principle of the new type system is introduced followed by the description of the vehicle and the damper in ITEAS. Secondly, according to theoretical mechanics and fluid mechanics, the dynamic model of ITEAS system and the hydraulic model of shock absorber are established under forced vibration. Then, the PID control simulation model of the front suspension is established in AMESIM with a passive model as reference, due to the special assemble features of the vehicle. The rear suspension adopts predictive control method and the simulation model is built in MATLAB/SIMULINK, whose theory can be summarized as adjusting the duty ratio of the valve in damper to improve the stability of the vehicle under the condition that the road surface information is already known. Lastly, this paper tests the suspension characteristics on the MTS bench, which verifies the proposed control method improves the ride comfort performance and the feasibility of predictive system.

Experimental comparison of smooth movement of an agricultural tractor with balancer suspension and torsion bar suspension

One of the reasons for the increased fatigue of tracked agricultural tractor operators is vibration. Reducing overall vibration is possible due to a change in suspension. All agricultural tracked tractors are equipped with an elastic balancing suspension, as a rule. Kharkov Tractor Plant has released an experimental batch of tractors with torsion bar suspension. The aim of this study was to determine the effect of the type of suspension on the smooth movement of the tractor. The experiment considered the real modes of operation of the tractor: plowing the ground in first and fourth gears, as well as the transport mode of movement. As a result of the tests, it was determined that the tractor with torsion suspension provides better ride comfort in transport mode. The torsion bar suspension has an advantage in the frequency range of 0.5–4 Hz, while the balancer suspension has an advantage in the high frequency range of 4–12 Hz when plowing the ground. The level of vibration acceleration of the floor of the tractor cab does not depend on the type of suspension in the frequency range above 12 Hz.

Design and simulation high aspect ratio torsion suspension of MEMS z-axis accelerometer

This paper presents new design torsion suspension of MEMS z-axis accelerometer. These prototypes Z-axis accelerometer are based on pantograph lever structure is out-of-plane devices. The results of finite element analysis of the structure are presented.

The research and verification of In-Arm Torsional Electromagnetic Active Suspension

This paper designs and manufactures a new type of arm suspension institution named In-Arm Torsional Electromagnetic Active Suspension (ITEAS) according to the structure and characteristic. The paper introduces the function and application scenarios of ITEAS and narrates the research value and scientific significance of the system. At first, the structure and principle of ITEAS are presented briefly, based on which the mathematical model of ITEAS suspension and height adjustment is built and analyzed. Next, the paper studies three critical components of ITEAS respectively. The mathematical solution is found to calculate the stiffness of the torsion bar. The structure and hydrodynamic model of the vane damper is researched, and the simulation model of the absorber is built in AMESim. The paper studies the theoretical principle of height adjustment and obtains the frequency characteristic of “Motor-Load” through the transfer function solved in MATLAB. Therefore, simulation models are built in AMESim in allusion to the three functions in the next chapter to verify the suspension characteristic, the height adjustment and the active displacement control of ITEAS independently. At last, several experiments are conducted on the test bench to check the feasibility of ITEAS. The results show that ITEAS is capable of being used as a vehicle suspension system and has a good impact on mitigation ability under road surface excitation, which enables us to adjust the body height and control the displacement actively according to the road condition.

On using the rotor acceleration mode to increase the accuracy of a two-stage gyrocompass

The article considers a two-stage gyrocompass with a rigid torsion suspension of the moving part. The principle of its action is based on balancing the elastic moment of the torsion bars with the gyroscopic moment. When this condition is met, the azimuth of the steady-state position of the rotor axis is calculated from the known kinetic moment , latitude and angular rigidity of the torsion bars, and the measured angle of rotation of the moving part of the gyroscope relative to its initial position. The “aging of the material” of the torsion bars, the effect of temperature on them, etc., leads to an uncontrolled change in the angular stiffness of the torsion bars, which, in turn, leads to an error in determining the position of the meridian.
 A method is proposed for determining the position of the meridian under conditions when the angular stiffness of the torsion is unknown. The method involves observing the motion of the gyroscope in a mode where the kinetic momentum changes linearly (the rotor accelerates). This movement is associated with the movement of the mathematical model of a two-stage gyrocompass in the same mode in the form of a differential equation of motion or in the form of its solution. As a result of minimizing the discrepancy between the real movement of the gyrocompass and the movement of its mathematical model, the “best estimate” of the parameter characterizing the position of the meridian and the “best estimate” of the angular stiffness of the torsion bars in this dimension are found. The results of modeling the corresponding information processing algorithms are considered. The advantages of the proposed method compared with traditional methods are indicated .

PARAMETRIC AMPLIFICATION OF THE SIGNALS IN THE ELECTROSTATIC GRAVIINERTIAL SENSOR

The challenges of designing simple, reliable, and high sensitivity graviinertial sensors are investigated. The sensor comprises a proof mass (PM) and is fixed with the housing by the elastic torsion suspension. PM makes small rotations under the action of gravitational forces or inertial forces.The distinctive features of the sensor are that the differential electrostatic system provides simultaneous reading of the desired signal and a control the torsional rigidity of suspension. In addition, the PM's rotational angular velocity transforms in the alternating current flowing through the capacitors. The presence of аlternating current (AC) voltage sources allows to get the parametric amplification of AC and significantly to improve the sensitivity of the sensor. In the simplest case, the sensor does not contain any feedback circuits.As an example, calculations of the micromechanical linear accelerations confirm that the periodic modulation of the coefficient of elastic stiffness of the suspension can significantly increase the sensitivity in the low frequency range, even in the absence of parametric resonance.Conditions for suppressions of background current participating in the output signal from a parametric pumping due to the asymmetry of the differential circuits are set. The frequency characteristics calculations of the sensor were carried out. It is expected, that the proposed sensor design ensures minimum noise level, which can be achievable in the graviinertial sensors. This design and the constructed theory can serve as a basis for creating a wide range of graviinertial devices operating on a movable base, for example, linear and angular accelerometer, gravity gradiometer, gravimeters, and inclinometers, which can be realized in the hybrid and in the micromechanical versions.

High-temperature thermomechanical treatment of hollow track pins of track-type machines

Very often the track pins of heavy-loaded track-type machines have insufficient fatigue safety margin, which causes their frequent breakage. One of the most rational solutions of the problem is the use of the high-temperature thermomechanical treatment of hot-rolled tubular billets for track pins. The analysis of the investigation results and engineering developments shows the possibility of improving the performance characteristic of hollow items (shafts, axis pins, track pins for a caterpillar mover, torsion suspensions of an undercarriage, etc.) by combining the thermomechanical treatment strengthening, various methods for improving the quality of the surface of tubular billets and the application of developed technological schemes in the factories producing tubular billets and items with diameter of Ø 10 ÷ 60 mm and the parameters of safety margin, precision and roughness required for the durability of the items.

Non-inertial low frequency vector sensor with torsional suspension

Conventional low frequency (from 10 Hz) velocity vector sensors utilize inertial approach using neutrally buoyant body with inertial sensor (accelerometer or moving coil geophone) inside. In order to achieve high sensitivity at the low frequencies these sensors must have relatively high inertia (mass). High mass leads to increased size (such as soccer ball) of the sensor in order to satisfy the condition of neutral buoyancy. The developed alternative non-inertial sensor utilizes torsional frictionless and extremely compliant suspension enabling very light and small, yet sensitive with low resonance sensor.

Synthesis of lever-blade dampers with enhanced mechanical structure

Introduction. The torsion suspensions are in wide use at contemporary automotive engineering. Such suspension operating elements are torsions: elastic bars, loaded with torsion force. The torsion bars are traditionally used as suspension structure of armored vehicles and cars. Moreover, torsion bars in automobile suspensions can be used both as the elastic element, and as an auxiliary device, i.e. a stabilizing bar, purposed to create the vehicle’s anti-roll resistance. Given that the torsion bar represents only an elastic element, the question of energy dissipation in suspensions including such bar is quite relevant. Firstly the problem of improving the torsion bar suspensions’ energy dissipation has been solved in the UK, when for the first time in parallel with the torsion bars the hydraulic piston shock absorbers have been installed. Due to this the suspension’s tendency to body longitudinal vibrations has been eliminated with greatly improved smoothness of suspension’s course. Currently, in addition to said hydraulic piston or gas shock absorbers, characterized by the movable member’s translational motion respectively to the housing in wide use at torsion suspension structure are lever shock absorbers (piston and vane types), characterized by the movable member’s rotational movement respectively to the housing. So on each side of the T-72 tank (USSR), the first, second and sixth suspensions are equipped with three lever-blade dampers (lever rotation angle of 87°) [1]. The existing hydraulic shock absorbers are usually implementing a performance, consisting of digression and regression areas, that is due to the throttle and the throttle-valve modes of operation. However, increasing demands to the suspension of the vehicle require the implementation of other performance characteristics not implementable when the existing shock absorbers’ passive constructions using due to their functionality limitations. An alternative in the form of active damping systems’ application with respect to their high cost and additional energy consumed is selective being welljustified only for original unique or cost-expensive equipment [2]. Therefore, the synthesis of passive

A MEMS Magnetometer Utilizing a NdFeB Magnet

A silicon MEMS magnetometer has been developed that utilizes a miniature NdFeB rare earth magnet attached to a silicon platform that is suspended by a dual torsional suspension system. An externally applied out-of-plane magnetic field will cause a magnetic torque to be produced between the external field and the NdFeB magnet, causing a deflection of the suspended silicon platform which can be sensed capacitively. The device measures 5.6 mm X 5.6 mm, with the silicon components being manufactured using bulk micromachining processes. The variable capacitive structure is realized by metalizing the bottom side of the suspended silicon platform to allow the silicon platform to serve as the top electrode. The bottom electrode is provided by a bare pad on a printed circuit board (PCB) to which the frame of the silicon device is attached. This results in a variable capacitance with a nominal value of approximately 3–6 pF, depending on the exact width of the gap. The variable capacitance is large enough to be converted into a variable frequency square wave using a CMOS relaxation oscillator circuit. To realize a practical device, multiple silicon components were manufactured. First, a silicon component had to be manufactured that included the anchor/frame, torsional springs, and suspended platform. To provide protection against destructive over-ranging of the mechanical components during very high accelerations or external magnetic fields, another silicon component was manufactured that provided mechanical stops at the limits of the useful displacement range. Two other components were also manufactured on the same wafer to provide for a cap over the device. Epoxy was used to bond the NdFeB magnet and the various silicon components together. The fabricated devices behaved similarly to their predicted theoretical performance, with a nominal oscillation frequency around 30 kHz, a sensitivity around 100 nT/Hz, and a noise floor around 50 nT. Several fabrication and assembly issues had to be solved in order to realize the device. The gap width of the capacitive structure is dependent on the thickness of the agent used to electrically connect the silicon anchor to a pad on a PCB. As it is desirable to minimize this gap width, some experimentation was required to find a suitable agent and assembly method. Additionally, the bonding agent used to attach the silicon anchor to the PCB must be applied at a temperature near the expected operating temperature of the device to prevent large stresses from being applied to the silicon frame due to the difference in the coefficients of thermal expansion between silicon and FR4. Also, during fabrication it was found that large flat areas, where a very uniform etch is critical, required wet KOH etching, while deep reactive ion etching could be used for areas where depth and a high aspect ratio were important. Significance This MEMS sensor represents a novel configuration for sensing magnetic fields. Without much optimization, the sensor already exceeds the sensitivity of many commercially available Hall-effect based MEMS magnetometers. As MEMS magnetometers are less developed than alternative magnetometer technologies, they may have more opportunities for improvement.

ABOUT DETERMINING THE POSITION OF THE GEOGRAPHIC MERIDIAN THREE-STAGE PENDULUM GYROCOMPASS DURING ACCELERATION OF ITS ROTOR

The article considers three-stage pendulum gyrocompass ground with torsion suspension unmanaged sensor, equipped with high-precision digital angle sensor azimuthal position sensor and information processing unit. During processing of information isused an indirect method to get facts about initial deviations of dynamical systems.In the process of improving the instrument have revealed that a further increasing of accuracy due to the necessity to consider the following factors. During the measurement around the vertical axis of the sensor operates permanent uncontrolled moment due to operational reasons are different from measurement to measurement. Specified point shifts the center of oscillation of the azimuthal sensor, which is in accordance with the procedure identified azimuth northerly direction on a constant value. For self-compensation of this error have been proposed several methods based on measurements with different but fixed parameters of the device. However, these measures have extended more than twice the measurement process.In this article there is proposing to define the position of the geographic meridian based on the analysis of the azimuthal motion sensor gyro during acceleration of its rotor. The proposal can bring dual gain in reducing measurement time: at first, the rotor becomes "staff " rather than ballast gyro operation mode, as it was before; secondly, there is no need for special measures to combat harmful vertical moments, as the shift of the equilibrium caused by the action of the latter, is variable in time, which allows to determine the magnitude of harmful moment during a single measurement.

EXPERIMENTAL INVESTIGATION ON TORSION BAR SUSPENSION SYSTEM USING E- GLASS FIBRE REINFORCED COMPOSITE MATERIAL

The purpose of this study is to investigate torsion deflections and energy storage of the composite bar in torsion bar suspension system. In this experimental study, round solid steel bar is machined and wounded with E-Glass/ Epoxy were manufactured by filament winding process. The experiment was carried out on a torsion test machine, which was built specifically to investigate the static and dynamic characteristics of torsion spring bar used in vehicle suspension system. This paper provides fundamental knowledge of torsion test and significant parameters such as torque, modulus of resilience in torsion and angle of twist has been highlighted. The torsion deflections were obtained experimentally. The results of experimental study are compared with the conventional torsion suspension system.

A MEMS DC Current Sensor Utilizing Neodymium Rare Earth Magnets

A silicon MEMS DC current sensor has been developed that utilizes a miniature NdFeB rare earth magnet attached to a silicon platform that is suspended by a dual torsional suspension system. An externally applied out-of-plane magnetic field, such as that produced by a DC current flowing through a nearby current trace, will cause a magnetic torque to be produced between the external field and the NdFeB magnet, causing a deflection of the suspended silicon platform which can be sensed capacitively. The device measures 5.6 mm X 5.6 mm, with the silicon components being manufactured using bulk micromachining processes. The variable capacitive structure is realized by metalizing the bottom side of the suspended silicon platform to allow the silicon platform to serve as the top electrode. The bottom electrode is provided by a bare pad on a printed circuit board (PCB) to which the frame of the silicon device is attached. This results in a variable capacitance with a nominal value of approximately 3–6 pF, depending on the exact width of the gap. The variable capacitance is large enough to be converted into a variable frequency square wave using just a simple CMOS relaxation oscillator circuit. To realize a practical device, multiple silicon components were manufactured. First, a silicon component had to be manufactured that included the anchor/frame, torsion springs, and suspended platform. To provide protection against destructive over-ranging of the mechanical components during very high accelerations or external magnetic fields, another silicon component was manufactured that provided mechanical stops at the limits of the useful displacement range. Two other components were also manufactured on the same die to provide for a cap over the device to seal it from the outside environment. Epoxy was used to bond the NdFeB magnet and the various silicon components together. The devices fabricated proved to behave similarly to their performance as predicted by mathematical modeling, with a test current of +/− 5 A causing a variation in the oscillation frequency of the CMOS oscillator circuit of +/− 8 kHz, from a nominal frequency of 26 kHz. Several fabrication and assembly issues had to be solved in order to realize the device. The gap width of the capacitive structure is dependent on the thickness of the agent used to electrically connect the silicon anchor to a pad on a PCB. As it is desirable to minimize this gap width, some experimentation was required to find a suitable agent and assembly method. Additionally, the bonding agent used to attach the silicon anchor to the PCB must be applied at a temperature near the expected operating temperature of the device to prevent large stresses from being applied to the silicon frame through the difference in the coefficients of thermal expansion between silicon and FR4. Also, during fabrication it was found that large, flat areas where a very uniform etch is critical required wet KOH etching, while deep reactive ion etching could be used for areas where depth and high aspect ratio were important.

Complex Research of Perspective Suspension for Locomotives

<b> </b>In this article questions on creation and calculation of a perspective design of adaptive torsion suspension for the locomotives, including hydromechanical dampers of fluctuations of adaptive type. The design procedure of the main kinematic and geometrical characteristics on a locomotive example 2ТЭ10Л, supplied with the specified technical solutions, and studying of fluctuations and power loading of its running gears is offered. Thus, the dynamic settlement scheme on the basis of Foygt-Kelvin's elastic and viscous model is developed. The bench pilot studies, allowed to specify parameters and characteristics of the above-stated designs are carried out. Expected economic effect of possible introduction of development will make 850 thousand rubles a year on one locomotive. Materials of this article were discussed at various conferences of leading higher education institutions of the Russian Federation. Results of researches are recommended to design, research and machine-building structures for their possible use in practice.

Choosing the suspension for agricultural category 5(6) tractor with triangular tracked bypass

Application of independent torsional suspension on agricultural tractors of drawbar class 5(6) with a triangular tracked bypass is grounded.