Stiffness Of Chassis Research Articles

Torsion test for a BAJA chassis using gyroscopic sensor and validation of CAE results

Vehicle dynamics plays an important role in vehicle stability, handling, ride quality and control. The dynamics of vehicle are also dependent on vehicle chassis and hence torsional stiffness of chassis is an important property to consider. High torsional stiffness results in less vibrations and better handling. This paper presents a torsional analysis of the chassis of an All-terrain Vehicle (ATV) used in BAJA SAE competition. Experimental analysis is performed where chassis is put under load and deflections are measured using a gyroscopic sensor. FEM simulations are performed and results are compared to calculate error. The paper concludes with ways to improve torsional stiffness.

Development and validation of vehicle wheel load scaling method for formation of durability testing loading cycle

For a vehicle durability study, performed with simulation or laboratory testing, impact on the object should be described as set of time-domain load signals, which reflects accelerated service modes of a vehicle operation. For a newly developed vehicle these load signals can be based on previously prepared loading cycle of a similar vehicle with use of the load scaling theory. Importance and certainty of the load scaling theory is approved by active use among foreign car makers and engineering centers. However, mathematical description of the theory and scaling procedure are strictly classified, despite of being based on fundamentals of vehicle dynamics. In this paper the method of scaling of time-domain wheel and driveline loads is suggested; the method is based on proportions of size and mass properties of the original and the new vehicles. Assumed that previously recorded loading cycle corresponds to the service life of a vehicle. It is worth noting that level of loading and damage accumulation, shown with scaled loading cycle and after first prototypes testing on a proving ground, will be different because of impact of chassis stiffness and damping properties. Suggested scaling theory is being studied in FSUE “NAMI” and is on the validation and verification stage. First completed experiments showed that a multiaxial test rig could perform the vehicle suspension loading cycle, obtained with the theory, with a satisfactory accuracy. This makes utilization of the theory limited to early stages of vehicle development.

Experimental analysis and Validation of torsional stiffness of a Tubular space frame chassis

Chassis is the pat that integrates all components of the vehicle and withstands the load. This load includes the weight of each component and the force that occurs when the vehicle is moving (acceleration, deceleration, and cornering). Chassis should also absorb energy when a collision occurs. The chassis provides a path for the forces that act on it. The suspension pickup points on the chassis are an important parameter in determining the suspension geometry of the vehicle. Torsional Stiffness is determined by the amount of Torque required to deflect the chassis by unit degree. The differences in forces from the suspension linkages that leads to a Twisting Moment. The moment will deflect the chassis about its Roll Axis. Predictable handling of a race car may be achieved by tailoring sis stiffness so that roll stiffness between sprung and un-sprung masses is due almost entirely to the suspension. In this work, the effects of overall chassis flexibility on roll stiffness will be determined using a finite element model (FEM) of a Formula Student Chassis and suspension. The Validation of the model is done by designing and fabricating a test rig to experimentally determine the Torsional Stiffness. The Suspension linkages are replaced with equivalent length solid tubes to eliminate the suspension compression. The test rig will be capable of applying force through one of the front wheel hubs, the other end of the front axle is kept at zero load. The deflection in chassis can be calibrated using a dial gauge.The objective of this project is to Design and optimize the design of the chassis for meeting the Chassis Stiffness target value to obtain the best Lateral Dynamics. Increasing the Torsional Rigidity will reduce the twist in the Chassis, improving vehicle handling by allowing the suspension components to control a larger percentage of a vehicle's kinematics.

Design and development of hybrid chassis for two wheeler motorcycle

The primary objective of this work is to design and develop a hybrid chassis for a two-wheeler motorcycle. Perimeter and Trellis are the most commonly used chassis types in motorcycles. Designing a new hybrid chassis of a two-wheeler for better high-speed stability and agility. Trellis frame is meant for good stiffness and rigidity, which is required for track scenarios, trellis frame consists of metal tubes arranged in triangulated reinforcements, these triangulated trusses eliminate additional resonance frequencies. While a Perimeter frame has a bit of flex and are compact in nature which is used for road-going scenarios. However, chassis stiffness is the most fascinating area of chassis design, as it reduces the overall vibrations induced in a frame which helps in having multiple ways to mount the engine depending on the resonance factors. Engineers want the frame and ancillaries to offer excellent longitudinal stiffness, so the bike stays straight and stable while pulling 1.5g during braking, and they also want enough stiffness so the bike reacts to rider steering inputs. By combining both the parameters and characteristics of perimeter and trellis frame, vibrations can be reduced and both stability and agility are achieved.

Stress Relaxation of a Sport Utility Vehicle Chassis Using a Dynamic Force Counteracting Approach

Structural failures in a Chinese sport utility vehicle (SUV) Land-wind X6 chassis were reported in recent years, thus, it is meaningful to conduct trouble-shooting and effective optimization to improve the chassis. Stress relaxation of the Land-wind X6 chassis using a novel dynamic force counteracting approach was carried out in this study. Finite Element Analysis (FEA) model of the chassis was firstly established and theoretical modal analysis was performed using the FEA model, experimental modal analysis was followed to validate the theoretical modal analysis and the FEA model. Further static and local stress analyses demonstrate that irrational designs between the longitudinal beams and the suspension components lead to inadequate stiffness and excessive stress concentrations which would cause fatigue and structural failure when the SUV chassis is subject to complex and severe excitations. A novel dynamic forces counteracting approach was introduced to optimize the chassis structure, FEA results show that excessive stress concentrations were obviously eliminated and the chassis stiffness, especially the torsional stiffness was greatly improved after optimization, followed industrial implementation also verifies that the FEA-based study and product optimization performed in this work are successful and significant.

Investigation into wear mechanisms of the bearing raceway used in bucket wheel excavators

This article presents the macro- and microstructural analysis of bearing raceways. Raceways of bearings, taken from two machines which had worked 100,000 and 30,000h, were examined. This provided crucial information on the exploitation history of both bearings, which is especially important for the future design process. After these initial macroscopic observations, it was determined which areas of the bearing had been most severely worn. This was indicated by the areas in which the chassis stiffness was highest. Further microscopic analysis of the individual bearing sections was useful for the identification of the dominating, destructive mechanisms in these areas.

Stress and Modal Analysis Assessment of Race Cars Chassis Structure

A simulation investigation was conducted to compare and validate results for using bended and non-bended chassis structure for race cars. In this study, the basic engineering design criteria which are material selection, type of material used and production processes were presented. Modal analysis was used to validate the effect of chassis stiffness between the two different frames which is bended and non-bended frame using torsional and bending loads. The results reveals that the maximum displacement and Von Misses stress of the frame occur at the non-bended frame, instead of the bended frame with the value of 539.93 mm and 4.67 x 1010 Nm2 respectively. However, the critical area occurs on the main roll bar instead of on the frame structure itself. It was found that in the bended frame, the maximum Von Misses stress occurs at the rear section of the frame structure, which indicates possible chassis failure at given frequency of 62.16 Hz. The results indicate that there is only slight difference in the natural frequencies for both frames and the modeshape of both frames starts with torsional mode. For the second modeshape of the frames, the non-bended frame still remain having the torsional mode while the bended frame start to have the bending mode. The results presented here may facilitate improvements in the race car frame where the non-bended frame is having better structural frame than the bended frame. This was proved by the bended frame had a changed of modeshape from torsional mode to bending mode. The significance of the results indicates that the bended frame has less stiffness than the non-bended frame and it is not permittable for a race car frame.