The brake system is critical for ensuring safe driving and has been the focus of development for many years. Pneumatic braking technology is commonly used in heavy vehicles,but it results in energy wastage and high service costs. Some countries mandate auxiliarybraking systems to assist in stopping the vehicle in addition to service brakes. One suchsystem is the regenerative braking system, which captures kinetic energy from braking andconverts it into electrical energy. Retarders are another commonly used auxiliary brakingsystem. These systems are essential due to heavy vehicle weight, which can weaken servicebrake performance.This thesis focuses on estimating net forces on the truck’s driven axle to understandhow auxiliary braking systems and vehicle traction affect the normal force on the drivenwheel axle. The expected result can assist in maintaining the slip ratio and increasing thelife span and performance of brakes.Scania uses a function to estimate forces on the driven axle and drive wheel slip. Theyneed to determine the normal force on the axle to improve performance of auxiliary brakingsystems, but tests showed that for the same specified slip ratio, the auxiliary braking forcerequired was smaller than that in an acceleration state. Scania believe that dynamic axleload transfer may be the cause, so a 6x2 electrified truck will be investigated in this thesis.The obtained results show the driven wheel axle’s behavior during different dynamicalscenarios.This research aimed to develop a model that can accurately simulate a truck’s movement and estimate the ground reaction force in response to variations in the scenario of thecontrol signal. By studying the quarter car model, bounce-pitch and half car model, theresearchers were able to obtain a model represented by 5 ODEs, which predicts the wheelaxle normal force. To verify the model, data from the CAN bus and measurements using ascale were collected and compared with the model’s output. The Mean Squared Error canbe used to evaluate and compare the model’s performance, and the results showed that themodel provides a reasonable estimate of the normal force on all axles. The study also analyzed the factors that contributed to the errors in the results. The behavior of the normalforce for each wheel axle during acceleration and braking was illustrated, explaining howthe normal force distribution becomes mirrored compared to the acceleration state duringbraking. The study’s discussions enhance the validity of the observed behavior and thereliability of the results.

Suspension systems and wheels play a critical role in vehicle dynamics performance of a car in areas such as ride comfort and handling. Lumped parameter models (LPMs) are commonly used for assessing the performance of vehicle suspension systems. However, there is a lack of clarity with regard to the relative capabilities of different LPM configurations. A comprehensive comparative study of three most commonly used LPMs of increasing complexity has been carried out in the current work. The study reported here has yielded insights into the capabilities of the considered LPMs in predicting response time histories which may be used for assessing ride comfort. A shortcoming of available suspension system models appears to be in representation of harsh situations such as jounce movement which cause full compression of springs leading to ‘jerks’ manifested as high values of rate of change of acceleration of sprung mass riding on a wheel. In the current research work, a modified nonlinear quarter-car model is proposed to account for the contact force that results in jerk-type response. The numerical solution algorithm is validated through the simulation of an impact test on a car McPherson strut in a Drop Weight Impact Testing Tower developed in CAR Laboratory, CPDM. This is followed by a detailed comparison of HCM and QCM to examine their suitability for such analysis. For decades, wheel bearings in vehicles have been designed using simplified analytical approaches based on Hertz contact theory and test data. In the present work, a hybrid approach has been developed for assessing the load bearing capacity of a wheel ball bearing set. According to this approach, the amplitude of dynamic wheel load can be obtained from a lumped parameter analysis of a suspension system, which can then be used for detailed static finite element analysis of a wheel bearing system. The finite element modelling approach has been validated by successfully predicting the load bearing capacity of an SKF ball bearing set for an acceptable fatigue life. For the first time, using a powerful commercial explicit finite element analysis tool, a detailed dynamic analysis has been carried of a deep groove ball bearing with a rotating inner race. The analysis has led to a consistent representation of complex motions consisting of rotations and revolutions of rolling elements, and generated insights into the stresses developed in the various components such as balls and races. In conclusion, a simple yet effective fuzzy logic-based yaw control algorithm has been presented in the current research. According to this algorithm, two inputs i.e. a yaw rate error and a driver steering angle are used for generating an output in the form of an additive steering angle which potentially can aid a driver in avoiding straying from an intended path.

This project was conducted as a case study at Öhlins Racing AB, a manufacturer of suspension systems for automotive applications. Öhlins usually manufacture their components by traditional methods such as forging, casting, and machining. The project aimed to investigate how applicable Additive Manufacturing (AM) is to manufacture products for suspension systems to add value to suspension system components. For this, a proof of concept was designed and manufactured. The thesis was conducted at Öhlins in Upplands Väsby via the consultant firm Combitech.  A product catalog was searched, screened, and one part was selected. The selected part was used as a benchmark when a new part was designed for AM, using methods including Topology Optimization (TO) and Design for Additive Manufacturing (DfAM). Product requirements for the chosen part were to reduce weight, add functions, or add value in other ways.  Methods used throughout the project were based on traditional product development and DfAM, and consisted of three steps: Product Screening, Concept Development, and Part Design. The re-designed part is ready to be manufactured in titanium by L-PBF at Amexci in Karlskoga.  The thesis result shows that at least one of Öhlin's components in their product portfolio is suitable to be chosen, re-designed, and manufactured by AM. It is also shown that value can be added to the product by increased performance, in this case mainly by weight reduction. The finished product is a fork bottom, designed with hollow structures, and is ready to print by L-PBF in a titanium alloy.