Browse Topic: Suspension linkages
The parametrized twist beam suspension is a pivotal component in the automotive industry, profoundly influencing the ride comfort and handling characteristics of vehicles. This study presents a novel approach to optimizing twist beam suspension systems by leveraging parametric design principles. By introducing a parameter-driven framework, this research empowers engineers to systematically iterate and fine-tune twist beam designs, ultimately enhancing both ride quality and handling performance. The paper outlines the theoretical foundation of parametrized suspension design, emphasizing its significance in addressing the intricate balance between ride comfort and dynamic stability. Through a comprehensive examination of key suspension parameters, such as twist beam profile, material properties, and attachment points, the study demonstrates the versatility of the parametric approach in tailoring suspension characteristics to meet specific performance objectives. To validate the effectiveness of this method, the research presents a series of case studies in which parametric variations are applied to existing twist beam suspension designs. The results reveal substantial improvements in ride comfort and handling dynamics, highlighting the potential for this approach to revolutionize suspension system development. In conclusion, the parametrized twist beam suspension approach offers a promising avenue for automotive engineers to achieve optimal ride and handling characteristics through systematic design iteration. By providing a structured framework for parameter adjustments, this research contributes to the advancement of suspension technology, ultimately leading to safer, more comfortable, and better-performing vehicles.
In most farm tractors through the middle of the 20th century, a pressed steel frame chassis is used as a supporting part of the tractor on which the engine, wheels, axle assemblies, transmission, steering mechanism, brakes, and suspension members were mounted together. Farm tractors generally used in the agricultural field experiences a variation in the load and vibrations, which leads to failure/fracture in the frame/chassis. In order to reduce the failure/fractures in the chassis/frame, high strength materials are used. Therefore, the main objective of the paper is to identify the best suitable high strength material and most suitable cross section for a mini tractor chassis, so as to make it very strong to bear the heavy loads and shocks received while working in the farms in static conditions. In the present work, ladder chassis is designed and analyzed with three different types of cross sections like C, I and Rectangular box type. Considering the maximum load condition, analysis is done to find the suitable material and cross section for the chassis. Mini tractor chassis designed for SAEISS (SAE India Southern Section) tractor design competition is taken for analysis with three different materials. Finite Element Analysis (FEA) is carried out for getting the chassis with high strength in order to minimize the failures, along with considering the factor of safety. So, a proper finite element model of the chassis is done using Solidworks software, and analysis is done using Ansys. Additionally, wave spring is introduced in between the seat and the tray system of the tractor in order to reduce the vibrations produced in it. From the results, it is observed that the rectangular box type cross-section with A356+B4C Composite is stronger than the other two types of cross-sections for the Ladder Chassis with a least deflection, Von Mises stress and Maximum Shear stress. Also, the wave spring is designed and analyzed with ASTM A401 material and it is found that the total deflection, Von Mises stress and Maximum Shear stress was minimum.
In automobiles, front axle assembly is a main load bearing member and houses steering linkages. Front axle assembly has two main parts namely axle beam and axle arm, interconnected by a kingpin. This kingpin allows the rotation of axle arm during steering events. To avoid metal to metal contact between axle arm and kingpin, bushes are housed on the top and bottom half of the axle arm & in axle beam. Due to radial load and steering rotation, as a weak member, bushes will wear out faster. This affects the proper functioning of steering mechanism. Hence, the bushes need to be evaluated prior to its implementation in vehicle. In general, bushes are evaluated using Pin-On-Disc test as a comparative study, but it does not simulate exact boundary conditions as in vehicle. Next option is vehicle level validation but leads to more testing time and cost. Hence, as an optimized solution, the same vehicle operating conditions can be replicated in component level testing. Considering the boundary conditions & test requirements, a new test facility is developed to measure the wear and validate the bushes. This helps to evaluate different material combinations in the shortest possible time.
Front suspension frame is an integral part of automobile chassis which acts as a major load carrying structural member and connects different suspension components with body. It provides the required stiffness for achieving desired vehicle dynamics performance. Acting as a major road load path from tire to body, it also acts as a mounting base for suspension arm, steering and compression rod. Considering the competitive market conditions, increased fuel efficiency demand along with enhanced structural durability, it is important to evaluate suspension frame for stiffness and durability using Computer Aided Engineering (CAE) methodology so as to reduce product development time and First Time Right cost effective design. In this paper focus is given on CAE methodology used to design a light weight tubular kind of suspension frame for light commercial vehicle with stiffness comparable to conventional sheet metal suspension frame and similar durability performance with reduced weight. Explained CAE methodology is also validated with bench test results and correlation between bench test and CAE analysis is studied.
Meeting various customer(s) requirements with the given automotive product portfolio within the stipulated time period is a challenge. Design of product configuration matrix is an intelligent task and it requires information about vehicle performance for different configurations which helps in deciding the level of new development. Most often the situation arises, particularly in the field of NVH, to strike the right balance between engine power and structural parameters of the body. The sensitivity of engine power on the overall NVH behavior is the key information necessary to take major business decisions. In this paper, the effect of change in torsional fluctuation of the engine on the NVH behavior of the rear wheel drive vehicle is experimentally studied. The torsional fluctuation of the driveline is given as an input with the help of an electric motor to the existing test vehicle at its differential end and the current NVH levels are measured. A test rig is built to change the levels of torsional vibration input to the vehicle. The threshold level of torsional fluctuation for the given vehicle structure is obtained by taking into account the target values of tactile vibration and subjective perception. The results are very useful in deciding the acceptable level of change in engine power without carrying any structural change. Also, for a given power, the set of structural changes necessary in the body and suspension linkages to meet the NVH criteria can be studied. The procedure is also extended to an all-wheel drive vehicle with the help of a two wheel drive chassis dynamometer. Obtaining subjective perception of the vehicle NVH even before making the vehicle of target configuration is an inherent advantage of the proposed technique. A good correlation is achieved with the objective results and subjective perception.
A range of axle suspensions, comprising hydro-pneumatic struts and diverse linkage configurations, have evolved in recent years for large size mining trucks to achieve improved ride and higher operating speeds. This paper presents a comprehensive analysis of different independent front suspension linkages that have been implemented in various off-road vehicles, including a composite linkage (CL), a candle (CA), a trailing arm (TA), and a double Wishbone (DW) suspension applied to a 190 tons mining truck. Four different suspension linkages are modeled in MapleSim platform to evaluate their kinematic properties. The relative kinematic properties of the suspensions are evaluated in terms of variations in the kingpin inclination, caster, camber, toe-in and horizontal wheel center displacements considering the motion of a hydro-pneumatic strut. The results revealed the CL and DW suspensions yield superior kinematic response characteristics compared to the CA and TA suspensions. Toe-in and horizontal wheel center displacements of the CA and TA vary significantly, which could strongly affect the vehicle handling performance and cause greater tire wear. The CL and DW suspensions may thus be considered desirable for future designs of high-speed and high-performance mining trucks.
A valid human biodynamic model is very useful for studying the human body's response to whole body vibration. Whole body vibration is one of the important factors in the study of vehicle ride comfort. The environmental vibrations are transferred to the human body through floor and seat. Seated posture is the most commonly used position in automobiles. Therefore, studying the human body response in a seated position has attracted a lot of attention. Because the human body is in direct contact with the seat, its design plays a very important role in vibration transmission. In seat design, two important components are seat suspension and cushion. The mechanical properties of these components are stiffness, damping and mass. These properties can be changed by adjusting cushion material and seat suspension linkages. In this paper, three types of seat models are used. The first one is a hard seat. The second one has only cushion, and the third one is called an isolated seat which has seat suspension and cushion. For evaluating responses, one linear 14-degree of freedom (DOF) multibody biodynamic model from literature is used. This model is in a seated position having a total mass of 71.32 kg with 5 body segments. Backrest support and feet contact are included in this model because a considerable amount of vibrations is transferred through it.
The larger chassis space requirements of hybrid vehicles necessitates considerations of the suspension synthesis with limited lateral space, which may involve complex compromises among performance measures related to vehicle ride and handling. This study investigates the influences of suspension linkage geometry on the kinematic and dynamic responses of the vehicle including the wheel load in order to facilitate synthesis of suspension with constrained lateral space. A kineto-dynamic half-car model is formulated incorporating double wishbone suspensions with tire compliance, although the results are limited to kinematic responses alone. An optimal synthesis of the suspension is presented to attain a compromise among the different kinematic performance measures with considerations of lateral space constraints. In the kineto-dynamic model, the struts comprising linear springs and viscous dampers are introduced as force elements. Kinematic formulations of the proposed model are derived using displacement matrix method. The kinematic responses, particularly the variations in the camber angles and the wheel track width are investigated under wheel vertical displacement, chassis roll, and simultaneous inputs of wheel center displacement and chassis roll. The results attained from a sensitivity analysis suggested that variations in the joint coordinates could yield reduction in the lateral space, while these would involve complex compromises among the kinematic responses of the suspension. A composite objective function of camber angle and track width measures under wheel vertical displacement and chassis roll excitations is subsequently formulated and solved with constraints on variations in the roll center height and the suspension lateral packaging space to seek optimal joint coordinates. The proposed synthesis with optimal joint coordinates could yield nearly 10% reductions in the lateral packaging space, and camber angle and wheel track variations with only minimal increase in the peak roll camber.
The Rover Analysis Modeling and Simulation (ROAMS) algorithm is to solve the kinematics of a wheeled mo- bile robot (rover) traversing on a rocky terrain. The rover is constructed using a “rocker-bogey-differential” type suspension and steering system as shown in the figure. By exploring the mechanical symmetry and the wheeled-terrain contact characteristics on a rough terrain profile, we developed a novel algorithm to carry out the rover’s configuration, including the vehicle’s wheels, steering and suspension linkages, and the position and orientation of the chassis. Because of its efficient and reliable numerical results, the ROAMS algorithm is well suited for the real-time simulation test bed, e.g., a simulation software system, of the mobile robotic vehicles in the planetary surface exploration missions. Currently, it is used to support the development of simulation and operation tools for the Mars Exploration Rover (MER) in the Mars ‘03 mission.
This SAE Recommended Practice is intended to outline basic nomenclature for axle designs in common use for automotive drives. Over a period of years, there have been many different designs; however, for the purpose of this report, only the most common designs have been selected and only their general construction is illustrated to show the nomenclature of the various parts.
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