Browse Topic: Independent suspension
This paper presents an analytical approach for identifying suspension kingpin alignment parameters based on screw axis theorem and differential calculation model. The suspension kingpin caster and inclination alignment parameters can produce additional tire force, which affects vehicle handling dynamics. In wheel steering process, the multi-link suspension control arms lead to movement of the imaginary kingpin, which can cause change in suspension kingpin alignment parameters. According to the structure mechanism of commercial vehicle multi-link independent suspension, the kinematics characteristics of imaginary kingpin were analyzed based on the screw axis theorem. The angular velocity and translation velocity vectors were calculated. In order to avoid the influence of bushing deformation, the unique differential identification model was established to evaluate the suspension kingpin alignment parameters, and the identification results were compared with the ADAMS/Car data. The results show that the method can be used in the development of commercial vehicle suspension and active chassis control.
Optimization of the steering trapezoid mechanism parameter has great significance for improving vehicular handling performance and steering safety. The mathematical model of the current trapezoid mechanism design is oversimplified; Thus, the value of the optimum parameter is often not achievable. In this paper, a design model for the trapezoidal steering mechanism is proposed taking into consideration the size and kinematic constraints. Based on combining Ackerman's principle and spatial geometric relation, a multi-body dynamics design method is used to derive a nonlinear optimization model of the split steering trapezoid mechanism. In this investigation, a hybrid genetic algorithm is developed to minimize the steering error and the corresponding optimum design parameters. The selected design parameters are the bottom angle and the steering arm length of steering trapezoid mechanisms. The objective function of the structural optimization is a weighted summation of the relative error between the theoretical rotational and actual rotational angles of the front axle. The derived mathematical model of the mechanism is verified through the steering experiment of the tested vehicle. According to the initial design, an independent front suspension model is established in ADAMS, and an Ackerman error simulation experiment is performed. The results of the proposed algorithm and ADAMS simulation show that the maximum angle error of the steering mechanism is 0.91° at the maximum rotational angle range. The optimized steering trapezoid mechanism improves the performance of steering angles in two directions, tracking the ideal Ackerman angle and also reduce tire wear while maintaining the automobile's tuning stability.
Electronic Stop-Start (ESS) system automatically stops and restarts the engine to save energy, improve fuel economy and reduce emissions when the vehicle is stationary during traffic lights, traffic jams etc. The stop and start events cause unwanted vibrations at the seat track which induce discomfort to the driver and passengers in the vehicle. These events are very short duration events, usually taking less than a second. Time domain analysis can help in simulating this event but it is difficult to see modal interactions and root cause issues. Modal transient analysis also poses a limitation on defining frequency dependent stiffness and damping for multiple mounts. This leads to inaccuracy in capturing mount behavior at different frequencies. Most efficient way to simulate this event would be by frequency response analysis using modal superposition method. In order to do the same, there is a major hurdle which is due to the nature of the signal being highly transient and of short duration, this event is difficult to be captured in frequency domain. Traditional FFT techniques used for domain transformation are not accurate enough to capture and transform these short duration events from time domain to frequency domain and vice-versa. Simulation in frequency domain helps in interpreting the effects of modal interactions and resonances. It also helps in providing enablers to mitigate issues and use frequency dependent stiffness for mounts and appropriate damping. This paper focuses on providing a comprehensive method to capture this short duration transient ESS start event in frequency domain accurately, by using Discrete Fourier Transform (DFT) along with additional modifications to the mathematical formulation. This paper also highlights the boundary conditions required to accurately simulate this event for different suspension architectures for instance solid axle suspensions and independent suspensions. Finally, this paper also showcases test vs virtual correlation case studies for ESS virtual analysis of a full vehicle system with different suspension architectures.
The objective of this project is to analyze potential design changes that can improve the performance of helical spring in an independent suspension. The performance of the helical spring was based upon the result measure of maximum value of stress acting on it and the amount displacement caused when the spring undergoes loading. The design changes in the spring were limited to coil cross section, spring diameter (constant & variable), pitch and length of the spring. The project was divided into Stage I & Stage II. For Stage I, using all the possible combinations of these design parameters, linear stress analysis was performed on different spring designs and their Stress and displacement results were evaluated. Based on the results, the spring designs were classified as over designed or under designed springs. Then in Stage II, it was checked if the under designed springs can be optimized and classified according to a relevant application of the vehicles (racing cars or luxurious cars). The driving factor for this project was the amount of research that has taken place to improve the performance of suspension spring. It was seen that most of the research done in this field was directly or indirectly connected to the manufacturing of the spring. It is correct direction indeed, because the helical springs used in suspensions are made of complex alloys and better manufacturing would definitely improve its performance. But for this project, the focus remained on trying new direction for improving performance of spring. After much thought it was decided that bringing design changes to the spring should be experimented and it should be checked if certain design parameters which theoretically could improve spring performance, can they be put together and give positive results.
Cadillac has unveiled the 2021 Escalade and will differentiate the full-size SUV from its Tahoe/Yukon platform-mates with a large dose of exclusive technologies including Super Cruise, audio systems from new partner AKG and the industry's slickest display-screen integration. Gaining similar mechanical benefits as its platform siblings, including wheelbase stretches and the new independent rear suspension (IRS) that should improve dynamics along with seating/cargo space, the all-new 2021 Escalade leverages the platform's new digital network architecture (see p.10) to raise the bar for integrated infotainment technology. The 2021 Cadillac Escalade makes use of GM's new GMT T1XX platform that began underpinning its pickup trucks in 2019, and serves as the basis of the upcoming MY2021 Chevy Tahoe/Suburban and GMC Yukon/Yukon XL full-size SUVs. In the fifth generation of Cadillac's longest-running nameplate, this equates to the same notable passenger space and interior volume gains for the 2021 Escalade, which was only revealed in the standard-length model. The longer Escalade ESV is expected to be unveiled at the 2020 New York Auto Show.
The present work aims to use complex tools for the calculation of vehicle dynamics, using optimization analysis. The study was applied to a single seat off-road prototype that has independent suspension, Double A or WishBones type, both on the front and rear axles and whose main objective will be the analysis of the prototype suspension arms fixing points. A multi-body model was created by MotionView software and straight-line acceleration and deceleration analyzes were applied to obtain better longitudinal load transfer ratios for the axes, besides the force measurements for the arm connections during these events. After the creation of the multi-body model, some studies using optimization tools, through HyperStudy software, were performed in order to obtain the new positions of the attachment points in the chassis, achieving a better dynamic suspension design. The new points change the longitudinal load transfer design and generate controlled alteration between predefined parameters in the behavior of the camber and toe in angles resulting in a different suspension arm geometry. In addition, the new geometry also had a pickup analysis of forces for comparison between models. At the end of the study, the prototype model generated allows full comparison of the macro operation of the prototype, and allowing the developers to evaluate if this model is more efficient and robust than the previous one. The optimization tool allows to find important results that allow the studied competition prototype to gain competitive advantages contributing to achieve better results and a better design.
Stressing that Nikola Motor's primary intent is to eliminate emissions related to Class 8 over-the-road trucking, company president and CEO Trevor Milton confirmed at a technology conference in Detroit that Nikola remains on track to deliver its first fuel cell-powered electric trucks beginning in 2021. Milton reinforced that the Nikola One truck-intended to be fueled by hydrogen generated from a network of nearly 350 company-built, solar-powered electrolysis stations across the nation-will have a driving range of 800-1200 mi (1287-1931 km), 1000 hp and 2000 lb·ft (2712 N·m) delivered to four rear wheels and dramatically lower operating costs.
The high level of reliability of virtual analysis for suspension system development should not be thinking only for comfort and performance purpose, considering the `growing number of failures due to the touch between components in dynamic condition. The study establishes a simple and optimized methodology, able to predict more accurately the flexible brake hose path subject to the steering motion and associates with the independent suspension course, aiming the best route in order to achieve a low cost and robust design. In turn, the flexible brake hose non-linear model invalidates the multibody study to get the best route. However, with the aid of motion making use of NX9 [1] CAD [2] software was prepared dynamic movement that subjects front independent suspension system that establishes a Cartesian routine that maps 977 points, much higher than 9 points from previous studies, comprising a more accurate path performed by the hose. This data served as input to the IPS [3] software for the construction of flexible model to be simulated, were assigned mechanical and geometrical properties for each component. Finally, it was set to IPS software the dynamic suspension system routine, thus yielding the flexible brake hose behavior under certain circumstances, verifying the effectiveness of the component to the package requirements, avoiding undesired dynamic interference and early degradation of the flexible element.
Suspension system is one of the most important systems in an automobile and the failure in the sub systems or parts would prove catastrophic. A semi-trailing arm (STA) suspension is an independent rear suspension system for automobiles where each wheel hub is located only by a large, roughly triangular arm that pivots at two points onto the chassis or the body. STA usually is subjected to three directional loads viz. vertical, longitudinal and lateral in service. The conventional methodology of validating the system is by applying multi-axial loads or by road load simulation consuming significant amount of time. In this paper an attempt is being made to validate the damper mounting pins by reproducing the damper loads locally instead of validating the entire system. STA was strain gauged at the critical locations and was mounted onto the vehicle. Accelerometer was mounted onto the wheel spindle and a displacement transducer (LVDT) was mounted parallel to the damper mounted to the body and the STA. The vehicle was run on the test tracks and the corresponding STA strain, spindle acceleration and damper displacement was recorded. The acceleration data was converted to velocity of the spindle which was then transformed to damper velocity. Range-mean histogram of the damper was plotted. Velocity vs damping force characteristics of the damper was generated. A test rig has been created where the actual damper has been replaced by a metal adapter and loads have been applied using a servo-hydraulic actuator. Forces corresponding to the observed velocities have been applied onto the pin and the corresponding strains have been recorded. These values were then compared to the vehicle level strains observed initially. This methodology reduces the test time and the complexity involved significantly.
According to the U.S. National Highway Traffic Safety Administration, 743 pedal cyclists were killed and 48,000 were injured in motor vehicle crashes in 2013. As a novel active safety equipment to mitigate bicyclist crashes, bicyclist Pre-Collision Systems (PCSs) are being developed by many vehicle manufacturers. Therefore, developing equipment for evaluating bicyclist PCS is essential. This paper describes the development of a bicycle carrier for carrying the surrogate bicyclist in bicyclist PCS testing. An analysis on the United States national crash databases and videos from TASI 110 car naturalistic driving database was conducted to determine a set of most common crash scenarios, the motion speed and profile of bicycles. The bicycle carrier was designed to carry or pull the surrogate bicyclist for bicycle PCS evaluation. The carrier is a platform with a 4 wheel differential driving system. Each wheel is attached to an independent suspension system to protect motors, gears and reduce the vibrations. The height of carrier was minimized to 78mm for reducing the interference to PCS sensors. To ensure it can be run over by the test vehicle during bicyclist PCS testing without being damaged, the size of the carrier is designed as 160x160cm with a protection mechanism. A finite element analysis (FEA) was conducted to verify the strength of the carrier. Moreover, a carrier control system was developed, which includes ZigBee based communication, safety sensor, and, vibration monitoring. A series of motion testing with different speed and trajectory profiles were successfully conducted. The safety and effectiveness of the bicyclist carrier was tested on a test track in various test scenarios.
Suspension plays an essential role in vehicle's handling stability and riding comfort. This paper discusses a novel suspension that has the capacity to trace a straight line in theory. Therefore it is called rectilinear suspension. So the alignment parameters are invariable during jounce and rebound if the elasticity of suspension components is ignored. According to the structure characteristics of the rectilinear suspension, it is suitable to mount on the rear axle. To evaluate its performance, the dynamics model is established through ADAMS. Moreover, a comparison of the rectilinear suspension with the twin-trapezoidal link suspension is carried out. Further, the K&C test results show that the alignment parameters of the rectilinear suspension are almost invariable compared with MacPherson suspension.
The automotive industry commonly uses two definitions of the suspension roll center, the Kinematic Roll Center (KRC) - of interest in studying suspension geometry, and the Force-based Roll Center (FRC) - of interest in studying steady-state vehicle dynamics. This paper introduces a third definition, the Dynamic Roll Axis (DRA) - of interest in studying transient vehicle dynamics. The location of each one of these roll centers has a unique application to vehicle design and development. Although the physical meaning of each roll center is significantly different, the generic term “roll center” is often used without proper specification. This can lead to confusion about how roll centers influence vehicle behavior. This paper hopes to clarify some of this confusion and is organized into three parts: (1) Describes calculation methods for each of the three vehicle roll centers (for independent suspensions) as well as their relevance to vehicle dynamics; (2) Explains the relationship between the kinematic and force-based roll centers; (3) Offers recommendations on considerations for choosing roll center(s) location during vehicle design.
The all-new premium sedan is the Korean automaker's ‘most technologically advanced’ vehicle ever on U.S. roadways. Kia's first full-size sedan represents the company's most powerful and technologically advanced product offering ever for the North American market. Several months after the Cadenza's January debut at the 2013 North American International Auto Show in Detroit, automotive and lifestyle media including AEI had the opportunity to test-drive the car and experience its 293-hp (218-kW) gasoline direct injection (GDI) V6, its sport-tuned suspension, and suite of active safety technologies including Kia's first application of advanced smart cruise control (ASCC) on the roads surrounding Del Mar, CA. The Cadenza succeeds in moving the Kia brand up-market, from its European-influenced design driven by Kia Motors' President and Chief Design Officer Peter Schreyer (who previously worked at Audi), to its long list of premium features such as an advanced navigation system with SiriusXM Traffic and UVO eServices telematics displayed on a high-resolution 8-in touch screen. (To read more on Kia's UVO infotainment system, go to http://articles.sae.org/11824.)
In this paper FR (Front Engine, Rear wheel Drive) based 4WD 5-link independent suspension systems are introduced which are developed for low friction road stability in the winter. The arrangement of the lower control arm of the newly developed suspensions has been changed in order to correspond to 4WD layout. And basic performance is satisfied due to the addition of the driveline. Also NVH (Noise, Vibration and Harshness) performance has improved, to enhance the comfort of the vehicle
This paper describes the design and the analysis of a stub axle front suspension developed to a rear-wheel drive of an automotive prototype. The automotive prototype is a vehicle developed for use on public roads with motor and transmission located at the rear and four-wheel independent suspension, with capacity for two occupants. By means of a finite element software, they were analyzed the efforts that acted on the steering and suspension components that interacted with the sleeve axis The stub axle is subjected to various loads in various ways, due to several conditions imposed by the motion that occur due to movement of the vehicle. They were analyzed three situations during the simulations: straight due to the movement of the vehicle, making a turn and during a braking situation. The analysis of the structure in those three situations allowed obtaining some characteristics, such as their strengths and critic regions where those efforts were higher. Based on the results obtained during the simulations, it was possible to improve the geometry of the stub axle, in order to have a resulting structure with appropriated stress levels distributed on the material in a suitable way and a mass reduction in some places, avoiding an overestimation. The mass reduction is important in the stub axle because it is a component of the unsprung mass of the vehicle. The smaller the unsprung mass of the vehicle, the faster it back to its initial position, which is of extreme importance in a good suspension.
The vehicle pull (sideways) is a complex outcome of many parameters in an automobile vehicle. This is mainly due to steering, suspension, brake, wheels and chassis parameters. The road conditions like road camber also plays an important role in vehicle pull behavior. All efforts are put in design and manufacturing processes to maintain controlled vehicle pull in normal driving condition. Even though normal vehicle pull seems to be in acceptance limit (subjectively), its intensity increases many folds at the time of harsh braking. In these kind of panic situations where driver firmly holds on the steering wheel, it is expected that the vehicle should stop without deviating too much sideways from its intended straight line path to avoid any kinds of accidents. This work is an outcome of systematic study carried out to understand the root cause of brake pull as a field complaint on current production vehicles and adopting best possible solutions to minimize the brake pull. This paper presents an experimental study and comparison of contribution of two basic kinds of steering linkage layouts type 1 and type 2 (detailed descriptions followed in section 1) on RHD (right hand drive) vehicle, used in front-wheel-steered vehicles having independent suspension on vehicle pull and brake pull. Brainstorming resulted in some critical hypothesis about possible contribution of these two basic layouts on vehicle pull while braking which was further supported by primary CAE (computer-aided engineering) analysis using classical approach (ADAMS® Model). Same has been validated through experimental tests also. While both of these mechanisms are widely used by different automobile OEM's (original equipment manufacturers) as they fulfill most of the design requirements of steering systems, the in-depth analysis of contribution of these two layouts on brake pull surely puts one on top of the other. The work helps in understanding the finer details of steering linkage design requirements and provides design guidelines to deliver better product through improved safety and better customer satisfaction.
The twist axle has highly complicated load paths because of its multiple functions of suspension components. This nature of the twist axle suspension makes the fixed reacted multi-axial suspension test more sophisticated than for other independent suspensions. GM has used Virtual Road Load Data Acquisition (vRLDA) for laboratory tests in the past, but this is the first application of vRLDA for a twist axle multi-axial suspension durability test. In order to utilize vRLDA data for the test input, a new approach to 8 channel multi-axial suspension durability test development was proposed for a twist axle rear suspension. vRLDA for a GM vehicle with twist axle rear suspension was performed and briefly discussed. Instead of using strain data from the twist axle for correlation channels, inboard channels such as shock tower vertical and trailing arm forces were used in the test development. Emphasis was placed on a high level of correlation for the inboard channels, while the correlation at the WFT (Wheel Force Transducer) channels was secondary. The test development results using the proposed approach were compared with strain data from a physical RLDA. The proposed test development responses showed good correlation with RLDA data. The test of the twist axle has been successfully executed.
Chrysler engineers wanted to maintain or enhance off-road capability while significantly boosting refinement. Over the past four years, Philip Jansen might have had one of the toughest challenges at Chrysler. As Chief Engineer with responsibility for the new 2011 Jeep Grand Cherokee, he had to see one of his company's most important vehicles through development during financial uncertainty and management upheaval. His vehicle had to not only satisfy existing Jeep customers with above-average off-road capabilities, but also had to appeal to heightened expectations for premium on-road refinement. “We listened to our customers and took it to the next level, adding significantly improved on-road performance while maintaining the Jeep brand's legendary four-wheel-drive capability,” said Jansen. Early customer input was clear. “They said, first and foremost, get the interior upgraded. Improve the rear-seat package. Make it feel [more] upscale, luxurious. I want better fuel economy; I don't like to fill my tank up too much. [But] give me the capability, the traction, the control that I've become accustomed to [with Jeep.]”
The articulated dump truck with independent suspensions is driven by six AC motors and each wheel is driven by one motor. Cooling system is configured in every electric wheel. The motor is the main heating source in the electric drive system. Hence, the cooling of the motor will affect the reliability and power-density of the whole electric drive system. According to the actual working conditions, the heating calculation about the cooling system has been carried out during the design process. The design concept of embedding spiral-shaped flow path in the shell of the stator has been drawn. The cooling water could pass through the path and accomplish cooling outside the stator. In this paper, the FLUENT has been used for the 3-D numerical simulation of the cooling system. The temperature field distributions of the cooling water and the shell are obtained. To analyze the influence of the shell structure on the cooling effect, the iSIGHT has been used to accomplish the structural and thermal optimization. The simulation and optimization results show that the cooling water velocity has little effect on the cooling, but the structure of the shell affects the cooling greatly. Finally, the section sizes of the shell flow path are optimized. As a result, the average temperature of the shell wall has reduced from 364K to 357K. The cooling effect can be improved significantly.
The company hopes the re-engineered Elise can out-maneuver its competition by showing the importance of performance through light weight. In July, Lotus began exporting to the U.S. a Federal version of the Elise-nearly a decade after it introduced the vehicle to other world markets. The first new Lotus model for the United States since 1991, the Elise is spearheading the company's market expansion plans in America. The Elise has been the best-selling Lotus ever, with about 20,000 units sold worldwide since the original Series 1 (S1) hit the UK market in 1996. That is nearly double the total sales of Lotus's longest-running car, the Esprit, which completes production this year after a 26-year run. The company expects to sell roughly 2200 Elises in the U.S. in its first full year, a significant increase from the 100-unit per year sales volume of the now-defunct Esprit.
Toyota is working to differentiate itself from the competition by continually evolving its unique design philosophy. The hills of Nagakute, 20 km (12 mi) east of Nagoya city, were the battleground between the two powerful warlords, Toyotomi and Tokugawa, in 1584 in feudal Japan. Tokugawa scored a decisive victory, paving the way for establishment of the House of Shogun. Toyota Motor Corp. is often likened to the Shogun for its might and main, the automaker securing an over-50% share of the Japanese domestic market. Nagakute is now the site of a more peaceful event, the forthcoming 2005 Aichi Earth EXPO, the theme of which is the preservation and enhancement of the global environment. Over 125 nations participate in the EXPO, as well as numerous private enterprises and companies. Toyota's presence will be prominent with many vehicular and other exhibits, both mobile and stationary. The chairman of the EXPO organizing committee is Shoichiro Toyoda, Honorary Chairman of Toyota Motor Corp.
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