Browse Topic: Chassis stiffness
Abrasion of the Electromechanical brake (EMB) brake pad during the braking process leads to an increase in brake gap, which adversely affects braking performance. Therefore, it is imperative to promptly detect brake pad abrasion and adjust the brake gap accordingly. However, the addition of extra gap adjustment or sensor detection devices will bring extra size and cost to the brake system. In this study, we propose an innovative EMB gap active adjustment strategy by employing modeling and analysis of the braking process. This strategy involves identifying the contact and separation points of the braking process based on the differential current signal. Theoretical analysis and simulation results demonstrate that this gap adjustment strategy can effectively regulate the brake gap, mitigate the adverse effects of brake disk abrasion, and notably reduce the response time of the braking force output. Monitoring is critical to accurately control EMB clamping force. Pressure transducers are
Electric vehicles (EV) are much quieter than IC engine powered vehicles due to less mechanical components and absence of combustion. The lower cabin noise in electric vehicles make customers sensitive to even small noise disturbances in vehicle. Road boom noise is one of such major concerns to which the customers are sensitive in electric vehicles. The test vehicle is a front wheel driven compact SUV powered by electric motor. On normal plain road, noise levels are acceptable but when the vehicle has been driven on coarse road, the boom noise is perceived, and the levels are objectionable. Multi reference Transfer Path Analysis (MTPA) is conducted to identify the path through which maximum forces are entering the body. Based on MTPA, modifications are proposed on the suspension bushes and the noise levels were assessed. Operational Deflection Shape (ODS) analysis is conducted on entire vehicle components like suspension links, sub frame, floor, roof, and doors to identify the
Customers expect more advanced features and comfort in electric vehicles. It is challenging for NVH engineers to reduce the vibration levels to a great extent in the vehicle without adding cost and weight. This paper focuses on reducing the tactile vibration in electric vehicle when AC is switched ON. Vibration levels were not acceptable and modulating in nature on the test vehicle. Electric compressor is used for cabin cooling and battery cooling in the vehicle. Compressor is connected to body with the help of isolators. Depending upon cooling load, the compressor operates between 1000 rpm and 8000 rpm. The 1st order vibration of compressor was dominant on tactile locations at all the compressor speeds. Vibration levels on steering wheel were improved by 10 dB on reducing the dynamic stiffness of isolators. To reduce the transfer of compressor vibration further, isolators are provided on HVAC line connection on body and mufflers are provided in suction and discharge line. With the
The test vehicle is All Wheel Drive (AWD) vehicle which is powered by four-cylinder engine. The power is transferred from the powertrain to the wheel through power transfer unit (PTU), propeller shaft, flexible rubber coupling and Integrated Rear Differential Assembly (IRDA) . Higher boom noise and vibration levels are observed when driving the vehicle in 4th gear WOT conditions. NVH levels are dominant between 1150 rpm to 2100 rpm and at 2200 rpm in 2nd order and 4th order respectively. Operational deflection shape (ODS) analysis is carried out on entire vehicle to identify the location where maximum deflection is observed at the problematic frequency. It is identified that higher torsional excitation from the powertrain is exciting the IRDA pitching mode and the propeller shaft bending mode which is the reason for higher 2nd order and 4th order NVH levels. The driveline forces are entering the body through the IRDA and rear cradle bushes. The dynamic stiffness of IRDA bushes is
This paper focuses on reducing abnormal noise originating from suspension when driving on rough road at the speed of 20 kmph. The test vehicle is a front wheel driven monocoque SUV powered by four cylinder engine. Cabin noise levels are higher between 100 to 800 Hz when driven on rough road at 20 kmph. Vibration levels are measured on front and rear suspension components, front and rear subframe, subframe connections on body to identify the noise source locations. Since the noise levels are dominant only in certain rough patches at very narrow band of time, wavelet analysis is used for identification of frequency at which the problem exist. Based on wavelet analysis, it is identified that the vibration levels are dominant on front lower control arm (LCA). The dynamic stiffness of LCA bushes is reduced by ~ 40% to improve the isolator performance which reduced the noise levels by ~ 9 dB (A) at the problematic frequency band. Modal analysis is conducted on front suspension components to
Globally all OEMs are moving towards electric vehicle to reduce emission and fuel cost. Customers expect highest level of refinement and sophistication in electric vehicle. At present, the customers are sensitive to high pitched tonal noise produced by electric powertrain which gives a lot of challenges to NVH engineers to arrive at a cost-effective solution in less span of time. Higher structure borne tonal noise is perceived in electric vehicle at the vehicle speeds of ~ 28 kmph, 45 kmph and 85 kmph. The test vehicle is front wheel drive compact SUV powered by motor in the front. The electric drive unit is connected to cradle and subframe with help of three mounts. Transfer path analysis (TPA) using blocked forces method is carried out to identify the exact forces of the electric drive unit entering the mounts. Powertrain mount is characterized by applying the predicted forces and dynamic stiffness at problematic frequency is measured. By reducing the dynamic stiffness of powertrain
Despite humble roots, Honda's 2023 Civic Type R is a Porsche for the rest of us: A small car destined for greatness, with more entertainment value than a three-day Netflix binge. In familiar Honda fashion, the roots of that greatness can be traced to smart tech and engineering rather than showy design (aside from bordello-red seats, best paired with Championship White paint that has for decades been a Type R signature). Chief engineer Hideki Kakinuma led the development effort for the 2023 Type R. It's the sixth generation of this affordable overachiever - but only the second sold in the United States
The Ferrari Purosangue scurries up the snowbound pitches of Italy's Monte Bondone, the Alpine peak whose auto-hillclimb exploits date to 1925. Ferrari's first “SUV” - really, more a genre-blurring crossover - slices through Bondone's 38 devilish corners, gaining nearly 4,900 ft (1,494 m) of elevation over an 11.2-mile (18-km) workout. Its 715-hp (533-kW) V12 sings like the tragically-fated opera hero it is, to an 8,250-rpm height that's as lofty as the surrounding Dolomites. Emissions regulations may soon spell the end of that barrel-chested, 6.5-L engine, whose 12 naturally-aspirated cylinders describe every roadgoing Ferrari built between 1947 and 1973. But the rest is modern magic, the kind of prestidigitation that's required to transform a 4,774-lb (2165-kg), AWD machine - the first Ferrari with four doors and four adult-sized seats - into a stunning performer that feels lighter and lither than any driver would ever expect
The body stiffness plays a key role in vehicle performance, such as noise and vibration, ride and handling, durability and so on. In particular, a body D-pillar ring structure is the most sensitive affecting the body stiffness on vehicle with tail gate. Therefore, since D-pillar body ring structure for high stiffness and lightweight is required, an optimized design methodology that simultaneously satisfies the requirements was studied. It focused on a methodology that body engineering designers can optimize design parameters easily and quickly by themselves in the preceding stages of vehicle’s styling distribution and design conceptual planning. First, it is important to establish the body stiffness design strategy by predicting the body stiffness with the vehicle’s styling at early design stage. The methodology to predict body stiffness with the styling and body dimension specification parameters was introduced. Next, design parameters such as a cross-section area, material and
Control of powertrain torsional vibration has always been important consideration to improve NVH performance of vehicle. Torsional couplings are used between engine flywheel and motor generator to isolate downstream driveline components from harmful and damaging torsional vibration. Low torsional stiffness of these coupling helps to isolate the torsional vibration during normal engine operation. But due to lower torsional stiffness, torsional mode of the coupling gets resonated during engine start and shutdown, which may result into coupling failures. Vehicle with engine auto start-stop feature is resulting into frequent engine starting event than traditionally observed, which results into more resonant cycles in coupling. The problem becomes more severe in hybrid electric vehicles where high inertia motor generator is directly coupled to engine. Traditionally damping has been used to control magnitude of torque peak at resonance. This study is focused on simulating transient torsional
As of today, multiple studies suggest a perceptible influence of the vehicle body stiffness on the drivability and steering feel. Most of them use subjective methods to score changes in stiffness but do not conduct further measurements to explain the underlying physical chain. This interaction between the body stiffness and vehicle dynamics is not fully understood and requires further research, especially in the on-center behavior and maneuvers of low-lateral dynamics. This research focuses on these two areas by measuring the steering inputs, the resulting vehicle response and the vibrational behavior of the body on a freeway and a comfort test track. Afterward, the main effects of different stiffening measures are analyzed and discussed. Regarding the influence on the steering feel, differences can be measured but seem too small to be perceptible for a normal driver. The magnitude of the effects is comparable to the influences of nuisance parameters, such as temperature or tire wear
A body joint is one of the most major factors affecting the overall body stiffness in a body system. Thus, in order to optimize the body system, the joint must be also optimized. In order to optimize a body joint, it is necessary to first identify the efficiency of the joint itself. Then, the joint stiffness targets for each joint must be set by analyzing the interaction between joint stiffness and overall body stiffness and the function of the joint in terms of vehicle performance. Finally, an optimal joint structure should be designed with an optimal design methodology. In this study, an optimal methodology for the joint stiffness and design is introduced. Based on this research, an optimized joint design for each joint was applied to the new SUV model resulting in a lightweight body with a required body stiffness
The transition from traditional gasoline-powered automobiles to electric vehicles has taken time. Two significant challenges of engine-powered vehicles are greenhouse gas emissions and fuel economy. Working with lightweight materials has emerged as a critical area for improvement in the automotive industry in today’s world. The most efficient method for increasing power output is to reduce the weight of vehicle components. Composite materials have significantly benefited from research and development because they are stronger, more recyclable, and easier to integrate into vehicles. The primary goal of this research is to design the body and chassis frame of a two-seater electric car. A computational fluid dynamics (CFD) analysis was performed to determine the body’s drag coefficient and structural analysis to obtain the frontal impact and torsional rigidity of the chassis to develop a practical electric car design. The design was carried out with the help of CATIA V5 software, while
The conceptual design of a full-body composite monocoque chassis has been presented at various student-level racing contests due to its high strength-to-weight ratio and torsional stiffness. However experimental studies to demonstrate the performance of the design are limited. This study aims to find the optimum configuration and number of stacked layers of carbon fiber sandwich panel using finite element analysis (FEA), as well as investigate the mechanical performance of the proposed sandwich configuration by experimentation in order to demonstrate the practical performance of a fully composite monocoque chassis made from the optimized configuration of the sandwich panel. A composite monocoque consisting of five stacked layers of [W45/UD0/W90/UD45/W0/core]symmetry was proposed, where W, UD, and the subscripts indicate woven and unidirectional (UD) carbon fibers and their orientation in the measurement unit of degrees. Three-point bending and perimeter shear tests were conducted on
Vehicles with manual transmission are still the most preferred choice in emerging markets like India due to their benefits in cost, simplicity and fuel economy. However, the ever-increasing vehicle population and traffic congestion demand a smooth clutch operation and a comfortable launch behaviour of any manual transmission vehicle. In the present work, the launch performance of a sports-utility vehicle (SUV) equipped with dual mass flywheel (DMF) and self-adjusting technology (SAT) clutch could be improved significantly by optimizing the clutch system. The vehicle was observed to be having a mild judder during clutch release (with 0% accelerator pedal input) in a normal 1st gear launch in flat road conditions. An extensive experimental measurement at the vehicle level could reveal the launch judder is mainly due to the 1st order excitation forces created by the geometrical inaccuracy of the internal parts of the clutch system. Moreover, the forces are amplified by the resonance of
The FSAE is a world-renowned competition, in which students from across the globe compete against each other. The chassis is the main framework of the car, which is inherently responsible for accommodating all the components. The chassis is broadly classified into two types—monocoque and spaceframe. The FSAE chassis is of spaceframe type. The chassis also provides structural rigidity to the body of the car. It was observed through literature study that very minimal amount of research has been done on analyzing and validating the chassis by applying the different meshing techniques, namely 1D, 2D, and 3D. The mesh quality is very essential to obtain precise results and hence, effective methods for creating the mesh have been dealt with in this article. This study is on new investigations on different meshing techniques that can be implemented on an FSAE chassis. The main objective is to analyze the chassis using three different meshing techniques—1D, 2D, and 3D to compare their
Aiming at improving safety (anti-roll performance) with consideration of ride comfort of vehicles during cornering and over road irregularities, magnetorheological (MR) fluid-based semi-active anti-roll bar is investigated in this article. The vehicle roll model with both roll stiffness and roll damping of the vehicle body influenced by the MR anti-roll bar is established to analyze the impact of the torsional stiffness and torsional damping. Combining with the Pareto front of the lateral load transfer ratio (LTR) of the front axle, the optimal roll stiffness and roll damping of a vehicle are determined, and correspondingly the torsional stiffness and torsional damping of the anti-roll bar are determined. And then the mathematical model and multibody dynamic model of the anti-roll bar are established, and the simulation of the MR semi-active anti-roll bar model is carried out via MATLAB/Simscape Multibody. CarSim vehicle model equipped with the MR anti-roll bar is built and a fuzzy
Items per page:
50
1 – 50 of 215