Browse Topic: Chassis stiffness

Items (223)
The suspension system could transmit and filter the forces between the body and road surface, which affects vehicle ride comfort and road maintenance capability. Compared to traditional passive and semi-active suspension, Active Suspension Systems (ASS) could automatically adjust the suspension stiffness, damping force, and body height according to changes in the vehicle's load distribution, travelling speed, and braking action through the addition of a power source such as a linear motor. Although the existing advanced control methods could help to effectively improve the driving quality of vehicles equipped with ASS, the conflict between ride comfort and road maintenance capacity is still a difficult problem to be solved. Therefore, an Active Suspension System optimal control strategy considering vehicle ride comfort and road maintenance capability is proposed in this paper. Firstly, a quarter ASS model and a road model are respectively developed based on the system dynamics
Zhu, BingZhang, ChaohuiSun, JihangWang, ShiweiDing, ShuweiLi, LunChen, Zhicheng
The half vehicle spindle-coupled multi-axial input durability test has been broadly used in the laboratory to evaluate the fatigue performance of the vehicle chassis systems by automotive suppliers and OEMs. In the lab, the front or rear axle assembly is usually held by fixtures at the interfaces where it originally connects to the vehicle body. The fixture stiffness is vital for the laboratory test to best replicate the durability test in the field at a full vehicle level especially when the subframe of the front or rear axle is hard mounted to the vehicle body. In this work, a multi-flexible body dynamics (MFBD) model in Adams/Car was utilized to simulate a full vehicle field test over various road events (rough road, braking, steering). The wheel center loads were then used as inputs for the spindle coupled simulations of the front axle with a non-isolated subframe. Three types of fixtures including trimmed vehicle body, a rigid fixture with softer connections and a rigid fixture
Gao, JianghuaSmith, DerekZhang, XinYu, Xiao
Electric vehicles (EVs) are particularly susceptible to high-frequency noise, with rubber eigenmodes significantly influencing these noise characteristics. Unlike internal combustion engine (ICE) vehicles, EVs experience pronounced variations in dynamic preload during torque rise, which are substantially higher. This dynamic preload variation can markedly impact the high-frequency behaviour of preloaded rubber bushings in their installed state. This study investigates the effects of preload and amplitude on the high-frequency dynamic performance of rubber bushings specifically designed for EV applications. These bushings are crucial for vibration isolation and noise reduction, with their role in noise, vibration, and harshness (NVH) management being more critical in EVs due to the absence of traditional engine noise. The experimental investigation examines how preload and excitation amplitude variations influence the dynamic stiffness, damping properties, and overall performance of
Hazra, SandipKhan, Arkadip Amitava
To investigate the static and dynamic mechanical properties of air springs and their influencing factors, two models were established in this paper to calculate the static and dynamic mechanical properties of air springs, including a simulation model based on the finite element method and a mathematical calculation model based on thermodynamic theory. First, a performance calculation model for rolling lobe air springs with aluminum tubes was established, which considered the thickness of the bellow and the impact of the inflation and assembly process on the state of the bellow. The static and dynamic mechanical properties of air springs were calculated using this model, including static load-bearing capacity and static/dynamic stiffness. The calculation results showed that both the static characteristics of the air spring under isothermal conditions and the dynamic characteristics under adiabatic conditions were able to be calculated accurately. However, the changes in dynamic
Wang, SiruiKang, YingziXia, ZhaoYu, ChaoLi, JianxiangShangguan, Wen-Bin
The primary functions of mounts include providing structural support, sound insulation, and vibration damping. Dynamic stiffness and loss angle are critical metrics for evaluating their NVH (Noise, Vibration, and Harshness) performance. This paper examines a floating decoupler hydraulic mount featuring a long decoupler membrane track. A nonlinear lumped parameter model is developed to calculate the dynamic stiffness and loss angle. The model incorporates fluid flow in the lower chamber and variations in the support reaction force of the decoupler membrane under switching conditions. Parameters of the nonlinear lumped parameter model, including rubber stiffness, equivalent piston area, and volumetric compliance of the fluid chamber, were analyzed and calculated using the finite element method. The influence of different decoupler membrane track structures on the frequency corresponding to the minimum high-frequency dynamic stiffness was investigated based on the established model. The
Li, ShenghaoZhang, ShenglanYu, ChaoTu, XiaofengShangguan, Wenbin
As a crucial connecting component between the powertrain and the chassis, the performance of rubber mounts is directly related to the NVH (Noise, Vibration, and Harshness) characteristics of electric vehicles. This paper proposes a double-isolation rubber mount, which, compared to traditional rubber mounts, incorporates an intermediate skeleton and features inner and outer layers of “cross-ribs”. The design parameters can be simplified to: skeleton diameter, skeleton thickness, main rib width, and main rib thickness. To comprehensively evaluate its performance, a finite element analysis (FEA) model of the proposed double-isolation rubber mount was first established in Abaqus, with static stiffness and dynamic performance analyzed separately. The results indicate that, compared to traditional rubber mounts with similar static stiffness, this design effectively controls dynamic stiffness in the high-frequency range. To expand the effective vibration isolation frequency range of the
Xu, CheKang, YingziTu, XiaofengShen, Dongming
Noise, Vibration, and Harshness (NVH) simulations of vehicle bodies are crucial for assessing performance during the design phase. However, these simulations typically require detailed computer-aided design (CAD) models and are time-consuming. In the early stages of vehicle development, when only high-level vehicle sections are available, designing the body-in-white (BIW) structure to meet target values for bending and torsional stiffness is challenging and often requires multiple iterations. To address these challenges, this study deploys a reduced-order beam modelling approach. This method involves identifying the beam-like sections and major joints within the BIW and calculating their sectional properties (area, area moments of inertia along the plane’s independent axes, and torsion constant). These components form a simplified skeleton model of the BIW. Load and boundary conditions are applied to the suspension mount locations at the front and rear of the vehicle, and torsional and
Khan, Mohd Zishan AliThanapati, AlokDeshmukh, Chandrakant
Customers are expecting higher level of refinement in electric vehicle. Since the background noise is less in electric vehicle in comparison with ICE, it is challenging for NVH engineers to address even minor noise concerns without cost and mass addition. Higher boom noise is perceived in the test vehicle when driven on the coarse road at a speed of 50 kmph. The test vehicle is rear wheel driven vehicle powered by electric motor. Multi reference Transfer Path Analysis (TPA) is conducted on the vehicle to identify the path through which maximum forces are entering the body. Based on the findings from TPA, solutions like reduction in the dynamic stiffness of the suspension bushes are optimized which resulted in reduction of noise. To reduce the noise further, Operational Deflection Shape (ODS) analysis is conducted on the entire vehicle to identify the deflection shapes of all the suspension components and all the body panels like floor, roof, tailgate, dash panel, quarter panel and
S, Nataraja MoorthyRao, Manchi VenkateswaraRaghavendran, PrasathSelvam, Ebinezer
Due to stringent emission norms, all OEMs are shifting focus from Internal combustion engine (ICE) to Electric vehicle (EV). NVH refinement of EVs is challenging due to less background noise in EVs in comparison with ICE vehicles. Motor whine noise is perceived inside cabin till the speed of 20 kmph. Vehicle is powered by electric powertrain (EPT). Electric powertrain is connected to the subframe with the help of three powertrain mounts. Subframe is connected to the body with the help of four mounts. With the help of Transfer Path Analysis (TPA), it is identified that the noise is structure borne and the dominant path is identified. By optimizing the stiffness of the EPT mounts, the structure borne noise levels are reduced. But reducing the stiffness of EPT mount deteriorated the road noise levels. The reason behind deterioration of road noise is investigated. The performance of double isolation of EPT is compared with single isolation of EPT with respect to both road and motor noise
S, Nataraja MoorthyRao, Manchi VenkateswaraRaghavendran, PrasathSelvam, Ebinezer
Sports Utility Vehicles (SUVs) Braking performance is a critical parameter, and it is described by the measure of stopping distance & stability of the vehicle at a specified speed. When it comes to electric vehicles, balancing tyre performance parameters like RRc, traction, wear, ride and handling, weight and NVH is challenging due to higher axle weights, higher moment of inertia and high instant torque delivery. This study presents the braking performances of EV-intended tyres at various contact surfaces in both dry & wet conditions. Impact of tyre design attributes like tyre tread pattern, contact patch, tread compound, tyre carcass construction & characteristics studied on 3 different tyres including ultra-high-performance tyres on braking performances. This paper contains the study & analysis of 1) Footprint analysis concerning the shape of the contact patch, pressure distribution, land-sea ratio, and contact area 2)Tyre tread design such as NSD, grooves, ribs & sipes design and
V, PadmasriVellandi, VikramanSundaram, RaghupathiSingh, Ram KrishnanP, PraveenChittibabu, Santhosh
Three dynamic models of a passenger car including the one-dimensional dynamic model, two-dimensional dynamic model, and three-dimensional dynamic model are built to evaluate the ride quality of the passenger car as well as the isolating performance of the SNS (structure of negative stiffness). The decrease of the root-mean-square (RMS) accelerations in the seat and car’s body shaking is the research goal. The investigation results indicate that under all working conditions including the various excitations of the road surface and various velocities of the passenger car, the seat’s acceleration with SNS is strongly ameliorated in comparison without SNS in all three models of the passenger car. Particularly, the RMS seat acceleration with SNS in one-, two-, and three-dimensional models is strongly reduced in comparison without SNS by 76.87%, 66.15%, and 70.59%, respectively. Thus, the seat’s SNS has a good effect in isolating the vertical vibration of the passenger car’s seat. However
Zhang, LeiLi, TaoYang, Guixing
The commitment to environmentally friendly transportation calls for efficient solutions with the evolution of automotive industry. Turbochargers are an important part of this development. The application of Gas or Air Foil Bearings (GFB) instead of traditional hydrodynamic bearings is recently very noticed, with which the fuel consumption, and emissions can be minimized as well as decreasing the maintenance costs and increasing the reliability. However, low viscosity of gas leads to lower dynamic stiffness and damping characteristics resulting in low load carrying capacity and instability at higher speeds. Gas bearings can be enhanced by adding a foil structure commonly known as gas foil bearings whose dynamic stiffness can be tailored by modifying the geometry and the material properties resulting in better stability and higher load carrying capacity. A detailed study is required to assess the performance of high-speed rotor systems supported on GFBs, therefore in this study a bump
Mandapalli, Prithvi RajuHoefler, DieterRohani, Rezvan
Automotive subframe is a critical chassis component as it connects with the suspension, drive units, and vehicle body. All the vibration from the uneven road profile and drive units are passed through the subframe to the vehicle body. OEMs usually have specific component-level drive point dynamic stiffness (DPDS) requirements for subframe suppliers to achieve their full vehicle NVH goals. Traditionally, the DPDS improvement for subframes welded with multiple stamping pieces is done by thickness and shape optimization. The thickness optimization usually ends up with a huge mass penalty since the stamping panel thickness has to be changed uniformly not locally. Structure shape and section changes normally only work for small improvements due to the layout limitations. Tuned rubber mass damper (TRMD) has been widely used in the automotive industry to improve the vehicle NVH performance thanks to the minimum mass it adds to the original structure. Therefore, this article establishes a
Gao, JianghuaZhang, XinYu, Xiao
In order to efficiently predict and investigate a vehicle’s vertical dynamics, it is necessary to consider the suspension component properties holistically. Although the effects of suspension stiffness and damping characteristics on vertical dynamics are widely understood, the impact of suspension friction in various driving scenarios has rarely been studied in both simulation and road tests for several decades. The present study addresses this issue by performing driving tests using a special device that allows a modification of the shock absorber or damper friction, and thus the suspension friction to be modified independently of other suspension parameters. Initially, its correct functioning is verified on a shock absorber test rig. A calibration and application routine is established in order to assign definite additional friction forces at high reproducibility levels. The device is equipped in a medium-class passenger vehicle, which is driven on various irregular road sections as
Deubel, ClemensSchneider, Scott JarodProkop, Günther
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
Zhang, YilongChen, ZixuanWu, JinglaiZhang, Yunqing
Recently, the market share of electric vehicles is becoming increasingly obvious. It is expected that electric vehicles are quieter than fuel vehicles. Actually, without the cover of low-frequency engine noise, the high-frequency noise of electric vehicles is more prominent, which seriously affect the perceived sound quality. The present work is related tonal noise resulted from electric drive system (EDS), which is one of the fundamental noise sources for battery electric vehicle (BEV). The dominant noise sources observed in the vehicle interior are 26th and 36th orders for reducer and drive motor separately. Poor vibration isolation of right mounting system is the fundamental cause identification of EDS noise which has been investigated with objective measurements and simulation tools. Dynamic stiffness analysis is carried out to optimize the passive bracket. An engineering solution is implemented to enhance bracket to improve resonance effect. The test results after improvement
Ding, ChaoJiang, XiaodongHe, WeikangYu, HuiqiangMa, Yan
Building upon prior research, this paper compares computer simulations to a previously conducted rollover crash test of a tractor-semitrailer. The effects of torsional stiffness were elucidated during the correlation of simulations to the rollover test. A commercially available vehicle dynamics and reconstruction software was used for the simulation. Unique aspects of the rollover crash test were modeled in the simulation. A tractor-semitrailer quarter-turn rollover crash test conducted by IMMI was reconstructed using impact and vehicle dynamics models within the simulation software HVE (Human, Vehicle & Environment). The SIMON (SImulation MOdel Non-linear) module and the DyMESH (Dynamic MEchanical SHell) module within HVE were used. During the IMMI test, onboard instrumentation recorded acceleration and roll rate data in six degrees of freedom to characterize both tractor and semitrailer dynamics before and during the rollover event. The roll angle and roll rate behavior of the HVE
Honeycutt, DanielRogers, GaryYang, ShuChinni, James
Electric motor noise mitigation is a challenge in electric vehicles (EVs) due to the lack of engine masking noise. The design of the electric motor mounting configuration to the motor housing has significant impacts on the radiated noise of the drive unit. The stator can be bolted or interference-fit with the housing. A bolted stator creates motor whine and vibration excited by the motor torque ripple at certain torsional resonance frequencies. A stator with interference fit configuration stiffens the motor housing and pushes resonances to a higher frequency range, where masking noise levels are higher at faster vehicle speeds. However, this comes with additional cost and manufacturing process and may impact motor efficiency due to high stress on stators. In this paper, a thin sheet metal NVH ring is developed as a tunable stiffness device between the stator and the motor housing. It is pre-compressed and provides additional torsional rigidity to mitigate torsional excitations. A CAE
He, SongTran, XuanNaismith, GregoryDu, IsaacPatruni, Pavan KumarBaladhandapani, Dhanasekar
In order to study the effects of different factors on the static and dynamic characteristics of air springs, three models were established to calculate the static and dynamic characteristics of air springs, including modeling at the design position, modeling only considering the straight state, and modeling considering the thickness of the bellows in the straight state. Static stiffness of air springs is calculated using three different models and are compared with experiments. In the straight state model considering the thickness of the bellow, the influence of aluminum tube and bellows thickness on the static stiffness are considered, and the modeling with the straight state solved the problem of the change in cord angle after the air spring was inflated and expanded. The established model is then used to calculate static and dynamic characteristics of air springs, such as static stiffness, hysteresis loop, and dynamic stiffness. The static stiffness, force versus displacement
Zhuo, Yi-FanWang, XihuiLi, JianxiangShangguan, Wen-Bin
Side doors are pivotal components of any vehicle, not only for their aesthetic and safety aspects but also due to their direct interaction with customers. Therefore, ensuring good structural performance of side doors is crucial, especially under various loading conditions during vehicle use. Among the vital performance criteria for door design, torsional stiffness plays an important role in ensuring an adequate life cycle of door. This paper focuses on investigating the impact of several door structural parameters on the torsional stiffness of side doors. These parameters include the positioning of the latch, the number of door side hinge mounting points on doors (single or double bolt), and the design of door inner panel with or without Tailor Welded Blank (TWB) construction. The findings of this study reveal that the change in latch position has the most significant influence on torsional stiffness, followed by the removal of TWB from the inner panel, upon implementation of suitable
Goyal, Vinay KumarSelvan, VeeraPandurangan, VenugopalUnadkat, SiddharthAlmeida, Neil Ricardo
This article presents a method for improving electric motor noise and vibration analysis based on rotor load. The method first obtains two key parameters, namely the characteristics of the stator and rotor core material and the connection stiffness between the rotor skewed poles, through modal testing and simulation calibration of the stator and rotor. Subsequently, the electromagnetic simulation is used to calculate the torque fluctuation of each segment of the rotor skewed poles, which is used as input load for the structural simulation. The vibration of the suspension point and the radiation noise of the transmission housing are then calculated under the action of torque fluctuation. The study highlights the significant contribution of the rotor torsional mode to noise and vibration. Finally, by improving the torsional stiffness of the rotor and the distribution of skewed poles, the noise and vibration problems caused by torsional mode can be significantly improved, leading to
Zhang, JingwenGeng, ZhirongLi, QiangLi, Shuangchi
Adhesively bonded joints have been applied in the automotive industry for the past few decades due to their advantages such as higher fatigue resistance, light weight, capability of joining dissimilar materials, good energy absorption, and high torsional stiffness for overall body structure. They also provide an effective seal against noise and vibration at a low cost. There exists the challenge of defining the fatigue characteristics of adhesive joints under cyclic loading conditions, and conventional methods have limitations in detecting the crack initiation of a bonded joint. This study introduces a method of detecting crack initiation by using the frequency method. It is found that stiffness change in the system is highly correlated to change in natural frequencies. By monitoring the change in natural frequencies, the crack initiation can be detected.
Huang, XiaobaoBarber, Gary
A chassis is the main skeleton of a go-kart containing distinct components such as the engine, brakes, fuel tank, rear axle, etc. It supports the entire weight and load of the components, so it must be steady enough to withstand shock, twisting, vibration, and other stress. This paper reviews the study carried out on the chassis, highlighting the area where the Nodes, Primary and Secondary members, Horizontal and Vertical members, and Chassis stiffness support the jacking effect with the constraints of maximum Torsional stress, deflection, and critical regions under loading conditions. AISI 4130 is used as the chassis material. When dealing with the software, SolidWorks 2023 and Fusion 360 are used for designing the chassis whereas ANSYS 2022 is used for the analysis of the designed chassis. In order to reduce weight, improve material consumption, and provide an appropriate cross-section, a simulation technique was used in design optimization.
Vignesh, D.Sanchan Kumar, S.Saravanan, V.Sudhakar, M.
One of the biggest challenges for automotive industry is with respect to material saving and to have control on cost of development and still meeting performance in each aspect. Stringent weight targets help industries to have good margin on component costs. In recent times we have seen vehicle underbody contribution to total vehicle is significant in range of 12% to 18%. Total weight directly impacts the range of electric vehicle which is a key metric for success from real-world usage point of view and customer appeal. Hence control on suspension and frame design for light weighting is prominent trend in industry, this leads to deterioration of suspension compliance as well as vehicle ride and handling performance. Sub-frame and knuckle play crucial role in definition of overall suspension stiffness. Present Study focusses on electric vehicle rear cradle design for weight saving with minimum reduction of stiffness. Understanding compliance which obtained from frame\cradle in vehicle
Asthana, ShivamRasal, ShraddheshNidasosi, BasavrajV, Jesse DanielGanesh, LingadaluRamkumar, JNayak, BhargavM, SudhanVellandi, Vikraman
For any two wheeler vehicle development, rider and pillion comfort while driving the vehicles over different kinds of road perturbations holds high importance. Designing a vehicle for comfort starts at the very beginning of its layout definition through vehicle geometric parameters, key hardpoints, mass-inertia distribution of subsystems and suspension characteristics. There is a need for highly reliable simulation models for comfort predictions as any change in layout during subsequent design stages is a very costly affair. Accurately predicting comfort using a full vehicle model is a challenging task though as it depends on how realistic the Simulation Model is to that of actual vehicle. While suspension stiffness and damping characteristics remain critical parameters for the comfort, selection of tyres are known to hold equal importance in vehicle comfort. The details to which the tyres are captured in the simulation model and the formulation of tyre interaction with roads in a
Govindula, SrikanthPandey, PradyumnSaraswat, UditMishra, Ashish
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
S, Nataraja MoorthyRao, ManchiRaghavendran, PrasathSelvam, Ebinezer
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
S, Nataraja MoorthyRao, ManchiRaghavendran, Prasath
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
S, Nataraja MoorthyRao, Manchi VenkateswaraRaghavendran, PrasathManivannan, Giridharan
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
S, Nataraja MoorthyRao, ManchiRaghavendran, PrasathSelvam, Ebinezer
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
S, Nataraja MoorthyRao, ManchiRaghavendran, PrasathManivannan, Giridharan
A robust process of specifying engine mounting systems for internal combustion engines (ICE) has been established through decades of work and countless applications. Vehicle vibration is a critical consideration in the early stage of vehicle development. Apart from comfort, it also affects the overall vehicle's performance, reliability, Buzz-squeak and rattle (BSR), parts durability and robustness. The most dynamic system in a vehicle is the powertrain, a source of vibration inputs to the vehicle over the frequency range. The mounting system supports a powertrain in a vehicle and isolates the vibration generated from the powertrain to the vehicle. In addition, it also controls the overall dynamic movement of the powertrain system when the vehicle is subjected to road load excitations and avoids contact between the powertrain and other adjacent components of the vehicle. This paper investigates the effect of the mounting position, stiffness, and progressivity on overall vehicle-level
Hazra, SandipMohare, Gourishkumar
The SAE (Society of Automotive Engineers) through its formula competition proposes the development of a complete competition vehicle in order to encourage the project in addition to new techniques in this area of study. Within the vehicle’s subsystems, there is the chassis being of great importance for the vehicle’s dynamic performance in addition to coupling all other subsystems. Therefore, the present work aimed to develop a new monocoque chassis geometry through a topological optimization made in Ansys. An initial geometry of the author himself was used when he participated in a competition team. From this geometry, a static analysis was generated to measure the deflection that influences the torsional stiffness of the chassis, this analysis being the limits or boundary conditions of the imposed minimization problem. With an element size analysis of 15 mm, 20 mm and 25 mm it was possible to define that the smaller size produced better results and the following results were obtained
Rocha, Vinícius Resende
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.
Ulrich, Lawrence
Truck maneuverability is one of the phenomena, which is considered in development stage of a commercial vehicle chassis structure. Torsional stiffness is one of the important properties of the chassis structure that significantly affects vehicle dynamic characteristics such as handling and rollover. The torsional stiffness is preferred to be as high as possible since lower torsional stiffness may cause resonance, vibration, poor handling, and rollover. Torsional stiffness can be improved through minor modification in the conventional ladder chassis frame. This paper presents the comparative study on improving the torsional stiffness of the chassis frame. The objective is to achieve the improved torsional stiffness by varying the neutral axis of the frame long member section at a desirable region. Torsional stiffness is dependent of the sectional modulus; this study provides an insight on increasing the torsional stiffness without addition of section modulus.
Gowtham, G.V.N.Baashkaran, M.K.Naveen, Sukumar N.
An Inline 4-cylinder engine is equipped with second-order balance shafts.When the engine is running under full load in 5000rpm,the engine generated severe structural radiation noise.The bench test analysis shows that the main reason is the resonance of the engine near 800Hz and 1500Hz. In this paper, a method for modeling and analyzing the vibration of the engine structure is proposed, and the sound quality of the engine is evaluated and imporved by the Moore–Glasberg loudness method. Firstly, the finite element model of the engine was established, and the experimental modes of the engine casing assembly, crankshaft and balance shaft were measured. The natural frequencies and modal shapes obtained by calculation and experiment were compared, which validates the established finite element model.Secondly, a flexible multi-body dynamic model of the engine was established. The inertia and torsional stiffness of the drive shaft at flywheel nose are taken into consideration in the model, and
Dong, Guo-QingShangguan, Wen-Bin
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.
Ulrich, Lawrence
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
Kim, HyungtaeLee, YoungHoHur, JungwooChoi, Jeehwan
Climate change has become a real problem in our world. Society is trying to contain it as much as possible, promoting more sustainable behaviors and limiting pollution. For the automotive industry, this leads to progressive electrification and reduction of tailpipe emissions and fuel consumption for conventional vehicles. In this framework, this paper presents the design of a vehicle to compete in the Urban Concept category of Shell Eco Marathon, a competition among universities that has the goal to release a vehicle with the lowest possible fuel consumption. This work describes the monocoque design phases of the vehicle JUNO. The complete design approach is described, through the analysis of the decisional workflow adopted to integrate every technical solution from the aerodynamic constraints to the structural ones passing from the vehicle dynamic requirements. The methodology adopted to size the monocoque is explained in depth through the analysis of the multi-step optimization
Messana, AlessandroBianco, LucaCarello, Massimiliana
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
Kabra, Sanjay
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
Derrix, DanielProkop, Günther
The number of stacked plies and orientations of carbon fiber/epoxy in a sandwich panel with an aluminum honeycomb core was optimized using finite element analysis to improve the structural performance of the monocoque chassis for the electric Formula SAE racecar. To establish the selection criteria for fabrics and orientations, the single unidirectional (UD) and woven plies (W) were simulated under tensile and simple shear tests to determine their off- and on-axis properties. Simulation results revealed that the unidirectional ply enhances the overall strength of laminate, while woven ply is responsible for shear strength. Thus, the combination of unidirectional and woven plies was proposed. The four anisotropic laminates consisting of four stacked plies with different orientations were simulated under three-point bending and plate twist tests to determine the flexural rigidity and twist stiffness, respectively. Their mechanical properties were then compared to the quasi-isotropic
Sratong-on, Pimpet
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.
Kim, Hyungtae
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
Aiyan, MohammedSagar, S. SumanthRaghav S., Sanjay
ABSTRACT We compared performance of a lightweighted and baseline vehicle and demonstrated how performance is affected by adjusting the spring and shocks using 2-D and 3-D simulations. 2-D lump-parameter model was constructed from physical vehicle parameters by transforming displacements and loads from the springs and dampers into wheel motion and spindle forces. For the 3-D model, a detailed model for each suspension was used including rotational inertia of moving parts. Ride quality was assessed for 16 ride-courses with varying RMS terrain roughness by finding maximum speed at which average absorbed power at the driver seat is lower than 6 W. Shock performance was evaluated by finding maximum speed for the driver not to exceed 2.5-G acceleration when riding over varying-size half-round obstacles. The forces on wheel axes and accelerations were measured for the vehicle dropped from the height of 6, 12, 18, and 24 in. Maximum longitudinal slope climbing capability was estimated on hard
Jelinek, BohumirSalmon, EthanMason, GeorgeGibson, MichaelHannis, TylerPachel, NathanJarrell, WalkerTowne, Brent
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
Sratong-on, PimpetWanthong, Sobree
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