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Regenerative braking is an effective approach for electric vehicles (EVs) to extend their driving range. To enhance the braking performances and regenerative energy, regenerative braking control strategy based on multi objective optimization is explained in this paper. This technical paper would be focusing on extracting optimum Range with effective brake performances without affecting drivability and performances in different drives modes. An extensive research study on public road driving patterns is done to understand the percentage utilization of brakes at various (low-mid-high) speeds as per the customer driving behavior. Multi-Objective optimization function with three vital factors is defined where output generated power, torque smoothness and current smoothness are selected as optimization objective to improve the driving range, braking comfort, and battery lifetime respectively.

In automotive market, with competitive car prices, build quality of a car will be a major distinguishing factor. Consumer's need for acoustic comfort has evolved from the removal of annoying noises to perceived sound quality. Operational sounds from electromechanical systems like sunroof system, window regulator, door lock system, HVAC etc. directly interact with users’ senses. The perceived acoustics comfort of these sounds are direct indicators of vehicle character and can influence customer’s buying decision. With the reduction in product development time and stringent cost constraints, a proper structured target setting methodology to benchmark & evaluate these operational sounds is crucial. In this paper, such a target setting methodology is proposed and discussed for operational sound quality evaluation. Electromechanical noises from various vehicles are measured using binaural head measurement system.

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.

The inherent capacity of electric motors to generate substantial instant torque can lead to significant load reversals in electric vehicle driveshafts under specific road conditions and driving maneuvers, highlighting the need for targeted improvements in driveshaft design, particularly in optimizing joint sizing. This paper presents a systematic approach to investigate the root causes of a catastrophic driveshaft failure that occurred during specific vehicle tests on a road with multiple speed bumps, resulting in numerous high torque reversals. The objective was to enhance system robustness through changes in driveshaft design and the manufacturing process, coupled with a software calibration technique to reduce torque demands under such operating conditions. The process encompassed torque measurements at the vehicle level, failure replication on a test rig, and correlation with simulations.

As the world rapidly moves from IC engine powered vehicles to the ‘more sustainable’ electrified vehicles, the Powertrain Mounting System needs to be re-engineered to meet refinement requirements of customer. Electric vehicles are quieter but due to lack of the “masking effect”, are sensitive to minor disturbances that are perceived to be objectionable by passengers. Also, E-powertrains are lighter, produce higher torque at low rpms & operate at higher rpms which calls for different countermeasures for mounting systems compared to conventional single isolation 3-point mounting system as used in IC engines. Double isolation mounting system, where powertrain is connected to an auxiliary mass (sub frame/cradle) via mounts, which is suspended to the vehicle body via subframe bushes results in 12 rigid body modes, 6 for each mass, is highly effective in lowering the transmission of vibration at high frequencies.

Customer comfort has been at the core of any vehicle design. A segment of vehicle wherein the provision given for roof to be removed to enhance the customer experience. A similar vehicle is the subject matter for the evaluation here. The vehicle being off-roader, customer buying such vehicles are passionate about these lifestyle vehicle’s performance aspects. The roof components are plastic and are bolted with the BIW structure with sealing in place at the interface. The windshield angle being close to vertical, there is a tendency for flow separation at the front tip of roof, while vehicle driven at speed. This creates significant pressure difference across the roof surface, leading to vertical deformation of roof between the bolted mounts. In case the magnitude of deformations not controlled, the reduced sealing effectiveness lets air gushing in the cabin and make noise which can be audible to customer.

In the automobile industry, the door closing effort spells out the engineering and quality of the vehicle. After the visual impact a vehicle has on the customer, the doors are most likely the very first part of the vehicle he/she encounters, to enter and exit the vehicle. One of the customer’s very first impressions about the quality of the car is given by the behavior of the doors when opening and closing, the swinging velocity and the energy that is required to obtain a full latching that the door makes when closed by the user. Door closing effort gives an indication of how good or bad the vehicle is engineered. The purpose of this paper is to propose modifications in the door system which help in reduction of door closing effort or velocity by two different methods, EZ Slam Door and Bungee Rope. In this paper, parameters like hinge friction, hinge axis inclination, sealing, latch and air bind effect are analyzed which affect door closing effort.

Multidisciplinary Design Optimization (MDO) of an automobile body structure is a challenging task as it involves multiple, often conflicting requirements of safety, durability & NVH. Conventionally MDO process requires running large number of design of experiments (DOE) to explore the full design space and to build response surface for optimization. As the safety simulations are highly nonlinear in nature, they typically require significant amount of computational time and resources. Hence the conventional MDO approach is too expensive if too many design variables are simultaneously considered. In this paper, an alternative approach using Equivalent Static Load (ESL) method has been suggested for MDO which is quicker & accurate. The basic idea of the Equivalent Static Load-Method (ESL) is to divide the original nonlinear dynamic optimization problem into an iterative linear optimization and nonlinear analysis process.

For Automatic transmission application, crankshaft torque is transferred to torque converter through flex plate. As the flex plate has no functional requirement of storing energy as in case of Manual Transmission (MT) flywheel, flex plate design can be optimized to great extent. Flex plate structure must have compliance to allow the axial deformation of torque convertor due to ballooning pressure generated inside the converter. Flex plate experiences dynamic torque and centrifugal forces due to high rotational speed. It should have compliance to accommodate the assembly misalignments with torque convertor in both axial and radial directions. In this paper, sequential and hybrid optimization techniques are described to optimize the flex plate design with stress, stiffness and mass as design constraints. The load path, corrugation length and axial stiffness of flex plate captured accurately using this hybrid optimization.

A vehicle drifts due to several reasons from its intended straight path even in the case of no steering input. Vehicle pull is a condition where the driver must apply a constant correction torque to the steering wheel to maintain a straight-line course of the vehicle. This paper presents an investigation study into the characteristics of a vehicle experiencing steering drift. The aim of the work is to study vehicle stability and the causes of vehicle drift/pull during straight line to minimize vehicle pull level and hence optimize safety measures. A wobble in the steering wheel feels like the steering wheel is shaking to the left and right. This may get worse, if speed increases. This paper focuses on modelling and evaluating effects of suspension parameters, differential friction, brake drag variation, Unbalanced mass in the wheel assembly and C.G. location of the vehicle under multibody dynamic simulation environment.

In today’s cost-competitive automotive market, use of finite element simulations and optimization tools has become crucial to deliver durable and reliable products. Simulation driven design is the key to reduce number of physical prototypes, design iterations, cost and time to market. However, simulation driven design optimization tools have struggled to find global acceptance and are typically underutilized in many applications; especially in situations where the algorithms have to compete with existing know-how decision making processes. In this study, systematic multi-phase approach for optimization driven design is presented. Approach includes three optimization phases. In first phase, topology optimization is performed on concept BIW design volume to identify critical load paths. Architectural inputs from topology are used to design base CAD.

Plenum is the part located between the front windshield and the bonnet of an automobile . It is primarily used as an air inlet to the HVAC during fresh air mode operation. It’s secondary functions include water drainage, aesthetic cover to hide the gap between windshield to bonnet, concealing wiper motors and mechanisms etc. The plenum consists mainly two sub parts viz. upper plenum and lower plenum. Conventional plenum design which is found in majority of global OEMs employ a plastic upper plenum and a metal lower plenum which spans across the entire width of engine compartment. This conventional lower plenum is bulky, consumes more packaging space and has more weight. In this paper, we propose a novel design for the plenum lower to overcome above mentioned limitations of the conventional design. This novel design employs a dry and wet box concept for its working and is made up of complete plastic material.

Stringent emission norms by government and higher fuel economy targets have urged automotive companies to look beyond conventional methods of optimization to achieve an optimal design with minimum mass, which also meets the desired level of performance targets at the system as well as at vehicle level. In conventional optimization method, experts from each domain work independently to improve the performance based on their domain knowledge which may not lead to optimum design considering the performance parameters of all domain. It is time consuming and tedious process as it is an iterative method. Also, it fails to highlight the conflicting design solutions. With an increase in computational power, automotive companies are now adopting Multi-Disciplinary Optimization (MDO) approach which is capable of handling heterogeneous domains in parallel. It facilitates to understand the limitations of performances of all domains to achieve good balance between them.

The customer of today is sensitive towards shift quality. The demand is for a crisp and precise gear shift with low shift effort. The impulses from synchronizers make shifts feel notchy. After synchronization the blocker ring releases the sleeve. The sleeve then hits the teeth of the clutch body ring. The second impulse causes a phenomenon called double bump. This can be felt at the hand and makes a shift feel notchy or sluggish. An ideal way to overcome this is to optimize the detent profile. This paper explains in detail the various factors that contribute to the perceived shift feel. Various methods to optimize the forces on the knob by changing the detent profile are discussed. Gear Shift Quality Assessment (referred as GSQA henceforth) is a tool to acquire the required shift feel data. Using this tool shift efforts and kinematics of a 5 speed manual transmission are plotted for illustration. The calculations required to optimize the detent profile are explained in detail.

In vehicle Front End Flow (FEF) analysis, the basic objective is to predict the mass flow/velocity of air at radiator inlet with constant fan rotation. In general, the Multiple Reference Frame (MRF) model is used to model the fan. The flow velocity distribution at radiator inlet due to fan rotation should be uniform in circumferential direction whereas, it should vary in radial direction depending upon the blade geometry. However, the drawback with MRF model is that, it gives higher velocities near radiator inlet at regions corresponding to the fan blades and lower velocities at other regions, which is not realistic. This issue is more predominant when the vehicle is at low speeds or when radiator is placed at mid or back of the vehicle or the fan is having less number of blades. In order to nullify this uneven velocity distribution at radiator inlet, Mixing Plane (MP) approach was used in addition to the MRF model.

Scooter segment growth is tremendously increasing in India. The increased competition challenges automotive manufacturers to deliver the high quality and high reliable product to the market. Higher reliability involves increased durability testing which involves time and cost. Stress testing a part of durability is initially conducted on prototype vehicles for structural design validation and then later on production units to ensure its structural integrity. The obtained data from the tests can be used for future structural design improvements. Scooters with small tires, suspension limitations transfers more loads to structure, challenges engineers to design robust structure without compromising on weight much. It is necessary to look at Real World Usage Pattern (RWUP) and to create a stress life cycle block for simulation of accelerated testing, thereby optimizing the testing time and the development costs.

Regulations on pedestrian safety have been introduced globally since the year 1990 and in India it will have to be met around the year 2016. Process of making vehicle compliant to this regulation requires rigorous design development and testing. Testing involves propelling head-forms (Child and Adult) on bonnet at 35 km/h and 40 km/h and leg-forms (Upper and Lower) on bumper at 40 km/h according to the different National / International / NCAP regulatory requirements A pedestrian protection test rig has been indigenously designed and developed in-house to perform pedestrian protection impact testing in-house. The paper describes the salient features of the pedestrian protection test rig, its functioning, operation and process of acquiring the data for determination of the values required by crash safety regulations.

The customer perception about the door slam noise and its feel would indicate the brand image of the car. In this paper the authors have made an effort to improve the door slam noise quality of the vehicle, which is currently in production. This paper describes the probable areas in the door to improve the slam noise quality by attempting modifications in the door design factors, such as door alignments, door panel stiffness, door trims, window glass rattle, latch striker alignment, door seals, air extractor. Since the door closing event is a transient phenomenon, it requires special tools such as wavelet transforms, Zwicker loudness to understand the slam events precisely. Subjective jury evaluations have been conducted to understand the effect of these modifications and rank the modifications based on their contributions to the door slam quality.

Airbags play a vital role in occupant protection during a crash event. Apart from the crash test the airbags have to additionally meet the requirements of the ECE R 12 headform impact test with Driver's Airbag (DAB) located in the steering wheel being deployed and the ECE R21 headform impact test for Passenger Airbag (PAB) in undeployed condition. Improper location of the PAB module below the Instrument Panel, the design of the air bag housing and the Instrument Panel are some of the factors that could lead to non compliance of the components of the uninflated PAB. The paper deals with the investigation conducted for compliance of the PAB to ECE R 21 with the uninflated air bag in meeting the requirements of 80 g at 19.3 km/h by proper location, changes to the design of the PAB cover, air bag housing brackets, etc.

This work discusses about the emission development of a 4 cylinder inline 3.3 liter CRDe to meet BS III emission norms applicable to 3.5 Ton and above category and upgradable to BS IV emission by suitable after treatment. This engine is developed from a 3.2l mechanical pump engine. During development the focus was on the usage of higher swept volume, selection of engine hardware like piston bowl, turbocharger, injectors and optimization of the injection parameters. A cost-effective solution for meeting the BS III norms in the LCV category without application of EGR and exhaust after treatment even though there is 15% increase of the power rating and 10% increase in Peak torque of the engine. Injection parameters like injection timing, injection quantity and pilot injection were optimized to meet the emission target.