Search Results

Vehicles have a wide range of resonance band due to design nature & characteristics of its aggregates. First order, vehicle speed dependent, wheel disturbance due to wheel imbalances can result in excitation of different vehicle aggregates. Steering wobble refers specifically to first order road wheel excitation effects, in frequency range of 10-16 Hz, that manifest themselves as significant steering wheel torsional vibrations at highway speeds i.e. at the range of 80 km/h to 120 km/h on smooth roads. The tire, being an elastic body analogous to an array of radial springs, may exhibit variations in stiffness about its circumference; hence, it may vibrate at different frequencies due to wheel imbalance. This paper introduces dynamic steering wobble analysis methodology either using vehicle speed at Discrete (individual speeds) or by Sweep (low to high speed) method to investigate steering wobble in the virtual environment using the full vehicle MBD model.

In recent years, there has been a rapid growing demand for laser brazing in the transportation industry for automotive-Body in White (BIW), steel sheet assembly. Implementation of laser brazing is aimed primarily to improve productivity, quality of joints and cost. Laser brazing works by filling the opening amongst two substrates by melting the filler wire with the help of laser beam (used as a heat source), whereas in conventional resistance spot welding, contacting metal surface points are joined by the heat obtained from resistance to electric current. BIW is essentially a welded metal structure which is meant to provide durability and crashworthiness to the vehicle and is conventionally assembled using resistance spot welding process. The BIW structure comprises of various steel grades having varying thicknesses, compositions, microstructures and mechanical properties.

The goal of reducing fuel consumption and CO2-Emission is leading to turbo-charged combustion engines that deliver high torque at low speeds (down speeding). To meet NVH requirements damper technologies such as DMF (Dual Mass Flywheel) are established, leading to reduced space for the clutch system. Specific measures need to be considered if switching over from SMF (Single Mass Flywheel) to DMF [8]. Doing so has an impact on thermal behavior of the clutch system, for example due to reduced and different distribution of thermal masses and heat transfer to the surroundings. Taking these trends into account, clutch systems within vehicle powertrains are facing challenges to meet requirements e.g. clutch life, cost targets and space limitation. The clutch development process must also ensure delivery of a clutch system that meets requirements taking boundary conditions such as load cycles and driver behavior into account.

Several sub-systems in a vehicle contribute to vehicle crashworthiness. One such system is the door latch and locking system. Correct functioning of this system is critical for facilitating occupant evacuation and preventing occupant ejection during crashes. Special care needs to be taken during vehicle safety development to achieve the desired intent. In crashes, it is observed that door opening or locking mainly occurs on account of inertial loads and deformation of the door structure. This paper studies the possible failure modes and their causes. Some likely solutions have also been discussed with a case study.

Transmission designs over the years have evolved significantly achieving more efficiency in terms of fuel economy, comfort and reduction in emissions. This paper describes a Dc motor based E-shift mechanism which automates an existing manual transmission and clutch system to give comfort and ease for gear shifting. The basic idea of E-shift mechanism is to make hassle free gear shifting of manual transmission at sole command of driver without any control strategy for automatic shifting as in case of Automated Manual transmission (AMT). The E-shift mechanism will eliminate the manual efforts required for pressing clutch pedal and shifting gear, giving more ease while driving. The developed mechanism can be retro fitted on existing manual transmission without any major modification at lower cost. The E-shift mechanism uses two actuators for gear shifting and one actuator for clutch actuation.

Low steering effort in mechanical steering system is very essential, besides meeting the regulatory norms, to have driving comfort and easy maneuverability on turns. All the components in steering and suspension system plays important role in the resultant steering effort of the vehicle. Of all the factors affecting steering effort, following are identified as high influencing parameters: 1 Steering geometry. 2 Steering system compliance. 3 Friction in steering system linkages like assembly steering column, assembly steering gear box etc. 4 Tyre static friction torque. Present paper describes the detailed analysis of the influence of each parameter on steering system. The above parameters were studied in isolation as well as in combination, to ascertain their effect on steering effort. In a mechanical steering system, the parameters listed above contribute to 35% on steering effort where-in frictional forces itself contributes to 25%.

Reduction in the drivetrain losses of a vehicle is one of the important contributing factors to amplify the fuel economy of vehicle, particularly in heavy commercial vehicle. The conversion of 6 × 4 drive vehicle into 6 × 2 drive has a benefit of improving the fuel economy of a vehicle by reducing the drivetrain losses occurring in the second rear axle. It was cultured by calculation that in 6 × 2 drive the tractive force available at the wheels, of heavy commercial vehicle with GVW of 44 tons and above, will be much higher than the frictional force transmission capacity of tires, when the engine is producing peak torque on the driving duty cycle like going on steep gradient road. In such situations the tires will start to slip and may result in deteriorating the fuel economy and excessive tire wear. On the other side the flat road driving duty cycle in 6 × 2 drive will give better fuel economy than 6 × 4 drive.

This paper highlights the transition of multi-axis suspension test rig from fixed reacted type to semi-inertial type and the benefits derived thereof in simulation accuracies. The critical influence of ‘Mx’ and ‘Mz’ controls on simulation accuracies has been highlighted. The vital role of ‘Mz’ control in the resonance of wheel pan along ‘Z’ axis and thereof arresting unwanted failures modes in spindle has been duly emphasized. Finally, the role of constraints and boundary conditions on simulation accuracies has been demonstrated by replacing the reaction frame with vehicle body.

In today’s automobile market, most OEMs use manual transmission for cars. Gear Shifting is a crucial customer touch point. Any issue or inconvenience caused while shifting gears can result into customer dissatisfaction and will affect the brand image. Synchronizer is a vital subsystem for precise gear shifting mechanism. Based on vehicle application selection of synchronizer for given inertia and speed difference is a key factor which decides overall shift quality of gearbox. For more demanding driver abuse conditions like skip shifting, conventional brass synchronizers have proved inadequate for required speed difference and gear inertia, which eventually results into synchronizer crashing and affects driving performance. To increase synchronizer performance of multi-cone compact brass synchronizer, a ‘Grit blasting process’ has been added. These components tested with an accelerated test plan successfully.

Electrical and Series Hybrid Vehicles are generally provided with single speed reduction gearbox. To improve performance and drive range, a two-speed gearbox with coordinated control of traction motor and gearshift actuator is proposed. For a two-speed gearbox, gearshift without clutch would increase the shifting effort. Active Synchronization is introduced for a smoother gearshift even without clutch. The quality of gearshift is considered as a function of applied shift force and time taken. To enhance the quality of the gearshift further, the location of the synchronizer in the transmission system is optimized. To validate the improvement in the quality of the gearshift, a mathematical model of the two-speed gearbox incorporating proposed location of synchronizer assembly along with active synchronization is developed. The qualitative and quantitative analysis of the results achieved is presented.

Automotive exterior lighting systems has to meet several regulatory requirements & manufacture specific internal standards to achieve desired performance. These test specifications are usually generic in nature and formulated mainly to validate the standalone product under standard laboratory conditions. Most of the time these specifications are common for entire vehicle portfolio. The rationale of these standards is to define the basic illuminance in the safe braking distance. Thus, however, using the requirements in these standards to evaluate the performance of front lighting systems is only qualitative. Research on working out method for quantitative evaluation of front lighting system is necessary [1] In practice, however, the luminance levels at road surfaces are usually very dynamic; depend largely on the variations in vehicle parameters, ambient weather conditions, road surface uniformities and effects of light intensity & color contrasts on target visibility.

The basic function of steering system is to control the direction of the vehicle. The driver applies effort on the steering wheel and receives feedback through the steering system as a result of tire to road interaction. This feedback consists of a haptic (force) feedback which is directly felt by the driver and it is termed as steering feel. Precise steering feel gives better driving experience and is decisive factor for customer to buy a vehicle as well as for OEMs in building brand image. Along with steering parameters, suspension and tire parameters also has significant impact on steering feel. In past, modelling of the steering system was done at component level or with simplified vehicle system. Such approaches had not given accurate results of steering feel metric and resulted in incorrect steering design parameter selection. In order to replicate actual vehicle characteristics, complex and detailed modelling of steering, tire and suspension subsystems is necessary.

Today, reducing the vehicle development time is a very crucial task. In the early development stages, the limited time and few vehicle prototypes are available for validation. In such scenarios, durability validation of different design iterations of critical components like engine mounts, with respect to the real road usage is a challenge. Road simulation testing in a laboratory is a reliable approach to fatigue and durability tests for the evaluation of platforms, components and subassemblies. Durability evaluation of engine mount is, generally, performed either at assembly level, using multi-axial road simulation approach or at component level, using uniaxial sinusoidal load testing. The new testing approach here allows testing of engine mounts at component level using road simulation approach by applying multi-axial loads or deflections as per the real road usage conditions.

In the automotive industry, multiple prototypes are used for vehicle development purposes. These prototypes are typically put through rigorous testing, both under accelerated and real world conditions, to ensure that all the problems related to design, manufacturing, process etc. are identified and solved before it reaches the hands of the customer. One of the challenges faced in testing, is the low repeatability of the real world tests. This may be predominantly due to changes in the test conditions over a period of time like road, traffic, climate etc. Estimating the repeatability of a real world test has been difficult due to the complex and multiple parameters that are usually involved in a vehicle level test and the time correlation between different runs of a real world test does not exist. In such a scenario, the popular and the well-known univariate correlation methods do not yield the best results.

The OEM's aim is to reduce development time and testing cost, hence the objective behind this work is to achieve a flexible stateflow model so that changes in the application during supply chain or development, on adding/deleting any switches, varying timer cycle, changing the logic for future advancements or else using the logic in different application, would end in minimal changes in the chart or in its states which would reflect least changes in the code. This research is about designing state machine architecture for chime/buzzer warning system and wiper/washer motor control system. The chime/buzzer stateflow chart includes various input switches like ignition, parking, seat belt buckle, driver door and speed accompanied with warning in the form of LED, lamp and buzzer. The logic is differentiated according to gentle and strong warning. Various conditions and scenarios of the vehicle and driver are considered for driver door and seat belt which is resolved in the chart.

Polymers are substituting traditional materials, such as metals, in existing as well as new applications, both for structural and aesthetic applications as they are lightweight, customizable and are easy to mould into complex shapes. With such an extensive use of polymers, there is a need to carefully scrutinize their performance to ensure reliability. This is particularly the case in the automotive and electronic industries where the aesthetic appeal of their products is of prime concern and any visible scratch damage is undesirable. Concern for aesthetics has led to a need for the quantification of visibility due to scratch damage on polymeric surfaces Many painted plastic parts used in vehicles are being replaced with the molded-in color plastics for cost reduction and also due to environmental concerns associated with solvent emissions. There are multiple methods used for scratch evaluation of polymers and paints.