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Vehicular Emission testing is gaining importance over the past years in the wake of requirements for real driving emissions with implementation of RDE packages across Europe / USA and various developing countries. Extending the same concept for other countries poses slight challenges in terms of geographical and climatic conditions prevailing in the country, where the climatic conditions are differing from Europe / USA. It is a challenge to accept the same boundary conditions as in Europe, at the same time the challenge is to find a threshold number in a more scientific manner. This study concentrates on determination and recommendation of thresholds for ambient temperature and altitude. The basis for temperature threshold would be to determine the percentage of time the temperature exceeded beyond the threshold over year in the country. The basis for Altitude is considered based on the percentage of total length of roads beyond the threshold altitude limit.

With a push for urbanization across cities, there is an increased demand for mobility in public transportation especially buses which are provided through state transport undertakings. Hence, the expectations of this class of vehicles will be high in terms of quality and comfort to the passengers. The noise inside the passenger area of the bus becomes an important parameter, which sets apart a bus manufacturer from its competitors. The driveline of the bus is the system responsible for the transfer of power from engine to the wheels. The noise and vibration problems associated with it are detected only in the late stages of the design chain, when all its elements are tested together over a wide range of conditions. Since, calibration of engine and the selection of transmission is freezed in early stages, satisfying power and torque requirements, the only viable option left to address the problem is by optimizing the clutch parameters.

In the emerging commercial vehicle sector, it is very essential to give a product to customer, which is very reliable and less prone to the failures to make the product successful in the market. In order to make it possible, the product is to be validated to replicate the exact field conditions, where it is going to be operated. Lab testing plays a vital role in reproducing the field conditions in order to reduce the lead time in overall product life cycle development process. This paper deals with the design and fabrication of the steering column slip endurance test rig. This rig is capable of generating wear on the steering column splines coating which predominantly leads to failure of steering column. The data acquired from Proving Ground (PG) was analyzed and block cycles were generated with help of data analyzing tools.

Durability analysis is essential for vehicle validation and is carried out with the inputs of different road conditions. The selection of roads for durability analysis is critical and should represent the actual working conditions for the selected vehicle. Generally, the road conditions are subject to change with respect to time. To overcome the above, road profile data is an essential parameter which helps to represent and categorize roads in terms of ISO (International Organization for Standardization) road class. The ISO road classes objectively classify the roads with respect to roughness. This classification holds good by categorizing the signals to the respective road classes rather than different test roads. The road profiles are measured using inertial profiler methodology along with vehicle acceleration and displacement responses, also analyzed and categorized with respect to ISO road class.

To capture market share in different regions of the world, the product must fit different road profiles and operating conditions. Designing a product which suits two different markets requires many factors to be considered like the topography, driving pattern and road load profiles. This project deals with once such situations and required a stringent validation protocol which shall encompass all possible driving scenarios. The fully built vehicle is to be exported to a different market and required powertrain change and subsequently required a new cradle design. Customer usage and road profile study was carried out in the new market to estimate the percent operation in each zone i.e. good road and bad road. CAE analysis carried out to capture stress hotspots and possible failure locations. Vehicle is taken to road to measure frame acceleration at different speeds i.e. 40 kmph to 100 kmph.

Lifting axles are auxiliary axles that provide increased load carrying capacity in heavy commercial vehicles. Lift axle gives better fuel efficiency as well as it reduces the operational costs by means of increasing the loading carrying capacity. These axles are raised when the vehicle is in unloaded condition, thus increasing the traction on remaining wheels and reducing the tire wear which in turn lower down the maintenance cost of the vehicle. Lifting height and force requires to lift the whole mechanism and are two main considerable factors to design the lifting axle mechanism. Although in India currently, the use of lift mechanism of single tire with continuous axle is more common. But in the case of pusher axle, continuous axle is unable to lift more after certain height because of the draft angle of the propeller shaft, and single tire axle which has less load carrying capacity up to 6T (Tons).

In the present scenario, delivering right product at the right time is very crucial in automotive sector. Today, most of the OEMs have started to produce FBS (Fully Build Solution) such as oil tankers, mining tippers and two-wheeler carriers based on the market requirements. During product development phase, all automotive components undergo stringent validation protocol either in on-road or laboratory which consumes most of the product development time. This project is focused on developing validation methodology for two-wheeler carrier structure (deck) of a commercial vehicle. For this, road load data were acquired in the typical routes of customers at different loading conditions. Roads were classified as either good or bad based on the axle acceleration. To shorten the test duration, actual road load data was compressed using strain based damage editing techniques. The spectrum and transmissibility of acceleration signals at the decks were analyzed to select a deck for validation.

Automotive vehicles are subjected to a variety of loads caused by road undulations. The load history data measured from the roads are one of the vital input parameters for physical test as well as virtual durability simulation of vehicles. In general, the automotive vehicles are instrumented and subjected to a variety of driving conditions in diverse roads to obtain representative road load time histories. Acquired road load time history signals from various roads are exhaustive and repetitive in terms of both time length and data size. This results in more computation and virtual simulation processing. Hence it is imperative to reduce the input time signals without compromising on the representation of the actual operating conditions. Signal reduction of measured road load histories for virtual simulation assumes greater significance for durability prediction.

Non air-conditioned buses constitute a major portion of public transportation facilities in many countries across the world. Inadequate cabin air circulation is a major cause of passenger discomfort in these buses. The aim of this study is to model the air flow pattern inside the passenger compartment of a bus and to establish the effect of solutions such as roof vents in improving the air circulation. RANS based CFD simulations with Shear Stress Transport (SST) turbulence model have been carried out using a commercial CFD solver. The CFD methodology has been verified by comparing results with experimentally validated LES simulation results available in literature. The vehicle model used in this study was the shell structure of a bus with an overall length of 7 m and a wheel base of 3.9 m. Simulations were carried out for a four vent configuration which showed an increase of 131% in the average in-cabin air velocity over the baseline model without any roof-vents.

Demand for a refined Heavy Commercial Vehicle (HCV) is increasing due to rapid Indian economic growth, while the operating conditions and road infrastructures are still in a transition state of development. The same vehicle model will be operated in a range of operating road conditions like mining sites, construction sites, and highways with varying payloads and speeds by customers that are spread across the country. This variety of road inputs, payloads and speeds has made ride tuning as one of the major challenging process in the development process. This paper describes the attempt to assess ride comfort of HCV with fully suspended cab using numerical based simulation tools and its correlation with physical test results. The best suspension combination was finalized based on vertical and pitch acceleration at Center of Gravity (CG) of the cab. The trend of vertical acceleration obtained from the virtual model was correlated with the same obtained from physical test.

The primary factors influencing vehicle's dynamic behavior are the vehicle hard point definition, driver behavior and road inputs. The more the latter two are random and incorrigible in nature, the former one is quantifiable and can be controlled from designer's standpoint. In this paper, we have made an attempt to set targets to the vehicle hard point definition and thereby to optimize the vehicle for better ride behavior. This approach hence helped to converge to vehicle specifications set fundamentally designed to respond to random operating conditions and driving behavior intelligently. The work also involves study of various methodologies to predict roll, pitch, bounce and dive behaviors on a typical commercial passenger vehicle and is concluded by a sensitivity analysis to understand significance of these hard points on vehicle's real time behavior.