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Due to recent infrastructural development and emerging competitive automotive markets, there is seen a huge shift in customer’s demand and vehicle drivability pattern in commercial vehicle industry. Now apart from ensuring better vehicle durability and best in class tyre life and fuel mileage, a vehicle manufacturer also has to focus on other key attributes like driver’s safety and ride comfort. Thus, for ensuring enhanced drivability, key parameters for ensuring better vehicle handling includes optimization of bump steer and brake steer. Both bump steer and brake steer are vehicle’s undesirable phenomenon where a driver is forced to constantly make steering wheel correction in order to safely maneuver the vehicle in the desired path.

The cost incurred to make design modifications to solve NVH problems increases with maturity of design in the development process. Hence NVH issues should be addressed in the initial phase to avoid any significant changes in structure and subsequent changes in overall performance of the vehicle. Hybrid methodology with application of advanced testing and Computer Aided Engineering (CAE) tools to achieve full vehicle NVH attribute targets is nowadays a must for this reason. This paper represents a case study on low frequency NVH performance evaluation and refinement for heavy commercial vehicle truck using Hybrid Test-CAE methodology. To achieve better NVH performance, it is important to set competitive overall vehicle level NVH targets and cascade it down to system and sub-system targets. Test-CAE correlation has been carried out to validate Finite element (FE) modeling procedure and methodology.

Oil strainer is used in engine oil sump, which prevents dirt, scale and other particle from clogging downstream orifice. In this paper, dynamic analysis was carried out using FEA tool. As a part of dynamic analysis, constrained modal analysis and frequency response (steady state dynamics) analysis was done. Frequency response analysis was done for different engine exciting frequency at different service load (vibration amplitude). Modal superposition method is used for doing frequency response analysis and load is applied as base excitation. The natural frequency from modal analysis and stress response from frequency response analysis is well correlated with test results. Based on achieved good correlation with test, several design modification could be carried out in CAE before finalizing the final design.

With advancement of technology, better safety and higher vehicle reliability is primary requirement of end customer especially in public transportation. Hence there exist challenges in design and development of steering system for long haulage and tipper application. In the steering system, track rod is used to steer both the front tyre under different operating condition assisted by power steering system. This paper deals with the failures observed on track rod in long haulage and tipper application with loading conditions. Also the methodology adapted to resolve the field failures.

Buses have been main means of mass transport in organized as well as unorganized sectors in India. Though the art and science of Chassis Designing had been practiced and matured by all Indian OEMs, Body design had long not been accorded high priority by them. Till 1989, there was no comprehensive set of rules enforced. Bus designs were developed with scant regard for safety and emission. OEMs sold their products in the form of drive away chassis and the Body Design & Body Building was largely left to Body Builders, many of whom employed poor design, build and quality control practices. Spurious materials, parts, non-uniform construction resulted in number of accidents and many of them were fatal. Central Motor Vehicle Rules (CMVR) kicked-in 1st July 1989. With roll out of CMVR, various safety related features like entry/exit door, emergency exits, window frames, their locations, dimensions and designs were defined.

The low-frequency noise effects passenger comfort causing headaches, tiredness, and pressure on the eardrum. The mid- and high-frequency noises of an automotive vehicle can be easily attenuated with passive methods. The passive method involves the usage of fibrous or porous acoustic materials for sound absorption. But the reduction of low-frequency noise with passive methods is difficult. Hence the noise must be reduced at the source. The present work is related to the root cause identification of low-frequency noise and vibration in a bus. After the analysis of vehicle interior noise and vibration data acquired in static and dynamic operating conditions, it is identified that 30-40 Hz is the main problematic noise frequency band. From the component vibration data and modal testing results, it is concluded that unbalance in propeller shaft and resonance in the upper berth structure are the sources of this low-frequency noise.

The suspension system in a vehicle isolates the frame and body from road shocks and vibrations which would otherwise be transferred to the passengers and goods. Heavier goods vehicles use tandem axles at the rear for load carrying. Both the axles should be inter-connected to eliminate overloading of any one axle when this goes over a bump or a ditch. One of the inter-connecting mechanism used is leaf spring with tie rod, bell crank & linkages, when the first rear axle moves over a bump, the linkages equalize the loading on the second rear axle. This paper details about the failure analysis methodology to simulate the tie rod field failure using a six poster road simulator and to identify the root cause of the failure and further corrective actions.

In the automotive industry several attributes needs to be considered for the development of a new vehicle which are important for the customer, such as vehicle dynamics, driveability, fuel consumption, emissions, durability and NVH among many others. Sometimes these characteristics are conflicting and often need is to create a robust trade-off where the design space is sufficient to fit all of them in a vehicle that rhymes with the brand image and is appealing to the intended customer. Automobile manufacturers try to meet the requirements with respect to quality and comfort and often, emotional, aspects supercede the previous objective, pragmatic demands. The satisfaction of the demands by the customers concerning comfort, driving pleasure, design appears dominant and functionality criteria sometimes takes a back seat. NVH is considered to be one of the key buy in factor among the above mentioned attributes.

The Indian automotive sector is experiencing a major shift, focusing predominantly towards the levels of quality, reliability and comfort delivered to the customer. Since the entry of global players into the market, there is a rising demand for timely product launches with utmost priority to reliability. In any vehicle, engine isolation systems play a critical role in isolating the engine vibrations from the vehicle chassis. This project details on how testing can aid in reducing the launch time as well as estimating the reliability of the component when used in a different application/vehicle. It proposes a methodology to formulate a life model for the engine mount considering various combinations of predictor parameters affecting its performance over its design life. In order to maintain good correlation with the field (which considers the loading pattern and the environmental factors), warranty data was analyzed and the predictors were chosen appropriately.

The new emission requirement norms in India calls for a robust Exhaust and After Treatment System (EATS) in automobiles. Its main purpose is to reduce the emission of harmful pollutants into the environment. EATS have a series of components that cleans the diesel exhaust emitted by the engine prior to releasing it through the tailpipe to the outside air. All the EATS components must undergo stringent testing protocol prior to its implementation in vehicle. During the exhaust treatment process, a very high temperature of about 550°C is produced in the EATS system. Hence, the effect of this higher temperature needs to be considered for validation. Moreover, the components will undergo multi-axial vibration in real road conditions which also need to be simulated during validation. In addition, engine vibrations are directly transmitted through a flex bellow to EATS system. These vibrations need to be captured and simulated in component level testing.