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A bus is integral part of public transportation in both rural and urban areas. It is also used for scheduled transport, tourism, and school transport. Buses are the common mode of transport all over the world. The growth in economy, the electrification of public transport, demand in shared transport, etc., is leading to a surge in the demand for buses and accelerating the overall growth of the bus industry. With the increased number of buses, the issue of safety of passengers and the crew assumes special importance. The comfort of driver and passenger in the vehicle involves the vibration performance and therefore, the structural integrity of buses is critically important. Bus safety act depicts the safety and comfort of bus operations, management of safety risks, continuous improvement in bus safety management, public confidence in the safety of bus transport, appropriate stakeholder involvement and the existence of a safety culture among bus service providers.

Integrating safety features may lead to changes in vehicle interior component designs. Considering this complexity, design guidelines have to take care of aspects which may help in package feasibility studies that consider systems performance requirements. Occupant restraints systems for protection in side crashes generally comprise of Side Airbag (SAB) and Curtain Airbag (IC). These components have to be integrated considering design and styling aspects of interior trims, seat contours and body structure for performance efficient package definition. In side crashes, occupant injury risk increases due to hard contact with intruding structure. This risk could be minimized by cushioning the occupant contact through provision of SAB and Inflatable IC. This paper explains the methodology for deciding the package definitions using Knowlwdge Based Engineering (KBE) tools.

In case of design of passenger vehicles, one of the priorities is how the dynamics behavior shall be perceived by the vehicle occupants. One of many such handling parameters is the vehicle body roll, which is usually quantified by the vehicle's Steady State Roll Gradient. This number gives an indication of the rotation of the vehicle body in response to unit lateral force acting on the vehicle, as in the case of cornering. However it does not necessarily indicate the roll as sensed by a person seated inside it. A study showed that the subjective feel is not entirely dependent on roll gradient. In some cases the occupant may feel more confident and comfortable in a vehicle with a relatively higher roll gradient, or vice versa. In such cases, designing for roll gradient alone may not serve the purpose of secure and comfortable feel. To account for this discrepancy, a study was carried out to quantify the motion felt by the occupant.

Vehicle dynamics is one of the most important vehicle attributes. It is classified into three domains, the longitudinal, vertical, and lateral dynamics. This paper focuses on optimizing the lateral vehicle dynamics which is driven by the straight ahead controllability and cornering controllability of the vehicle. One of the important parameters that dictates these sub-attributes is the steering ratio. Therefore, designing the right steering ratio is critical to meet the vehicle “specific” targets. Significant amount of work has been done by many researchers on variable steering ratio by implementing variable gear ratio (VGR) rack, active steering, and steer-by-wire systems. This paper discusses the methodology and considerations to optimize the steering ratio for a constant gear ratio rack by optimizing the steering column layout, viz., orientation and the phase angle in universal joints.

The automotive world is rapidly moving towards achieving shorter lead time using high-end technological solutions by keeping up with day-to-day advancements in virtual testing domain. With increasing fidelity requirements in test cases and shorter project lead time, the virtual testing is an inevitable solution. This paper illustrates method adopted to achieve best approximation to emulate driver behavior with 1-D (one dimensional) simulation based modeling approach. On one hand, the physical testing needs huge data collection of various parameters using sensors mounted on the vehicle. The vehicle running on road provides the real time data to derive durability test specifications. One such example includes developing duty cycle for powertrain durability testing using Road Torque Data Collection (RTDC) technique. This involves intense physical efforts, higher set-up cost, frequent iterations, vulnerability to manual errors and causing longer test lead-time.

The automotive world has seen an increase in customer demands for vehicles having low noise and vibrations. One of the most important source of noise and vibrations associated with vehicles is the vibration of driveline systems. For commercial vehicles, the refinement of drivelines from NVH point of view is complex due to the cost and efficiency constraints. The typical rear wheel drive configuration of commercial vehicles mostly amplifies the torsional vibrations produced by engine which results into higher noise in the vehicle operating speed range. Theoretically, there are various options available for fine tuning the torsional vibration performance of the vehicle drive train. The mass moments of inertia and stiffness of the drivetrain components play significant role in torsional vibration damping, however, except minor changes to flywheel mass, it is hardly possible to change other components, subject to design limitations.

Improvised Explosive Devices (IEDs) and Anti-Tank (AT) mines are a significant threat for military vehicles and their occupants. These explosive devices are designed for the destruction and damage of armored and other vehicles, by using them in battle fields on routes of army vehicles. The blast event results in effects like shockwave, fragments, fire, gases, blast overpressure as well as the vertical impulse load. A blast event affects occupants inside the vehicle in the form of various types of injuries (lower leg, spinal, chest, head etc) and trauma. The Lower leg is the foremost injured body region in a blast event. The term lower leg is used to designate the tibia, fibula and the foot/ankle complex in this paper. Detonations occurring under a vehicle produce high velocity floorboard flutter/deformation and transmit axial loads to lower leg and create injuries.

In the commercial vehicle business, Tractor-trailer combination vehicles are mostly used for carrying heavy loads for longer distances. To improve operating economy of the vehicle by reducing turn around time, it becomes a necessity to have a better driving comfort level for the vehicles. In a Tractor-trailer combination vehicle, due to point load acting on the tractor, pitching effect on the cab is very dominant. To overcome this pitching effect, a fully suspended cabin (suspended at four points) has been designed in order to have better ride comfort as compared to the fixed cabin. This paper discusses some of the measures taken to reduce the overall cabin pitching effect on Tractor -trailer combination vehicles.

Restraints systems (airbags and seat belts) have been proven to be very effective in occupant protection in crashes. Timely deployment of these devices is very essential for meeting performance requirements. Precision and reliability in restraints deployments demand selection of a robust sensing configuration that caters to the wide variations of real world. This paper highlights complexities involved in engineering of restraints sensing configurations through different case studies on vehicle programs. The paper explains the need for restraints sensing configuration optimization and well defined sensing strategies for a robust solution in real world. A methodology is discussed to achieve good discrimination between crashes of different types and severities. Virtual and physical test data collected at different stages of vehicle development is used. It is found that criteria for threshold levels in restraints sensing requires efforts to identify real world usage variations.

Adaption of EV powertrains in existing vehicle architecture has created many unique challenges in meeting performance, reliability, safety, ease of manufacturing & serviceability at optimum cost. Mounting of large size battery packs in existing vehicle architecture is one of them. Specific energy & the energy density of Lithium ion batteries are very lower compared to Diesel & Petrol, which requires high volume & weight for equivalent energy storage. For movement of many passengers and to ensure sufficient range EV buses typically needs large amount of energy and for storage of same bigger size battery packs are required. These large size batteries directly affect vehicle architecture, seating layout, ease of assembly & serviceability. Moreover the heavy mass of batteries directly influences vehicle dynamics & performance characteristics such as vehicle handling, roll & NVH. The most important consideration in design of EV vehicles in general and buses in specific is safety.

Computer Aided Engineering (CAE) plays an important role in the product development. Now a days major decisions like concept selection and design sign off are taken based on CAE. All the Original Equipment Manufacturers (OEMs) are putting consistent efforts to improve accuracy of the CAE results. In recent years confidence on CAE prediction has been increased mainly because of good correlation of CAE predictions with the test results. Defining proper correlation criteria and using a systematic approach helps significantly in building the overall confidence level for predictions given by CAE simulations. Representation of manufacturing effects on material properties and material failure in the simulation is still a big challenge for achieving a good CAE correlation. This paper describes side impact test vs CAE correlation. The important parameters affecting the CAE correlation were discussed.

Error in suspension asymmetry or tire parameters may lead to vehicle drifting laterally from its intended straight-line path, which is called vehicle pull. Driver then needs to apply constant steering correction to maintain the vehicle in straight line which will lead to high driver fatigue and deteriorate driving experience. Manufacturing a perfectly symmetric suspension system is impractical, however an insight into the manufacturing tolerances of suspension system at the early design stage can be extremely useful. Also tire force and moment parameters at straight line operation and its maximum allowable variations will help in defining the tire parameter specifications and tolerances. The objective of this study was to develop a 1D model of suspension and tire system which can predict the torque experienced in steering and drift of the vehicle from straight line due to the tire force and moment and asymmetric suspension geometry.