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Vehicle handling is an important attribute that is directly related to vehicle safety. The rapid development of road infrastructure has resulted in a greater focus on safety and stability. Commercial vehicle stability and safety assumes higher significance because of high center of gravity (CG) and heavier loads. A gamut of parameters influence vehicle handling directly and indirectly. However, it is quite difficult to gauge through physical testing, the extent of each parameter's influence on handling. Therefore, this paper examines vehicle handling by way of a sensitivity analysis through numerical simulation. A prototype vehicle is also instrumented and tested to confirm trends and validate the results of the simulation. An Intermediate Commercial Vehicle (ICV) with Gross Vehicle Weight (GVW) of around 13 tonnes is modeled and parameters like wheelbase and tyre stiffness are altered and the effect of these changes on handling parameters (yaw rate, lateral acceleration) is observed.

Engines of commercial vehicles deliver significant amount of power (more than 25% of propulsive power) for non-propulsive loads such as air-conditioner, alternator, air compressor, radiator fan, steering oil pump, lights etc. Use of these auxiliaries cause sub-optimal utilization of engine power resulting in increased fuel consumption and emissions. A fuel cell powered auxiliary power unit (FC-APU) is proposed to isolate the auxiliaries from the engine. Use of FC-APU shall help improve load carrying capacity, gradeability, fuel efficiency and emissions of the vehicle. This paper describes a mathematical system level model developed using MATLAB-SIMULINK to estimate auxiliary power consumption and simulate FC-APU system. A statistical analysis is performed on the power consumed by various auxiliaries during different duty cycles. The data is used to propose a FC- APU system. Fuel cell is the most expensive component in the system.

In today’s competitive world to stay in the commercial vehicle business, technological advancement is vital. Understanding the various operation modes of a vehicle considering the vibration becomes essential for developing a vehicle free from failures. ODS analysis is a method which is used to visualise the vibration pattern of a vehicle when influenced by known external operating forces. ODS provide very useful information for understanding and evaluating the behavior of the vehicle. This paper discusses about the experiments carried out in vehicle. It details the process of data collection at varying frequency input, understanding the modes at various frequencies, identifying the resonant frequency of various components, understanding the comparison between road inputs and resonance frequencies and the transfer of vibration (Transmissibility) from one component to another.

Design decisions based on the virtual simulations leads to reduced number of prototype testing. Demonstrated correlation between the computer simulations and experimental test results is vital for designers to confidently take simulation driven design decisions. For the virtual design evaluation of durability, ride, handling and NVH performance, demonstration of correlation of structural dynamic characteristics is critical. Modal correlation between CAE and physical testing validates the stiffness and mass distribution used in the FE model by correlating mode shape and mode frequency in the desired frequency range. The objective of this study is to arrive at a method for establishing modal correlation between CAE and experimental test for a bare frame and thereby enabling evaluation of design iterations in virtual environment to achieve modal targets.

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.

Commercial vehicles have steering systems with one or more steering links connecting the steering gear box pitman arm and front axle steering arm. In case of twin steer vehicles, intermediate pivot arm is used to transfer the motion proportionately between the two front axles. Intermediate pivot arm is also used in some longer front over-hang vehicles to overcome their packaging constraints and to optimize the mechanical leverage. The pivot shaft is a mechanical part of the intermediate pivot arm assembly upon which pivot arm can swivel in one axis. Steering forces transferred through the drag links generates resultant forces and bending moments on the pivot shaft. In this work, study has been carried out on premature failure of the pivot shaft in city bus application model (Entry + 1 step). Metallurgical analysis of failed part indicated the failure to be due to fatigue. Pivot shaft was tested in rig with similar load conditions in order to replicate the failure.

In this paper, experimental evaluation was carried out on a 6.0 L heavy duty CNG engine which has been optimized for 18 percent hydrogen blended CNG (HCNG). Optimization test results shows that use of HCNG results in reduced CO, THC & CH4 emissions by 39, 25 & 25 percent respectively and increase in NOx by 32 percent vis-a-vis CNG. After optimization the engine was subjected to endurance test of 600 hours as per 15 mode engine simulated city driving cycle with HCNG. The performance & emission characteristics of the engine were analyzed after completion of every 100 hours as per European Transient Cycle (ETC). Test results indicate that there were no significant changes observed in engine power output over the complete endurance test of 600 hrs with HCNG. Specific fuel consumption (SFC) measurements were consistent at all the 15 modes of engine simulated city driving cycle.

This case study involves the failure analysis of the wheel arch structure for a commercial truck. The wheel arch is an important vehicle trim aggregate from both the regulatory perspective (spray suppression) as well as from the aesthetics of the truck. But, the durability of this part is affected by the vehicle architecture, vehicle load capacity as well as the operating conditions. This is more critical due to the nature of the overhang experienced by the mounting bracket assemblies that hold these wheel arches/mud flaps. This generally consist of tubular and sheet metal welded structures bolted on to the main chassis long members. These failures were observed in a legacy vehicle, where very little details of the complete vehicle digital simulation and testing performance were readily available.

All automotive components undergo stringent testing protocol during the design validation phase. Nevertheless, there are certain components in the field which are seldom captured during design validation. One of these components is the battery isolator switch. This project aims at optimizing a validation methodology for this component based on field usage and conditions. The isolator switch is the main control switch which connects and disconnects the electrical loads from the battery. This switch is used in the electrical circuit of the vehicle to prevent unwanted draining of battery when it is not needed and when the vehicle is in switched off. An electrical version of this switch uses electromagnetic coils to short the contacts. The failure mode being investigated is a high current load causing the input and output terminal to be welded.

Tippers used for transporting blue metal, construction and mining material is designed with different types of load body to suit the material being carried, capacity and its application. These load bodies are constructed with high strength material to withstand forces under various operating conditions. Structural strength verification of load body using FEM is conducted, by modelling forces due to payload as a pressure function on the panels of the load body. The spatial variation of pressure is typically assumed. In discrete element method (DEM) granular payload material such as gravel, wet or dry sand, coal etc., can be modelled by accounting its flow and interaction with structure of load body for prediction of force/pressure distribution. In this paper, coupled FE-DEM is used for determining pressure distribution on loading surfaces of a tipper body structure of a heavy commercial vehicle during loading, unloading and transportation.

A full-bodied validation of automotive system emphasis on a comprehensive coverage of failure modes of component on one hand and evaluation with full system for the intended function of single component on the other has for long been cumbersome to most commercial vehicle manufacturers. This paper focuses on optimizing the test method in rig testing to relieve the complexity in the structural validation as whole system level. The methodology proposed by authors focuses on accelerating the vibration testing of component by compressing the validation timelines by using CSCPV (Combined Systematic Calculated and Pre Validation) method. This method selects the components of the system for validation by VFTM (Vital Few and Trivial Many) approach from existing testing database failure data and selects the worst predominant failure cases. This CSCPV method uses systematically calculated representing mass from analysis to validate the intended component alone instead of entire system.

The modern day automobile customers’ expectations are sky-high. The automotive manufacturers need to provide sophisticated, cost-effective comfort to stay in this competitive world. Air conditioning is one of the major features which provides a better comfort but also adds up to the increase in operating fuel cost of vehicle. According to the sources the efficiency of internal combustion engine is 30% and 70% of energy is wasted to atmosphere. The current Air conditioners in automobiles use Vapour compression system (VCS) which utilizes a portion of shaft power of the engine at its input; this in turn reduces the brake power output and increases the specific fuel consumption (SFC) of the engine. With the current depletion rate of fossil fuels, it is necessary to conserve the available resources and use it effectively which also contributes to maintain a good balance in greenhouse effect thus protecting the environment.

The commercial vehicle industry is evolving faster with the rise in multifarious aspects deciding a company's progress. In the current scenario, vehicle performance and its reliability in the areas of payload, fuel economy, etc. play vital roles in determining its sustenance in the industry, in addition to reducing driver fatigue and improving comfort levels. Test quality and time is the key to assure and affirm, smooth and quick launch of the product into the market. This paper details on the design of Multi-Axis road data simulator which entails realistic loads onto the components for capturing meaningful information on behavior of the product and recreate the field failure modes. The design was conceptualized keeping in mind both cost (for initial installation and running cost) and time for testing without loss in the convergence factor.