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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.

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.

Diesel engine pollutants include Oxides of Nitrogen (NOx) and Particulate Matter (PM) which are traditionally known for their trade-off characteristics. It’s been a challenge to reduce both pollutants at the source simultaneously, except by efforts through low temperature combustion concepts. NOx formation is dependent on the combustion temperature and thus the in-cylinder reduction of NOx formation remains of utmost importance. In this regard, water injection into the intake of a heavy-duty diesel engine to reduce peak combustion temperature and thereby reducing NOx is found to be a promising technology. Current work involves the use of 1-D thermodynamic simulation using AVL BOOST for modeling the engine performance with water injection. Mixing Controlled Combustion (MCC) model was used which can model the emissions. Initially, the model validation without the water injector was carried out with experimental data.

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.

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.

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.

Automotive component light weighing is one of the major goals for original equipment manufacturers (OEM's) globally. Significant advances are being made in developing light-weight high performance components. In order to achieve weight savings in vehicles, the OEM's and component suppliers are increasingly using ultra-high-strength steel, aluminum, magnesium, plastics and composites. One way is to develop a light weight high performance component through multi material concept. In this present study, a bimetal brake drum of inner ring cast iron and outer shell of aluminum has been made in two different design configurations. In two different designs, 40 and 26% weight saving has been achieved as compared to conventional gray cast iron brake drum. The component level performance has been evaluated by dynamometer test. The heat dissipation and wear behavior has been analyzed. In both designs, the wear performance of the bimetal brake drum was similar to the gray cast iron material.

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.

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.

Commercial vehicle payload depends on the client for which the vehicle fleet owner is operating. Load carriers like flatbed trailer offer the flexibility to be loaded with a large number of light payloads or a few numbers of massive payloads. Such load carriers have to be evaluated for various possibilities of loading patterns that could happen in the market. The objective of this work is to evaluate flatbed trailer for its structural strength for different customer application cases, using computer simulation. Structural load cases due to payloads like containers, steel coils and cement bags are arrived at. Static structural analysis using MSC Nastran is performed to evaluate for the worst customer loading pattern from structural stress point of view. This paper also describes a simplified method for simulating the effect of trailer suspension, tractor suspension and the fifth-wheel coupling in the analysis whose detailed modeling is not possible at the concept level.

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.

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.

The emerging trends in commercial vehicle technology have increased the necessity for critical attribute engineering refinements. Drivability is emerging as one of the most significant attributes in the automotive sector. The degree of smoothness in a vehicle's response to the driver's input is termed as drivability. This attribute has to be rigorously refined in order to achieve brand specific vehicle characteristics, which will ensure a thorough product differentiation. In order to calibrate for a positive drivability feel, a methodology for evaluation of drivability is a prerequisite. The scope of this paper is aimed at describing the methodology for subjective and objective evaluation of drivability attributes in commercial vehicles. Drivability is a highly subjectively perceived attribute, therefore a subjective assessment technique to assess drivability attributes and sub-attributes are essential.

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.

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.

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.

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.

Ventilation is a crucial factor affecting passenger comfort in any vehicle. In a non-air-conditioned bus, ventilation caters to the dual requirement of fresh breathing air as well as providing a cooling sensation by enhanced evaporation of sweat. The higher the velocity of air around the passengers, the greater the cooling effect experienced by them. The ventilation mechanism of a non-air-conditioned bus is primarily the air flow through the windows due to relative motion between the bus and the air around it. This paper describes studies carried out to identify the right combination of open windows which would provide optimum air flow at the passenger head level plane in a bus. A bus model with 12 windows, 6 on each side is used for the study and air velocity at certain points in the head level plane, arising out of different combination of window openings is evaluated using CFD.