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The commercial vehicle sector (especially trucks) has major role in economic growth of a nation. With improving infrastructure, increasing number of commercial vehicles and growing amount of Vulnerable Road Users (VRUs) on roads, accidents are also increasing. As per RASSI (Road Accident Sampling System India) FY2016-21 database, commercial vehicles are involved in 43% of total accidents on Indian roads. One of the major causes of these accidents is Driver Drowsiness and Inattention (DDI) (approx. 10% contribution in total accidents). This paper describes novel driver-in-loop performance assessment methodology for comprehensive verification of Driver Monitoring System (DMS) for commercial vehicle application. Novelty lies in specification of test subjects, driving styles and variety of road traffic scenarios for verification of DMS system. Test setup is made modular to cater to different platform environments (Heavy, Intermediate, Light) with minor modifications.

Corrosion in automotive industry is broadly categorized into cosmetic & perforation corrosion. Cosmetic corrosion comprises of superficial red rust which is deleterious to the overall aesthetic appeal of the vehicle but can be rectified. Perforation corrosion involves complete erosion of the panel, compromising structural integrity of the respective part. Perforation corrosion demands part replacement. In order to tackle this menace, automotive OEMs have formulated varied corrosion strategies in terms of selection of appropriate substrate, part design & surface protection scheme. Validation of various corrosion strategies become pivotal during the development phase of various parts and assemblies. Traditionally, Salt Spray Test (SST) has been used to determine corrosion life of materials/parts/assemblies. This test however does not simulate real-world conditions.

Structural automotive components are subjected to fatigue damage under cyclic stresses and strains. The fatigue damage initiates at stress levels lower than the elastic limit of the material and results in cracks. The Initial fatigue cracks are difficult to detect, such cracks can develop rapidly and cause sudden and brittle failure in structures. Many structural automotive components are fabricated involving weld induced local conditions such as geometry of weld toe and localized tensile residual stresses. These conditions are favorable for initiation of fatigue damage at weld toe. In current work, sever plastic deformation (SPD) which is based on high frequency impact treatment using ultrasound energy was applied on weld toe of representative weld joints. The effect of SPD on weld toe geometry modification, microstructure and residual stresses were evaluated. Microscopic and X-ray diffraction techniques were used to study the effects of SPD.

Twist-beam suspensions are an example of design solution presenting acceptable performance when applied to passenger cars & light vehicles and it can provide an optimal between cost & performance in the automotive market. For these reasons, twist beam is quite popular in use in rear suspension of light vehicles. In contrary to other types of suspension, the twist-beam has a flexible torsion beam connecting the swing arms. The study of the deformation of this flexible element becomes important to understand its performance and durability behavior. As the name signifies, twist beam major performance attribute is control of twist or opposite wheel travel arising from vehicle roll or road input. Current approach for the study this deformation is through FEA & Multi-body dynamics software tools.

In current scenario, there is trend to use stainless steels in place of carbon steels and aluminized carbon steels for Exhaust application. In response to changing regulatory requirements and durability performance requirements of exhaust systems, the ferritic stainless steels are proven to be best suited for the purpose. There are multiple ferritic stainless steels available as options for exhaust system. The material in an exhaust system is subject to heat, oxidation, corrosion and condensate. These environment condition demands that exhaust material should possess high temperature corrosion and oxidation resistance along with required mechanical performance such as vibration and thermo-mechanical load cycles. This work is an attempt to develop simulated test methods for corrosion and thermal environment and evaluate performance of commonly used ferritic stainless steels.

This paper takes a review of fretting phenomenon on splines of the engaging gears and corresponding splines on shaft of automotive transmission and how it leads to failure of other components in the gearbox. Fretting is a special wear process which occurs at the contact area of two mating metal surfaces when subject to minute relative oscillating motion under vibration. In automotive gearbox, which is subjected to torsional vibrations of the powertrain, the splines of engaging gears and corresponding shaft may experience fretting, especially when the subject gear pair is not engaged. The wear debris formed under fretting process when oxidizes becomes very hard and more abrasive than base metal. These oxidized wear particles when comes in mesh contact with nearby components like bearings, gears etc. may damage these parts during operation and eventually lead to failure.

The primary function of an engine mounting bracket is to support the powertrain system in all road conditions without any failure. The mount has to withstand different road conditions and driving maneuvers which exert loads on it. Also, it is challenging to change the mounting locations and types after the engine is built; hence it is paramount to verify the mounting brackets against all abuse loads in the design stage. The Car manufacturers ensure engine mount bracket design meets CAE's (Computer-aided engineering) static and fatigue load cases. The CAE is performed using digital RLD (Road load data) loads. The design checks cumulative strain or stress against specified service life requirements during break and fatigue FOS (Factor of safety) calculations. However, it is difficult to simulate the material's fracture toughness to estimate the effect of the impact load on the mounting bracket.

This paper discusses the test setup and methodology required to validate complete lift axle assembly for simulating the real time test track data. The correlation of rig vs track is discussed. The approach for reduction of validation time by eliminating few of the non-damaging tracks/events, its correlation with real life condition is discussed, and details are presented. With increased competition, vehicle development time has reduced drastically in recent past. Bench test procedure using accelerated test cycle discussed in this paper will help to reduce development time and cost. Process briefed in this paper can also be used for similar test specification for other structural parts or complete suspension system of heavy commercial vehicles.

Spot-weld joinery plays a major role in maintaining structural integrity of vehicle during an accident scenario. Robust failure definitions are important for accurate prediction of spot-weld failure in crash safety simulations. Spot welds have a complex metallurgical structure, consisting of fusion and heat affected zones. Identifying material failure definitions for huge number of spot-weld joint combinations in a typical Body in White (BIW) of a vehicle is highly challenging. In conventional LS-DYNA-MAT100 material model, spot-weld failure prediction accuracy is limited under complex crash loading scenarios, especially angular and bending load conditions. In order to enhance the failure predictions, a novel mathematical failure model is developed by considering instantaneous resultant loading along with bending moment as a key failure parameter to determine spot weld joint failure.

Polymers are substituting traditional materials, such as metals, in existing as well as new applications, both for structural and aesthetic applications as they are lightweight, customizable and are easy to mould into complex shapes. With such an extensive use of polymers, there is a need to carefully scrutinize their performance to ensure reliability. This is particularly the case in the automotive and electronic industries where the aesthetic appeal of their products is of prime concern and any visible scratch damage is undesirable. Concern for aesthetics has led to a need for the quantification of visibility due to scratch damage on polymeric surfaces Many painted plastic parts used in vehicles are being replaced with the molded-in color plastics for cost reduction and also due to environmental concerns associated with solvent emissions. There are multiple methods used for scratch evaluation of polymers and paints.

Tailgate stoppers play vital role in exerting preload on the Tailgate latch mechanism and also restrict the relative motion of the Tailgate against vehicle Body in White (BIW). These stoppers act as over-slam dampeners and reduce the transmissibility of vibrations thereby reduce the risk of Squeaks & Rattles (S&R) noises. S&R noises from Tailgate are most annoying to the rear passengers in the vehicle and are recurring in nature. Preventing these issues during design is a challenging task. S&R risk simulations enable us to conduct virtual Design of Experiments (DOEs) and arrive at optimal solutions. This approach helps in reducing the cost of the design changes that are required in the physical prototype at the later stages of product development and save time. The risk evaluation in the simulations is based on the relative displacement at the interfaces of two components.

The main objective of the exhaust system is to offer a leakage proof, noise proof, safe route for exhaust gases from engine to tailpipe, where they are released into the environment, while also processing them to meet the emission norms. New stringent emission norms demand ‘near-zero’ leakage exhaust systems, throughout vehicle life bringing the joints into focus as they are highly susceptible to leakage. Needless to say, this necessitates them to endure not only structural but also the environmental loads, throughout their life. Thus, the fatigue life or durability tests become the most critical part of the exhaust system development. Test acceleration and result correlation (for life prediction), to meet the stringent project timelines and stricter environmental norms are the key considerations for developing a new testing methodology. Quality of accelerated tests is ensured by deploying all possible multiple loads, to simulate real-life conditions.

Automotive door seal has an important function which is used extensively where interior of the vehicle is sealed from the environment. Problem with door seal system design will cause water leakage, wind noise, hard opening or closing of doors, gap and flushness issue which impair customer’s satisfaction of the vehicle. Moreover, improper design of seal can lead to difficulty in installation of door seal on body panel. The design prudence and manufacturing process are important aspect for the functionality and performance of sealing system. However, the door sealing system involves many design and manufacturing variables. At the early design stage, it is difficult to quantify the effect of each of the multiple design variables. As there are no physical prototypes during rubber profile beading-out stages, engineers need to carry out non-linear numerical simulations that involve complex phenomena as well as static and dynamic loads for door seal.

To cope up with the market requirements, OEMs need to react fast and develop advanced and highly refined vehicles keeping in mind multiple factors and Perceived Quality is one of the most important amongst those. Annoying squeak and rattle noises from the vehicle, whether it is new or used car, is the most customer irritant factor; which needs to be addressed in the vehicle development program. BSR (Buzz, Squeak and Rattle) and NVH (Noise, Vibrations and Harshness) performance is the critical in providing quieter experience to the customer and it is becoming more and more important due to transformation from ICE (Internal Combustion Engine) to Hybrid and Electric Powertrains. Among BSR noises, body squeak and creak is the most annoying and difficult to detect and correct, if reported on the prototype test or customer cars. Whereas, squeak and rattles from body fitment and underbody aggregates are relatively easy to address and correct.

Powertrain mounts locations and stiffness in vehicle plays very important role in improving vehicle noise and vibration, which is caused by engine firing forces and road disturbances. Once locations are finalized, based on initial calculation and packaging then it is very much critical to play with mount stiffness to achieve required NVH level in vehicle. This paper describes the effect of mount stiffness on the bolted joint integrity. Stiffness fine tuning is done to improve vehicle level NVH and various iteration are done with change in stiffness values of A, B and C mounts. When stiffness specifications are finalized, it is recommended to acquire road load data on the finalized stiffness mount and check for bolted joint integrity since load signature is varying significantly on mount w.r.t stiffness change. If we change mount stiffness value from 128N/mm to 98N/mm, then loads on particular mount is getting increased from 4.5KN to 6.5KN in one of the track testing.

This paper is an application of ISO 26262 functional safety standards for fail-safe design, development and validation of Electric Power Assisted Steering (EPAS) System. As part of safety feature to save lives, prevent injuries and reduce economic loss due to accidents, many research institutes are working to ensure the safety and reliability of emerging safety-critical Electronic Control Systems in automobile applications. As, Advanced Driver Assistance Systems (ADAS) and other emerging technologies are introduced in the automobile application, the overall safety of these advanced electronic systems relies on the vehicle safety systems, such as steering systems. This paper outlines the approach of performing the Hazard Analysis & Risk Assessment (HARA) and developing a Functional Safety Concept. This approach incorporates several analysis methods, including Hazard and Operability study, Functional Failure Modes and Effects Analysis.

Traditionally, vehicle ride and comfort is evaluated, subjectively as well as objectively. Based on the outcome of subjective and objective tests, it is refined by optimizing primary suspension system, secondary suspension system, seating system, rubber bushings, frame and BIW for mass, stiffness, damping, geometry etc. Many a time subjective assessment results stands in contradiction to the objective assessment results; emphasizing need for having good correlation between subjective and objective test results. In such cases, it is ambiguous to decide suitable design refinement action and can lead to no improvement situation. Hence, it is essential to have concurring test procedures for subjective and objective ride evaluation. This paper describes a novel methodology to address the above said challenge. There are defined set of test events and measurement data points to be used in subjective and objective testing.

Exhaust Noise attenuation is one of the important functions of exhaust muffler. Transmission Loss (TL) is a measure of noise attenuation used in designing exhaust mufflers for NVH. TL is a logarithmic difference between inlet and outlet pressures for unit velocity input at inlet of the muffler and anechoic termination at outlet of the muffler as boundary conditions. TL amplitude and its frequency tuning depends on a combination of various muffler design parameters like volume, length, muffler cross section, pipe cross sections, pipe perforations, number of chambers, baffle perforations, etc. Achieving the desired TL performance with no valleys over a wide frequency range is very challenging. Manual design iterations with large numbers of permutations and combinations of design variables are difficult and time-consuming. It also needs a highly experienced professional to balance TL performance, design variables and design constraints.

During every clutch engagement energy is dissipated in clutch assembly because of relative slippage of clutch disc w.r.t. flywheel and pressure plate. Energy dissipated in clutch is governed by many design parameters like driveline configuration of the vehicle vis-a-vis vehicle mass, and operational parameters like road conditions, traffic conditions. Clutch burning failure, which is the major failure mode of clutch assembly, is governed by energy dissipation phenomenon during clutch engagement. Clutch undergoes different duty cycles during usage in city traffic, highways or hilly regions during its lifetime. A test schedule was derived using energy dissipated during every clutch engagement event as a base and using road load data collected on the vehicle. Road load data was collected in different road mix conditions comprised of city traffic, highway, hilly region, rough road for few hundred kilometers.

In today’s automobile market, most OEMs use manual transmission for cars. Gear Shifting is a crucial customer touch point. Any issue or inconvenience caused while shifting gears can result into customer dissatisfaction and will affect the brand image. Synchronizer is a vital subsystem for precise gear shifting mechanism. Based on vehicle application selection of synchronizer for given inertia and speed difference is a key factor which decides overall shift quality of gearbox. For more demanding driver abuse conditions like skip shifting, conventional brass synchronizers have proved inadequate for required speed difference and gear inertia, which eventually results into synchronizer crashing and affects driving performance. To increase synchronizer performance of multi-cone compact brass synchronizer, a ‘Grit blasting process’ has been added. These components tested with an accelerated test plan successfully.