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Head impact protection is one of the major criteria for occupant safety. Testing labs across the world use two kinds of impactor i.e. linear impactor and pendulum impactor for development of interior fitments. There has always been debate on the usage of these impactors among vehicle manufacturers and testing agencies. Three different kinds of impact methods are widely used by OEM's and testing agencies are namely: Linear Impactor in Longitudinal Plane (LILP) Pendulum Impactor in Longitudinal Plane (PILP) Pendulum Impactor in Accidental Plane (PIAP) This paper studies different impact testing methods. Large numbers of head form impacts have been carried out on standard instrument panel at selected points in order to reduce the statistical variations. Further has been used to correlate the results obtained in laboratory. CAE methods have been used all over the world for development purposes [1].

With the stringent legislative requirements for noise in automobiles, gensets etc., the concern for properly designed silencers for specific applications is increasing. Optimized design of silencer requires an integrated study of acoustical and engine performance viz. Insertion loss and backpressure. However, the insertion loss itself depends upon engine characteristics geometry indicated by the transmission loss, flow induced noise, type of silencer - reactive, absorptive, hybrid, etc. Most of the work till date covers the acoustical and engine performance in isolation rather than in an integrated fashion due to the multidisciplinary nature of the problem. The objective of this study is to develop an integrated methodology to predict the performance of the silencer at the design stage resulting in an optimized time and cost effective design. In the present study, the acoustical and engine performance of silencer was predicted using FEM/BEM and CFD techniques.

Ever increasing demands for NVH related comfort have substantially reduced the exterior and interior noise of automobiles worldwide. This involves identification of the noise sources, paths of vibro-acoustic transfer paths and their reduction measures. Many a time, NVH is looked at after the product has been designed and even prototypes have been fabricated. The major source of noise in a vehicle is the driveline. Any changes in the driveline for noise optimization affect the performance as well as exhaust emissions of the vehicle. This makes the changes for improvement of NVH limited. One of the important criteria for the marketability of the vehicle is NVH. Hence, lot of development work is going on for noise reduction. The diesel engine plays a vital role in automobiles and agricultural equipments in the Indian scenario due to economic considerations.

The latest requirements for automotive cabin comfort require lower sound levels inside the cabin. There are many sources contributing to this noise of which fan is an important one. The blade passage noise of the cooling fan is often unpleasant and it is generally expensive to build and test different prototypes for optimum noise performance. Also, traditional unsteady computational approaches for predicting the fan noise are time and resource consuming and do not fit within the design cycle time. This paper proposes use of a steady state computational technique to predict the fan noise performance which provides for effective design study with optimum resources. The steady state data is used with the wave analogy to predict the overall sound pressure level. First, the computational results were validated with the experimental data for a base case and then parametric study was carried out to have optimum design.

This paper describes the procedure of root cause analysis and evaluation of the life of a component that is prone to fatigue failures. The durability testing of components subjected to continuous vibrations in their operating conditions tend to fail after long period of exposure. This makes it difficult and time consuming to test and analyse them in the actual operating conditions. This paper establishes a method of accelerated durability testing for failure modes and life cycle based on the results of Frequency Response Function and modal analysis. This helped in reducing the product development / improvement time.

The paper describes simulation of frontal barrier impact of a car body shell structure for crashworthiness analysis using non linear explicit finite element package LS-DYNA3D. Predicted overall collapse modes of different structural component viz.apron, side rails etc. are in a good agreement with published results and also to some extent with experimental results. In this paper crash analysis of above car structure with crash guard is simulated using LS-DYNA3D and comparative analysis of crash behaviour of car structure in the presence of crashguard is shown to indicate its possible role on crash behaviour of a vehicle.

The dynamic properties of the structure plays an important role in deciding the NVH behaviour of the structure. Finite element methods become the most handy tool to study and find out the right solution for the NVH control. The validity of the finite element model for a particular structure is a very important step in the solution process. The experimental modal analysis is an important technique to correlate the finite element model by evaluating the dynamics of the structure. The modal properties i.e. natural frequencies, and mode shapes are the parameters used for correlating the finite element results. The present paper explains the case studies carried out for the experimental validation of the finite element model of a rectangular plate and oilpan.

For high degree of engine performance, it is imperative that all critical parts are designed and optimised through durability assessment. The conventional engine development programme based on actual engine test on test bed is time consuming and expensive, and is being replaced by use of simulation tools and accelerated component testing. The present work is a systematic fatigue strength evaluation programme for connecting rod of an up-rated Naturally Aspirated, Direct Injection, Inline Diesel Engine The established staircase method of fatigue test is slightly modified to minimise the effect of scatter in the results and to arrive at a consistent and dependable factor of safety. Also analytical tools like Finite Element Analysis (FEA) and Statistical Techniques were used; which helped to keep design and tooling iterations to a minimum and facilitated connecting rod development in the given time frame.

Buses are commonly used mode of transport in less motorized countries. With growth in economy, the numbers of buses have increased tremendously both in rural and urban areas. With increased number of buses, the issue of safety of passengers and the crew assumes special importance. A large number of bus accidents involve rollovers and falling into ditches or downhill sides. Therefore, the structural integrity of buses is critically important. In order to provide buses with minimal rollover resistant superstructure, Economic Commission for Europe, Regulation Number 66 (ECE R - 66) was issued in the early eighties. Type approval can be granted on the basis of rollover test on complete vehicle or body section or pendulum test on body section or by calculations. This paper includes the numerical simulation of rollover test of a full bus body according to ECE R-66. It also includes similar simulation of a representative bus section and validation with the experimental rollover test.

The increasing trends towards smaller power units running at high speeds together with the increasing use of diesel engines in passenger vehicles have resulted in higher vehicle interior noise and vibration levels. The customer awareness towards comfort of vehicle specifically with reference to perceived noise levels has become a selling point for vehicle manufacturers. In this paper experimental and analytical techniques used to study the influence of cabin related parameters on interior noise are presented. These techniques were applied to study interior noise of truck cabins. The noise and vibration signals were measured at body panels and at Operators Ear Location (OEL) for different engine speeds. The natural frequencies of body panels were identified by using frequency response function measurements. The modal analysis of acoustic cavity was carried out using finite element technique.

The demands resulting from stringent noise legislations are increasing rapidly. It has become necessary to establish optimum design methods for low noise engines. In this paper, a methodology for structure borne engine noise control using the combination of experimental and computer aided techniques is presented. Sensitivity analysis for noise reduction is carried out for various structural modifications. The major structural improvements include addition of ribs, stiffening plate and crankcase shape modifications. The final models were validated using experimental analysis techniques.

The acceptance criterion of any vehicle in terms of user comfort invariably depends on the vehicle interior noise and vibration characteristics. The levels of sound energy and structural excitation inside the vehicle compartment measures the amount of annoyance in terms of quality and comfort. For vehicle interior noise abatement and noise treatment, it is desirable to quantify the noise sources by determining the sound power contribution from each vehicle component/panel, acoustic leakages inside the vehicle, body panel vibrations, gearshift lever and steering wheel vibrations. Many a times, it is necessary to arrive at benchmarks or targets for the various sources of noise in order to refine the systems. The present paper describes a methodology for interior noise source identification and its analysis for benchmarking. Two different vehicles of the same class but of different makes were compared and evaluated for interior noise and vibration levels.

The transportation noise is one of the major sources of noise exposure in residential areas and causes substantial annoyance particularly during night. Considering this, many countries have enacted legislation limiting the noise levels in residential areas and also the noise levels emitted by vehicles. In India also, the Ministry of Environment and Forests enacted Environment (Protection) Rules through Air Pollution Act in 1986. Various international as well as Indian standards for vehicles consider two types of noise measurement viz., Pass-By Noise (PBN) and Stationary Noise (SN). There is a debate going on whether in-use vehicle noise should be considered as a parameter for the Inspection and Maintenance (I&M) regime, which is to be introduced shortly in India. A detailed study was conducted to understand the relation between PBN and SN for both new and in-use vehicles.