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Active control mainly comprises of three parts; sensor-detects the input disturbance, actuator -provide counter measures and control logic -processing of input disturbances and converting it into logical output. Lot of methods for active vibration control are available but this paper deals with active control of steering wheel vibrations of an LCV. A steering wheel is, one such component that directly transfers vibration to the driver. Active technique described here is implemented using accelerometer sensor, IMA (Inertial Mass Actuator) and feed forward Fx-LMS (Filtered reference Least Mean Square) control algorithm. IMA is a single-degree-of-freedom oscillator. To enable a control, IMA needs to be coupled to the structure at a single point, acting as an add-on to the passive system. Fx-LMS is a type of adaptive algorithm which is computationally simple and it also includes compensation for secondary path effects by using an estimate of the secondary path.

Diesel powered electric generators are used in a variety of applications, such as emergency back-up power, temporary primary power at industrial facilities, etc. As regulatory and customer requirements demand quieter designs, special attention is given to the design of acoustic enclosures to balance the need of noise control with other performance criteria like ventilation and physical protection. In the present work, Statistical Energy Analysis (SEA) approach augmented by experimental inputs is used to carry out Vibro-acoustic analysis of an enclosure for higher capacity Diesel generator set. The exterior sound radiated from an enclosed generator is predicted and further enclosure is optimized for an improved sound-suppression. The airborne sources such as engine, alternator, radiator fan and exhaust are modelled explicitly using experimental noise source characterization. Structure borne inputs are also captured in the test for improving modelling accuracy.

The Exhaust Noise is one of the major noise pollutants. It is well-known that for higher noise reduction, the engine has to bear high back pressure. For a race car, back-pressure plays a major role in engine's performance characteristics. For a given condition of engine rpm & load, conventional muffler has a fixed value of back-pressure and noise attenuation. Better acceleration requires low back-pressure, but the exhaust noise should also be less than the required (Norm) value (110 dBA). This contradicting condition is achieved here by using a ‘Butterfly Valve’ in this novel exhaust muffler. The butterfly valve assumes 2 positions i.e. fully open & fully closed. When the valve is fully closed, the noise reduction will be higher, but the back-pressure will also shoot up. When open, noise reduction will be less and so the back-pressure. So, when better performance is required, the valve is opened and back-pressure is reduced. The muffler is designed for a 4 cylinder 600 cc engine.

Last decade has been era of environmental awareness. Various programs have launched for making devices and appliances eco-friendly. This initiative has lead automobile industry toward hybridization and now total electrification of vehicles. As electric motor is being added to automobile as a prime mover, due to high frequency vibrations along with higher torque electric motor needs to be isolated properly & carefully as this vibration can damage other automobile parts. Dynamic response of electric motor is different from response of IC engines, so use of engine mounting design method may not be suitable for designing mounting system for electric motor. First, both 4- point and 3- point mounting system are considered for analytical and experimental investigation of force and displacement transmissibility. Position and orientation of elastomeric mounts plays important role in design of mounting system for electric motor.

Design of vehicle for targeted customer usage is one of the key steps during vehicle development process. Due to globalization, most of vehicles, aggregates, components are being designed for global market considering worldwide load spectrum. Generally for doing this the vehicle response is being measured for different markets but this process is very time consuming. Also for getting these vehicle dependent parameters, exercises need to be repeated on each type/class of vehicle. So there is a need to have a robust procedure, tools which will helps OEM’s to predict the loads, vehicle response for different market segments at an early stage of vehicle development program using the inputs which are vehicle independent. The solution for this could be to use vehicle independent input such as digitized road profiles (2D or 3D) of target customer markets in combination with proper MBD simulation tools.

The automotive and related industries are concentrating their efforts on improving comfort by lowering engine, wind, and road noise and vibrations. However, as background noise levels decrease, the squeaks and rattles (S&R) generated by the vehicle's many components become more noticeable and distracting. As a result of the absence of a dominant noise source from a traditional petrol/diesel car, (S&R) noise becomes more dominant than other types of noise in electric vehicles. In this paper, we propose a novel simulation technique for developing a systematic approach to identifying and solving (S&R) problems in vehicle components/sub-assemblies during the primary stage of product development cycle, thus reducing the overall product development time. This paper will present a novel approach to comprehending various methods and Design of Experiments (DOE) techniques used to determine the root cause of (S&R) problems and to solve those using numerical methods.

Now-a-days, Advanced driver-assistance systems (ADAS) is equipping cars and drivers with advance information and technology to make them become aware of the environment and handle potential situations in better way semi-autonomously. High-quality training and test data is essential in the development and validation of ADAS systems which lay the foundation for autonomous driving technology. ADAS uses the technology like radar, vision and combinations of various sensors including LIDAR to automatize dynamic driving tasks like steering, braking, and acceleration of vehicle for controlled and safe driving. And to integrate these advance technologies, the ADAS needs labeled data to train the algorithm to detect the various objects and moments of driver. Image annotation is one the well-known service to create such training data for computer vision. There are number of open source annotated datasets available viz. COCO, KITTI etc.

With emission norms getting more and more stringent, the trend is shifting towards electric and hybrid vehicles. Electric motor replaces engine as the prime mover in these vehicles. Though these vehicles are quieter compared to their engine counterpart, they exhibit certain annoying sound quality perception. There is no standard methodology to predict the noise levels of these motors. Electric motor noise comprises of mainly three sources viz., Aerodynamic, Electromagnetic and Mechanical. A methodology has been developed to predict two major noise sources of electric motor out of the three above viz. Mechanical and Aerodynamic noise. These two noise sources are responsible for the tonal noise in an electric motor. Aerodynamic noise arises most often around the fan, or in the vicinity of the machine that behaves like a fan. This noise is predominant at higher motor speed and also in electric vehicle due to higher speed fluctuation.

This work aims at demonstrating nodes and antinodes at various frequencies of vibrations. Chladni plate is used for this purpose. When the plate is excited because of vibrations from a vibrator source, the sand of the plate creates specific patterns. These patterns are related to the excitation frequency. The sand on the plate moves away from antinodes where the amplitude of the standing wave is maximum and towards nodal lines where the amplitude is minimum or zero, forming patterns known as Chladni figures. The formation of patterns depends on material properties, geometry of plate, and thickness of plate and frequency/vibration pattern of the vibrator. The experimental setup consisted of a aluminum rectangular plate of 16 cm × 16 cm and aluminum circular plate of diameter 16 cm are having thickness of 0.61 mm placed over a mechanical vibrator (GelsonLab HSPW-003), which was driven by a sine wave signal generator (Ningbo Hema scientific).

With growing demand of comfort of cars, number of small electric motors used for adjustment of different functional units is steadily increasing. Due to the various rotational components and the forces they accord, electric motors radiate significant amount of noise at high frequencies with tonal components that can be annoying. Motor noise comprises three sources namely: electromagnetic, aerodynamic and mechanical. This study considers mechanical and electromagnetic sources of Electric Power Assisted Steering (EPAS) motor used in passenger cars. This paper describes an approach to assess noise and vibration parameters between field motors and fresh motors. Noise and vibration spectrums are analyzed in terms of frequency contents and dominancy of mechanical sources in sound power radiated by motor is discussed. FE modal analysis of motor is performed and correlated with impact hammer measurements to quantify structure borne energy contribution.

NVH has gained importance in the field of earth moving equipment due to the demand of quieter machines and stringent in-cab as well as exterior noise emission norms. Several parts of the world have adopted strict legislation on noise emission by earth moving equipment, but many countries have not adopted any regulations till date. The aim of this study is to help governing bodies as well as machine manufacturers in adopting simple yet accurate testing method for compactor machine. The study consists of directivity analysis, noise source identification, noise source ranking and 4-point microphone position sound power evaluation method applied to compactors with wide range of engine power ratings. All the tests in 4-point method and directivity analysis were performed under stationary as well as dynamic conditions.

Sound Quality (SQ) of brake and clutch pedal assembly plays an important role in contributing to vehicle interior noise and perception of sound. Quiet operation of brake and clutch units also reflects the vehicle built and material quality. Noise emitted from these sub-assemblies has to meet certain acceptance criteria as per different OEM requirements. Not much work has been carried on this over the years to characterize and quantify the same. An attempt has been made in this paper to study the sound quality of brake and clutch pedal assemblies at component level and validate the same by identifying the parameters affecting SQ. Effect on noise at different environmental conditions was studied with typical operating cycles in a hemi-anechoic chamber. The effect of sensor switches integrated within the clutch and brake pedal on sound quality is analyzed. It is found that the operating characteristics of switches drives the noise and SQ.

The parameters such as lower noise levels, quietness, etc. of a vehicle has no longer remained the only driving features since the passenger car buyers are greatly influenced by the perception of the sound. In a scenario like this, the sound quality becomes of great importance especially for smaller diesel powertrains as they are more annoying than their gasoline counterparts. The idling noise is critical as its noise creates the first impression of the vehicle on the buyer. The Indian passenger car market is dominated by diesel cars equipped with smaller engines less than 2 liter capacity. Present work describes the methodology to formulate the equation for annoyance/pleasantness for the diesel powertrains used in Indian passenger cars. The index, Sound Annoyance Rating (SAR) developed through this work is significant for powertrain level target setting and benchmarking purposes.

Greater customer awareness is driving the automotive industry to constantly look to innovate and ensure that greater time, efforts and considerable resources are spent in developing a better vehicle. As we move away from noisy vehicles, the differentiating parameter in vehicles is the perception of quality in the vehicle noise or sound. As the masking effect due to overall vehicle noise level abates, many low noise sources gain prominence, which directly influences the perception of noise refinement. Hence, the concept of vehicle interior noise is not only limited to lower noise levels but has also extended to better sound quality (SQ). SQ technique involves use of relevant parameters for quantifying a subjective quality into an objective quantity. This paper will look at parameters relevant to subjective perception of vehicle interior noise and consider a benchmarking methodology targeting vehicle sound quality.

In order to reduce development time and costs, application of numerical prediction techniques has become common practice in the automotive industry. Among the wide range of simulation applications, prediction of the vehicle interior noise is still one of the most challenging ones. The Finite Element Method (FEM) is well known for acoustic predictions in the low-frequency range. As part of the development of a full sized bus model, noise levels at Driver Ear Levels (DEL) and Passenger Ear Levels (PEL) were targeted. The structural and acoustic analysis were performed for a bus to reduce interior noise in the low-frequency range. Various counter measures were identified and structural optimization/modifications were performed from virtual simulation to reduce the DEL and PEL. Structure-borne noise due to both road-induced vibration and engine vibration were considered by using FEM techniques.

Designers and analysts need to compare and conduct synthesis for selection of materials based on their properties involving simulation, optimization and correlation with test data. An example is that of acoustic material properties such as random and normal incidence sound absorption coefficient and sound transmission loss. The international test standards necessitate having standard operating procedures for characterization of these materials. This procedure is quite involved and addresses steps including test data acquisition, post processing, calculations, classification, report generation and most importantly, storage of such innumerable material properties in a structured manner to facilitate ease of retrieval and updating of properties. It is also highly desirable to have a synergy of the databank directly with simulation tools. Further, all of these steps need to be accurate, non-speculative and quick.