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This paper describes an investigation of the suitability of FE analysis using the virtual fluid mass (VFM) in fuel tank validation. It produces a mass matrix which represents the fluid coupled to a boundary consisting of structural elements and other effects, such as free surfaces, planes of symmetry and infinite fluids. The incompressible fluid produces a mass matrix defined with full coupling between accelerations and pressures on the flexible structural interfaces. This capability is used to model fuel tank with fuel filled inside. Hence, using the VFM method modal analysis is performed keeping the fuel tank 90% filled and results are compared with physical testing. The VFM method is much more reliable and accurate than the NSM or density adjusted method. The modal frequencies obtained in VFM technique are in proximity with the physical testing results. Further, the fuel tank and its mountings are evaluated for frequency response analysis with excitation in vertical direction.

In this paper the approach to predict engine noise under combustion forces is presented. This Methodology is divided into three stages: 1. Multi body dynamic (MBD) Simulation to determine excitation forces 2. Vibration analysis of engine under combustion load 3. Acoustic analysis of engine to predict Sound Pressure Level (SPL). Important parts of motorcycle engine with single cylinder are considered as flexible bodies for MBD simulation. It is necessary to accurately model crankshaft ball bearing for capturing the accurate transmissibility of combustion forces from crankshaft to casings. In this work crankshaft ball bearing is modeled with 6×6 stiffness matrix. It provides coupling between radial, axial and tilting deflections of bearing and it also allows moment transfer from crankshaft to casing. It helps to predict the realistic forces at bearings. Forces predicted from MBD simulation are applied to engine FE model for carrying out vibration analysis.

High fuel efficiency, low ownership/ maintenance cost and favorable driving climate are the major reasons for the increasing demand for low-power commuter motorcycles and scooters, particularly in developing countries like India, Brazil and China. Noise Vibration and Harshness (NVH) has now become a new subject for the battle between competing manufacturers in attracting customers. Valvetrain noise is quite significant in the engines of these cost gasoline vehicles as they don't incorporate a Hydraulic Lash Adjuster (HLA) to keep the manufacturing costs less. The aim of this study was to understand how the cam ramp velocity and height affects the noise generated by the engine and what effect they have on its performance.For this study, a small scooter gasoline engine with an Over Head Camshaft (OHC) and a rocker arrangement with a roller-follower was considered. A commercially available numerical code was used to simulate the kinematic and dynamic behaviour of the valvetrain system.

In this paper the approach to predict vibrations in motorcycles is presented. It can be divided mainly in two parts: prediction of engine forces using multi body dynamics (MBD) simulation and prediction of vibration response using FEA. Dynamic forces predicted at each engine mount through MBD simulation are used as input to FE analysis for vibration prediction. Single cylinder SI engine having primary balancer shaft is considered to develop this methodology. Flexibilities of important parts are considered for MBD simulation. Crankshaft ball bearing which is used in almost all two wheeler engine is modeled with 6×6 stiffness matrix. It provides coupling between radial, axial and tilting deflections of bearing and it also allows moment transfer from crankshaft to casing. This helps to predict realistic forces at each bearing and engine mounts. Distribution of primary and secondary forces at crank bearings and at different engine mounts is studied.

Two wheelers are widely used as a medium of transportation in Asia. The increased competition challenges automotive manufacturers' to deliver the high quality product to the market. Better acoustic performance of vehicle conveys the impression of a superior quality to the customer. The better acoustic performance of the vehicle gives the competitive edge to the manufacturers. This is putting pressure on the automotive manufactures' to achieve the superior NVH performance of the vehicle. In a two wheeler, apart from the power train noise, transmission noise and exhaust tonal quality; the structure-borne rattle noise threatens to achieve the better acoustic performance of the vehicle. Because of the presence of audible structure borne rattle noise in a motorcycle can convey the impression of poor quality to the customer. In this paper, the focus is on experimental methodology for evaluation and elimination of structure-borne rattle noise in motorcycle.