Search Results

The transmissibility technique has been traditionally used for evaluating the NVH performance of isolated, rigid structures such as the elastomer mount isolated automobile engine. The transmissibility quantity provides information on how a structure reduces vibration as subjected to dynamic loading and thereby attenuates noise. In the present study, the transmissibility is applied to a non-rigid, plastic structure - the engine cylinder-head cover module. The cover module includes primarily a thin, plate-like cover and the elastomer isolation system. At low frequencies, the cover will behave as a rigid mass and thus display a major peak at its resonant frequency. At high frequencies, the cover will vibrate as a flexible panel and thus display multiple peaks with magnitudes differing from point to point across the cover surface. As a result, the transmissibility calculated would have a spatial resolution, called the spatial transmissibility.

A comparative study of two different chassis frames when subjected to independent front and rear towing loads has been made. These frames have different structures and are made of two different non-linear materials. The applied towing loads subject the frame material to very high stresses (above the yield point). Hence a non-linear large deflection analysis needs to be performed to find out the resulting plastic deformation after the towing loads are removed. It has been observed that one of the frames is strong in the front while the other is strong in the rear. Abaqus, which is a non-linear finite element (FE) solver has been used to evaluate the two designs.

A web based software program has been developed to do a Finite Element (FE) analysis of a simplified driveline system. In the past, an expert analyst had to make a Finite Element Model, analyze and then report results. It has been observed that this process is time consuming besides the difficulties of doing quick parametric studies, geographical location of designers, analysts, etc. The web-based software program aims to solve these issues. The designer could get analytical & Finite element results anywhere around the world (where the designer has access to the web) without any expertise in FE modeling. This software is a joint effort of Engineering and Information Technology (IT) software groups. It is based on Active Server Page (ASP) technology and MSC/NASTRAN technologies combined. Input data deck is prepared from user inputs and submitted over the internet to a remote system, solved and results are retrieved and plots shown in minutes, instead of days earlier.

The exhaust manifold heat shield is made of different material layers and is bolted to the engine exhaust manifold. The exhaust manifold heat shield has been identified as a potential major noise contributor among the engine components during normal operation, which is to protect nearby components from damage due to high heat. To reduce the noise radiated from the exhaust system, a thermal acoustic protective shield (TAPS) has been developed to act as a partial acoustic enclosure. This paper will discuss the importance of controlling NVH and what can be done design-wise to improve the TAPS characteristics. The paper discusses the impact of damping and vibration, how they are modeled. Further the present study analyzes the radiated sound pressure level (SPL) of a thermal acoustic protective shield by using the finite element analysis (FEA). The analyses are performed using the fully coupled structural-acoustic method and the sequentially coupled structural-acoustic method.

A fuel filter system essentially consists of a center tube, which is screwed on to a head and rests against a bowl. A thin circular plate, called end-cap, slides inside the bowl with spline teeth. The fuel filter material is inside the bowl and rests on the end-cap. When the bowl is tightened an input torque is transferred to the center tube and on to the head. It is required to estimate the stresses of the various components when a maximum tightening torque is applied to the bowl. A non-linear large deflection contact analysis of the fuel filter system needs to be performed. A number of contacts between the different deformable bodies, i.e. head and bowl, end-cap and center tube, etc. are resolved for equilibrium.

A methodology of using topological optimization technique for bring down the weight of a structure has been discussed. Special variables are defined for each of the finite elements, which are related to the thickness, density and Young's Modulus of the material. A Topology optimization problem is set up to solve for these special variables. The major advantage in this method is that the user can give additional stress and displacement constraints. Optimization solvers, which can handle discrete variables, are required. At the end of the optimization the special variables are snapped on to pre-defined extreme values which determine which elements could be successfully eliminated to reduce weight of the structure.

In a power transmission module a snap-ring is fitted inside a groove of a clutch drum. When a hydraulic pressure is applied at one end of a clutch piston it presses against a clutch pack and an end plate. The end plate then presses against the snap ring, which reacts against the groove of the drum. It is required to estimate the pressures, deflections and stresses of the various components when a maximum hydraulic pressure acts. A non-linear large deflection analysis of the snap-ring, which fits into the groove, is performed. A number of contacts between the different deformable bodies, i.e. end plate and snap ring, snap-ring and the groove, etc. are resolved for equilibrium.

In a power transmission module, a circular splined clutch end plate hits against a snap-ring, which is fitted inside a groove of a clutch drum. It is required to estimate the stresses on the clutch end plate when a maximum pressure acts on one of the sides of the end plate and it presses against the snap ring on its other side. A non-linear large deflection analysis of the snap-ring, which fits into the groove, is performed. A rigid contact problem between two deformable bodies, i.e. end plate and snap ring, and another rigid contact between the snap-ring and the groove are then solved to find out the stresses on the end plate.

Design analysts, who work with finite element shape optimization, face a daunting task of handling cylindrical parts like a pusher for a crimp. The shape vectors generated by any of the existing methods/tools cannot constrain nodes to move in a circular path. Since the pusher is not a complete cylinder and the loading is only along axial direction, shape optimization was performed after flattening out the cylindrical pusher. The existing shape optimization tools could now be applied to the flat plate. A numerical interpolation method, based on ‘Autodv’, has been used to generate shape vectors. Both weight and stresses have been brought down and the final design was verified with solid finite element analysis.