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The Hybrid Finite Element Analysis (HFEA) method is based on combining conventional Finite Element Analysis (FEA) with analytical solutions and energy methods for mid-frequency computations. The method is appropriate for computing the vibration of structures which are comprised by stiff load bearing components and flexible panels attached to them; and for considering structure-borne loadings with the excitations applied on the load bearing members. In such situations, the difficulty in using conventional FEA at higher frequencies originates from requiring a very large number of elements in order to capture the flexible wavelength of the panel members which are present in a structure. In the HFEA the conventional FEA model is modified by de-activating the bending behavior of the flexible panels in the FEA computations and introducing instead a large number of dynamic impedance elements for representing the omitted bending behavior of the panels.

The Energy Finite Element Analysis (EFEA) has been validated in the past through comparison with test data for computing the structural vibration and the radiated noise for Naval systems in the mid to high frequency range. A main benefit of the method is that it enables fast computations for full scale models. This capability is exploited by using the EFEA for a submarine pressure hull design optimization study. A generic but representative pressure hull is considered. Design variables associated with the dimensions of the king frames, the thickness of the pressure hull in the vicinity of the excitation (the latter is considered to be applied on the king frames of the machinery room), the dimensions of the frames, and the damping applied on the hull are adjusted during the optimization process in order to minimize the radiated noise in the frequency range from 1,000Hz to 16,000Hz.

The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration and the interior noise level of complex structural-acoustic systems by solving numerically governing differential equations with energy densities as primary variables. In this paper a complete simulation process for evaluating airborne noise in an automotive vehicle is presented and validated through extensive comparison to test data. The theoretical elements associated with the important paths of the noise transfer from the exterior of the vehicle to the interior acoustic space are discussed. The steps required for developing an EFEA model for a vehicle are presented. The model is developed based on the physical construction of the vehicle system and no test measurements are utilized for adjusting the numerical model.

A two-brick gasoline engine aftertreatment system with advanced washcoat technology was developed for LEV2 PZEV2 legislation, and its application to the upcoming LEV3 SULEV30 emission standard was demonstrated. The system was comprised of 1) a palladium only catalyst in the close coupled position with improved catalytic performance and high phosphorus poisoning resistance compared with 09MY technology, and 2) an underfloor palladium rhodium catalyst technology in which the nitric oxides (NOx) reduction activity was enhanced by preventing the deactivation of rhodium under rich conditions. As a result, the palladium only + palladium rhodium catalysts system met the LEV2 PZEV standard with three quarters of the PGM and half the rhodium of the system used on the Honda 09MY Accord vehicle. The system was also demonstrated to meet the LEV3 SULEV30 standard with some margin.

This paper describes the development results of S tolerant Pt-Pd-based Diesel Oxidation Catalyst (DOC) which can be applied for passive DOC application, targeting Euro 4 and India BS4 emission standards with a view of the fact that in India the sulfur content is different in the 13 main cities compared to rest of the country. In order to develop a cost-effective DOC to meet Euro 4 and India BS4 legislation, Pt-Pd-based DOC was studied. Firstly, the effect of Pd used together with Pt in catalytic oxidation performance was studied. DOCs having different Pt to Pd ratios were evaluated in the engine exhaust. The results revealed that CO (Carbon Monoxides) and HC (Hydrocarbons) oxidation activity over Pt-Pd DOC were significantly improved as compared to Pt-only DOCs. It was also revealed that there is an optimum Pt to Pd ratio to give the best light-off performance under conditions tested. Advantage of Pd use with Pt was also confirmed in terms of thermal stability.

Vehicle design is a complex process requiring interactions and exchange of information among multiple disciplines such as fatigue, strength, noise, safety, etc. Simulation models are employed for assessing and potentially improving a vehicle's performance in individual technical areas. Challenges arise when designing a vehicle for improving mutually competing objectives, satisfying constraints from multiple engineering disciplines, and determining a single set of values for the vehicle's characteristics. It is of interest to engage simulation models from the various engineering disciplines in an organized and coordinated manner for determining a design configuration that provides the best possible performance in all disciplines. The multi-discipline design process becomes streamlined when the simulation methods integrate well with finite element or computer aided design models.

The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration and the interior noise level of complex structural-acoustic systems by solving governing differential equations with energy densities as primary variables. A finite element approach is employed for the numerical solution of the governing differential equations. Results from EFEA simulations have been compared successfully with test results for Naval, automotive, and aircraft structures. The Energy Boundary Element Analysis (EBEA) has been developed for conducting exterior acoustic simulations using the acoustic energy density as primary variable in the formulation. EBEA results have been compared successfully to the test results in the past for predicting the exterior acoustic field around a vehicle structure due to external noise sources. In this paper, the EBEA and EFEA methods are combined for predicting the interior noise levels in a vehicle due to exterior acoustic sources.

In order to be effective and maximize the weight and cost savings when designing for noise and vibration attributes, the structural-acoustics design effort must be concurrent with the efforts of other engineering disciplines (i.e. durability, crashworthiness, etc.). In this manner, it will be possible to account for the effects of structural changes across disciplines and improve the NVH performance while the structure is being configured rather than attempting to improve NVH characteristics after the structural design has been completed.

Environmental problems have raised much attention recently. Automotive manufacturers are strongly required to suppress tailpipe emission world wide. To meet tight legislations such as PZEV and EU5 which are stringent regulation, it is well known that improving the quick light-off performance and hot-NOx conversion are critical issues with limited precious group metals (PGM) usage. Due to the strong pressure of recent PGM prices, further PGM reduction is strongly required for tight regulation applications. Moreover, there is a requirement of utilizing lower cell density substrates to decrease catalyst backpressure for the improvement of vehicle drivability. This paper will present a newly designed formulation that has excellent quick light-off and NOx reduction performance. In the developed catalyst, new thermally stable OSC material and porous washcoat technologies were adopted. Also, the washcoat loading of the catalyst was lowered against current formulations.

It is challenging to perform probabilistic analysis and design of large-scale structures because probabilistic analysis requires repeated finite element analyses of large models and each analysis is expensive. This paper presents a methodology for probabilistic analysis and reliability based design optimization of large scale structures that consists of two re-analysis methods; one for estimating the deterministic vibratory response and another for estimating the probability of the response exceeding a certain level. The deterministic re-analysis method can analyze efficiently large-scale finite element models consisting of tens or hundreds of thousand degrees of freedom and large numbers of design variables that vary in a wide range. The probabilistic re-analysis method calculates very efficiently the system reliability for many probability distributions of the design variables by performing a single Monte Carlo simulation.

An approach for Probabilistic Reanalysis (PRA) of a system is presented. PRA calculates very efficiently the system reliability or the average value of an attribute of a design for many probability distributions of the input variables, by performing a single Monte Carlo simulation. In addition, PRA calculates the sensitivity derivatives of the reliability to the parameters of the probability distributions. The approach is useful for analysis problems where reliability bounds need to be calculated because the probability distribution of the input variables is uncertain or for design problems where the design variables are random. The accuracy and efficiency of PRA is demonstrated on vibration analysis of a car and on system reliability-based optimization (RBDO) of an internal combustion engine.

In this paper the development of statistical metamodels and statistical fast running models is presented first. They are utilized for propagating uncertainties in a multi-discipline design optimization process. Two main types of uncertainty can be considered in this manner: uncertainty due to variability in design variables or in random parameters; uncertainty due to the utilization of metamodels instead of the actual simulation models during the optimization process. The value of the new developments and their engagement in multi-discipline design optimization is demonstrated through a case study. An underwater vehicle is designed under four different disciplines, namely, noise radiation, self-noise due to TBL excitation, dynamic response due to propulsion impact loads, and response to an underwater detonation.

Utilizing simulation technology is important for designing a structure with increased survivability to a load from an explosion. The pressure wave from the blast and the fragments hitting the structure must be simulated in such an analysis. Commercial software can be utilized through the development of appropriate interfaces for performing such computations. In this paper an approach is presented for combining commercially available Eulerian and Lagrangian solvers for performing blast event simulations. A capability has been developed for automatically creating the Eulerian finite element given the finite element model for the structure. The effect of moisture in the soil properties is considered during the generation of the soil - explosive - air model used by the Eulerian solver. Tracers are defined in the Eulerian model for all structural finite elements which are on the outer part of the structure and are subjected to the load from the blast.

In recent years, automobile emission limits have been tightened world wide. PZEV (Partial Zero Emission Vehicle) which is the most stringent regulation has been imposed in California. To meet the strict PZEV regulation, automotive manufacturers are requesting the catalyst system to have quick light-off characteristics and excellent steady state performance with limited precious group metals (PGM) usage due to the strong price pressure. Moreover, the catalyst can not use high cell density substrate for increasing geometric surface area and reducing heat mass, since the backpressure of exhaust system must be decreased to improve the vehicle power for the PZEV application. This paper will present an efficient catalyst formulation that has been designed to maximize the performance with considerably reduce PGM loading. The catalyst washcoat has been optimized by improving the catalyst geometric surface area, gas diffusivity and thermal mass.

A new state of the art DOC (Diesel Oxidation Catalyst) having superior light-off and exothermic activity for forced regeneration compared to conventional Pt base passive DOC, was investigated for LDD application. The DOC uses the latest Pt/Pd technology resulting cost effective DPF system. The newly developed DOC demonstrated improved catalytic activities from Pt only DOC in model gas or engine bench tests. In this study, DOC at early development stage showed excellent light-off activity in model gas and engine bench test compared to conventional Pt only DOC, however, it showed “extinction” phenomenon which is one of the deactivation mode while the post injection and it was observed when post injection operation was done at lower DOC inlet temperatures, e.g. below 250 C. Temperature profiles along diameter and length into DOC bed while active regeneration suggested extinction would be caused by fouling of supplied hydrocarbons derived from diesel fuel.

This paper presents a validation case study for an Energy Finite Element Analysis (EFEA) formulation through comparison to test data. The EFEA comprises a simulation tool for computing the structural response of a complex structure and the amount of the radiated power. The EFEA formulation presented in this paper can account for periodic stiffeners, for partial fluid loading effects on the outer part of the structure, and for internal compartments filled with heavy fluid. In order to validate these modeling capabilities of the EFEA two 1/8th scale structures representing an advanced double hull design and a conventional hull design of a surface ship are analyzed. Results for the structural vibration induced on the outer bottom part of the structure are compared to available test data. The excitation is applied at two different locations of the deck structure. Good correlation is observed between the numerical results and the test data.

In applications of the Energy Finite Element Analysis (EFEA) there is an increasing need for developing comprehensive models with a large number of elements which include both structural and interior fluid elements, while certain parts of the structure are considered to be exposed to an external fluid loading. In order to accommodate efficient computations when using simulation models with a large number of elements, joints, and domains, a substructuring computational capability has been developed. The new algorithm is based on dividing the EFEA model into substructures with internal and interface degrees of freedom. The system of equations for each substructure is assembled and solved separately and the information is condensed to the interface degrees of freedom. The condensed systems of equations from each substructure are assembled in a reduced global system of equations. Once the global system of equations has been solved the solution for each substructure is pursued.

Finite element analysis is a well-established methodology in structural dynamics. However, optimization and/or probabilistic studies can be prohibitively expensive because they require repeated FE analyses of large models. Various reanalysis methods have been proposed in order to calculate efficiently the dynamic response of a structure after a baseline design has been modified, without recalculating the new response. The parametric reduced-order modeling (PROM) and the combined approximation (CA) methods are two re-analysis methods, which can handle large model parameter changes in a relatively efficient manner. Although both methods are promising by themselves, they can not handle large FE models with large numbers of DOF (e.g. 100,000) with a large number of design parameters (e.g. 50), which are common in practice. In this paper, the advantages and disadvantages of the PROM and CA methods are first discussed in detail.

The Energy Boundary Element Analysis (EBEA) has been utilized in the past for computing the exterior acoustic field at high frequencies (above ∼400Hz) around vehicle structures and numerical results have been compared successfully to test data [1, 2 and 3]. The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration of complex structures at high frequencies and validations have been presented in previous publications [4, 5]. In this paper the EBEA is utilized for computing the acoustic field around a vehicle structure due to external acoustic noise sources. The computed exterior acoustic field comprises the excitation for the EFEA analysis. Appropriate loading functions have been developed for representing the exterior acoustic loading in the EFEA simulations, and a formulation has been developed for considering the acoustic treatment applied on the interior side of structural panels.

Global environmental consideration is now one of the essential components in automotive design. This concern needs be addressed not only by aftertreatment systems but also engine control technologies. In this paper, we will present an efficient emission control system that has been designed based upon the combination of advanced engine control and catalyst technologies. The system has successfully achieved the stringent US ULEV2 emission regulations and the vehicle installed with this system has been commercialized in the marketplace. In this system, the advanced fuel control system was able to facilitate quick light-off of the catalyst so that the cold start emission could be minimized. The engine A/F control is so precise that the catalyst can use the material which is most effective at the stoichiometric point.