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The first example concerns the use of agricultural fuels and, in particular, the use of the so-called “biodiesel” in lieu of diesel fuel. The overall environmental impact of this product has been evaluated by examining all quantifiable effects. From an examination of the results, it can concluded that biodiesel is less detrimental than diesel fuel where the greenhouse effect, energy and non renewable raw materials and biodegradability are concerned. On the other hand, where all other aspects are concerned, its effects are equivalent or even more adverse. The second example deals with the evaluation of the impact on the environment of substances meant to replace CFC's both as expanding agents for polyurethane foams and as cooling fluids in air conditioning systems. The use of such subtonics has become necessary to prevent a further reduction in the ozone layer present in the stratosphere.

The first LCA study conducted by the Japan Automobile Manufacturers Association was carried out to calculate energy consumption and CO2 emissions for average passenger cars in Japan. Five stages including mining and producing material, parts and automobile production, operation, maintenance, and disposal and recycling; and inter-stage transportation was included in the scope of evaluation. Energy consumption and CO2 emissions was evaluated and the influence of the average running speed during operation and the influence of part changes were examined.

How does a company determine if a new product or process has less or more impact on the environment? Or do we just assume that because it has recycled content it has less impact on the environment? A life cycle assessment can be used to better understand the impacts and the trade-offs. The authors have prepared an analysis in which large volume, currently valueless material is recovered and recycled by chemical depolymerization. A careful selection of boundaries will reduce the amount of data needed to perform a meaningful life cycle assessment; however, it may also introduce new questions regarding the allocation of burdens. This paper will present the difficulties experienced in understanding the proper way to view burden allocation for a closed-loop system with limited boundaries.

For many automotive components, Remanufacturing can be the optimum solution to Total Life Cycle Planning. The ultimate result of Remanufacturing is the rebirth of the original product -- thereby completing the product life cycle by providing a new beginning. Not only are the raw materials preserved, but the functionality as well, by manifesting once again the original intent and purpose of the product. Proactive, upfront planning in the design stages of the original product -- “Design for Remanufacturability” -- can significantly contribute to the overall efficiency and effectiveness of this transformation, thereby enhancing the product life cycle. While providing a solution for life cycle planning, Remanufacturing facilitates environmental conservation and reduces overall life cycle support costs.

A nonlinear transient finite element method was developed to analyze brake squeal occurrence. It overcomes the drawbacks associated with the conventional methods such as modal analysis and complex eigenvalue analysis. It includes the prediction of contact surface variation during the braking process and the complex friction phenomena at rotor-pad interfaces. A new solid element was also developed to suit the brake squeal analysis. A fast Fourier transformation (FFT) was employed to convert the results in the time domain generated from nonlinear transient analysis into the frequency domain to identify the frequencies associated with noise. Good correlation, between the squeal frequencies predicted by the proposed method and those obtained from tests, has been established.

A new procedure for component mode synthesis has been developed where the residual flexibility effects due to modes truncated from the analysis are properly accounted for. Superelement disk storage is minimized in the new method by saving the boundary and transformation matrices only. A special DMAP was developed to save the transformation matrices for data recovery degrees of freedom only. An external superelement is created with a small read only data base. Using this method with a frozen body design, full vehicle models can run on desktop workstations. The number of design iterations that an analyst can do in a given time is increased dramatically in the new method.

The purpose of this paper is to present numerical solution for three-dimensional flow about rotating short cylinders using the computer program AIRFLO3D. The flow Reynolds number was kept at 106 for all computations. The drag forces on the cylinder were obtained for different rotational speeds. Predictions were obtained for both an isolated cylinder and a cylinder on a moving ground. The standard k-ε model was employed to model the turbulence. Computed drag coefficients agreed well with the previous experimental data up to a spin ratio (=rω/V) of 1.5.

This paper discusses the ongoing real-world effects on the wearers of restraint systems which are subject to a retractor's failure to lock in a timely manner. Investigation of the ELR performance using both detailed physical examination and inductive methods enables accurate assessment of successful ELR locking at the first opportunity in the crash sequence. Available methods to determine the reliability of the ELR's crash performance are considered and analyzed for assessment of reliability to enable adequate seat belt wearer protection. Corrective measures are analyzed to probe the feasibility of federal safety regulation amendments to mandate a reliability analysis on the propensity for the ELR's failure to lock in a timely manner.

An experimental method for nondestructive estimation of damage in joints due to high mileage degradation in cars is presented. The method estimates damage by comparing transfer functions of the same car at zero and at high mileage. The potential of the method is demonstrated analytically using a three dimensional concept Finite Element Model (FEM) of a car body to simulate the transfer functions of this car body at zero and at high mileage. The results demonstrate that the method is effective for identifying the damaged joints as well as the relative degree of degradation.

A hybrid approach to predict road-induced loads in vehicle structures is presented. The technique involves full vehicle dynamic simulation using measured wheel forces, absolute wheel vertical displacements, and steering angle as input. The wheel vertical displacement is derived from the measured wheel acceleration. This approach avoids the use of tire-road interface modeling. It also improves the conventional loads measuring process with minimum instrumentation and data acquisition. Existing load data from a test vehicle is used to validate this approach. Computed component loads show good agreement with measurements.

One powerful tool for the optimization of engineering components is solution 200 of MSC/Nastran. The user is able to define nearly every kind of objective function and restriction with the help of synthetic responses, in addition to the usual responses. For sizing problems, solution 200 is well-established and reasonably user-friendly. This is not the case in the field of shape optimization. The main problem is the creation of basis vectors, which are needed to describe the shape variations. There are some methods included in solution 200 to create these vectors, but for complex engineering components these methods are difficult to use and very time-consuming. The program Shape200 has been developed to reduce the effort required to create basis vectors.

In the current design process, the designer generates the detailed geometry of the component based on experience. Prototypes of this design are built and tested to verify the performance. This design - build - test iterative process is continued until performance targets/criteria are met. Computer Aided Engineering is often used to verify the design. This paper presents a new product development process to substantially reduce the number of design - analysis - build - test iterations. This Upfront Analysis Driven Design process incorporates several state of the art technologies in finite element structural analysis, optimization, and Computer Aided Design. This process ensures a near optimum design in the first design level itself.

In this paper we present a numerical shape optimization method of continua for solving min-max problems and identification problems. The min-max shape optimization problems involve minimization of maximum stress or maximum displacement; the shape identification problems involve the determination of shapes that achieve a given desired stress distribution or displacement distribution. Each problem is formulated and sensitivity functions are derived using the Lagrangian multiplier method and the material derivative method. The traction method, which is a shape optimization method, is employed to find the optimal domain variation that reduces the objective functional. The proposed numerical analysis method makes it possible to design optimal structures for maximizing strength and rigidity and for controlling stress and displacement distributions. Examples of computed results are presented to show the validity and practical utility of the proposed method.

The current study is application of an acoustic emission sensing technique in fatigue damage measurement. It focuses on fatigue damage of the below-threshold cycles when they are excited by overloads. Acoustic emission (AE) is monitored while cracks are propagating. Some studies are carried out to reduce and isolate noises from the fatigue acoustic emission signal. Results shows that below-threshold cycles do cause fatigue damage measured by acoustic emission activities under the variable-amplitude loading condition. Acoustic emission signals from fatigue propagation are of an intermittent nature.

A mathematical model was developed for the analysis of a fuel filler door with a torsional spring. The model calculates performance indices such as opening and closing forces, kinetic energy during opening and closing and the maximum spring stress. The model was integrated with an optimization program. Two types of optimization problems were formulated: the traditional problem which does not include the effects of random design parameters, and the stochastic type optimization, which does. An example shows how the mathematical model, in conjunction with optimization techniques, can help determine fuel filler door designs.

A method is proposed for simulating the effects of dimensional variation from geometric dimensioning and tolerancing (GD&T) specifications. The method converts GD&T specifications into equivalent covariance matrices which are needed in the statistical simulation of random processes. Examples are given to show how the method can be implemented.

This paper presents a method to obtain improved foam/pillar structural designs to help enhance occupant interior impact protection. Energy absorbing foams are used in this study with their thickness and crush strength being selected as primary design variables for optimization. The response surface techniques in the design of experiment are used in the optimization process. Head impact analyses are conducted by a CAE model with explicit, nonlinear, dynamic finite element code LS-DYNA3D. A baseline model is developed and verified by comparing the simulation results with the experimental data. Based on this model, the anticipated effects of stiffness of the pillar structure and the trim on the Head Injury Criterion (HIC) results are also assessed. The optimization approach in this study provides a comprehensive consideration of the factors which affect the HIC value.

To reduce the low frequency noise, a new method in optimal stiffener design is presented in this paper. A Microstructure-based Design Domain Method is employed to formulate a topology optimization problem. Using the MDDM, sensitivity of coupled system can be easily derived. The optimal stiffener design is solved using a sequential convex approximation method called Generalized Convex Approximation (GCA). Examples from this approach are presented to demonstrate its effectiveness.

Low frequency vibration characteristics of a vehicle are mainly influenced by the stiffnesses of the beam type structures such as pillars and rockers, and by the stiffnesses of the joint structures, at which several beam structures are jointed together. In the early design stage of the car body structure a simple FE model has been used, in which joints are modeled as linear springs to represent the stiffnesses of the joint structures. In this paper a new modeling technique for the joint structure is presented using an equivalent beam, instead of using a spring. The modeling technique proposed is utilized to design optimal joint structures that meet the required vibration performance of the total vehicle structure.

The air passages in tailpipe end geometries are investigated with Computational Fluid Dynamics (CFD) simulations. The overall objective of the simulations is to select an optimum design which has a mimimum capacity for noise generation. This is accomplished by comparing pressure drops between inlet and outlet and by examining the turbulent kinetic energy levels in the flow domain. Two designs for the tailpipe end geometries were evaluated. It was found that turbulent kinetic energy levels and pressure drops were lowest in a single pipe design which had relatively smooth internal contours. We conclude that the present CFD approach can provide useful design information in a short time frame (a few weeks) for exhaust pipe tip geometries for reduced pressure drop and noise generation.