Search Results

There are many opportunities for lightweighting with ductile iron castings. Current research shows ductile iron castings free of massive carbides can be achieved at under 2 mm (0.080”) through alloying or process changes which means that significant weight reductions are possible. In fact, for aluminum components over 4 mm thick, ductile iron may provide lightweighting opportunities at a cost savings. However, the conventional guidelines for casting design are inadequate when using ductile iron at dimensions less than the typical machine stock. This paper will discuss the current research on thin walled ductile iron, when it is superior to aluminum, design considerations, and current DOE SBIR funded research efforts to address these inadequacies. Research results on efforts to quantify and improve surface roughness in expanded polystyrene for lost foam casting are also discussed.

It is postulated that the value-adding intellectual activity in an enterprise can be formulated as an engineering design problem, using axiomatic design. Axiomatic design formulates a decomposition structure that includes four domains: customer, functional, physical, and process. Knowledge exists within the entities in domains and in the relation between the entities in adjacent domains. Once an entity has been identified in one domain, a properly designed knowledge management system can suggest all the known solutions in the adjacent domains, and the interactions between the domains, along with details about how well these solutions work.

This study utilizes an eddy current proximity probe to approximate the acceleration of a valve in a SOHC valve train. Several techniques are discussed for extrapolating acceleration data from displacement data through numerical differentiation. The data were compared to acceleration data as measured by an accelerometer mounted on the valve face. It was found that valve train acceleration behavior can be reasonably approximated using displacement data as measured by a proximity probe when differentiated using a three-point, Lagrangian interpolation. But the frequency response of the proximity probe is severely restricted by the limitations of the measurement and data collection instrumentation, the limitations of the differentiation method and the continuity of the base measured data.

This study analyzes the vibration characteristics of the valve train of a 2.0L SOHC Chrysler Corp. Neon engine over a range of operating speeds to investigate and demonstrate the advantages and limitations of various dynamic measurements such as displacement, velocity, and acceleration in this application. The valve train was tested in a motoring fixture at speeds of 500 to 3500 camshaft rpm. The advantages of analyzing both time and frequency domain measurements are described. Both frequency and order analysis were done on the data. The theoretical order spectra of cam displacement and acceleration were computed and compared to the experimental data. Deconvolution was used to uncover characteristic frequencies of vibration in the system. The theoretical cam acceleration spectrum was deconvolved from measured acceleration spectra to reveal the frequency response function of the follower system.

A numerical study of an automotive windshield ice-clearing was successfully accomplished. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield clearing analysis employed conjugate heat transfer and enthalpy methods to simulate the ice-melting pattern and the melting duration. This study is a joint project between Chrysler Corporation and CFD Research Corporation. A Chrysler prototype windshield and test vehicle were utilized. The meshing was done using ICEM/CFD package by Control Data Corporation (CDC). A seamless data transfer was achieved by developing an interface between ICEM/CFD and CFD-ACE. The analysis of air flow, conjugate heat transfer, and weather clearing was performed using the multi-domain CFD-ACE code developed by CFD Research Corporation (CFDRC).

A numerical model that utilizes Computational Fluid Dynamics (CFD) techniques has been developed for the analysis of underhood engine cooling systems of large slow moving vehicles. Several physical models have been developed and incorporated into a CFD code including; a) a model for predicting pressure losses due to screens and grills; b) a model for approximating the forces exerted by the fan on the flow; and c) a model for calculating the heat transfer inside the radiator. The CFD code and physical models have been demonstrated and validated against experimental data. Several three dimensional computational grids that represent various engine enclosures have been created and used to analyze the fluid flow and heat transfer inside the engine enclosure system. The computational results are compared to test data which were obtained for this study.

This study is a joint development project between Chrysler Corporation and CFD Research Corporation. The objective of this investigation was to develop a 3D computational flow and heat transfer model for a vehicle windshield de-icing process. The windshield clearing process is a 3D transient, multi-medium, multi-phase heat exchange phenomenon in connection with the air flow distribution in the passenger compartment. The transient windshield de-icing analysis employed conjugate heat transfer methodology and enthalpy method to simulate the velocity distribution near the windshield inside surface, and the time progression of ice-melting pattern on the windshield outside surface. The comparison between the computed results and measured data showed very reasonable agreement, which demonstrated that the developed analysis tool is capable of simulating the vehicle cold room de-icing tests.

This paper presents a novel computational method for the flow simulations in the automotive oil pumps. The objective of this effort is to develop an advanced Computational Fluid Dynamics (CFD) tool to improve oil pump designs and efficiency by detailed analysis of unsteady fluid flow patterns inside stationary and rotating passages of an oil pump. To achieve this goal, several state-of-the-art computational technologies have been implemented into a general purpose unstructured grid code to handle numerical difficulties posed by complex geometry and moving parts of oil pumps. Most challenging numerical issues resolved in this paper include moving/deforming cells inside pump pockets, arbitrary sliding interface to connect moving and stationary parts and large grid distortions due to the great volume change of the pump pockets etc. A practical validation case, a vane oil pump, is studied using the presented method. The numerical results are compared with available experiment data.

This paper presents a Computational Fluid Dynamic(CFD) model for the oil pump simulations aimed at better understanding the flow characteristics for improving their designs and reducing product development cycles. Several advanced numerical technologies have been developed to handle the complex geometries of oil pumps and the moving interfaces between the rotating and stationary parts. Two basic oil pump configurations, a vane oil pump and a gerotor oil pump, have been studied with the present method. The numerical results are compared with the existing experimental data.

Current state-of-the-art in automotive computational aerodynamics relies on either multi-block structured grids or homogeneous unstructured tetra or hexa meshes. This paper presents a novel approach of unstructured solution-adaptive grids and a generalized tree-based Adaptive Cartesian/Prismatic (ACP) grid concept for automotive aerodynamic applications. The proposed concept resolves several problems which plague tetrahedral grids such as boundary layer grid cell aspect ratio or large grid count. ACP employs unstructured adaptive layer of prisms (or quads in 2D) near solid walls intersected with an adaptive tree-based Cartesian mesh in the rest of the computational space. The prismatic layer resolves the viscous wall layer with high aspect ratio mesh whereas the Cartesian tree mesh provides the smooth grid transition, allows grid coarsening and offers the best support for accurate numerical schemes.

A fire exposure test was conducted on a 72.4 liter composite (Type HGV-4) hydrogen fuel tank at an initial hydrogen pressure of 34.3 MPa (ca 5000 psi). No Pressure Relief Device was installed on the tank to ensure catastrophic failure for analysis. The cylinder ruptured at 35.7 MPa after a 370 kW fire exposure for 6 min 27 seconds. Blast wave pressures measured along a line perpendicular to the cylinder axis were 18% to 25% less the values calculated from ideal blast wave correlations using a blast energy of 13.4 MJ, which is based on the ideal gas internal energy at the 35.7 MPa burst pressure. The resulting hydrogen fireball maximum diameter of 7.7 m is about 19% less than the value predicted from existing correlations using the 1.64 kg hydrogen mass in the tank.

This paper introduces a comprehensive system of production planning for mass customization of non-rotational parts. The combined features are defined based on the concept of part families. The process parameters are associated with the feature parameters so that a rapid production planning can be achieved for product design changes. Setup planning is carried out based on both the best practice knowledge in industry and the analysis based generation of setups. Manufacturing resource, fixture design, and tolerance issues are considered in the system. The cycle time estimation and standard documentation are included in the system.

This paper proposes a method to adapt backward induction, which is used to solve the vehicle speed optimal control problem for energy efficiency, to a computer with a GPU to accelerate the computation. A common application of this type of problem is to control a vehicle on a given route with surrounding vehicles, road grades, traffic signals, stop signs, speed limits, and other conditions. Several indicators can be used to determine the performance of the controller, including the energy consumption of the trip, the driving speed smoothness, and the traveling time to a given destination. Solving this optimization problem globally by backward induction is time-consuming, due to the large searching space of the vehicle’s distance, velocity, and acceleration. The proposed method converts the single thread implementation to a parallel process that runs on a consumer-level GPU.

A state-of-the-art review of the technical meaning and application of the term ‘maneuver’, used by the U.S. Army and ground vehicle engineering communities, was performed with regard to various military activities, including modeling and simulation (M&S), to focus on the value and applicability of the term to military vehicle dynamics. As shown, U.S. military doctrine has built through history and experience a unique concept of maneuver-in-general and its application in U.S. Army unified land operations. Yet, the term ‘maneuver’ needs further technical categorization and characterization for the purpose of dynamics of military unmanned ground vehicles (UGVs) and vehicle design for maneuver. While the NHTSA and SAE standards and definitions provide solid foundations for M&S of cars and trucks to enhance the safety of those vehicles (manned and autonomous), occupants, and pedestrians on roads, the standards cannot address all needs of military vehicles in maneuver.

The absence of a design and manufacturing template that can be used to develop a product is the basis for this paper. A machine grouping algorithm based on machine utilization factors is discussed. The algorithm was developed based on traditional machine grouping models, but has been modified to use the machine utilization factors to group machines into cells. Different floor layouts for a factory are considered and an optimal floor layout is determined. The WPI World Formula SAE manufacturing facility is used as a model to demonstrate the algorithm. The FSAE competition required the design of an optimal factory layout manufacturing 1000 cars/year. Total costs and times of manufacture for each sub-component of the WPI FSAE racecar are determined. These total times and costs are used to develop the machine and labor requirements for a fictitious company producing 1000 racecars/year. The proposed algorithm is used to group machines into cells on the factory floor.

Testing of an OHC valve train with hydraulic lash adjuster in which the valve displacements, velocities and accelerations were measured and analyzed in both time and frequency domains, coupled with analysis of the frequency content of the valve acceleration function and its ramps, show that traditional designs of the opening and closing ramps used on some IC engine valve cams can exacerbate vibration in the follower system causing higher levels of spring surge and noise. Suggestions are made for improvement to the design of the beginning and ending transitions of valve motion which can potentially reduce dynamic oscillation and vibration in the follower train.

Microcellular urethane jounce bumpers are used in many automotive suspension systems. This study experimentally determined the dynamic force, acceleration, displacement, dynamic stiffness, and natural frequencies of constant-cross-section bumper samples made with microcellular urethane materials of three different densities. Four impact energy levels were used. Dynamic responses were analyzed in both time and frequency domains. The dynamic displacement, acceleration, and force responses are nonlinear and the dynamic stiffness exhibits a hysteresis loop. A mathematical model for dynamic stiffness and damping is developed. Average dynamic stiffness proved to be approximately twice that of the static stiffness for the same materials as independently measured over the same range of deflection by the bumper manufacturer. Natural frequencies of the sample bumpers were measured by two methods with close correlation of the results which ranged from 320 to 420 Hz for the samples tested.

Aluminum alloy castings are attractive when a light weight, inexpensive, near net shape component is desired. Unfortunately, the presence of internal porosity within these materials can have a significant detrimental effect upon the mechanical properties, appearance, and function of these parts. Hot isostatic pressing (HIP) and Densal® (a proprietary hot isostatic densification process) have been employed to reduce or eliminate porosity in cast metals. This paper compares the fatigue strength and microstructures of end chill sand cast A356 and high pressure, die cast 380 and 383 aluminum alloys which have undergone either HIP or Densal® processing with identical components in the as-cast condition. The castings which underwent isostatic processing show decreased porosity and improved fatigue strength and functionality. Additionally, the economics and suitability for high volume production of these two post-cast processes are reviewed.

Supervised, unsupervised and active learning techniques can be used to develop prognostics and diagnostics in connected vehicle networks, where a wide variety of sensors are available for data collection. However, constraints placed by the on-board equipment, vehicle network, time, and human resources limit the amount of sensor data and labels for machine learning. When no prior information about the data distribution or domain knowledge is available, it becomes a challenging task to collect limited and relevant data to train a machine learning model matching the desired performance threshold. To tackle this challenge, techniques such as experimental design, feature selection, and active learning can be applied, and the data collection process can be advanced to a closed-loop system where new data collection decisions are made based on the feedback from collected data.