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Technical Paper

Drag Evaluation of the Bellanca Skyrocket II

The Bellanca Skyrocket II, possessor of five world speed records, is a single engine aircraft with high performance that has been attributed to a laminar flow airfoil and an all composite structure. Utilization of composite materials in the Skyrocket II is unique since this selection was made to increase the aerodynamic efficiency of the aircraft. Flight tests are in progress to measure the overall aircraft drag and the wing section drag for comparison with the predicted performance of the Skyrocket. Initial results show the zero lift drag is indeed low, with CDO = 0.016.
Technical Paper


Flight tests of a new 13% General Aviation Airfoil - the GA(W)-2 - gloved full span onto the existing wing of a Beech Sundowner have generated chordwise pressure distributions and wake surveys. Section lift, drag and moment coefficients derived from these measurements verify wind tunnel data and theory predicting the performance of this airfoil. The effect of steps, rivets and surface coatings upon the drag of the GA(W)-2 was also evaluated.
Technical Paper

Predicting Aircraft Performance Degradation Due to Ice Accretion

An analytical method to predict the performance degradation of aircraft with ice accretion is presented. Early research on airfoil icing and the effects of ice on aircraft are reviewed. Data on the performance degradation of airfoils due to ice are presented as they apply to the aircraft performance analysis. A computer code has been written and results are discussed.
Technical Paper

Testing and Modeling of Elevator Door Retention During Hallway Applied Lateral Loads

Most do not consider there to be a risk in pushing on, bumping into or falling against an elevator door from the hallway side. However, the lack of the elevator cars presence alone, and the potential for severe injury or even death make this seemingly mundane situation potentially critical. Standards exist relative to such situations, and past and current designs attempt to account for this possibility, still people get injured interacting with these doors every year. In order to evaluate a real-world elevator door system's ability to withstand the quasi-static and impactive loads that can be placed on it by the general public during its life, both intentionally and unintentionally, a predictive tool is needed. This work represents the combination of empirical laboratory testing and numerical modeling of a typical elevator door system exposed to quasi-static and dynamic loading.
Technical Paper

Application of Enhanced Least Square to Component Synthesis Using FRF for Analyzing Dynamic Interaction of Coupled Body-Subframe System

The component response synthesis approach utilizing frequency response function (FRF) has been used to analyze the dynamic interaction of two or more vehicle components coupled at discrete interface points. This method is somewhat suitable for computing higher frequency response because experimental component FRFs can be incorporated into the formulation directly. However its calculations are quite sensitive to measurement errors in the FRFs due to the several matrix inversion steps involved. In the past, researchers have essentially used a combined direct inverse and truncated singular valued decomposition (TSVD) technique to ensure a stable calculation, which is typically applied semi-empirically due to the lack of understanding of the influence of measurement error.
Technical Paper

Correlation of a CAE Hood Deflection Prediction Method

As we continue to create ever-lighter road vehicles, the challenge of balancing weight reduction and structural performance also continues. One of the key parts this occurs on is the hood, where lighter materials (e.g. aluminum) have been used. However, the aerodynamic loads, such as hood lift, are essentially unchanged and are driven by the front fascia and front grille size and styling shape. This paper outlines a combination CFD/FEA prediction method for hood deflection performance at high speeds, by using the surface pressures as boundary conditions for a FEA linear static deflection analysis. Additionally, custom post-processing methods were developed to enhance flow analysis and understanding. This enabled the modification of existing test methods to further improve accuracy to real world conditions. The application of these analytical methods and their correlation with experimental results are discussed in this paper.
Technical Paper

Structure-Borne Noise Measures and Their Correlation to Sound Radiation over a Broad Range of Frequencies

Structure-borne noise within vehicle structures is often transmitted in a multi-dimensional manner and thus the vibro-acoustic model(s) of automotive powertrain or chassis must incorporate longitudinal and transverse (flexural) motions as well as their couplings. In this article, we employ the continuous system theory to model a typical vibration isolator (say the engine mounting system) and a compliant receiver that could simulate the body structure. The powertrain source is however assumed to be rigid, and both harmonic force and moment excitations are considered. Our analysis is limited to a linear time-invariant system, and the frequency domain based mobility method is utilized to synthesize the overall system. Contributions of both in-plane and flexural motions to structure-borne and radiated noise are incorporated. Two examples are considered to illustrate the methodology.
Technical Paper

Development of a Computer Controlled Automated Steering Controller

This paper describes the design and development of the hardware, electronics, and software components of a state-of-the-art automated steering controller, the SEA, Ltd. ASC. The function of the ASC is to input to a vehicle virtually any steering profile with both high accuracy and repeatability. The ASC is designed to input profiles having steering rates and timing that are in excess of the limits of a human driver. The ASC software allows the user to specify steering profiles and select controller settings, including motor controller gains, through user-interface windows. This makes it possible for the test driver to change steering profiles and settings immediately after running any test maneuver. The motor controller used in the ASC offers self-contained signal input, output, and data storage capabilities. Thus, the ASC can operate as a standalone steering machine or it can be incorporated into typical existing, on-vehicle data acquisition systems.
Technical Paper

Examination of Some Vibration Isolator Models and Their Effects on Vibration and Structure-borne Noise Transmission

A vibration isolator or mount is often modeled by the Voigt model describing uni-axial (longitudinal) motion with frequency-invariant parameters. However, wave effects due to the mass distribution within the isolator are observed as the frequency is increased. Further, flexural stiffness components play an important role, leading to off-axis and coupling effects. Thus, the simplified mount models could lead to erroneous predictions of the dynamic behavior of an overall system such as automotive powertrain or chassis mounting systems. This article compares various approximate isolator models using a multi-dimensional mobility model that is based on the continuous system theory. Harmonic force and moment excitations are separately applied to a rigid body source to investigate the multi-dimensional vibratory behavior. Analysis is however limited to a linear time-invariant system and the mobility synthesis method is utilized to predict the frequency domain behavior.
Technical Paper

Vibration Characteristics of Cardboard Inserts in Shells

A study has been conducted to determine the noise and vibration effect of inserting a cardboard liner into a thin, circular cross-sectioned, cylindrical shell. The relevance of such a study is to improve the understanding of the effects when a cardboard liner is used in a propeller shaft for noise and vibration control purposes. It is found from the study that the liner adds significant modal stiffness, while an increase in modal mass is also observed for a particular shell type of mode. Further, the study has shown that the additional modal damping provided by the liner is not appropriately modeled by Coulomb friction damping, a damping model often intuitively associated with cardboard materials. Rather, the damping is best modeled as proportional viscous damping.
Technical Paper

MADYMO Modeling of the IHRA Head-form Impactor

The International Harmonization Research Activities Pedestrian Safety Working Group (IHRA PSWG) has proposed design requirements for two head-forms for vehicle hood (bonnet) impact testing. This paper discusses the development of MADYMO models representing the IHRA adult and child head-forms, validation of the models against laboratory drop tests, and assessment of the effect of IHRA geometric and mass constraints on the model response by conducting a parameter sensitivity analysis. The models consist of a multibody rigid sphere covered with a finite element modeled vinyl skin. The most important part in developing the MADYMO head-form models was to experimentally determine the material properties of the energy-absorbing portion of the head-form (vinyl skin) and incorporate these properties into MADYMO using a suitable material model. Three material models (linear isotropic, viscoelastic, hyperelastic) were examined.
Journal Article

The Design of a Suspension Parameter Identification Device and Evaluation Rig (SPIDER) for Military Vehicles

This paper describes the mechanical design of a Suspension Parameter Identification Device and Evaluation Rig (SPIDER) for wheeled military vehicles. This is a facility used to measure quasi-static suspension and steering system properties as well as tire vertical static stiffness. The machine operates by holding the vehicle body nominally fixed while hydraulic cylinders move an “axle frame” in bounce or roll under each axle being tested. The axle frame holds wheel pads (representing the ground plane) for each wheel. Specific design considerations are presented on the wheel pads and the measurement system used to measure wheel center motion. The constraints on the axle frames are in the form of a simple mechanism that allows roll and bounce motion while constraining all other motions. An overview of the design is presented along with typical results.
Journal Article

Effect of Local Stiffness Coupling on the Modes of a Subframe-Bushing System

The elastomeric joints (bushings or mounts) in vehicle structural frames are usually described as uncoupled springs (only with diagonal terms) in large scale system models. The off-diagonal terms of an elastomeric joint have been previously ignored as they are often unknown since their properties cannot be measured in a uniaxial elastomer test system. This paper overcomes this deficiency via a scientific study of a laboratory frame that is designed to maintain a high fidelity with real-world vehicle body subframes in terms of natural modes under free boundaries. The steel beam construction of the laboratory frame, with four elastomeric mounts at the corners, permits the development of a highly accurate, yet simple, beam finite element model. This allows for a correlation study between the experiment and model that helps shed light upon the underlying physical phenomenon.