Search Results

In this study, three dummies were evaluated on the component level and as a whole. Their responses were compared with available volunteer and embalmed Post Mortem Human Subject (PMHS) data obtained under similar test conditions to evaluate their biofidelity The volunteer and PMHS data, used as comparators in this study, were used previously to establish some of the biofidelity requirements of the Hybrid III. The BioRID II, the Hybrid III, and the RID2 were all subjected to rear impact HYGE sled tests with ΔVs of 17 and 28 km/hr to determine their biofidelity in these conditions. A static pull test, where a load was manually applied to the head of each dummy, was used to evaluate the static strength of their necks in flexion and extension. Finally, pendulum tests were conducted with the Hybrid III and RID2 to evaluate the dynamic characteristics of their necks in flexion and extension.

A test fixture for use on the Hyge Sled was fabricated to NHTSA specifications, matching the fixture used at Heidelberg University to measure forces on cadavers in side impact configurations. Tests were conducted at 16, 22, 24, and 32 km/h to simulate both the APR cadaver drop tests and Heidelberg sled tests. Comparisons to the cadaver data were made with the Ford Side Impact Body Block and the APR and SID dummies. Test results are shown and discussed.

Biomechanical data on the response of the face to localized and distributed loads are analyzed to provide performance goals for a biomechanically realistic face. Previously proposed facial injury assessment techniques and dummy modifications are reviewed with emphasis on their biomechanical realism. A modification to the Hybrid III dummy, called the GM Hybrid III Deformable Face, is described. The modification produces biomechanically realistic frontal impact response for both localized and distributed facial loads and provides for contact force determination using conventional Hybrid III instrumentation. The modification retains the anthropometric and inertial properties and the forehead impact response of the standard Hybrid III head.

A short survey of wing tip geometries for drag reduction is presented. These devices have been divided into two broad categories of passive and active. The first category is made of fixed geometries, while the second group is made of those employing moving parts. The former group is further divided into planar and nonplanar designs. In every case, a brief explanation of the underlying logic is given. Altogether, more than fifteen completely different designs and over seventy references have been cited. Some of these designs, such as winglets, have been explored for many years and have proven to be very effective at reducing the induced drag at higher values of lift coefficient. Some others, such as wing tip turbines, have just begun to attract attention. Wing tip fuel tanks, not being solely employed for drag reduction, have not been included in this paper.

One of the primary issues in the interpretation of vehicle impact response data, observed from vehicle crash test events, is coping with variability. This vehicle response inconsistency generally causes test results to be unpredictable and makes CAE test validation work difficult as well. This paper, considering the uncertain characteristics of vehicle impact events, has implemented a stochastic assessment of vehicle NCAP response variation through a CAE vehicle impact model, and it has accomplished the three primary study objectives as stated follows: 1) Identify the response variation causing factors stochastically from various structural and environmental factor candidates and quantify the degree of their influences on crash response, 2) Develop a methodology for interpreting the significance of the factor effects in conjunction with vehicle impact mechanics and physics, and 3) Implement a stochastic improvement of the vehicle NCAP responses and their repeatability

In this work, a newly developed iced-aircraft modeling tool is applied to wings, engine inlets, and helicopter rotors. The tool is based on a multiscale-physics, unstructured finite-volume CFD approach and is applicable to general purpose aircraft icing applications. The present approach combines an Eulerian-based droplet-trajectory solver that is loosely coupled, in a time-accurate manner, to a surface-film and ice-evolution model. The goal of the model is to improve the fidelity of ice accretion modeling on dynamic geometries and for three-dimensional ice shapes typical of helicopter rotors. The numerical formulation is discussed and presented alongside 2D and 3D static validation cases, and dynamic helicopter rotors. The present results display good validation for predicting ice shape on a variety of geometries, and a strong initial capability of modeling ice forming on helicopters in forward flight.

Computational Fluid Dynamics (CFD) surely has played a fundamental role in the design of the bodies and shapes of both commercial and racing vehicles in the last decades. This circumstance was mainly due to the connected substantial improvement in the design timings and to the possibility of producing numerous flow field and surface data that are difficult to obtain from a physical experimental method. Such a local analysis leads to a further understanding of the interactions of components with the overall aerodynamics. The development of wing performances, with respect to racing vehicles, has to deal with very short times but also with a very detailed description of the physics occurring. Starting from these constraints, a coupling procedure was developed by the joining of a CFD code with a Finite Element Method (FEM) structural code to better evaluate the aerodynamic performance of the wing deformed under the fluid dynamic loads.

This work presents the implementation and validation efforts of a 3D ice accretion solver for aeronautical applications, MESS3D, based on the advanced Messinger model. The solver is designed to deal with both liquid phase and ice crystal cloud conditions. In order to extend the Messinger model to 3D applications, an algorithm for the water run-back distribution on the surface was implemented, in place of an air flow stagnation line search algorithm, which is straightforward in 2D applications, but more complicated in 3D. The developed algorithm aims to distribute the run-back water in directions determined by air pressure gradients or shear forces. The data structure chosen for MESS3D allows high flexibility since it can manage the necessary input solutions on surface grids coming from both structured and unstructured solvers, regardless the number of edges per surface cells.

The relationship between designing for both rigid fixed barrier (RFB) and vehicle-to-vehicle tests is a topical area of research. Specifically, vehicle-to-vehicle compatibility has been a topic of keen interest to many researchers, and the interplay between the two aspects of design is presently addressed. In this paper, the studied vehicles for potential vehicle-to-vehicle impacts included: sport utility vehicles (SUVs), Pickups (PUs), and passenger cars. The SUV/PU-to-Car frontal impact tests were compared to those obtained from vehicle-to-rigid fixed barrier frontal impacts. Acceleration pulses at the B-pillar/rocker as well as dash and cabin intrusions were monitored and compared. Additionally, the energy distributions in SUV/PU-to-Car crash tests were compared to those of single vehicle-to-RFB tests. It was concluded from the analysis that vehicle weight and front-end stiffness were not always the overriding factors dictating performance.

The most important tool used in testing methods for evaluating the performance of seat-systems in rear-end impacts is a biofidelic crash test dummy. It has been reported that there are differences in response between two kinds of such dummies, BioRID P3 and Hybrid III, in rear-end impacts at Δ V=9.2 km/h. The objective of this study is to compare the responses of these two types of dummies, at moderate speeds with HYGE sled tests (Δ V=15 km/h, 25 km/h). At Δ V=25 km/h or less, the BioRID and HYIII dummies showed clear differences in their response to a rear-end collision, and the BioRID showed higher biofidelity than the HyIII in this condition.

The military aviation services pay a phenomenal price due to turbine engine stall. Several of the major factors which comprise a substantial portion of the total price are presented. Included are weapon system development time, operational limitations, field maintenance problems, overhaul costs and accident rates. Also presented, in a general fashion, are several technical approaches to the solution of turbine engine stall. Fundamental research and orderly development of basic engine components, power control systems, and airframe and installation factors are discussed. Emphasis is placed on the need for tighter control of production tolerances and the requirement for united efforts in the integration of components into a complete system.

The test procedures and some of the results obtained in a carburetor icing field test at Vancouver, British Columbia, during the Winter of 1962-1963 are described. One hundred twenty-nine cars were involved in the test which lasted approximately four months. A total of about 15,000 test runs was made. Fifty percent of the cars stalled at much higher rates under weather conditions conducive to carburetor icing than under other conditions. Thus, carburetor icing was found to be a significant field problem even with effective antiicing additives present in the gasoline. There was much variation among car makes in their tendencies to stall, indicating the possibilities of design improvements in reducing the problem. There was an indication that recent model cars stalled at lower rates than earlier models, showing that some improvement has been made.

From the literature, theoretical analyses and subscale windtunnel aerodynamic investigations of canard aircraft configurations indicate benefits which are enhanced by close-coupling the canard to the wing. To properly evaluate the advantages and to investigate some solutions to the problems associated with the close-coupled canard, a full-scale aircraft development was initiated. A dual purpose of this development was to create a proof-of- concept vehicle designed to satisfy a general aviation requirement, and demonstrate a subsonic, close-coupled canard technology. This paper describes the development together with the aerodynamic considerations of the design. Ultimately, flight-test data are to be used in establishing correlations with windtunnel model data and analytical methodology.

Accelerator-type sled systems have been very useful to the automotive industry for many years. These systems have allowed engineers to effectively evaluate a safety component in a frontal crash environment without having to conduct a full-scale crash test. While accelerator-type sleds are an excellent tool for frontal crashworthiness development, the energy required to simulate a side impact or lateral pole impact test is just a small fraction of the total capacity of the system. In light of this, a project was undertaken to develop a system which incorporated many features of the current accelerator-type sled system, but was designed to simulate non-frontal crash test cases. This paper describes the development and test applications for the new sled system. The operating theory and general design is similar to current accelerator-type sled systems, although the new system has been scaled down significantly.

A comparative analysis has been performed on the Boeing 727-100 using three conceptual design codes. These programs were: The Aircraft Synthesis Program, ACSYNT, Advanced Aircraft Analysis, AAA, and RDS-Student. The objective of this study was to investigate differences in the conceptual design methodologies of these three programs. All three codes showed reasonable prediction of drag in the subsonic flow regime. However all three programs had difficulty predicting transonic drag rise characteristics. The principal cause was the inability to accurately predict the critical drag rise Mach number. Difficulties in estimating the shape of the drag rise curve, relative to the critical Mach number, also contributed to the errors in drag prediction. AAA and RDS-Student gave reasonable predictions of maximum lift coefficient. ACSYNT could not model the triple-slotted flap system on the 727-100. The three codes showed a consistent trend towards under-prediction of empty weight.

The objective of this study is to compare the risk of injury to pedestrians involved in vehicle-pedestrian impacts as predicted by two different types of risk assessment tools: the pedestrian subsystem impactors recommended by the European Enhanced Vehicle-Safety Committee (EEVC) and post-mortem human surrogates (PMHS). Seven replicate full-scale vehicle-pedestrian impact tests were performed with PMHS and a mid-sized sedan travelling at 40 km/h. The PMHS were instrumented with six-degree-of-freedom sensor cubes and sensor data were transformed and translated to predict impact kinematics at the head center of gravity, proximal tibiae, and knee joints. Single EEVC WG 17/EuroNCAP adult headform, upper legform and lower legform impactor tests of the same vehicle were selected for comparison based on the proximity of their impact locations to that of the PMHS.

The objective of this paper is to illustrate the methods and tools developed to size and synthesize a stopped rotor/wing vehicle using a reaction drive system, including how this design capability is incorporated into a sizing and synthesis tool, VASCOMP II. This new capability is used to design a vehicle capable of performing a V-22 escort mission, and a sized vehicle description with performance characteristics is presented. The resulting vehicle is then compared side-by-side to a variable diameter tiltrotor designed for the same mission. Results of this analysis indicate that the reaction-driven rotor concept holds promise relative to alternative concepts, but that the variable diameter tiltrotor has several inherent performance advantages. Additionally, the stopped rotor/wing needs considerably more development to reach maturity.

The flow through most turbomachinery blade rows is characterized by unsteady, viscous, transitional flow. The accurate prediction of the onset of transition from laminar to turbulent flow is essential for calculating heat transfer and performance quantities. The purpose of this investigation is to evaluate the accuracy of four different algebraic transition models which have been combined with an algebraic turbulence model. Numerical experiments have been performed for flow through a turbine rotor cascade with heat transfer, and a cascade of compressor blades. In addition, a study was performed to determine the effects of the computational grid density on the transition location.

This paper focuses on the energy absorbing characteristics and progressive deformation behavior of woven jute-polyester composite cylindrical tubes subjected to an axial impact load. In this study, the impact energy absorption characteristics and crushing mechanisms of composite tubes of different thicknesses and number of plies are investigated. To start with, coupon specimens are made from laminates of jute and glass fiber-based polyester composites. These are then tested in a UTM for mechanical characterization of the composites under tensile and compressive loading conditions. Experiments are then conducted in a drop-weight impact testing device to investigate crash performance characteristics such as mean crush load, absorbed energy and specific energy absorption (SEA) of woven jute-polyester composite cylindrical tubes.