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Technical Paper

Is There a Need for Human Factors and Error Management in General and Corporate Aviation?

1999-04-20
1999-01-1595
This paper explores the need for human factors and error management within the context of the general and corporate aviation environments. It discusses strategies currently employed in other segments of the aviation industry and how they might be utilized in the corporate and general aviation arenas. It also relates research findings and program successes experienced within the airline industry and makes recommendations as to how a consortial effort by industry organizations might be utilized to employ these strategies in corporate and general aviation operations.
Technical Paper

Analysis of Widespread Fatigue Damage in Lap Joints

1999-04-20
1999-01-1586
This paper describes research to analyze widespread fatigue damage in lap joints. The particular objective is to determine when large numbers of small cracks could degrade the joint strength to an unacceptable level. A deterministic model is described to compute fatigue crack growth and residual strength of riveted panels that contain multiple cracks. Fatigue crack growth tests conducted to evaluate the predictive model are summarized, and indicate good agreement between experimental and numerical results. Monte Carlo simulations are then performed to determine the influence of statistical variability on various analysis parameters.
Technical Paper

THE EFFECT OF PROPLETS AND BI-BLADES ON THE PERFORMANCE AND NOISE OF PROPELLERS

1981-02-01
810600
A analytical technique for predicting the aerodynamic performance of propellers with tip devices (proplets) using vortex lattice method shows that the ideal efficiency of a fixed diameter propeller can be improved by 1-5%. By suitable orientation and sweep of the proplet, the noise analysis method presented predicts that propellers with tip devices will have approximately the same noise as propellers without tip devices. Therefore proplets can be added to a fixed diameter propeller to improve the efficiency with no increase in noise or the noise may be reduced by decreasing the diameter with no loss in aerodynamic efficiency.
Technical Paper

Average Value Modeling of Finite Inertia Power Systems with Harmonic Distortion

2000-10-31
2000-01-3648
Typically, average-value models of power system components neglect harmonic information. Herein, a systematic method of including harmonic information in average-value models based on the theory of multiple reference frames is set forth. Computer simulation results show that when there is significant harmonic distortion of the ac distribution bus the models presented herein are more accurate than traditional average-value models. Furthermore, much of the computational advantage of average-value techniques over detailed modeling techniques is retained.
Technical Paper

Modeling of Nonlinear Elastomeric Mounts. Part 1: Dynamic Testing and Parameter Identification

2001-03-05
2001-01-0042
A methodology for modeling elastomeric mounts as nonlinear lumped parameter models is discussed. A key feature of this methodology is that it integrates dynamic test results under different conditions into the model. The first step is to model the mount as a linear model that is simple but reproduces accurately results from dynamic tests under small excitations. Frequency Response Functions (FRF) enables systematic calculation of the parameters for the model. Under more realistic excitation, the mount exhibits non-linearity, which is investigated in the next step. For nonlinear structures, a simple and intuitive method is to use time-domain force-displacement (F-x) curves. Experiments to obtain the F-x curves involve controlling the displacement excitation and measuring the induced forces. From the F-x curves, stiffness and damping parameters are obtained with an optimization technique.
Technical Paper

A Parametric Simulation Model for Analyzing the Performance of a Steel-Tracked Feller Buncher

1999-09-13
1999-01-2785
A parametric simulation model of a steel-tracked feller buncher was developed1. This model can be used to predict the lift capacity, side tipping angles, grade-ability, and joint forces during a cutting cycle. The feller buncher is defined parametrically, allowing the user to quickly analyze different machine configurations simply by changing the value of a variable. Several simulations were performed to illustrate the application of the model.
Technical Paper

Dynamic Simulation Techniques for Steering of Tracked Agricultural and Forestry Vehicles

1999-09-13
1999-01-2786
A procedure for simulating the dynamics of agricultural and forestry machines using mechanical system simulation software is presented. A soil/track interface model including rubber-track and steel-track was introduced as well as equations that can be used to model mechanical and hydraulic power trains commonly found in tracked vehicles. Two rubber-tracked vehicles (agricultural tractors) and two steel-tracked machines (forestry vehicles) were simulated to illustrate the technique, and some analysis results are presented. The examples given in this paper are based on the author’s research over the past several years.
Technical Paper

Human Factors Best Practices

1999-08-10
1999-01-2977
Throughout the industry, organizations struggle with the task of implementing effective human factors programs aimed at reducing maintenance errors. Almost universally, many barriers have frustrated these efforts. In 1998 and 1999, the National Transportation Safety Board sponsored two workshops designed at identifying barriers to the implementation of human factors programs and to explore what was working and what was not working among the many industry efforts. This paper explores the findings of these workshops. In addition, it will report findings of Purdue University studies that reveal a rapid deterioration of even the most successful human factors programs. The research findings disclose several “disconnects” within most organizations which rapidly negate the positive effects of successful human factors and error management training and nullify many proactive human factors programs.
Technical Paper

The Analysis of Counter-Rotating Propeller Systems

1985-04-01
850869
A vortex lattice method for the aerodynamic analysis of counter-rotation propellers was developed. This model along with an unsteady Sears analysis for correcting the quasi-steady loadings that are obtained from the vortex lattice model were used to predict the performance of counter-rotation propeller systems. The method developed shows good correlation with experimental results. The investigation into the unsteady loadings on each of the propellers indicates that significant variations in loading occur due to the unsteady flow and due to the propeller blade passage. These variations were found to be as high as 17 percent of the mean value. The parametric studies that were performed indicate that reducing the rear propeller's diameter or rotational speed results in a loss of efficiency.
Technical Paper

Swirl-Spray Interactions in a Diesel Engine

2001-03-05
2001-01-0996
Swirl in Diesel engines is known to be an important parameter that affects the mixing of the fuel jets, heat release, emissions, and overall engine performance. The changes may be brought about through interactions of the swirling flow field with the spray and through modifications of the flow field. The purpose of this paper is to investigate the interaction of the swirl with sprays in a Diesel engine through a computational study. A multi-dimensional model for flows, sprays, and combustion in engines is employed. Results from computations are reported with varying levels of swirl and initial turbulence in two typical Diesel engine geometries. It is shown that there is an optimal level of swirl for each geometry that results from a balance between increased jet surface area and, hence, mixing rates and utilization of air in the chamber.
Technical Paper

Truck Ride — A Mathematical and Empirical Study

1969-02-01
690099
“Truck Ride” in this study refers to some vehicle ride parameters involved in tractor-trailer combinations. For the study, a mathematical model of a tractor-trailer vehicle as a vibrating system was developed. Principles of vibration theory were applied to the model while a digital computer was employed to investigate the complex system. To parallel the analytical investigation of the tractor-trailer vehicle, vehicle studies were conducted using a magnetic tape recorder and associated instrumentation installed in the tractor. Parameters studied included coupler position on the tractor, laden weight of trailer, spring rates of the different axles of the combination, damping capacity associated with each spring rate, vehicle speed, and “tar strip” spacing of the highway and cab mountings. The mathematical results were used as a basis for empirical study. A comparison of calculated and empirical data are reported.
Technical Paper

Concepts of Human Factors Engineering

1969-02-01
690163
This paper discusses the necessity for designing farm tractors which have logical, rather than arbitrary, safety features. The paper is directed primarily to those who buy and use industrial equipment and urges this group to exercise their influence on tractor design by purchasing only those vehicles which meet recommended standards for safety and construction.
Technical Paper

Modeling of Machine Tool Dynamics and Chatter Prediction

1998-06-02
981840
Dynamics of machine tool components play a critical role in the outcome of machining processes. This paper addresses several important issues on machine tool and machining dynamics. It illustrates the dynamic behavior of structural components under operating conditions and presents an improved technique for modeling structural non-linearity. It also describes spindle modeling capability that has been developed to predict dynamic and thermal characteristics of spindle systems. Finally, the paper discusses the impact of non-linear dynamics on machining stability.
Technical Paper

Simulation of MADMEL Power Systems Components

1998-04-21
981258
Detailed computer models of system components for More Electric Aircraft have been developed using the Advanced Control System Language (ACSL) and its graphical front-end, Graphic Modeller. Among the devices modeled are a wound-rotor synchronous generator with parallel bridge-rectifier outputs, a switched-reluctance generator, and various loads including a DC-DC converter, an inverter-driven induction motor, and an electro-hydrostatic actuator. Results from the simulations are presented together with corroborating experimental test results.
Technical Paper

An Automated State Model Generation Algorithm for Simulation/Analysis of Power Systems with Power Electronic Components

1998-04-21
981256
In this paper, a recently-developed algorithmic method of deriving the state equations of power systems containing power electronic components is described. Therein the system is described by the pertinent branch parameters and the circuit topology; however, unlike circuit-based algorithms, the difference equations are not implemented at the branch level. Instead, the composite system state equations are established. A demonstration of the computer implementation of this algorithm to model a variable-speed, constant-frequency aircraft generation system is described. Because of the large number of states and complexity of the system, particular attention is placed on the development of a model structure which provides optimal simulation efficiency.
Technical Paper

Multi-Material Topology Optimization for Crashworthiness Using Hybrid Cellular Automata

2019-04-02
2019-01-0826
Structures with multiple materials have now become one of the perceived necessities for automotive industry to address vehicle design requirements such as light-weight, safety, and cost. The objective of this study is to develop a design methodology for multi-material structures accountable for vehicle crash durability. The heuristic topology synthesis approach of Hybrid Cellular Automaton (HCA) framework is implemented to generate multi-material structures with the constraint on the volume fraction of the final design. The HCA framework is integrated with ordered-SIMP (solid isotropic material with penalization) interpolation, artificial material library, as well as statistical analysis of material distribution data to ensure a smooth transition between multiple practical materials during the topology synthesis.
Technical Paper

Design for Crashworthiness of Vehicle Structures Using an Extended Hybrid Cellular Automaton Method

2019-04-02
2019-01-0842
This paper introduces a design methodology to tailor the acceleration and displacement responses of a vehicle structure subjected to a dynamic crushing load. The proposed approach is an extension of the hybrid cellular automaton (HCA) method, through which the internal energy density is uniformly distributed within the structure. The proposed approach, referred here to as an extended HCA (xHCA) method, receives the suitable combinations of volume fraction and a finite element meta-parameter for which the algorithm synthesizes the load paths that allow the desired crash response. Lower meta-parameter values lead designs obtained by traditional optimizers, while larger values lead to designs obtained by the HCA method. Simultaneous implementation of multiple values of meta-parameters is presented here as a further development of xHCA method.
Technical Paper

Structural Optimization of Thin-Walled Tubular Structures for Progressive Collapse Using Hybrid Cellular Automaton with a Prescribed Response Field

2019-04-02
2019-01-0837
The design optimization of thin-walled tubular structures is of relevance in the automotive industry due to their low cost, ease of manufacturing and installation, and high-energy absorption efficiency. This study presents a methodology to design thin-walled tubular structures for crashworthiness applications. During an impact, thin-walled tubular structures may exhibit progressive collapse/buckling, global collapse/buckling, or mixed collapse/buckling. From a crashworthiness standpoint, the most desirable collapse mode is progressive collapse due to its high-energy absorption efficiency, stable deformation, and low peak crush force (PCF). In the automotive industry, thin-walled components have complex structural geometries. These complexities and the several loading conditions present in a crash reduce the possibility of progressive collapse. The Hybrid Cellular Automata (HCA) method has shown to be an efficient continuum-based approach in crashworthiness design.
Technical Paper

A Comparison of Near-Field Acoustical Holography Methods Applied to Noise Source Identification

2019-06-05
2019-01-1533
Near-Field Acoustical Holography (NAH) is an inverse process in which sound pressure measurements made in the near-field of an unknown sound source are used to reconstruct the sound field so that source distributions can be clearly identified. NAH was originally based on performing spatial transforms of arrays of measured pressures and then processing the data in the wavenumber domain, a procedure that entailed the use of very large microphone arrays to avoid spatial truncation effects. Over the last twenty years, a number of different NAH methods have been proposed that can reduce or avoid spatial truncation issues: for example, Statistically Optimized Near-Field Acoustical Holography (SONAH), various Equivalent Source Methods (ESM), etc.
Technical Paper

Development of a Torque-Based Control Strategy for a Mode-Switching Hydraulic Hybrid Passenger Vehicle

2018-04-03
2018-01-1007
An increase in the number of vehicles per capita coupled with stricter emission regulations have made the development of newer and better hybrid vehicle architectures indispensable. Although electric hybrids have more visibility and are now commercially available, hydraulic hybrids, with their higher power densities and cheaper components, have been rigorously explored as the alternative. Several architectures have been proposed and implemented for both on and off highway applications. The most commonly used architecture is the series hybrid, which requires an energy conversion from the primary source (engine) to the secondary domain. From he re, the power flows either into the secondary source (high-pressure accumulator) or to the wheels depending upon the state of charge of the accumulator. A mode-switching hydraulic hybrid, which is a combination of a hydrostatic transmission and a series hybrid, was recently developed in the author’s research group.
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