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Fundamentals of Fatigue Analysis

Fatigue is a structural failure mode that must be recognized and understood to develop products that meet life cycle durability requirements. In the age of lightweighting, fatigue strength is an important vehicle design requirement as engineers struggle to meet stringent weight constraints without adversely impacting durability. This technical concept course introduces the fatigue failure mode and analysis methods. It explains the physics of material fatigue, including damage accumulation that may progress to product failure over time, and it provides the needed foundation to develop effective fatigue prediction capabilities.
Standard

Test Method for Catalytic Carbon Brake Disk Oxidation

2013-12-04
WIP
AS6289
The scope of the test method is to provide stakeholders including fluid manufacturers, brake manufacturers, aircraft constructors, aircraft operators and airworthiness authorities with a relative assessment of the effect of deicing chemicals on carbon oxidation. This test is designed to assess the relative effects of runway deicing chemicals by measuring mass change of contaminated and bare carbon samples tested under the same conditions.
Standard

Missionized Wear Testing

2019-01-02
WIP
ARP6979
Publicize Aircraft Recommended Practice for Missionized Wear Testing on Wright Patterson’s Landing Gear Test Facility’s 168i dynamometer.
Standard

Landing Gear Based Weight and Balance Systems

2019-04-18
WIP
AIR6941
This document outlines historical systems which have used the landing gear as a sensor or installation point for full aircraft weight and balance systems. A number of systems have been developed, installed, certified, and placed in service but few systems remain in regular use. The document will capture the history of these systems, reasons (where known) for their withdrawal from service, and lessons learned.
Standard

Wheels - Radial Impact Test Procedure - Road Vehicles

2019-05-22
WIP
J3203
The SAE recommended practice provides a uniform laboratory test procedure for evaluating radial(road hazard) impact collision resistance of all wheels intended for use on passenger vehicles and light trucks.
Collection

Exhaust Emissions Control & System Integration and Durability, 2019

2019-04-02
Papers in this collection focus on technology developments and the integration of these technologies into new emission control systems. Topics include the integration of various diesel particulate matter (PM) and diesel Nitrogen Oxide (NOx) reduction technologies plus analogous technologies for the growing population of direct injection gasoline engines. Novel developments in sensors and control systems will also be considered. This collection encompasses studies in the area of exhaust aftertreatment integration and durability. Topics of interest include detailed studies on the caveats of aftertreatement system design, integration and performance. Other topics of interest include studies documenting the challenges and solutions related to durability and robustness of catalytic solutions.
Technical Paper

Casting and Characterization of An Aluminum Alloy Car Engine Bracket Produced By Squeeze Casting Technology

1996-04-01
91A114
The following paper describes the experimental activity regarding the setting-up and characterization of a car engine bracket in Al-Si12Cu2FeZn-F alloy produced by the new technology squeeze casting. LExperimentation was carried out at the Alures squeeze casting pilot plant. Static and dynamic characterization (fatigue resistance on test samples and the component itself) was carried out at Teksid and Fiat Auto. Characterization test have demonstrated the considerable advantages offered by the new technology compared with conventional production processes.
Technical Paper

Toothed Couplings for Diesel Engines: An Example of Steel Substitution With Fiber Reinforced Plastics

1996-04-01
91A100
The replacement with plastic of an important component, formerly in steel, in the timing drive of a heavily duty diesel engine has been studied and realized. The substituted part is the toothed coupling connecting the injection pump to the timing drive. Torque that stresses the coupling has been measured with laboratory tests. The tooth stresses have been calculated with FEM analysis. Finally, fatigue tests have been carried out directly on the engine at different loadings. The test results are consistent with the predicted behavior of this component.
Technical Paper

A Fatigue Data-Bank Developed as a Design Support for Structures in Composite Materials

1996-04-01
91A092
A data bank developed to give a concrete help to the designer concerned with fatigue-prone structures made of composite materials is described. The data bank not only collects the available results of fatigue tests on these materials, but also makes easy their statistical analysis and comparison for design purposes. It is then believed to constitute also an useful research instrument for the development of design rules for well defined classes of composite materials.
Technical Paper

A Driving Simulator Using Microprocessors

1988-03-01
871156
An inexpensive driving simulation system with sufficient fidelity has been developed. The system produces motion cues of four degrees of freedom, visual and auditory cues, and control feel on the steering wheel. This paper describes the features of this newly developed system and gives examples that demonstrate its effectiveness. The motion cues provided in this system are yaw, heave, and lateral and fore/aft accelerations. The lateral and fore/aft accelerations are simulated by tilting the simulator compartment. A computer-processed road image is given through a CRT monitor. The restoring torque of the steering wheel is produced by an electrical servosystem via a coil spring. Cruising sound is given in order to improve speed perception. Since the system uses digital computers, the vehicle characteristics are altered easily by merely rewriting the software. This enables us to simulate special vehicle dynamics such as front & rear wheel steering.
Technical Paper

Trends and Forecasts for Turbocharging

1988-03-01
871147
Predictable and unpredictable forces will change the direction of the charge-air systems industry. The driver of diesel engine development will be the stringent emissions regulations of the 1990s. The drivers in the gasoline engine market will be improved fuel economy, performance, durability and emissions. Forces will also influence the charge-air marketplace, including changes in emission standards, national fiscal policies, political issues, fuel prices, alternate fuels and consumer tastes. The world community mandate for engines that are clean, quiet, durable and fuel efficient will be satisfied, increasingly, by first-tier component suppliers developing integrated systems solutions.
Technical Paper

A Study on the Performance of Guideway Bus Steering Control System

1988-03-01
871231
In this paper a computer simulation study on the effects of steering parameters on lateral dynamics of the guideway bus to contribute to a development practice of designing optimum steering control system are dealt with. A stability limit of vehicle lateral motion is analyzed and an emphasis is laid on the effects of moment of inertia of a conventional steering wheel and lateral elasticity of the guide rail which have proven to reduce the critical vehicle speed. It is pointed out conclusively that a normal bus equipped with additional simple guidance equipments can be guided smoothly on a simple guideway at adequately high vehicle speed.
Technical Paper

Evaluation and Analysis of Strength of All-Ceramic Swirl Chamber for Diesel Engines

1988-03-01
871205
An all-ceramic swirl chamber has been developed and analyses and evaluations concerning the strength of silicon nitride ceramic (Si3N4) have been performed with a view to using it for the entire internal wall surface of the swirl chamber. The strength characteristics of Si3N4 and their effect and variation have been determined. On the basis of measurements and analyses of thermal stresses, assembling stresses, etc., investigation of the most suitable construction and assembling methods to reduce load stresses on ceramic, and various kinds of duration tests, the swirl chamber has been confirmed to have the required durability. This engine was found to comply with the 1987 U.S. diesel particulate regulation.
Technical Paper

Integration of Reliability, Maintainability and Quality Parameters in Design

1975-02-01
830001
Synthesizing different customer and functional requirements into an acceptable design configuration within a given space constraints is a challenging task for design engineers. The principles for designing efficiency, noise levels, maneuverability, safety, durability, etc. into the product are well understood. However, designing for reliability, maintainability and quality turns out to be a long-drawn laborious process due to unavailability of simplified design procedures. The author in this paper develops the understanding of reliability, maintainability and quality design principles and methods for products, with specific reference to vehicle designs.
Technical Paper

Improvement of Dynamic Characteristics of Electromechanical Commutating Devices

1999-05-17
1999-01-1710
Modern production is intensified by the extensive application of computing art to structure design. This paper deals with the results of numerical simulation of electromechanical commutating devices. Speed of operation, vibrostability, reliability and durability are basic characteristics, which can be satisfied by studying mathematical models of mechanical and magnetic systems. During the impact interaction of elastic links several modes of vibrations are excited. By developing certain conditions, the amplitudes of the higher modes can be increased by changing the intensity of energy dissipation and responsiveness of the mechanical system. Such parameters as the position and configuration of the contact elements, ratio of their natural frequencies and others should guarantee the smallest amplitudes of rebounds with a possibility to minimize transient processes occurring in the building ofthe operation.
Technical Paper

Analysis Tools for DaDTA on Riveted Lap Joints

1999-04-20
1999-01-1587
Two specific concerns that could affect safety limits for aging aircraft are the effects of corrosion damage and widespread fatigue damage (WFD) on structural integrity. A common joint in fuselage structure is the riveted lap joint, which overlaps two fuselage skin panels. This design creates complex loading conditions that require various analysis methods for accomplishing a durability and damage tolerance (DaDT) analysis. Under an Air Force research project, Boeing evaluated the capabilities of several advanced analysis tools for assessing the effects of corrosion and WFD on the structural integrity of riveted lap joints.
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

A Study on Engine Bearing Wear and Fatigue Using EHL Analysis and Experimental Analysis

1999-05-03
1999-01-1514
The possibility of predicting engine bearing durability by elastohydrodynamic lubrication (EHL) calculations was investigated with the aim of being able to improve durability efficiently without conducting numerous confirmation tests. This study focused on the connecting rod big-end bearing of an automotive engine. The mechanisms of wear and fatigue, which determine bearing durability, were estimated by comparing the results of EHL analysis and experimental data. This comparison showed the possibility of predicting the wear amount and the occurrence of fatigue by calculation.
Technical Paper

Shoebox Converter Design for Thinwall Ceramic Substrates

1999-05-03
1999-01-1542
Shoebox catalytic converter design to securely mount thinwall substrates with uniform mounting mat Gap Bulk Density (GBD) around the substrate is developed and validated. Computational Fluid Dynamic (CFD) analysis, using heat transfer predictions with and without chemical reaction, allows to carefully select the mounting mat material for the targeted shell skin temperature. CFD analysis enables to design the converter inlet and outlet cones to obtain uniform exhaust gas flow to achieve maximum converter performance and reduce mat erosion. Finite Element Analysis (FEA) is used to design and optimize manufacturing tool geometry and control process. FEA gives insight to simulate the canning process using displacement control to identify and optimize the closing speed and load to achieve uniform mat Gap Bulk Density between the shell and the substrate.
Technical Paper

Fatigue Analysis of an Aircraft Wing Spar

1999-04-20
1999-01-1561
During full body fatigue testing, an aircraft wing spar initiated a crack from a rivet hole and crack growth data was obtained unique to the test spectrum loading. Fatigue testing of the 7050-T73511 spar material was used to obtain crack growth rate data and variable amplitude fatigue crack growth tests were performed on specimens fabricated from the spar material. Calculated results were in excellent agreement with these experimental results. A layered analysis of the adhesively bonded spar showed that the stress intensity in the lower cap was approximately constant, independent of crack length. When the constant stress intensity is used in a variable amplitude fatigue crack growth analysis, there is good correlation between the predicted and observed crack growth rates.
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