Automotive Stirling engine development program

The major accomplishments were the completion of the Basic Stirling Engine (BSE) and the Stirling Engine System (SES) designs on schedule, the approval and acceptance of those designs by NASA, and the initiation of manufacture of BSE components. The performance predictions indicate the Mod II engine design will meet or exceed the original program goals of 30% improvement in fuel economy over a conventional Internal Combustion (IC) powered vehicle, while providing acceptable emissions. This was accomplished while simultaneously reducing Mod II engine weight to a level comparable with IC engine power density, and packaging the Mod II in a 1985 Celebrity with no external sheet metal changes. The projected mileage of the Mod II Celebrity for the combined urban and highway CVS cycle is 40.9 mpg which is a 32% improvement over the IC Celebrity. If additional potential improvements are verified and incorporated in the Mod II, the mileage could increase to 42.7 mpg

Estimating fatigue life of steel bridges using continuous response monitoring: Methodology and applications

The fatigue life of structural steel bridges is governed by the time-history of stresses generated in-situ in its fatigue-critical structural details under service conditions. However, these stresses are often not directly and accurately measurable due to the complex geometry of structural elements or access restrictions. Therefore, there is a need for an approach to infer stresses at a detail using measurements taken away from the detail. Another practical issue is that instrumenting all structural details is infeasible owing high cost. An approach to infer stresses across the bridge only a limited number of sensors is therefore essential. This thesis aims to address the aforementioned two critical issues in monitoring-based fatigue life evaluation. It accomplishes this by investigating the following hypothesis: detailed finite element models of fatigue-critical connections and in-service strain measurements that capture the shear, flexure, and axial demands of the modelled connections can be combined to estimate accurately the in-situ hot spot/nominal stresses. This will enable much more reliable assessment of fatigue life than is possible by current methods. Proving this hypothesis will also permit expanding the approach to predicting hot spot/nominal stresses at uninstrumented connections by combining numerical models with real-time measurements from a few instrumented connections. This thesis focuses specifically on investigating this hypothesis on the fatigue-sensitive web-gap welded details in ladder-type bridge decks although the presented ideas are applicable to riveted/bolted connections in this type of bridges. The proposed approaches are evaluated using measurements from three full-scale bridges. Results illustrate that the methodology accurately predicts fatigue stress response. Results also confirm that the methodology can be utilised to infer stress time-histories at uninstrumented connections and to plan for retrofits. The study demonstrates that the proposed methodology is applicable for interpreting measurements from full-scale bridges, and can be integrated within a measurement interpretation platform for continuous bridge monitoring

A Hybrid Testing Platform for Realistic Characterization of Infrastructure Sensor Technology

In America's transportation infrastructure, maintaining safe and serviceable bridges is of paramount importance to America's transportation officials. In order to meet the increasing demands for information-based maintenance and repair of civil infrastructures such as highway bridges, an increasing number of structural health monitoring sensors and other non-destructive evaluation (NDE) devices have begun to be implemented on these structures. Before these health monitoring sensors can be implemented on a large scale, they must first be validated and characterized in a controlled environment. This thesis proposes and demonstrates the use of a hybrid testing platform to create a more realistic testbed to evaluate these structural health monitoring sensors for steel bridges. The details of this hybrid testing platform are discussed including the effects of ramp time, stress level, complexity of the virtual model, fatigue, and high temperature testing. The accuracy and practical implementation of this hybrid testing platform are also addressed

Simulation of the Spindle Coupled Multi-Axial Loading Fatigue Test of a Rear Axle

This study aims to establish a practical method for simulating the spindle coupled multi-axis loading fatigue test of a rear axle. A dynamic finite-element model of the rear axle was constructed and validated using a static calibration test. Based on the theory and methodology of the Schenck ITFC system, a simulation process was devised which includes system identification, calculation of the input loading signals for the finite-element model, calculation of the response stress signals based on this model, calculation of the response strain signals from the corresponding stress signals, and finally, a comparison of the desired and achieved signals. The corresponding data processing programs were made using Matlab, ensuring their easy reproducibility. The desired signals were measured on the Hainan proving ground for a duration of 2441.216 s, using strain gauges and rosettes placed in important stress-prone locations of the rear axle. The results indicate that the desired signals can be reproduced comparatively accurately, ensuring that the strain distribution of the rear axle in the field can be reasonably predicted.Предложен практический метод моделирования многоосного циклического нагружения задней оси автомобиля с учетом взаимодействия различных факторов. Разработана динамичная конечноэлементная модель задней оси и выполнена ее верификация с помощью калибровочных тестов при статическом нагружении. С использованием испытательной системы Schenck ITFC моделируется процесс, включающий идентификацию системы, вычисление входных сигналов нагрузки для конечноэлементной модели, выходных сигналов напряжения и деформации, а также сравнение расчетных сигналов с реальными. С помощью программного обеспечения Matlab реализованы легко воспроизводимые программы обработки данных. Проведено измерение динамических сигналов напряжения в течение 2,441.216 с нагружения на автомобильном стенде Hainan посредством тензодатчиков, размещенных в ключевых точках задней оси автомобиля. Получено удовлетворительное согласование между расчетным и экспериментальным распределением деформации в задней оси автомобиля.Запропоновано практичний метод моделювання багатовісного циклічного навантаження задньої вісі автомобіля з урахуванням взаємодії різних чинників. Розроблено динамічну скінченноелементну модель задньої вісі та виконано її верифікацію за допомогою калібрувальних тестів при статичному навантаженні. Із використанням випробувальної системи Schenck ITFC моделюється процес, який включає ідентифікацію системи, обчислення вхідних сигналів навантаження для скінченноелементної моделі, вихідних сигналів напружень та деформації, а також порівняння розрахункових сигналів із реальними. За допомогою програмного забезпечення Matlab реалізовано програми обробки даних, що легко відтворюються. Проведено вимірювання динамічних сигналів напружень протягом 2441,216 с навантаження на автомобільному стенді Hainan за допомогою тензодатчиків, розміщених у ключових точках задньої вісі автомобіля. Отримано задовільний збіг розрахункового розподілу деформації у задній вісі автомобіля з експериментальним

Eleventh International Conference on the Bearing Capacity of Roads, Railways and Airfields

Innovations in Road, Railway and Airfield Bearing Capacity – Volume 2 comprises the second part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field

Integrated durability analysis of a vehicle through virtual simulation.

The intent of this research is to create a high fidelity multibody dynamics model of a compact Sport Utility Vehicle (SUV) using CATIA, ADAMS and NASTRAN software suites. These software packages together are used to conduct virtual proving ground simulations. An MTS 329 series Road Test Simulator (RTS), which uses servo-hydraulic actuators to replicate vehicle proving ground is used to correlate results. The overall objective is to be able to predict component failure earlier in the design process, and to reduce the amount of time spent conducting physical durability tests. This thesis builds on research currently being conducted by many auto manufacturers in the area of virtual road test simulation. The development of a complete durability model is very complex, and involves many steps in simulating physical phenomena. This research focuses primarily on model creation techniques that are used to build a virtual multibody dynamics model, with an emphasis being placed on the construction, implementation and background theory of flexible bodies. (Abstract shortened by UMI.)Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2003 .W66. Source: Masters Abstracts International, Volume: 44-01, page: 0428. Thesis (M.A.Sc.)--University of Windsor (Canada), 2003

Combining virtual simulation and physical vehicle test data to optimize automotive durability testing.

This thesis describes a project to model a vehicle on a computer with a multibody dynamics simulation software package and to combine that work with physical laboratory tests for the purposes of optimizing durability testing. The intention was to mirror as closely as possible the behavior of a physical vehicle on a road test simulator to assist in determining its durability characteristics under varying road conditions. This modeling work is important because, if done with sufficient fidelity, it can be used to assess vehicle responses using different suspension configurations or payloads. Also, problems associated with changes to a vehicle\u27s payload, structure and suspension systems can be observed on a computer without performing physical tests. The process has the potential to improve greatly automobile quality and durability, while dramatically reducing product development time and costs. The virtual dynamic vehicle model was assembled using computer aided drafting (CAD) models and ADAMS (Automatic Dynamic Analysis of Mechanical Systems) software packages. Inputs to the virtual model were forces and displacements acquired from the responses of a physical vehicle and a road test simulator (RTS) during a durability testing cycle. (Abstract shortened by UMI.)Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2002 .F47. Source: Masters Abstracts International, Volume: 43-05, page: 1763. Adviser: Peter R. Frise. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004

Development of Stationary and Mobile Tailgating Detection Solutions for Ground Vehicles

Improving the safety of North American roadways is a top priority for government agencies and transportation organizations alike. Regulations on appropriate driving behavior have been developed to minimize the likelihood of crashes occurring, but law enforcement tools remain to be fully developed and applied in the field. One prominent example of this is tailgating – the dangerous act of one ground vehicle following another too closely. This activity is responsible for thousands of crashes every year, but police officers currently have few tools to accurately detect and document tailgating events. Though tailgating often occurs in a wide variety of vehicle scenarios, the most hazardous class of tailgating is that which occurs when a semitrailer, more commonly called an 18-wheeler, follows a passenger vehicle too closely. The difference in mass between a semitrailer and a passenger vehicle results in a stopping distance nearly twice as long for the former. In addition, truck drivers may be fatigued and unable to react as quickly to emergency situations, further increasing the risk of a deadly crash. Therefore, a tool is necessary that enables officers to determine when tailgating occurs, and allows them to document the event for use by prosecutors in a court of law

Suspension forces on a tri-axle air suspended semi-trailer

The aim of this study is to investigate the use of multi-body vehicle simulation models to predict the suspension forces acting on the chassis of the vehicle, in order to perform durability analyses. Traditionally, durability of vehicles is evaluated with proving ground tests. This implies that a physical prototype of the vehicle is required before its durability can be evaluated. If we were able to evaluate the durability of the vehicle without any physical part or a full prototype of the vehicle available, great cost and time savings may be gained. These possible gains have lead to the use of computer aided engineering (CAE) tools. These tools have supplemented the proving ground durability test by using historical measured data and/or predicted data from vehicle simulation models, as input to the durability analyses i.e. Finite Element Analyses (FEA). The usefulness of the historical test data is limited and many of the vehicle simulation models that are used to predict the input data, have not been validated. In this study a validated mathematical model of a 40 ton flat bed tri-axle semi-trailer, able to predict the suspension forces, is created. The validation of the full vehicle model includes correlations for displacements, velocities, accelerations and forces of various vehicle parameters. A validated mathematical model of the air springs, that includes mass transfer and flow effects for use in full vehicle dynamic simulations, is also developed. The results obtained indicate that the air spring model, integrated into the full vehicle model, is able to give relative accurate predictions of displacements, velocities, accelerations and forces of various vehicle parameters, over a discrete road event and over a rough road.Dissertation (MEng)--University of Pretoria, 2009.Mechanical and Aeronautical EngineeringUnrestricte

Fatigue performance of existing bridges under dynamic loads from winds and vehicles

During the life cycle of bridges, varied amplitude of stress ranges on structural details are induced by the random traffic and wind loads. The progressive deteriorated road surface conditions might accelerate the fatigue damage accumulations. Micro-cracks in structural details might be initiated. An effective structural modeling scheme and a reasonable fatigue damage accumulation rule are essential for stress range acquisitions and fatigue life estimation. The present research targets at the development of a fatigue life and reliability prediction methodology for existing steel bridges under real wind and traffic environment with the capability of including multiple random parameters and variables in bridges’ life cycle. Firstly, the dynamic system is further investigated to acquire more accuracy stresses for fatigue life estimations for short and long span bridges. For short span bridges, the random effects of vehicle speed and road roughness condition are included in the limit state function, and fatigue reliability of the structural details is attained. For long-span bridges, a multiple scale modeling and simulation scheme based on the EOMM method is presented to obtain the stress range history of structural details, while the calculation cost and accuracy are saved. Secondly, a progressive fatigue reliability assessment approach based on a nonlinear continuous fatigue damage model is presented. At each block of stress cycles, types and numbers of passing vehicles are recorded to calculate the road surface’s progressive deterioration and nonlinear cumulative fatigue damage, and the random road profiles are generated. Thirdly, this study discussed the fatigue design of short and long span bridges based on the dynamic analysis on the vehicle-bridge or vehicle-bridge-wind system. For short span bridges, a reliability-based dynamic amplification factor on revised equivalent stress ranges (DAFS) is proposed. For long span bridges, a comprehensive framework for fatigue reliability analysis under combined dynamic loads from vehicles and winds is presented. The superposed dynamic stress ranges cannot be ignored for fatigue reliability assessment of long-span bridges, although the stresses from either the vehicle loads or wind loads may not be able to induce serious fatigue issues alone