Evaluation of Pavement Roughness and Vehicle Vibrations for Road Surface Profiling

The research explores aspects of road surface measurement and monitoring, targeting some of the main challenges in the field, including cost and portability of high-speed inertial profilers. These challenges are due to the complexities of modern profilers to integrate various sensors while using advanced algorithms and processes to analyse measured sensor data. Novel techniques were proposed to improve the accuracy of road surface longitudinal profiles using inertial profilers. The thesis presents a Half-Wavelength Peak Matching (HWPM) model, designed for inertial profilers that integrate a laser displacement sensor and an accelerometer to evaluate surface irregularities. The model provides an alternative approach to drift correction in accelerometers, which is a major challenge when evaluating displacement from acceleration. The theory relies on using data from the laser displacement sensor to estimate a correction offset for the derived displacement. The study also proposes an alternative technique to evaluating vibration velocity, which improves on computational factors when compared to commonly used methods. The aim is to explore a different dimension to road roughness evaluation, by investigating the effect of surface irregularities on vehicle vibration. The measured samples show that the drift in the displacement calculated from the accelerometer increased as the vehicle speed at which the road measurement was taken increased. As such, the significance of the HWPM model is more apparent at higher vehicle speeds, where the results obtained show noticeable improvements to current techniques. All results and analysis carried out to validate the model are based on real-time data obtained from an inertial profiler that was designed and developed for the research. The profiler, which is designed for portability, scalability and accuracy, provides a Power Over Ethernet (POE) enabled solution to cope with the demand for high data transmission rates.

Aeronautical engineering: A continuing bibliography with indexes (supplement 303)

This bibliography lists 211 reports, articles, and other documents introduced into the NASA scientific and technical information database. Subject coverage includes: design, construction, and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Aeronautical engineering: A continuing bibliography with indexes, supplement 164, August 1983

This bibliography lists 296 reports, articles and other documents introduced into the NASA scientific and technical information system in July 1983

Aeronautical engineering, a continuing bibliography with indexes

This bibliography lists 419 reports, articles and other documents introduced into the NASA scientific and technical information system in March 1985

Aeronautical engineering: A continuing bibliography with indexes, supplement 98

This bibliography lists 399 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 197

Aeronautical Engineering: A continuing bibliography with indexes, supplement 104

This bibliography lists 532 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in December 1978

Vibration of discretely stiffened skew plates and bridge/vehicle interaction analysis.

The vibration of orthogonally stiffened skew plates is studied by using the pb-2 Rayleigh-Ritz method. By minimizing the Rayleigh quotient, the natural frequencies and mode shapes are obtained. The dimensionless natural frequencies of orthogonally stiffened skew plates with different boundary conditions are determined. Since this problem has not been previously studied, the conventional finite element method is used as a comparative check. Numerical results have been presented here for different skew angles, edge ratios, and stiffener height-plate thickness ratios. The results provide rich information to better understand the dynamics of existing orthogonally stiffened plate structures and provide design information.A general method is proposed to model multi-axle tractor-trailer type vehicles. As an example, a three-axle vehicle is considered. The vehicle model consists of two rigid mass and six wheel masses with eleven degrees of freedom (DOF), which include heave, pitch, and roll motions. The equations of motion are derived with the use of the principle of virtual work. Newmark's method is used to predict the dynamic response of the vehicle.Then a semi-analytical method is proposed to study the vibration of the bridge under moving vehicles with the use of mode superposition. The response is expressed as the sum of the contribution of different modes. The normal coordinates can be solved explicitly. An iterative approach has been developed to treat the coupling between the bridge and the vehicle.The interaction problem concerning bridges subjected to dynamic vehicle loading has received considerable attention. The difficulty common to a tremendous amount of efforts involves finding a suitable way to treat the dynamic coupling between the bridge and the vehicle. To be more general, skew bridges subjected to multi-axle vehicles are considered in the dissertation.An existing highway bridge, the Walnut Creek Bridge, is considered. By using the pb-2 Rayleigh-Ritz method, its natural frequencies and mode shapes are obtained and compared with test results. Simulations are conducted for the Walnut Creek Bridge due to moving vehicles. The dynamic amplification factors are computed and compared with test results. The bridge/vehicle interaction problem is further discussed with examination of the effects of the bridge entrance and surface roughness. In this study, different irregularities are used, including perfectly smooth, the measured profile at the Walnut Creek Bridge entrance, and four types of road surface roughness for very good, good, average and poor roads according to the International Organization for Standardization (ISO) specifications. Other factors examined are the vehicle characteristics including vehicle type, axle spacing, vehicle model and speed, and the bridge characteristics including damping, span length and skew angle. The effect of traffic condition is also investigated. Further research is recommended

Design and dynamic analysis of metal rubber isolators between satellite and carrier rocket system

To achieve mobility and rapid-response, vehicles are used to launch satellites, and such systems will inevitably undergo random vibrations caused by uneven ground excitations. However, cameras or other high-precision satellite payloads cannot withstand such harsh mechanical environment in the absence of isolators. Hence, in the present paper, due to the advantages of the superior damping properties of metal rubber (MR), we designed MR structures to absorb vibrations. Correspondingly, the dynamical behaviours of the integrated system were comprehensively analysed to ensure that vibrations would not cause the payloads to collide with the fairing. In addition, the effects of geometric parameters of the isolated structures on the vibration properties of the system were investigated. This work provides a feasible design method of using simple MR structures, instead of very complicated isolators, for a mobile satellite launching system moving on rough roads.</p

Aeronautical engineering: A continuing bibliography with indexes, supplement 100

This bibliography lists 295 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in August 1978

NASA SBIR abstracts of 1991 phase 1 projects

The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included