Utilizing Dynamic Fuel Pressure Sensor For Detecting Bearing Spalling and Gear Pump Failure Modes in Cummins Pressure Time ( PT ) Pumps
The objective of this paper is to highlight the results of the fault detection investigation conducted to ascertain the feasibility of exploiting the existing on-board M2/M3 Bradley fuel pressure sensor for the purpose of detecting mechanical bearing spalling and gear pump failure modes of the pressure-time (PT) fuel pump used on the Cummins VTA-903T engine. To investigate this fluid-mechanical cross domain detection approach, a Bradley fuel system test bed was built. Fault tests for four PT pump failure modes were conducted including bearing faults, gear pump fault, idle adjust mis-calibration, and air-fuel control fault. The results of the first two fault tests are summarized in this paper. Due to limited number of pumps available for testing (2), these preliminary findings are not statistically substantiated. With this stated, the findings present a method for investigating the presence of a narrowband frequency-domain-based predictive fault detection capability using the existing pressure sensor installed on the Chassis Modernization and Embedded Diagnostics (CMED) variant Bradley. The test stand based seeded fault analysis was not capable of detecting an 0.080 inch outer raceway bearing spall, but there is preliminary evidence to warrant further study that a nominal 0.001 inch foreign object debris accumulation on the gear teeth of the gear pump might be detectable using a simple kurtosis based calculation using a pressure sensor with a 0-500 Hz dynamic bandwidth.
Platform degrader analysis for the design and development of Vehicle Health Management Systems
The US Armypsilas Heavy Brigade Combat Team (HBCT) is investigating the implementation of Vehicle Health Management Systems across its fleet of platforms. A vehicle degrader analysis was conducted to determine where the application of vehicle health management systems (VHMS) could potentially have the greatest impact on increasing maintainer effectiveness and operational availability. The analysis was conducted for M1 Abrams tanks and M2/M3 Bradley Fighting Vehicles using data from three sources: (1) multi-year statistical data on repairs, operating and support costs, and logistics data, (2) interviews with maintainers, service representatives and operators, and (3) questionnaires completed by the platform OEMpsilas. The paper will describe how these alternative data and information sources were used when ideal data and information sources were not available. The statistical data provided an indication of vehicle consumable and repairable cost drivers, part replacement quantity and some indication of component failure isolation for vehicle systems. The interviews with vehicle maintainers, field service representatives and operators provided insight into platform reliability, maintainability and human factors issues. The maintainability, reliability and diagnostic coverage information from the OEMpsilas, provided information about mission criticality and general diagnostic capability for specific vehicle sub-systems and components. The results of the degrader analysis include a list of components and sub-systems that contribute most to maintainability, reliability and vehicle operational availability issues. The degrader results, were used to develop the conceptual design of the optimum application of embedded vehicle diagnostics and prognostics for more effective and efficient HCBT platform maintenance, logistic support and platform life cycle management.
Mesozoic rifting and basin inversion along the northern African Tethyan margin: an overview
Abstract The northern African Tethyan margin registered three major rifting episodes from the latest Palaeozoic-earliest Mesozoic to the earliest Cenozoic. Break-up of Gondwana was initiated in the late Carboniferous. Along the northern African-Arabian plate margin rifting propagated westward from the northeastern Arabian margin to Morocco during the Permian and Triassic, and was accompanied by Mid-Late Triassic-earliest Liassic extensive alkaline flow basalts. Rifting continued during the Liassic, e.g. in the Moghrebian Atlas troughs. A second stage of rifting occurred in the Late Jurassic and continued into, or was rejuvenated during, the Early Cretaceous. Along the east Mediterranean margin, some large E-W trending rifts formed, often with associated volcanism, e.g. southern Sirt and Abu Gharadig. Most researchers believe the oceanization of the eastern Mediterranean basin occurred at this time. Flexural subsidence affected the Moghrebian Atlas, including the Riffian-Tellian domain, where a thick flysch series was deposited. Two short-lived, but widespread and tectonically important, compressional or wrench-dominated events occurred during the Santonian and the latest Maastrichtian. From Morocco to Oman, most sedimentary basins were folded and inverted at these times. The Santonian event resulted from onset of the collision between the African-Arabian and Eurasian plates. New stress-fields favoured NE-SW extension along the African plate margin, generating or rejuvenating some rifts, e.g. in the Euphrates trough and in the Libya-Tunisia region (northwestern Sirt, Pelagian Sea). Rifting and magmatism continued in these regions into the Paleocene. During the Mesozoic, therefore, the northern margin of the African-Arabian plate registered both rifting resulting in the oceanization of the Tethys and rifting resulting from the initiation of the closure of the Tethys. The intraplate domain exhibited echoes of the tectonic events affecting the margin.