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The question of how the static strength of angle-plied nylon cord-reinforced rubber composites simulating aircraft tire carcass is affected by damage accumulation or materials degradation was examined in this study. Upon cyclic loading at 1 Hz, residual tensile strength was gradually lowered with the progression of fatigue damage. The degradation of the residual strength became more drastic toward the end of the fatigue life because of worsening delamination. In contrast, the residual strength after cyclic loading of 10 Hz exhibited a rapid decrease at the beginning of the fatigue life, presumably due to thermal degradation, and then remained virtually constant throughout the life. Acoustic emission (AE) activities were monitored to assess the extent of damage and to explore a possibility of indirect monitoring of residual strength of composites.

Tires are one of the dominate sources of exterior vehicle noise. In this study, Nearfield Acoustical Holography (NAH) is used to investigate the sources of noise generated by tire interaction with an outdoor road surface. One tire on a two wheel trailer is examined while towed by a vehicle at 56 km/hr (35 mph) along a smooth, consistent road surface. The complex pressure is measured at discrete points along a plane parallel to the side of the tire by scanning with an array of five microphones. Because of the incoherence of noise generated at the leading and trailing edges of the contact patch, and radiation from the side wall, three reference microphones are used. NAH is used to reconstruct the pressure on planes towards and away from the tire, thereby obtaining a three dimensional image of the acoustic pressure, particle velocity, and intensity for noise generated at the contact patch leading edge and trailing edge, and by the tire sidewall vibrations.

As one of the fifteen universities in North America taking part in the EcoCAR 2: Plugging into the Future competition, The Pennsylvania State University Advanced Vehicle Team (PSUAVT) designed and implemented a series plug-in hybrid electric vehicle (PHEV) that reduces fuel consumption and emissions while maintaining high consumer acceptability and safety standards. This architecture allows the vehicle to operate as a pure electric vehicle until the Energy Storage System (ESS) State of Charge (SOC) is depleted. The Auxiliary Power Unit (APU) then supplements the battery to extend range beyond that of a purely electric vehicle. General Motors (GM) donated a 2013 Chevrolet Malibu for PSUAVT to use as the platform to implement the PSUAVT-selected series PHEV design. A 90 kW electric traction motor, a 16.2 kW-hr high capacity lithium-ion battery pack, and Auxiliary Power Unit (APU) are now integrated into the vehicle.

This paper presents follow-on material and conclusions to a previously published paper that presented work to develop and validate life prediction models for SiC device packaging [ 1 ]. The first step in this work was to determine the most probable failure modes in the device packaging. After determining the expected dominant failure modes of a SiC semiconductor packaging, appropriate models were identified and applied to the packaging in order to track remaining useful life. Once failure modeling was completed, the life prediction models were validated. Validation consisted of accelerated life testing designed to stress specific parts of the device package so as to stimulate the desired failure mechanism. This paper will review the three testing methodologies designed to excite the three dominant failure mechanisms in the electronic packaging. These tests can be broken into two types of general tests: power cycling and high temperature reverse bias testing (HTRB).

Methods of estimating tractor performance including power efficiency and fuel consumption under field operational conditions were discussed based on a tractor and a large square baler. Methods recommended by ASAE standards were used and results indicated that ASAE standards predicted 15% higher fuel consumption compared to that tested by Nebraska tractor test center. Field trials were conducted in switchgrass fields to verify and demonstrate these methods. Fuel consumption and the material capacity of the tractor-baler system were measured and also estimated using ASAE standards and Nebraska tractor test results. Field test results indicated that the fuel consumption of baling switchgrass was approximately 60% of the fuel consumption estimated with ASAE standards and tested by Nebraska tractor test center. Measured material capacity of the large square baler was approximately 40% of its theoretical capacity.

The effect of minimum stress on the fatigue life has been assessed for an angle-plied nylon cord-reinforced elastomer composite which represents the bias aircraft tire carcass. The S-N curves were established under constant minimum stress rather than constant R-ratio. In this manner, all data points in each S-N curve could be associated with the same level of creep stress. Composite laminate specimens exhibited a normal failure sequence of fiber-matrix debonding developing into the delamination under cyclic tension. A trend of longer fatigue life of the composite was clearly observed at a given stress amplitude with a higher level of minimum stress. The use of a higher level of minimum stress also caused the increase of the fatigue endurance limit of the composite. The trend of longer fatigue life with a higher level of minimum stress stems from the fact that the stress and strain are not linearly related to each other.

The advent of stainless steel automotive exhaust systems presents a significant opportunity for powder metallurgy (P/M) parts and the inherent economic advantages of this near net shape metalworking technology. A study was performed to determine the viability of ferritic P/M stainless steel parts for exhaust applications such as coupling flanges and hot exhaust gas oxygen sensor (HEGOS) bosses. In order to help achieve the automotive industry's stated goal of extending the functional life of exhaust components while remaining competitive, the authors developed a program to develop a database of the mechanical properties and performance characteristics of several grades of P/M stainless steel. Among the data generated and analyzed for these ferritic alloy systems are room temperature, tensile stress-strain curves, fatigue and endurance properties, hardness levels, and corrosion resistance.

Results from an experimental study of the effect of incomplete fuel-air mixing on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at 1 atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6%, 13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. The overall fuel/air equivalence ratio was unity in all cases. The flow characteristics were measured by LDV. The RMS fluctuation in the fuel/air equivalence ratio was characterized using NO2-based laser induced fluorescence. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined.

In 1976 the author presented an SAE paper on ride quality in which a two-degree-of-freedom ride quality simulation was developed for measuring vertical motions. The present paper reports on the work done since that time. Side-to-side motion has been added to the simulator developed for the Association of American Railroads as well as the studies needed to find the impedance of humans when subjected to side-to-side and fore-and-aft motion. These studies found that rough rides are better endured during warmer weather and that women do not resonate as readily as men at the two critical and annoying side-to-side frequencies. Last, the paper deals with the use of a rigid mass to measure seat acceleration. Through a transfer function, a computer simulation has been developed to find the vertical seat acceleration.

A multi-axial dynamic test instrument was designed to perform wear testing of actual aircraft tires as well as tread/carcass composite specimens under laboratory loading conditions which simulate the elements of take-off, landing and taxiing operations. The wear tester consists of a self-spinning abrading head, mounted on the actuator of a servo-hydraulic test system, which faces either (1) the tread surface of a composite specimen clamped by a horizontal stretch frame or (2) the tread region of actual inflated tires. The test concept has been partially proven in the case of tread/carcass composite specimens by building a proto-type test apparatus and operating it successfully. In the current test set-up, the specimen is subjected to static tension to simulate a circumferential load in the tire footprint and the tread surface is in periodic contact with an abrading head under a specific level of pressure.