Magnesium alloy tubes have good formability at elevated temperatures. In this paper, firstly, uniaxial tensile tests are conducted to evaluate the flow stress of AZ61 magnesium alloy at different temperatures and strain rates. Secondly, a hydraulic warm forming machine with axial feeding, counter punch and internal pressure is designed and manufactured. Using this testing machine with the FEM results, experiments of hydraulic forming of AZ61 magnesium alloy tubes at different temperatures are carried out. The effect of loading paths on the product shape and formability at different temperature are discussed.

Syftet med studien var att undersöka vad känslor spelar för roll för beslutet att donera pengar till välgörande ändamål. Dessutom undersöktes om motivet ”social signaling” (publikt/anonymt) har någon påverkan på beslutet att ge pengar till en välgörenhetsorganisation. I ett experiment fick försökspersoner fatta ekonomiska beslut om donation till Rädda Barnen. Resultaten visade att generellt är människor generösare när de fattade besluten publikt än anonymt. Positiva/negativa känslor styrde hur personer fattar donationsbeslut. Känslor påverkades dock inte av att de fattade beslutet publikt eller anonymt. Överlag kände de sig positivare när de förlorade mindre pengar och välgörenhetsorganisationen fick mer pengar, dock inte när de både förlorade mer och välgörenhetsorganisationen fick mer. Sammantaget visar studien att både känslor och sociala motiv påverkar donationsbeteende.

Aluminum (1050) was deformed by plane strain compression (PSC) up to 75% reduction. The total deformation conditions include four temperatures (from 150oC to 300oC) and two strain rates (5¡Ñ10-2s-1 and 5¡Ñ10-4s-1). After the deformation, the specimens were examined by TEM for observing the morphology of the microstructures and measuring various parameters, which includes the sizes and aspect ratios of dislocation cells, as well as the distribution of misorientation angles for dislocation walls.

This thesis examines the equation of state of copper at Warm Dense Matter states, between 1-100 eV and .1-10 times solid density. Protons accelerated off a thin metal foil irradiated with a high intensity laser beam flash heat solid density copper to between 5-10 eV before significant expansion occurs. The measured temperature and expansion are compared against simulations using various equations of states. The production and characterization of the laser system and proton beam used to heat the matter is also presented. / text

Warm mix asphalt (WMA) is an environmental friendly technology that contributes to the workers safety, reduction of energy consumption and emissions. In this study, the rheological properties of a PG 64-22 asphalt binder blended with Cecabase RT, Rediset, Evotherm, and Sasobit WMA additives are investigated as a function of laboratory aging. Binders modified with WMA additives and the control samples were both aged in the rolling thin film oven (RTFO) at 143°C and at 163°C, respectively. All samples were then long-term aged in an environmental chamber kept at 60°C. The longterm aged samples were collected at different intervals during a six-month period. Rheological data were collected on each aged sample by performing dynamic shear rheometer (DSR) frequency sweep from 25 to 0.1 Hz. at three different temperatures, i.e. 45°C, 60°C, and 76°C. Samples were also evaluated with the Bending Beam Rheometer (BBR) and Fourier-Transform Infrared (FTIR) Spectroscopy. Gauss-Newton method was vii used for non-linear parameter estimation for modeling the relationship of complex modulus (G*) with temperature, frequency, and aging. Regression analysis was also used for modeling BBR creep stiffness and BBR m-value. Although FTIR results show higher oxidation levels for control than all WMA samples, DSR and BBR results show that Sasobit tends to behave closely to control while Cecabase, Evotherm, and Rediset exhibit lower stiffness than both. / text

The current research addresses the formability of two magnesium sheet alloys, a conventional AZ31B and a rare earth alloyed ZEK100. Both alloys had a nominal thickness of 1.6 mm. Both Limiting Dome Height (LDH) and Cylindrical Cup Draw experiments were performed between room temperature and 350°C. To examine the effect of sheet directionality and anisotropy, LDH experiments were performed in both the sheet rolling and transverse directions. In addition, strain measurements were performed along both sheet orientations of the cylindrical cup and LDH specimens for which the geometry is symmetric. The LDH tests were used to study the formability of ZEK100 and AZ31B (O and H24 tempers) magnesium alloy sheet between room temperature and 350°C. At room temperature, AZ31B-O and AZ31B-H24 exhibit limited formability, with dome heights of only 11-12 mm prior to the onset of necking. In contrast, the dome heights of ZEK100 at room temperature reached 29 mm (a 140% improvement over AZ31B). Increasing the temperature above 200°C did not affect the relative ranking of the three sheet samples, however it did reduce the magnitude of the difference in dome heights. The rare earth alloyed ZEK100 had pronounced benefits at intermediate temperatures, achieving an LDH of 37 mm at 150°C; this dome height was only reached by AZ31B at a much higher temperature of 250°C. To further characterize the formability of ZEK100, forming limit curves (FLCs) were developed from the LDH tests in both the rolling and transverse directions. Comparisons to AZ31B were made at selected temperatures. Surface strain data was collected with an in situ digital image correlation (DIC) system incorporating two cameras for stereo observation. Results from these experiments further highlighted the enhanced formability relative to AZ31B over the entire temperature range between room temperature and 350°C, with the most dramatic improvements between room temperature and 150°C. The plane strain forming limit (FLC0) for ZEK100 at 150°C was 0.4 which equals that of AZ31B at 250°C. At higher temperatures (300°C), the two alloys exhibited similar performance with both achieving similar dome heights at necking of 37 mm (AZ31B) and 41 mm (ZEK100). To round out the investigation of ZEK100 for industrial applications, cylindrical cup deep drawing experiments were performed on ZEK100 sheet between 25°C and 250°C under isothermal and non-isothermal conditions. Draw ratios of 1.75, 2.00 and 2.25 were considered to examine the effects of draw ratio on draw depth. The effect of sheet anisotropy during deep drawing was investigated by measuring the earring profiles, sheet thickness and strain distribution along both the rolling and transverse directions. Isothermal test results showed enhanced warm temperature drawing performance of ZEK100 over AZ31B sheet; for example, a full draw of 203.2 mm (8”) blanks of ZEK100 was achieved with a tool temperature of 150°C, whereas a tool temperature of 225°C was needed to fully draw AZ31B-O blanks of this diameter. Non-isothermal deep draw experiments showed further improvement in drawability with significantly lower tooling temperatures required for a full cup draw using ZEK100. ZEK100 achieved a full draw of 228.6 mm (9") blanks with a die and blank holder temperature of 150°C and a cooled punch (25°C) while the same size blank of AZ31B required a die and blank holder temperature 225°C and a cooled punch (150°C). Temperature process windows were developed from the isothermal and non-isothermal results to show a direct comparison of drawing behaviour between ZEK100 and AZ31B. Overall, ZEK100 offers significantly improved forming performance compared to AZ31B, particularly at temperatures below 200°C. This lower temperature enhanced formability is attractive since it is less demanding in terms of lubricant requirements and reduces the need for higher temperature tooling.

Economic, environmental and engineering benefits promote the rapid implementation of WMA technologies. However, concerns remain based on changes in the production process that may lead to moisture susceptibility in the early life as compared to HMA. To evaluate WMA moisture susceptibility during this critical period, standard laboratory tests were used for three field projects each with an HMA control mixtures and multiple WMA mixtures. Different specimen types were also evaluated to capture differences in mix design, quality control/quality assurance, and field performance. Specimens were evaluated for moisture susceptibility by Indirect Tensile (IDT) Strength, Resilient Modulus (MR) and Hamburg Wheel-Track Testing (HWTT). Specimens for IDT and MR were tested dry and then tested wet after conditioning as described in AASHTO T283 with one freeze-thaw cycle. HWTT was used to assess both moisture susceptibility and rutting potential under repeated loads in the presence of water at elevated temperatures (i.e., 122°F [50°C]), and the output parameters used for evaluation were the calculated Stripping Inflection Point (SIP) and the rut depth at 5000 load cycles. Based on the results of the laboratory tests performed on PMFC cores acquired at construction and with time, WMA during its early life exhibited inferior moisture resistance when compared to HMA. However, with time, specifically after one summer, the dry and wet properties of WMA became equivalent to those of HMA. For WMA constructed in the fall, the results from this study suggest that the inclusion of recycled asphalt pavement (RAP) or an anti-stripping agent may alleviate possible moisture susceptibility issues in the early life during wet, winter weather conditions. While some laboratory test results demonstrated that WMA is more moisture susceptible than HMA, field performance reported to date from the three projects used in this study shows no evidence of moisture damage. Therefore the search for a laboratory test to screen mixtures for moisture susceptibility continues. An alternative approach, applying Griffith crack growth theory and utilizing IDT, MR and air voids% the adhesive bond energy of asphalt mixtures was calculated for Texas field project. This value holds promise for characterizing performance of asphalt mixtures by considering basic properties and grouping into one representative value.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 83-89). Also available on the World Wide Web.

This study aimed to compare the acute effects of two independent warm-up (WU) protocols, neuromuscular warm-up (NMWU) and standardized soccer warm-up (STWU), on three soccer-specific performance tests in adolescent male and female soccer players. Substantial evidence exists of NMWU programs reducing Anterior Cruciate Ligament (ACL) injuries, particularly in soccer. Regardless of this reduced risk of injury, NMWU program adherence is low. Enhanced athletic performance has been reported to encourage consistent WU adherence more effectively than injury risk, especially in youth athletes. Therefore this study compared the effects of a NMWU and a STWU on physical performance in youth soccer players to encourage adherence and implementation. Following familiarization with a locally developed NMWU, 35 (11 female, 24 male) student-athletes (mean age: 14.7 yrs) from two high school-based soccer academies completed four sessions over a two week period evaluating the effects of WU on three soccer specific performance tests. Performance tests included T-test (agility), vertical jump (Peak Power Output), and 20-m sprint (acceleration and speed). The first week of testing consisted of NMWU familiarization, Yo-Yo Intermittent Recovery Test Level 1, and the collection of physical characteristics. The second week of testing consisted of two testing sessions, WU protocols were randomly assigned to the testing sessions ahead of time (session 1: STWU; session 2: NMWU) and were completed at the beginning of the session prior to testing. A series of five two-tailed repeated measures ANOVA were conducted to determine significant differences in WU means. The overall group demonstrated a significant increase in Peak Power Output (p=0.001) and agility (p=0.016) following the STWU compared to the NMWU. Neither WU demonstrated a measurable effect on 5m,10m, and 20m times. The findings of this research may have been influenced by the single use of the NMWU which may have limited the NMWU potential to enhance the three soccer-related performance tests. In order to explore the effectiveness of NMWU on performance enhancement as a means of improving its adherence in youth players, further research implementing NMWU over an extended period of weeks or months should be carried out, consistent with studies demonstrating NMWU impact on ACL injury risk in youth and adults. / Graduate

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