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The right-angled geared systems are used in automotive and aerospace applications. Most of the right-angled geared systems fail due to contact fatigue. Several articles reported discussing contact fatigue failure of parallel axis geared systems, and the contact fatigue conditions of hypoid and spiral bevel geared systems are seldom studied. This work aims to bridge the gap and proposes a simplified method to model contact fatigue in the right-angled geared system under dry contact conditions. Initially, the gear contact is modeled using a tooth contact analysis methodology for a given load, speed, and operating conditions. The above step is followed by obtaining stress histories based on suitable interpolation conditions, finite element computation, and Hertzian contact conditions. These stress histories form the basis of the Characteristic plane method. The contact fatigue life of the gears is calculated based on the equivalent bending amplitude of a multiaxial stress condition. The equivalent bending amplitude is then used to determine the number of cycles of operation the gear can endure from the SN-curve for that material. This method is then used to perform parametric analysis based on the size, material type, and gear contact ratio.

A spline clutch maneuvered by an actuator provides a Power Transfer Unit (PTU), the functions of power disconnection, or speed selection. In the driveline system, the PTU actuator is the core mechatronic component to realize the essential functionality. This paper focuses on increasing the performance and stability of the PTU using analytical mechatronic modeling and analysis with ADAMS-Simulink co-simulation. By utilizing the Adams, the PTU was modeled, and the characteristics of the sleeve walk-out were revealed. The motor and partial mechanical components were modeled in the Simulink and combined with the Adams model for co-simulation. The fuzzy logic with PID position control is developed to suppress the on-set of the walk-out. The effectiveness of the control strategy was validated by the co-simulation. This method can be extended to other actuators with spline clutch applications to minimize the risk of walk-out.

After deep venous thrombosis (DVT), many patients have impaired quality of life (QOL). We aimed to assess whether pharmacomechanical catheter-directed thrombolysis (PCDT) improves short-term or long-term QOL in patients with proximal DVT and whether QOL is related to extent of DVT.The Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial was an assessor-blinded randomized trial that compared PCDT with no PCDT in patients with DVT of the femoral, common femoral, or iliac veins. QOL was assessed at baseline and 1 month, 6 months, 12 months, 18 months, and 24 months using the Venous Insufficiency Epidemiological and Economic Study on Quality of Life/Symptoms (VEINES-QOL/Sym) disease-specific QOL measure and the 36-Item Short Form Health Survey (SF-36) physical component summary (PCS) and mental component summary general QOL measures. Change in QOL scores from baseline to assessment time were compared in the PCDT and no PCDT treatment groups overall and in the iliofemoral DVT and femoral-popliteal DVT subgroups.Of 692 ATTRACT patients, 691 were analyzed (mean age, 53 years; 62% male; 57% iliofemoral DVT). VEINES-QOL change scores were greater (ie, better) in PCDT vs no PCDT from baseline to 1 month (difference, 5.7; P = .0006) and from baseline to 6 months (5.1; P = .0029) but not for other intervals. SF-36 PCS change scores were greater in PCDT vs no PCDT from baseline to 1 month (difference, 2.4; P = .01) but not for other intervals. Among iliofemoral DVT patients, VEINES-QOL change scores from baseline to all assessments were greater in the PCDT vs no PCDT group; this was statistically significant in the intention-to-treat analysis at 1 month (difference, 10.0; P .0001) and 6 months (8.8; P .0001) and in the per-protocol analysis at 18 months (difference, 5.8; P = .0086) and 24 months (difference, 6.6; P = .0067). SF-36 PCS change scores were greater in PCDT vs no PCDT from baseline to 1 month (difference, 3.2; P = .0010) but not for other intervals. In contrast, in femoral-popliteal DVT patients, change scores from baseline to all assessments were similar in the PCDT and no PCDT groups.Among patients with proximal DVT, PCDT leads to greater improvement in disease-specific QOL than no PCDT at 1 month and 6 months but not later. In patients with iliofemoral DVT, PCDT led to greater improvement in disease-specific QOL during 24 months.

Three types of commonly used local stress approaches recognized by Codes and Standards for fatigue of welded joints are reviewed and evaluated with respect to a comprehensive collection of multi-axial fatigue test data available in literature. These local stress approaches are surface-extrapolated hot spot stress, effective notch stress and traction structural stress. The hot spot stress and notch stress approaches are based on those stipulated in Eurocode 3 (2005) and IIW Recommendations (2016). Traction structural stress is based mainly on ASME VIII Div 2 Code (2007) and its latest development. The results show traction structural stress method offers a significantly improved data correlation over hot spot stress and notch stress approaches.

Classical fatigue limit prediction models and material-dependent characteristic length parameters for notched components are critically reviewed before a modified stress gradient based approach is proposed to integrate the non-propagation behavior of microstructurally small crack. Assuming fatigue limit (strength) as a general function of root surface stress and stress gradient defined over a characteristic length, an effective stress parameter is derived to characterize the resistance of a notch to fatigue limit (high cycle fatigue) loading. The model is validated by comparing with reviewed models through a large amount of test data. Physical interpretation and perspectives on the model are also discussed.

Visceral artery aneurysms (VAAs), which were once considered uncommon, are now being diagnosed with increasing frequency, a fact that reflects the routine use of computed tomography (CT), magnetic resonance imaging, and ultrasonography. Diagnostic radiology plays a major role in the detection and characterization of VAAs. Cross-sectional imaging can help exclude aneurysm rupture, which requires emergent treatment. CT angiography or catheter angiography can clearly depict the aneurysm and help identify other aortic, visceral, or peripheral aneurysms. Most important, radiologic examination can help determine the adequacy of the collateral blood supply to the vascular bed distal to the aneurysm, information that is essential prior to the initiation of endovascular treatment. Advances in endovascular therapy have allowed interventional radiologists to contribute to the management of VAAs. Coil embolization or covered stent placement can now be used to treat patients with aneurysms whose size or location would make a surgical approach problematic, as well as patients in whom surgery is considered to pose considerable risk.

Due to their high strength and stiffness carbon nanotubes (CNTs) have been considered as candidates for reinforcement of polymeric resins. It is also known that the addition of CNTs to polymeric matrix results in highly conductive nanocomposites, making the material multifunctional. Most of the CNT reinforced polymeric nanocomposite systems reported in the literature have been studied at room temperature. However, in many applications, materials may be subjected from low to elevated temperatures. Thus, the aim of this research is to study CNT reinforced polypropylene (PP) specimens at room, elevated and low temperatures. ASTM standard Type I specimens manufactured via injection molding and reinforced with 0.2%, 1%, 3%, and 6% CNTs were first subjected to tensile loads in a universal testing machine at room temperature. Neat PP resin specimens were also tested to provide baseline data. The tests were repeated at −54°C (−65°F), −20°C (−4°F), 49°C (120°F) and 71°C (160°F). The results were plotted as stress-strain curves and analyzed to delineate the effect of CNT reinforcement percentage and temperature on the mechanical properties. It was noted that as the percentage of CNT reinforcement increases, the resulting nanocomposite becomes stiffer (higher Young’s modulus), has higher strength and becomes more brittle. Temperature has a drastic effect on the behavior of the nanocomposite. As the temperature increases, at a given reinforcement percentage the material becomes more ductile with significantly lower Young’s modulus and strength compared to room temperature. At lower temperatures, the nanocomposite becomes more brittle with higher stiffness and strength, but significantly reduced failure strain. Also electrical measurements were conducted on the specimens to measure their resistance. For specimens reinforced with up to 3% of CNTs no electrical conductivity was detected. As expected at 6% CNT reinforcement (which is above the approximately 4% percolation limit reported in the literature), the specimens became electrically conductive. To predict the mechanical properties obtained experimentally, a micromechanics based model is presented and compared with the experimental results.Copyright © 2011 by ASME

In this study, the mechanical properties of nanoclay reinforced polymeric resins are investigated at various temperatures. In recent years there has been heightened interest to develop nanoclay reinforced composites due to their superior performance compared to neat resins at high temperatures under various loading conditions, including impact. First, polypropylene (PP) resin specimens reinforced with varying weight fractions of nanoclay (0%, 1%, 3%, 6% and 10%) some instrumented with strain gages, were subjected to tensile loads and the stress-strain curves were obtained to determine the mechanical properties of the nanocomposite. Extensive experimental data were obtained. The results indicate that as the weight percentage of nanoclay increases, the strength and stiffness of the resulting nanocomposites also increase. Most of PP specimens exhibited significant deformation (more than 100%) and did not break. High temperatures have a deleterious effect on the strength and stiffness of nanoclay reinforced PP specimens. However, the addition of nanoclay, somewhat mitigates the deterioration of these properties. At lower temperatures the material stiffens, has higher strength and becomes more brittle as failure occurs at much lower strains. Also the tests using different PP resins indicate that the type of resin used has significant effect on the properties of the nanocomposite. A micromechanics model based on the Mori-Tanaka formulation was used to predict the results obtained experimentally. The comparison of theoretical/numerical and experimental results indicates that the Mori-Tanaka formulation may be a useful tool in predicting these properties.Copyright © 2010 by ASME

Rolls of flexible displays or electronic paper have recently been prepared by a high-speed roll-to-roll manufacturing process based on SiPix's novel Microcup® and top-sealing technologies.1-5 Both Microcup® electrophoretic displays (EPDs) and LCDs have been demonstrated. The display rolls are format flexible and may be cut into desirable size and shape for a variety of applications. High-performance flexible passive-matrix Microcup® EPDs having a wide range of threshold voltages have also been demonstrated.

Rolls of flexible electrophoretic panels have been prepared by the SiPix roll-to-roll manufacturing process based on novel Microcup® and top-sealing technologies. The resultant Microcup® passive matrix electrophoretic displays (PMEPDs) and a-Si TFT active matrix electrophoretic displays (AMEPDs) have shown outstanding contrast ratio, switching rate, image bistability, threshold characteristics, grayscale capability, operation temperature latitude, and physicomechanical properties.