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The use of hollow airfoils in turbomachinery applications, in particular fans and turbines, is an essential element in reducing the overall engine weight. However, state-of-the-art airfoil geometries are of low aspect ratio and exhibit unique characteristics associated with plate like modes. These modes are characterized by a chordwise form of bending and high modal density within the engine operating speed range. These features combined with the mistuning effects resulting from manufacturing tolerances make accurate frequency and forced response predictions difficult and increase the potential for High Cycle Fatigue (HCF) durability problems. The present paper summarizes the results of an experimental test program on internal damping of hollow bladelike specimens. Friction damping is provided via sheet metal devices configured to fit within a hollow cavity with various levels of preload. The results of the investigation indicate that such devices can provide significant levels of damping, provided the damper location and preload is optimized for the modes of concern. The transition of this concept to actual engine hardware would require further optimization with regard to wear effects and loss of preload particularly in applications where the preload is independent of rotational speed. Excellent agreement was achieved between the experimental results and the analytical predictions using a microslip friction damping model.

To evaluate the clinical application of arthroscopy in the diagnosis and treatment of anterior impingement syndrome of the ankle joint in physical workers.A retrospective study was carried out at the Department of Orthopedics, the First Hospital affiliated to Nanhua University, Hengyang, China from March 2005 to December 2011. Seventeen cases of anterior impingement syndrome of the ankle joint were confirmed, and treated through arthroscopy. All these patients conformed to regular follow-up postoperatively, and clinical details, as well as postoperative prognosis were retrieved and analyzed retrospectively. The efficacy was evaluated by the American Orthopedic Foot and Ankle Society (AOFAS) hindfoot-ankle scoring system, and pain relief was assessed by visual analogue scoring (VAS).Anterolateral impingement syndrome was found in 11 patients, anteromedial impingement syndrome in 4, while anterior impingement syndrome in 2 via arthroscopic examination. The VAS was reduced from 5.2-1.1, and the AOFAS score was elevated from 76.4-95.8 postoperatively; both of which demonstrated statistical differences when compared to preoperative scores. It was also found that concomitant cartilage damage was an indicator of poor prognosis in arthroscopic treatment of impingement syndrome of the ankle joint.Satisfactory results could be achieved for physical workers with anterior impingement syndrome treated by arthroscopy. As the cartilage damage is an indicator of poor prognosis, an early operation is advocated when the prognosis of anterior impingement syndrome is confirmed.

To investigate the surgical techniques and results of open reduction and internal fixation for the treatment of Sanders type III, IV calcaneal fractures.From January 2004 to January 2010, 58 feet of Sanders type III, IV in 51 patients were treated with open reduction and plate fixation through L incision. There were 29 males and 22 females,the age ranged from 17 to 58 years with an average of 29.5 years old. The time between injury and operation ranged from 7 to 14 days (mean, 10 days). All the patients underwent systematic CT scan with coronal and horizontal images and sagittal reconstruction. The classification of the fractures by the Sanders scale showed that there were 26 feet of type III, 32 feet of type IV. The Böhler angle and Gissane angle were compared before and after operation. The clinical results were evaluated with the Maryland foot score: pain (45 scores), function (55 scores: distance walked 10 scores, stability 4, support 4, limp 4, shoes 10, stairs 4, terrain 4, cosmesis 10, motion 5).All 58 feet in 51 patients were followed up,and the duration ranged from 6 to 24 months,with an average of 13 months. The incidence of complications was 13.8% (8/58). Incision superficial necrosis in 2 feet,choronicity pain in 4 feet,subtalar joint arthrositis of advanced stage in 2 feet. According to Maryland foot score, the results were excellent in 23 feet, good in 27, fair in 5, poor in 3.The surgical techniques and results of internal fixation to fractures are related to anatomic features of calcaneus and their injury mechanism. It is an effective method for the treatment of calcaneal fractures with Sanders type III, IV.

The use of hollow airfoils in turbomachinery applications, in particular fans and turbines, is an essential element in reducing the overall engine weight. However, state–of–the–art airfoil geometries are of low aspect ratio and exhibit unique characteristics associated with plate–like modes. These modes are characterized by a chordwise form of bending and high modal density within the engine operating speed range. These features combined with the mistuning effects resulting from manufacturing tolerances make accurate frequency and forced response predictions difficult and increase the potential for High Cycle Fatigue (HCF) durability problems. The present paper summarizes the results of an experimental test program on internal damping of hollow blade–like specimens. Friction damping is provided via sheet metal devices configured to fit within a hollow cavity with various levels of preload. The results of the investigation indicate that such devices can provide significant levels of damping provided the damper location and preload is optimized for the modes of concern. The transition of this concept to actual engine hardware would require further optimization with regard to wear effects and loss of preload particularly in applications where the preload is independent of rotational speed. Excellent agreement was achieved between the experimental results and the analytical predictions using a micro–slip friction damping model.