• Composites Research
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• v.17 no.3
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• pp.29-37
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• 2004

The aeroelastic stability analysis of composite bearingless rotors is investigated using a large deflection beam theory in hover. The bearingless rotor configuration consists of a single flexbeam with a wrap-around type torque tube and the pitch links located at the leading edge and trailing edge of the torque tube. The outboard main blade, flexbeam and torque tube are all assumed to be an elastic beam undergoing flap bending, lead-lag bending, elastic twist and axial deflections, which are discretized into beam finite elements. For the analysis of composite bearingless rotors, flexbeam is assumed to be a rectangular section made of laminate. Two-dimensional quasi-steady strip theory is used for aerodynamic computation. The finite element equations of motion for beams are obtained from Hamilton's principle. The p-k method is used to determine aeroelastic stability boundary. Numerical results are presented for selected bearingless rotor configurations based on the lay-up of laminae in the flexbeam and pitch links location. A systematic study is made to identify the importance of the stiffness coupling terms on aeroelastic stability for various fiber orientation and for different configuration.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.28 no.3
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• pp.358-363
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• 2024

Backgrounds/Aims: Pancreaticoduodenectomy (PD) is being performed more frequently. A pancreaticojejunostomy (PJ) leak is the major determinant of patient outcomes. An omental flap around PJ might improve postoperative outcomes. Methods: A prospective randomized controlled trial was planned at PGIMER, Chandigarh. Fifty-eight patients meeting the criteria were included in the study. Group A underwent PD with omental roll-up and group B underwent standard PD. Results: The mean age of patients in group A was 57.1 ± 14.3 years and 51.2 ± 10.7 in group B. Jaundice (p = 0.667), abdominal pain (p = 0.69), and co-morbidities were equal among the groups. The body mass index of patients in group B was higher at 24.3 ± 5.4 kg/m² (p = 0.03). The common bile duct diameter (12.6 ± 5.3 mm vs. 17.2 ± 10.3 mm, p = 0.13) and the pancreatic duct diameter (4.06 ± 2.01 mm vs. 4.60 ± 2.43 mm, p = 0.91) were comparable. The intraoperative blood loss (mL) was significantly higher in group B (233.33 ± 9.57 vs. 343.33 ± 177.14, p = 0.04). Drain fluid amylase levels on postoperative day (POD) 1 (p = 0.97) and POD3 (p = 0.92) were comparable. The rate of postoperative pancreatic fistula (POPF) grade A (p ≥ 0.99) and grade B (p = 0.54) were comparable. The mean postoperative length of stay among was similar (p = 0.89). Conclusions: An omental wrap can be performed without increase in complexity of the procedure. However, its utility in preventing POPFs and morbidity remains unclear.