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Effect of Hinge Stiffness on Flutter Characteristics of Flat Plate Wing with Flap
Pratik Shrestha,Min-Soo Jeong,In Lee 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.4
Flutter of flight vehicle structure can lead to catastrophic structural failure of aircraft. For this reason, aeroelastic simulation should be performed to understand flutter characteristics and to avoid any disastrous event which may occur due to such dynamic aeroelastic phenomenon. In this paper, the stiffness of the hinge, connecting the lifting surface to the control surface, is examined to see its effect on flutter characteristics by performing aeroelastic analysis. Flat plate wing with flap is modeled using MSC. Patran Flight Loads. Modal and flutter analysis of the wing for varying hinge stiffness is conducted using MSC.NASTRAN solver. P-k method is used for carrying out flutter analysis in MSC.NASTRAN solver. Results obtained from the analysis shows improved flutter characteristics with increase in hinge stiffness.
Pratik Shrestha,Jin-Hyuk Kim,Yurim Park,Chun-Gon Kim 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11
Low velocity impacts can cause barely visible impact damages on composite structure which are difficult to detect through conventional non-destructive inspection approach. Therefore continuous structural health monitoring (SHM) of the composite structure is needed to identify such impacts. In this paper, impact localization on composite plate is investigated using fiber Bragg grating (FBG) sensors while the structure is being excited using a shaker to simulate operational noise conditions. A high speed FBG interrogator is used to sample the impact signals at 100 kHz and reference database impact localization algorithm is used for estimating the location of the impact point. Moreover, through the present study it is demonstrated that even under simulated noise conditions the use of FBG sensors together with reference database algorithm can effectively localize the impact location on the composite specimen with maximum localization error of less than 35 mm from the actual impact location.
Composite Structure Damage Detection Using FBG Sensor and Reference Database Algorithm
Pratik Shrestha,Jin-Hyuk Kim,Yurim Park,Chun-Gon Kim 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4
Continuous structural health monitoring (SHM) instead of conventional non-destructive inspection (NDI) of the composite structure is needed to detect and localize low velocity impacts which can cause barely visible impact damages (BVID). Furthermore, SHM system to identify occurrence of damage due to such low velocity impact is highly desirable. In this paper, damage detection on composite plate is investigated using fiber Bragg grating (FBG) sensors. A high speed FBG interrogator is used to sample the response signals from the FBG sensor at 100 kHz and a damage detection algorithm based on similarity comparing reference database method is used for identifying undamaged or damaged state of the composite specimen. Moreover, through the present study it is demonstrated that FBG sensors together with reference database algorithm are suitable not only for localizing the impact location on the composite specimen but also for detecting damage on the composite specimen.
Giant leiomyoma in distal, intra-thoracic oesophagus: Is laparoscopic approach feasible?
Pratik Biswas,Vishakha Kalikar,Tanveer Majeed,Roy Patankar 소화기인터벤션의학회 2021 International journal of gastrointestinal interven Vol.10 No.3
Leiomyomas are the most common benign tumor of the oesophagus. symptomatic patients are candidates for excision, we have discussed a case report of a 43-year-old male patient who had complains of progressive dysphagia. Imaging studies suggested a distal oesophageal mass with calcific foci. The tumor was enucleated laparoscopically with an operative time of 160 minutes. The patient was gradually started on oral feeds from the 3rd postoperative day after an upper gastrointestinal contrast study. The patient was discharged on the 5th postoperative day. We found this minimally invasive approach to be effective with a shorter hospital stay and a faster recovery as compared to a thoraco abdominal approach.
Pratik Suthar,Sonal Shah,Pushkar Waknis,Gandhali Limaye,Aditi Saha,Pranav Sathe 대한구강악안면외과학회 2020 대한구강악안면외과학회지 Vol.46 No.1
Objectives: The need for proper wound closure is of paramount importance after any intra-oral surgery. Various wound closure techniques have been described in literature using traditional non-absorbable suture materials. These include like synthetic absorbable sutures, surgical staples and tissue adhesives. Cyanoacrylates are among the most commonly used biocompatible tissue adhesives. To evaluate and compare intraoral wound healing using 3-0 silk sutures and n-butyl-2-cyanoacrylate after alveoloplasty. Materials and Methods: A total of 20 patients requiring bilateral alveoloplasty in the same arch (upper or lower) were included in this study. Patients with any pre-existing pathology or systemic disease were excluded. After alveoloplasty was performed, the wound was closed using 3-0 braided silk sutures on one side, and using n-butyl-2-cyanoacrylate bio adhesive on the other side. Patients were evaluated based on the following parameters: time required to achieve wound closure; the incidence of immediate and postoperative hemostasis; the time to the use of the first rescue medication; the side where pain first arises; and the side where wound healing begins first. Results: Compared to 3-0 silk sutures, cyanoacrylate demonstrated better hemostatic properties, reduced operative time, reduced postoperative pain and better wound healing. Conclusion: These data suggest that cyanoacrylate glue is an adequate alternative to conventional sutures to close the surgical wound after alveoloplasty, and better than are 3-0 silk sutures.
Pratik Shrestha,Jin-Hyuk Kim,Yurim Park,Chun-Gon Kim 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.4
Composite materials are widely being used as an alternative to conventional materials for their superior material properties. However, these material have damage mechanism significantly differing from the conventional materials, which makes it considerably challenging to inspect for damages though traditional structural maintenance approach. Low velocity impacts on composite materials can cause barely visible impact damages, hence continuous structural health monitoring (SHM) of the composite structure is needed to identify such impacts. Therefore, in this paper impact localization on composite plate is investigated using fiber Bragg grating (FBG) sensors. A high speed FBG interrogator is used to sample the impact signals at 100 kHz and reference database impact localization algorithm is used to localize the impact point. Moreover, through the present study it is demonstrated that using FBG sensors can effectively localize the impact location on the composite specimen with maximum localization error limited to within 28 mm of the actual impact location.
Effect of Inboard and Outboard Folding Angles on Aeroelastic Characteristics of a Folding Wing
Pratik Shrestha,Min-Soo Jeong,Eun-Ho Kim,In Lee,Jae-Sung Bae 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.11
Morphing aircrafts such as folding wing can fly efficiently at varying flight conditions and therefore they have the potential to replace existing fixed wing aircrafts. Structural changes in aircrafts wing form can have vast effect on the structural and aerodynamic characteristics of folding wing. Dynamic aeroelastic instability such as flutter of flight vehicle structure can lead to catastrophic structural failure of aircraft. For this reason, flutter characteristics should be thoroughly investigated and research needs to be performed to determine possible means of improving flutter characteristics of morphing wings. In this paper, flutter characteristics of baseline folding wing with varying inboard folding angle is investigated and validated, then parametric study is carried out by varying outboard folding angle. Folding wing is modeled using MSC. Patran Flight Loads. Flutter analysis of the flat plate folding wing is performed using P-k method in MSC.NASTRAN solver. Results obtained from the flutter analysis demonstrates that up to certain inboard folding angle flutter speed improves with the increase of inboard wing folding angle and through combination of inboard and outboard folding angle optimal flutter speed can be achieved.
Giant leiomyoma in distal, intra-thoracic oesophagus: Is laparoscopic approach feasible?
Pratik Biswas,Vishakha Kalikar,Tanveer Majeed,Roy Patankar 소화기인터벤션의학회 2021 Gastrointestinal Intervention Vol.10 No.3
Leiomyomas are the most common benign tumor of the oesophagus. symptomatic patients are candidates for excision, we have discussed a case report of a 43-year-old male patient who had complains of progressive dysphagia. Imaging studies suggested a distal oesophageal mass with calcific foci. The tumor was enucleated laparoscopically with an operative time of 160 minutes. The patient was gradually started on oral feeds from the 3rd postoperative day after an upper gastrointestinal contrast study. The patient was discharged on the 5th postoperative day. We found this minimally invasive approach to be effective with a shorter hospital stay and a faster recovery as compared to a thoraco abdominal approach.