Optimization of welding parameters of hot plate welded PC/ABS blends by using the Taguchi experimental design method

WOS: 000429869000006This study aims to investigate the influence of welding parameters in hot plate welding (HPW) process of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blends using Taguchi method. Three welding parameters, namely the plate temperature, heating time, and welding displacement, were optimized in terms of joint strength using the results of tensile tests. Taguchi experimental design method is implemented as a statistical design of experiment technique so as to set the optimum welding parameters and determine the optimal levels. For HPW of the specimens, the combination of process parameters based on three levels of L-9 orthogonal array was utilized. The signal to noise ratio and the analysis of variance were employed to find the optimum levels and to indicate the impact of the welding parameters on joint strength after tensile tests of the welded joints were carried out. It was shown that it might achieve the improved joint strength using 290 degrees C of plate temperature, 1.25 mm of welding displacement, and 25 s of heating time. For the optimized parameters, it was verified that the most effective factor on joint strength is plate temperature and second effective factor is welding displacement and heating time only slightly influenced on joint strength. After the optimum levels of process parameters are set, in order to demonstrate the effectiveness of Taguchi method, a confirmation run is also performed. An improvement by about 70% from initial welding parameters was observed, and joint efficiency has increased from 22.5% to 38.2% regarding base material properties

Application of the Taguchi method for the optimization of the strength of polyamide 6 composite hot plate welds

WOS: 000354792300007The purpose of this study is to investigate the influence of the welding parameters in the hot plate welding process of polymer composites, polyamide 6 glass fiber reinforcement 15 wt.-%, by using the Taguchi method. Four welding parameters, namely the plate temperature, heating time, welding displacement and welding time, were optimized under the consideration of the joint strength. The Taguchi approach of the parameter design was used as a statistical procedure to set the optimal welding parameters. For hot plate welding of the specimens, the combination of process parameters based on three levels of the L-9 orthogonal array was utilized. The signal to noise and the analysis of variance were employed to find the optimum levels and to indicate the impact of the welding parameters on joint strength by tensile tests of welded joints. It was shown that choosing 270 degrees C as plate temperature, 1.0 mm of weld displacement and 25 s of heating time, reveals an improved joint strength. For the optimized parameters it was verified that the welding time does not have a significant influence and the most effective factor on joint strength is the plate temperature. The weld displacement and heating time only slightly influenced the joint strength. A confirmation run was also performed to prove the effectiveness of the Taguchi method after determination of the optimum levels of the process parameters. The results showed that the joint strength was improved by about 27 % as compared to the initial welding parameters and the joint efficiency increased from 56 % to 71 %.Scientific Research Project Program of Ege UniversityEge University [BAP 2011 EMYO 001]; Scientific Research Project Program of Dokuz Eylul University, TurkeyDokuz Eylul University [BAP 2011.KB.FEN.026]; Ege UniversityEge University; Dokuz Eylul UniversityDokuz Eylul UniversityThis work was supported by the Scientific Research Project Program of Ege University (Project No. BAP 2011 EMYO 001) and Scientific Research Project Program of Dokuz Eylul University (BAP 2011.KB.FEN.026), Turkey. The authors would like to acknowledge the financial support provided by Ege University and Dokuz Eylul University. The authors also wish to express their sincere thanks to Ege University, Ege Vocational School, Rubber and Plastics Technology Laboratory for conducting hot plate welding trials and to Dokuz Eylul University, Department of Mechanical Engineering, Mechanics Laboratory for providing facilities to test tensile specimens of welded joints

Fatigue Damage in Composite Cylinders

In this study, optimal angle-ply orientation of symmetric composite cylinders under fatigue loading is investigated. The fiber-reinforced plastic cylinders were manufactured from E-glass/epoxy. The layers were manufactured symmetrically in [+/- 75 degrees](2), [+/- 60 degrees](2), [+/- 55 degrees](2), and [+/- 45 degrees](2) Orientations. Burst pressure of filament-wound composite cylinders under alternating pure internal pressure was measured experimentally. Internal fatigue pressure testing method was applied to the composite cylinders in closeended condition. For this study, a PLC controlled hydraulic pressure testing machine has been employed. The static burst pressure values of specimens were measured; subsequently, fatigue test pressure was applied in 70, 60, and 50% stress levels of burst pressure for each orientation. Damage propagations of the composite cylinders on these stress levels were observed as whitening, leakage, and final failure for [+/- 60 degrees](2), [+/- 55 degrees](2), and orientations. When the damage propagation of [+/- 75 degrees](2) angle-ply cylinder was observed, whitening and leakage did not occur and final failure occurred suddenly. Stress-cycle curves obtained from the tests are given in graphics. Experimental results reveal that variation in stress levels and the winding angles have considerable effects on final failure cycles, which is also presented graphically. The optimum winding angle for the composite pressure cylinders or vessels under internal fatigue pressure load was obtained as [+/- 45 degrees](2) orientation. POLYM. COMPOS., 31:707-713, 2010. (C) 2009 Society of Plastics Engineer

Safety of hospital discharge before return of bowel function after elective colorectal surgery

© 2020 BJS Society Ltd Published by John Wiley & Sons LtdBackground: Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods: A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien–Dindo classification system. Results: A total of 3288 patients were included in the analysis, of whom 301 (9·2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4–7) and 7 (6–8) days respectively (P < 0·001). There were no significant differences in rates of readmission between these groups (6·6 versus 8·0 per cent; P = 0·499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0·90, 95 per cent c.i. 0·55 to 1·46; P = 0·659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34·7 versus 39·5 per cent; major 3·3 versus 3·4 per cent; P = 0·110). Conclusion: Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients

Safety of hospital discharge before return of bowel function after elective colorectal surgery

Background: Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods: A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien\u2013Dindo classification system. Results: A total of 3288 patients were included in the analysis, of whom 301 (9\ub72 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4\u20137) and 7 (6\u20138) days respectively (P &lt; 0\ub7001). There were no significant differences in rates of readmission between these groups (6\ub76 versus 8\ub70 per cent; P = 0\ub7499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0\ub790, 95 per cent c.i. 0\ub755 to 1\ub746; P = 0\ub7659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34\ub77 versus 39\ub75 per cent; major 3\ub73 versus 3\ub74 per cent; P = 0\ub7110). Conclusion: Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients

Safety of hospital discharge before return of bowel function after elective colorectal surgery

Background Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien-Dindo classification system. Results A total of 3288 patients were included in the analysis, of whom 301 (9 center dot 2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4-7) and 7 (6-8) days respectively (P &lt; 0 center dot 001). There were no significant differences in rates of readmission between these groups (6 center dot 6 versus 8 center dot 0 per cent; P = 0 center dot 499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0 center dot 90, 95 per cent c.i. 0 center dot 55 to 1 center dot 46; P = 0 center dot 659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34 center dot 7 versus 39 center dot 5 per cent; major 3 center dot 3 versus 3 center dot 4 per cent; P = 0 center dot 110). Conclusion Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients

Safety and efficacy of non-steroidal anti-inflammatory drugs to reduce ileus after colorectal surgery

Background: Ileus is common after elective colorectal surgery, and is associated with increased adverse events and prolonged hospital stay. The aim was to assess the role of non-steroidal anti-inflammatory drugs (NSAIDs) for reducing ileus after surgery. Methods: A prospective multicentre cohort study was delivered by an international, student- and trainee-led collaborative group. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The primary outcome was time to gastrointestinal recovery, measured using a composite measure of bowel function and tolerance to oral intake. The impact of NSAIDs was explored using Cox regression analyses, including the results of a centre-specific survey of compliance to enhanced recovery principles. Secondary safety outcomes included anastomotic leak rate and acute kidney injury. Results: A total of 4164 patients were included, with a median age of 68 (i.q.r. 57\u201375) years (54\ub79 per cent men). Some 1153 (27\ub77 per cent) received NSAIDs on postoperative days 1\u20133, of whom 1061 (92\ub70 per cent) received non-selective cyclo-oxygenase inhibitors. After adjustment for baseline differences, the mean time to gastrointestinal recovery did not differ significantly between patients who received NSAIDs and those who did not (4\ub76 versus 4\ub78 days; hazard ratio 1\ub704, 95 per cent c.i. 0\ub796 to 1\ub712; P = 0\ub7360). There were no significant differences in anastomotic leak rate (5\ub74 versus 4\ub76 per cent; P = 0\ub7349) or acute kidney injury (14\ub73 versus 13\ub78 per cent; P = 0\ub7666) between the groups. Significantly fewer patients receiving NSAIDs required strong opioid analgesia (35\ub73 versus 56\ub77 per cent; P &lt; 0\ub7001). Conclusion: NSAIDs did not reduce the time for gastrointestinal recovery after colorectal surgery, but they were safe and associated with reduced postoperative opioid requirement

Safety of hospital discharge before return of bowel function after elective colorectal surgery

Background: Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function. Methods: A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien–Dindo classification system. Results: A total of 3288 patients were included in the analysis, of whom 301 (9·2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4–7) and 7 (6–8) days respectively (P &lt; 0·001). There were no significant differences in rates of readmission between these groups (6·6 versus 8·0 per cent; P = 0·499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0·90, 95 per cent c.i. 0·55 to 1·46; P = 0·659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34·7 versus 39·5 per cent; major 3·3 versus 3·4 per cent; P = 0·110). Conclusion: Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients

Safety of hospital discharge before return of bowel function after elective colorectal surgery

Background: Ileus is common after colorectal surgery and is associated with an increased risk of postoperative complications. Identifying features of normal bowel recovery and the appropriateness for hospital discharge is challenging. This study explored the safety of hospital discharge before the return of bowel function.Methods: A prospective, multicentre cohort study was undertaken across an international collaborative network. Adult patients undergoing elective colorectal resection between January and April 2018 were included. The main outcome of interest was readmission to hospital within 30 days of surgery. The impact of discharge timing according to the return of bowel function was explored using multivariable regression analysis. Other outcomes were postoperative complications within 30 days of surgery, measured using the Clavien-Dindo classification system.Results: A total of 3288 patients were included in the analysis, of whom 301 (9.2 per cent) were discharged before the return of bowel function. The median duration of hospital stay for patients discharged before and after return of bowel function was 5 (i.q.r. 4-7) and 7 (6-8) days respectively (P &lt; 0.001). There were no significant differences in rates of readmission between these groups (6.6 versus 8.0 per cent; P = 0.499), and this remained the case after multivariable adjustment for baseline differences (odds ratio 0.90, 95 per cent c.i. 0.55 to 1.46; P = 0.659). Rates of postoperative complications were also similar in those discharged before versus after return of bowel function (minor: 34.7 versus 39.5 per cent; major 3.3 versus 3.4 per cent; P = 0.110).Conclusion: Discharge before return of bowel function after elective colorectal surgery appears to be safe in appropriately selected patients