The main objective of this research was to examine the suitability of aluminium alloy to design a piston of an internal combustion engine for improvement in weight and cost reduction. The piston was modelled using Aut...The main objective of this research was to examine the suitability of aluminium alloy to design a piston of an internal combustion engine for improvement in weight and cost reduction. The piston was modelled using Autodesk Inventor 2017 software. The modelled piston was then imported into Ansys for further analysis. Static structural and thermal analysis were carried out on the pistons of the four different materials namely: Al 413 alloy, Al 384 alloy, Al 390 alloy and Al332 alloy to determine the total deformation, equivalent Von Mises stress, maximum shear stress, and the safety factor. The results of the study revealed that, aluminium 332 alloy piston deformed less compared to the deformations of aluminium 390 alloy piston, aluminium 384 alloy piston and aluminium 413 alloy piston. The induced Von Mises stresses in the pistons of the four different materials were found to be far lower than the yield strengths of all the materials. Hence, all the selected materials including the implementing material have equal properties to withstand the maximum gas load. All the selected materials were observed to have high thermal conductivity enough to be able to withstand the operating temperature in the engine cylinders.展开更多
Objective; TO observe the clinical outcome of total knee arthroplasty (TKA ) with posterior cruciate ligament (PCL ) retention in patients with severe varus deformity. Methods We reviewed the clinical treatment result...Objective; TO observe the clinical outcome of total knee arthroplasty (TKA ) with posterior cruciate ligament (PCL ) retention in patients with severe varus deformity. Methods We reviewed the clinical treatment results of primary TKA in patients with severe varus deformity (≥20°) between January 1990 and July 1995. All patients, suffered from ostecoarthritis, were performed on a single surgeon using a minimally constrained "Hybrid" Miller-Galante knees (MG-I). Cliniccal evaluation were assessed by using the Knee Society clinical rating system. The Student’s t test was used to analyse the data. Results At a mean follow-up of 6 years (4-9years), 56 knees in 38 patients were available for review. 5 patients (7 knees) lost follow-up and 3 patients (4 knees) died. The average knee score improved from 33 points before operation to 91 points in the latest follow-up with excellent results in 84% of all patients. The Knee Society functional score improved from 39 to 76 points. The improvements were statistically significant (P < 0. 01 ). A functionally acceptable range of motion (ROM) of more than 90° were achieved in 86% of all patients. Most of cases (50/56 ) had postoperative alignment inside the normal range of 5° to 7° valgus. The other 6 cases had postoperative residual deformity of 5°-10°varus. Total revision rate was 21 % (12 /56 ), the average revision time was 5. 5 years after surgery. Other complications included patellar subluxation in 1 case, anterior pain of knee in 4 cases, and superficial cellulitis in 1 case. No early or late infection, aseptic loosening or anterioposterior instability occurred in this series. Conclusion Severs varus deformity can he successfully corrected at the time of primary TKA by using PCL-retention prosthesis. There were more problems from postoperative medial-lateral instability of knee which contributed significantly to early failure after an average of 6. 0 years.展开更多
文摘The main objective of this research was to examine the suitability of aluminium alloy to design a piston of an internal combustion engine for improvement in weight and cost reduction. The piston was modelled using Autodesk Inventor 2017 software. The modelled piston was then imported into Ansys for further analysis. Static structural and thermal analysis were carried out on the pistons of the four different materials namely: Al 413 alloy, Al 384 alloy, Al 390 alloy and Al332 alloy to determine the total deformation, equivalent Von Mises stress, maximum shear stress, and the safety factor. The results of the study revealed that, aluminium 332 alloy piston deformed less compared to the deformations of aluminium 390 alloy piston, aluminium 384 alloy piston and aluminium 413 alloy piston. The induced Von Mises stresses in the pistons of the four different materials were found to be far lower than the yield strengths of all the materials. Hence, all the selected materials including the implementing material have equal properties to withstand the maximum gas load. All the selected materials were observed to have high thermal conductivity enough to be able to withstand the operating temperature in the engine cylinders.
文摘Objective; TO observe the clinical outcome of total knee arthroplasty (TKA ) with posterior cruciate ligament (PCL ) retention in patients with severe varus deformity. Methods We reviewed the clinical treatment results of primary TKA in patients with severe varus deformity (≥20°) between January 1990 and July 1995. All patients, suffered from ostecoarthritis, were performed on a single surgeon using a minimally constrained "Hybrid" Miller-Galante knees (MG-I). Cliniccal evaluation were assessed by using the Knee Society clinical rating system. The Student’s t test was used to analyse the data. Results At a mean follow-up of 6 years (4-9years), 56 knees in 38 patients were available for review. 5 patients (7 knees) lost follow-up and 3 patients (4 knees) died. The average knee score improved from 33 points before operation to 91 points in the latest follow-up with excellent results in 84% of all patients. The Knee Society functional score improved from 39 to 76 points. The improvements were statistically significant (P < 0. 01 ). A functionally acceptable range of motion (ROM) of more than 90° were achieved in 86% of all patients. Most of cases (50/56 ) had postoperative alignment inside the normal range of 5° to 7° valgus. The other 6 cases had postoperative residual deformity of 5°-10°varus. Total revision rate was 21 % (12 /56 ), the average revision time was 5. 5 years after surgery. Other complications included patellar subluxation in 1 case, anterior pain of knee in 4 cases, and superficial cellulitis in 1 case. No early or late infection, aseptic loosening or anterioposterior instability occurred in this series. Conclusion Severs varus deformity can he successfully corrected at the time of primary TKA by using PCL-retention prosthesis. There were more problems from postoperative medial-lateral instability of knee which contributed significantly to early failure after an average of 6. 0 years.
