A ductile fracture criterion is introduced into numerical simulation to predict viscous pressure forming limit of the automotive body aluminum alloy 6k21-T4. The material constant in the ductile fracture criterion is ...A ductile fracture criterion is introduced into numerical simulation to predict viscous pressure forming limit of the automotive body aluminum alloy 6k21-T4. The material constant in the ductile fracture criterion is determined by the combination of the viscous pressure bulging (VPB) test with numerical simulation. VPB tests of the aluminum alloy sheet are carried out by using various elliptical dies with different ratios of major axis to minor axis(β), and the bugling processes are simulated by the aid of the finite element method software LS-DYNA3D. On the basis of the stress and strain calculated from numerical simulations, the forming limits of bulging specimens obtained are predicted by the ductile fracture criterion, and compared with experimental results. The fracture initiation site and the minimal thickness predicted by the ductile fracture criterion are in good agreement with the experimental results.展开更多
Indroduction: National Aids control Organisation in India implementing National AIDS control?program uses WHO’s immunological criteria to screen virological failure. Using immunological criteria to detect virological...Indroduction: National Aids control Organisation in India implementing National AIDS control?program uses WHO’s immunological criteria to screen virological failure. Using immunological criteria to detect virological failure has to be assessed. Predicting virological failure with immunological criteria in resource limited settings had low sensitivity. Factors that influence the outcome are studied. Methods: Retrospective study in tertiary care centre for HIV and TB, Chennai, India. Out of 35,044 on ART between January 2008 and September 2009, 452 suspected immunological failures were referred. 273 screened for virological failure.?Frequency, sensitivity/specificity, positive/negative predictive values, chi-square test, odds-ratio, independent sample t test for viral load greater than 10,000 and 1000 of each immunological criterion using Epi-Info and SPSS version 19. Results: 172 had virological failure (62.09%). Average age of failed was 37.33. Single criteria’s sensitivity was 60 to 84 for detecting virolological failure. Two or more criteria had specificity 55 to 79. Combination of two or more criteria increased odds ratio for virological failure. Positive predictive value was above 63 for all criteria. PPV was above 80 to the criterion all three positive. Conclusions: ART naive patients with >95% adherence the sensitivity of immunological criteria to detect virological failure is three times than earlier studies. Combination of criteria is more significantly associated with virological failure. Odds ratio doubled for two or more combination of criteria. Immunological criteria is affordable/acceptable for screening virological failure, with adherence > 95% and longer the duration of ART.展开更多
In this work, forming limit diagram for aluminum alloy 3105 is performed experimentally and forming limit based on stress (FLSD) calculated from strains that resulted from experimental procedure. In addition, numerica...In this work, forming limit diagram for aluminum alloy 3105 is performed experimentally and forming limit based on stress (FLSD) calculated from strains that resulted from experimental procedure. In addition, numerical prediction by ductile fracture criteria using simulation is considered and it is shown that they are well suited with the experimental results. The strain paths from finite element simulations are found fairly acceptable to represent both sides of the FLD.展开更多
文摘A ductile fracture criterion is introduced into numerical simulation to predict viscous pressure forming limit of the automotive body aluminum alloy 6k21-T4. The material constant in the ductile fracture criterion is determined by the combination of the viscous pressure bulging (VPB) test with numerical simulation. VPB tests of the aluminum alloy sheet are carried out by using various elliptical dies with different ratios of major axis to minor axis(β), and the bugling processes are simulated by the aid of the finite element method software LS-DYNA3D. On the basis of the stress and strain calculated from numerical simulations, the forming limits of bulging specimens obtained are predicted by the ductile fracture criterion, and compared with experimental results. The fracture initiation site and the minimal thickness predicted by the ductile fracture criterion are in good agreement with the experimental results.
文摘Indroduction: National Aids control Organisation in India implementing National AIDS control?program uses WHO’s immunological criteria to screen virological failure. Using immunological criteria to detect virological failure has to be assessed. Predicting virological failure with immunological criteria in resource limited settings had low sensitivity. Factors that influence the outcome are studied. Methods: Retrospective study in tertiary care centre for HIV and TB, Chennai, India. Out of 35,044 on ART between January 2008 and September 2009, 452 suspected immunological failures were referred. 273 screened for virological failure.?Frequency, sensitivity/specificity, positive/negative predictive values, chi-square test, odds-ratio, independent sample t test for viral load greater than 10,000 and 1000 of each immunological criterion using Epi-Info and SPSS version 19. Results: 172 had virological failure (62.09%). Average age of failed was 37.33. Single criteria’s sensitivity was 60 to 84 for detecting virolological failure. Two or more criteria had specificity 55 to 79. Combination of two or more criteria increased odds ratio for virological failure. Positive predictive value was above 63 for all criteria. PPV was above 80 to the criterion all three positive. Conclusions: ART naive patients with >95% adherence the sensitivity of immunological criteria to detect virological failure is three times than earlier studies. Combination of criteria is more significantly associated with virological failure. Odds ratio doubled for two or more combination of criteria. Immunological criteria is affordable/acceptable for screening virological failure, with adherence > 95% and longer the duration of ART.
文摘In this work, forming limit diagram for aluminum alloy 3105 is performed experimentally and forming limit based on stress (FLSD) calculated from strains that resulted from experimental procedure. In addition, numerical prediction by ductile fracture criteria using simulation is considered and it is shown that they are well suited with the experimental results. The strain paths from finite element simulations are found fairly acceptable to represent both sides of the FLD.
