Dissertation > Excellent graduate degree dissertation topics show

Research on the Application of the Mento-Carlo Simulation Based on Importance Sampling Method in the Analysis of Probabilistic Fracture Mechanics

Author: ZhaoLei
Tutor: GaoZengLiang
School: Zhejiang University of Technology
Course: Chemical Process Equipment
Keywords: probabilistic fracture mechanics(PFM) Monte-Carlo(MC)simulation importance sampling surface crack plate combined loading
CLC: TQ050
Type: Master's thesis
Year: 2013
Downloads: 12
Quote: 0
Read: Download Dissertation


Reactor pressure vessels and other large equipments which usually limited by manufacturing processes, are inevitably contains defects, the safety of those structures are related to uncertainties such as initial crack location and size, the material properties and fracture toughness, etc. Probabilistic fracture mechanics (PFM) methodology by considering these uncertainties as random variables, quantitatively evaluates the structure safety in the form of failure probability. As a common numerical simulation, Monte-Carlo (MC) simulation has been increasingly applied in the field of PFM analysis, however, it was mainly limited to simple-sampling-based MC simulation for the existing research, which, in order to ensure the precision, always low in efficiency as it requires a large number of iterations. A PFM analysis program based on the MC simulation of importance sampling is developed. Using the program, the PFM analysis of the plate under combined tension and bending, combined primary stress and secondary stress are discussed.(1) Combined with probability theory, random number generator program is developed, and the random numbers generated from the program are tested. The importance sampling method, including the structure of the importance density function and the solutions for design points are studied. C languages are used for developing PFM analysis programs based on importance sampling MC simulation. Through an example analysis, it’s indicated that the optimal coefficient of variation (COV) of the importance density function equal to the COV of the probability density function can get the most accurate results.(2) The stress intensity factor and J-integral of the crack tip are estimated for the plates under combined tension and bending with different crack shapes and different crack depths, the results are compared with the finite elements results. Furthermore, the failure probability based on both linear and non-linear crack initiation criteria are calculated. Comparisons of the failure probability between different failure criteria under various load ratios are discussed. The results show that the stress intensity factor and the J-integral are reliable; under a giving failure criterion, the load level and the failure criteria have significant effect on the failure probability. However, the load ratio makes a little contribution to the failure probability for a given failure criterion. As the load ratio, λ increases, the maximum failure probability corresponding to the model appears crack depth a/t becomes smaller, but the maximum failure probability occurred in the plates with crack depth a/t=0.2~0.4.(3) The double criterions of R6are applied for calculating the failure probability of the plates under various load ratios and temperature field with different crack shapes, different crack depths under different number of iterations. Comparisons of the failure probability between the simple sampling method and the importance sampling method under different crack depths, a/t and load ratios, A are studied. The results show that the importance sampling method can effectively improve the calculating efficiency. When0<λ<1, the maximum failure probability appeared in the plates with crack depth a/t=0.3~0.4. Sensitivity analysis shows that the effective measures with improving the fracture toughness, reducing the loads and improving the level of crack detection, can enhance the reliability of structure with defects.

Related Dissertations

  1. Heat Transfer Performance of the Metallic Honeycomb and Regenerative Cooling Channel,V215.4
  2. Research and Simulation on Droplet Distribution in φ38mm Pulsed Sieve-Plate Extraction Column,TQ028.3
  3. Solid-State Fermentation Process for Production of Antimicrobial Lipopeptide by Bacillus Amyloliquefaciens ES-2-4,TQ936.16
  4. Research on Control Algorithm of Ball&Plate System,TP13
  5. The Efficacy of Locking Plate and Anatomic Plate in Treatment of Distal Femur Fractures,R687.3
  6. Preliminary Effects of Clavicular Hook Plate Technique on Treating Acromioclavicular Joint Dislocation,R687.3
  7. Analysis on Curative Effect of Internal Fixation of Femoral Shaft Fracture Intramedullary Interlocking Nail and Compression Plate,R687.3
  8. Open reduction and internal fixation combined with bone intra-articular calcaneal fractures efficacy analysis,R687.3
  9. Research on the Fault Tectonic Style and Main Fault Sealing of Western Huimin Depression,P542.3
  10. Research on License Plate Location Algorithm of License Plate Recognition System,TP391.41
  11. Study on the Stress of Distribution in Surrounding Rock and Anti-Rockburst Design in Boundary Coal Stope,TD311
  12. Research of License Plate Recognition Based on Rough Sets and Fuzzy SVM,TP391.41
  13. Correlation of Single Nucleotide Polymorphisms of NPR3 Gene and COL11A2 Gene with Idiopathic Short Stature,R723
  14. The Research on Mammographic Images Registration,TP391.41
  15. Vehicle License Plate Recognition Algorithm Based on the PowerPC Architecture,TP391.41
  16. Preparation of Novel Environment-Friendly Sticky Insect Glue,TQ437
  17. Research on Kinematics and Dynamics Analysis and Structural Optimization of Compound Pendulum Jawbreaker,TD451
  18. The Model Research and System Implementation of Plate Mill AGC and Automatic Rolling,TG334.9
  19. The Effect of Rolling and Cooling Ways on the Microstructure and Mechanical Property of Extra-thick Steel Plate Q460,TG335.5
  20. The Coherence Analysis of Plate Rotation and Paleomagnetic Declination Change,P318.44
  21. Study on Non-linear Vibration of Honeycomb Sandwich Plate with Simplify Supported,O322

CLC: > Industrial Technology > Chemical Industry > General issues > Chemical machinery and apparatus, equipment > General issues
© 2012 www.DissertationTopic.Net  Mobile