Three-dimensional effects influencing failure in bend-free, variable stiffness composite pressure vessels

2020 ◽  
pp. 113346
Author(s):  
Shahrzad Daghighi ◽  
Paul M. Weaver
Keyword(s):  
Three Dimensional ◽  
Variable Stiffness ◽  
Free Variable ◽  
Pressure Vessels ◽  
Dimensional Effects ◽  
Composite Pressure Vessels

FAILURE PERFORMANCE OF BEND-FREE VARIABLE STIFFNESS COMPOSITE PRESSURE VESSELS

2021 ◽  
Author(s):  
SHAHRZAD DAGHIGHI ◽  
PAUL M. WEAVER
Keyword(s):  
Failure Load ◽  
Three Dimensional ◽  
Variable Stiffness ◽  
Failure Criteria ◽  
Free Variable ◽  
Pressure Vessels ◽  
Design Factor ◽  
Constant Stiffness ◽  
Bending Stresses ◽  
Composite Pressure Vessels

Pressure vessels are designed to store liquids and gases and have various applications spanning from chemical plants to automotive and aerospace industries. Currently, lightweight composite pressure vessels are desirable, especially in transportation industry applications because of their subsequent benefits in fuel consumption, cost and environmental issues. Using composite materials for pressure vessels along with advanced manufacturing technologies such as automated fiber placement provides excellent scope to tailor stiffness through the structural surface using fiber steering to achieve desirable structural performance. Recently, variable angle tow (VAT) technology has been used to suppress bending in super ellipsoids of revolution composite pressure vessels, resulting in minimizing the inefficient bending stresses and deformations and increasing their load-carrying capacity. It is worth noting that such geometries can provide excellent packing efficiency. These advantages make the bend-free super ellipsoids of revolution composite pressure vessels potential candidates for the next generation of pressure vessels. Therefore, their failure performance as the most important design factor should be studied carefully due to safety reasons. In this study, the maximum allowable internal pressure for VAT bend-free ellipsoidal pressure vessels, using the first-ply failure based on both Tsai-Wu and three-dimensional invariant-based failure criteria is determined. Subsequently, VAT bend-free pressure vessels’ failure performance is compared against that obtained for conventional constant stiffness composite vessels. Among structures considered, the VAT bend-free composite vessel has the best failure performance. Moreover, the predicted failure load using the three-dimensional invariant-based failure criterion for the VAT bend-free design is 34% lower than the failure load predicted by the Tsai- Wu. Finally, the effect of various material properties on the difference in predicted failure load using these criteria is assessed. Results provide physical insight useful for designers in materials selection.

French RPV PTS Assessment: An Overview of EDF Research and Development in Progress on Thermalhydraulic, Materials and Mechanical Aspects

2003 ◽  
Author(s):  
Dominique Moinereau ◽  
Jean-Michel Frund ◽  
Henriette Churier-Bossennec ◽  
Georges Bezdikian ◽  
Alain Martin
Keyword(s):  
Structural Integrity ◽  
Three Dimensional ◽  
Crack Arrest ◽  
Pressure Vessels ◽  
Short Description ◽  
Constraint Effect ◽  
Materials Properties ◽  
Integrity Assessment ◽  
Pressurized Thermal Shock ◽  
Reactor Pressure

A significant extensive Research & Development work is conducted by Electricite´ de France (EDF) related to the structural integrity re-assessment of the French 900 and 1300 MWe reactor pressure vessels in order to increase their lifetime. Within the framework of this programme, numerous developments have been implemented or are in progress related to the methodology to assess flaws during a pressurized thermal shock (PTS) event. The paper contains three aspects: a short description of the specific French approach for RPV PTS assessment, a presentation of recent improvements on thermalhydraulic, materials and mechanical aspects, and finally an overview of the present R&D programme on thermalhydraulic, materials and mechanical aspects. Regarding the last aspect on present R&D programme, several projects in progress will be shortly described. This overview includes the redefinition of some significant thermalhydraulic transients based on some new three-dimensional CFD computations (focused at the present time on small break LOCA transient), the assessment of vessel materials properties, and the improvement of the RPV PTS structural integrity assessment including several themes such as warm pre-stress (WPS), crack arrest, constraint effect ....

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