Ductile tearing simulation of STS410 pipe fracture test under load-controlled large-amplitude cyclic loading: Part II – effect of load amplitude and sequence

2020 ◽  
Vol 240 ◽  
pp. 107363
Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Hune-Tae Kim ◽  
Yun-Jae Kim ◽  
Naoki Miura
Keyword(s):  
Cyclic Loading ◽  
Large Amplitude ◽  
Fracture Test ◽  
Load Amplitude ◽  
Ductile Tearing

Ductile Tearing Simulation of Circumferential Cracked Pipe Under Cyclic Loading Using Damage Criteria Determined by Monotonic Pipe Test Data

2018 ◽  
Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Naoki Miura ◽  
Yun-Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Ductile Fracture ◽  
Test Data ◽  
Strain Energy ◽  
Fracture Strain ◽  
Damage Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Damage Criteria

To evaluate the structural integrity of nuclear power plant piping, it is important to predict ductile tearing of circumferential cracked pipe from the view point of Leak-Before-Break concept under seismic conditions. CRIEPI (Central Research Institute of Electric Power Industry) conducted fracture test on Japanese carbon steel (STS410) circumferential through-wall cracked pipes under monotonic or cyclic bending load in room temperature. Cyclic loading test conducted variable experimental conditions considering effect of stress ratio and amplitude. In the previous study, monotonic fracture pipe test was simulated by modified stress-strain ductile damage model determined by C(T) specimen fracture toughness test. And, ductile fracture of pipe under cyclic loading simulated using damage criteria based on fracture strain energy from C(T) specimen test data. In this study, monotonic pipe test result is applied to determination of damage model based on fracture strain energy, using finite element analysis, without C(T) specimen fracture toughness test. Ductile fracture of pipe under variable cyclic loading conditions simulates using determined fracture energy damage model from monotonic pipe test.

Ductile Tearing of Welds in Pipe Submitted to Cyclic Loading

2017 ◽  
Author(s):  
Philippe Thibaux ◽  
Steven Cooreman ◽  
Antonio Carlucci ◽  
Johan Vekeman ◽  
Koen Van Minnebruggen ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Cyclic Loading ◽  
Flow Behavior ◽  
Base Material ◽  
Small Deformation ◽  
Automatic Identification ◽  
Ductile Tearing ◽  
Damage Models ◽  
Fracture Tests ◽  
Tearing Resistance

Flowlines and risers can be submitted to plastic deformation, sometimes cyclically, due to the installation technique, or sometimes due to exceptional events. In this case, a specific evaluation of defect acceptance in the girth weld is necessary. The present study investigates the possibility to predict ductile tearing during installation when the performed fracture mechanics tests are only high triaxiality specimens and that the effective application requires cyclic loading. A classical analysis is performed using DNV RP F108 to determine the acceptable defect size of for the case in which a pipe is submitted to cyclic loading. In the present investigation, tearing resistance was characterized with SENB specimens. An engineering critical assessment (ECA) was performed considering the size of the expected defects and the amount of plastic deformation to which the pipeline would be submitted. A validation of the ECA was performed by segment tests. While the application of ECA based on the fracture tests would predict ductile tearing with the considered defect, the results of segment tests only revealed blunting for the considered plastic deformation. It confirms the effect that in lower constraint conditions (like in segment tests), SENB test results are overly conservative. The tearing phenomenon was then simulated by the finite element method using two different damage models (Gurson-Tvergard-Needlemann and the Bai-Wierzbicki model) and compared to the experimental results. As the deformation at the crack tip is typically very large, one needs to have knowledge about the hardening behavior in the post-necking region. As this behavior cannot be directly deduced from standard measurements, an automatic identification procedure was developed to determine the post-necking flow behavior of the weld metal and the base material transverse to the weld. As reported in the literature, simplified models like Rambord-Osgood are then inadequate and model including two hardening zones is necessary: one for small deformation and one for large deformation. The calibration of the damage models was only performed on the tearing curve obtained from the SENB experiments, and the segment tests were then “blindly” simulated.

scholarly journals Analysis of Cumulative Damage Characteristics of Long Spiral Belled Pile under Horizontal Cyclic Loading at Sea

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Haian Liang ◽  
Hao Zeng ◽  
Kaiwei Cao ◽  
Chao Liu ◽  
Xinjun Cheng
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Power Function ◽  
Cumulative Damage ◽  
Model Parameters ◽  
Function Model ◽  
Load Amplitude ◽  
Cycle Times ◽  
Energy Dissipation Capacity ◽  
Energy Dissipation Coefficient

In order to study the cumulative damage and failure characteristics of long spiral belled pile under horizontal cyclic loading of offshore wind and waves, a series of indoor experiments on single piles under horizontal cyclic load were carried out. The cycle times as well as load amplitude at the same frequency were considered during the horizontal pseudo-static cyclic tests. On the basis of the distribution of pile deflection, bending moment, and Earth pressure around the pile, the pile-soil interaction was comprehensively discussed. The cumulative energy dissipation characteristics were introduced to describe the damage of test piles. Meanwhile, the effects of load amplitude and cycle times on the cumulative damage of long spiral belled piles were discussed. A power function model for energy dissipation coefficient prediction under multi-stage cyclic load was proposed. The results show that the horizontal peak bearing capacity of long spiral belled pile is increased by 57.2% and 40.4%, respectively, as compared with the straight pile and belled pile under the same conditions. The horizontal displacement mainly occurs at the upper part of the pile. Under the condition of limited cyclic times, the load amplitude has more significant effect on the bearing characteristics of the long spiral belled pile. In contrast to the straight pile and belled pile, the long spiral belled pile has better energy dissipation capacity, and the rank of the energy dissipation capacity of these three piles is long spiral belled pile > belled pile > straight pile. The power function model can well reflect the cumulative damage characteristics of long spiral belled pile under horizontal cyclic loading, and there is a good linear relationship between power function model parameters and load amplitude. The energy dissipation coefficient of long spiral belled pile with diverse cycle times at different mechanical stages of test pile is analysed. Then, the recommended power function model parameters according to different failure stages are proposed. The verification example indicates that the prediction results are close to the measured values with a calculation error of 22%. The prediction model can provide a certain reference for the application of long spiral belled pile in marine structures.

Comparison Between J and Collapse Load Approaches Applied to Fracture Test Results on Ni Base Alloy 600 Surface Cracked Plates

2010 ◽  
Author(s):  
Philippe Gilles ◽  
Yann Andrieu ◽  
Claude Amzallag
Keyword(s):  
Base Alloy ◽  
Initial Crack ◽  
Test Results ◽  
Collapse Load ◽  
Fracture Test ◽  
Ductile Tearing ◽  
Inconel 600 ◽  
Cracked Plates ◽  
Safety Margins ◽  
Fracture Assessment

The paper presents a fracture mechanics analyses of CT and surface cracked plate specimens (CCT) made from material Inconel 600. The main issue is to determine whether the plates fracture by ductile tearing or collapse with the aim of determining a simplified fracture assessment of steam generator partition plates. The paper compares J based analyses to several collapse load formulae. It is shown that estimating the tearing initiation load is almost unachievable in the present tests designed as demonstrative tests. It is also proven that most of the case collapse load formulae are very conservative. The results contribute to evidence that partition plates exhibit sufficient safety margins to failure up to the end of service life in spite of the presence of a very deep initial crack.

Four Points Bending Test on an EPR Type DMW Pipe Containing a Through-Wall Defect: Experimental and Numerical Analysis From Small Specimens Until Pipe Scale

2014 ◽  
Author(s):  
M. Bourgeois ◽  
S. Chapuliot ◽  
S. Marie ◽  
O. Ancelet ◽  
Y. Kayser
Keyword(s):  
Numerical Analysis ◽  
Ferritic Steel ◽  
Large Scale ◽  
Bending Test ◽  
Small Scale ◽  
Narrow Gap ◽  
Fracture Test ◽  
Ductile Tearing ◽  
Four Point Bending ◽  
Four Point Bending Test

Within the framework of European project STYLE [1], a fracture test on a pipe containing a through wall crack in a narrow gap Inconel Dissimilar Metals weld (welds named hereafter DMW) has been performed. The work is focusing on the Inconel - ferritic steel interface which is the weakest area of such welded pipes in front of ductile tearing. The study temperature is 300°C, which covers typical temperatures in components like hot pipes in the primary coolant system of pressurized water reactors. The four point bending test was carried out by the French Atomic Energy Commission and Alternative Energies (CEA), in order to study the mechanical properties and integrity of component such as the DMW pipes provided and designed by AREVA France. The observations made post-mortem showed a small 2.5 mm ductile tearing at the interface of Inconel and ferritic steel, and after this point, a large crack that has deviated from the interface to propagate in the Inconel and then in the stainless steel. The DMW Mock-up is presented with previous results concerning the mechanical characterizations of his constitutive materials. The second part of this paper is devoted to the four point bending test at 300°C: procedure, instrumentation and interpretation of large-scale test in terms of initiation and propagation of cracks. A comparison is made with tests performed at a smaller scale on multi-material CT specimens. The third part deals with first numerical analysis of fracture test. The results are interpreted on a small scale using finite element analysis to obtain the parameters of damage models that are needed for global approach. Finally, numerical approaches is presented and applied to simulate the fracture of the large-scale pipe. The aim of this paper is to propose and discuss the validity of new assessment methods of ductile propagation in a large scale pipe containing a through wall crack in a narrow gap dissimilar metal weld.

Fabrication and Fracture Test of Functionalized Graphene-PETI 5 Composite

2014 ◽  
Author(s):  
Adam McLaughlin ◽  
Byungki Kim
Keyword(s):  
Cyclic Loading ◽  
Fracture Strength ◽  
Room Temperature ◽  
Fuel Tank ◽  
Exfoliated Graphite ◽  
Functionalized Graphene ◽  
Fracture Test ◽  
Temperature Changes ◽  
The Matrix ◽  
The Ideal

The development of a composite cryogenic fuel tank is desirable for the creation of a reusable single-stage launch vehicle. The cyclic loading and temperature changes experienced during launch and re-entry conditions result in the microcracking of conventional composites. To increase the fracture strength of this composite, a property often limited by the matrix, the nanoplatelet known as graphene or exfoliated graphite, has been introduced. Three nanocomposites were produced using graphene and Phenylethynyl Terminated Imide oligomer (PETI-5). The nanocomposites were machined in to flexure samples and tested at room temperature. Results from these tests indicate that the ideal concentration of graphene in our PETI-5 nanocomposite is 0.08%.

Sign in / Sign up

Export Citation Format

Share Document