Next Generation Ductile Fracture Arrest Analyses for High Energy Pipelines Based on Detail Coupling of CFD and FEA Approach

2018 ◽  
Author(s):  
K. K. Botros ◽  
E. J. Clavelle ◽  
M. Uddin ◽  
G. Wilkowski ◽  
C. Guan
Keyword(s):  
Ductile Fracture ◽  
Test Data ◽  
Fracture Propagation ◽  
Crack Tip ◽  
Propagation Speed ◽  
High Energy ◽  
Computational Effort ◽  
Pipe Material ◽  
The Past ◽  
Toughness Parameter

Axial ductile fracture propagation and arrest in high energy pipelines has been studied since the early 1970’s with the development of the empirical Battelle Two-Curve (BTC) model. Numerous empirical corrections on the backfill, gas decompression models, and fracture toughness have been proposed over the past decades. While this approach has worked in most cases, the dynamic interaction between the decompression of the fluid in the vicinity of the crack tip and the behaviour of the pipe material as it opens to form flaps behind the crack has been very difficult to solve from a more fundamental approach. The effects of the pressure distribution on the flap inner surface making up the crack-driving force which drives the crack propagation speed has been suggested in the past, but due to intensive computational effort required, it was never realized. The present paper attempts to tackle this problem by employing an iterative solution procedure where the gas pressure field in the vicinity of the crack tip is accurately solved for by computational fluid dynamics (CFD) for a given flap geometry determined from a dynamic FEA model to render a new flap geometry. In this model a cohesive-zone element at the crack tip is employed as a representation of the material toughness parameter. The final outcome is the determination of the cohesive energy in the FEA (as a representation of the material toughness parameter) to match the measured fracture propagation speed for the specific case. A case study was taken from full-scale rupture test data from one of the pipe joints from the Japanese Gas Association (JGA) unbackfilled pipe burst test data conducted in 2004 on the 762 mm O.D., 17.5 mm wall thickness, Gr. 555 MPa (API 5L X80) pipe.

Ductile Fracture Resistance Measurements in High Grade Steels

2006 ◽  
Author(s):  
L. N. Pussegoda ◽  
A. Fredj ◽  
A. Fonzo ◽  
G. Demofonti ◽  
G. Mannucci ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Ductile Fracture ◽  
Fracture Resistance ◽  
Process Zone ◽  
Fracture Propagation ◽  
Crack Tip ◽  
Opening Angle ◽  
Displacement Curve ◽  
High Grade

Recent developments in ductile fracture resistance measures in high grade steels in the pipeline industry include the crack tip opening angle (CTOA) and “steady state” fracture propagation energy, using 3-point bend specimens. The CTOA has been found to be a function of specimen ligament size. With the availability of instrumented hammers, it became possible to resolve propagation energy using the load-displacement curve using a single specimen. This paper focuses on refining the steady state fracture propagation energy, using back-slotted Drop Weight Tear Test (DWTT) specimens. The study included numerical simulation of the dynamic response of back-slotted specimens. The significance of the back-slot in altering the stress/strain field ahead of the propagation crack is discussed. The numerical simulation was also used to determine the strain rate in the “process zone” of the crack tip during steady state fracture propagation.

Ductile Fracture Propagation and Arrest in Offshore Pipelines

1988 ◽  
Vol 41 (2) ◽  
pp. 85-95 ◽  
Author(s):  
G. Demofonti ◽  
A. Maresca ◽  
G. Buzzichelli
Keyword(s):  
Ductile Fracture ◽  
Fracture Propagation ◽  
Fracture Initiation ◽  
Correct Choice ◽  
Buried Pipelines ◽  
Offshore Pipelines ◽  
The Past ◽  
Research Institutes ◽  
Full Scale Tests ◽  
Main Effects

The problem of ductile fracture propagation in pipelines, already extensively studied in the past in the case of buried pipelines, has been receiving the close attentions of research institutes and companies in the last decade or so for offshore pipelines too; the aim is to allow a correct choice of toughness levels of the steels employed for such applications. The first studies in the field consisted essentially in model tests; more recently full-scale tests were performed, while at the same time the first attempts were made to interpret and model marine backfill. As a result the main effects of marine backfill on ductile propagation were put into evidence and quantified. In particular, because of the overpressure field generated around the pipe subsequently to fracture initiation, the marine backfill comes out to be more effective than soil in arresting a running fracture, and consequently very low toughness levels are required for offshore pipelines.

scholarly journals Effect of Charpy Striker Configuration on Low- and High-Energy NIST Verification Specimens

2018 ◽  
Vol 123 ◽  
Author(s):  
Enrico Lucon ◽  
Jolene Splett
Keyword(s):  
Test Data ◽  
Energy Levels ◽  
High Energy ◽  
Low Energy ◽  
Absorbed Energy ◽  
The Past ◽  
Edge Radius ◽  
Charpy Absorbed Energy ◽  
Certified Values

Charpy machines can be equipped with strikers having two different configurations, corresponding to an edge radius of 2 mm or 8 mm. Both striker types are covered by ASTM E23 and ISO 148-1. The effect of striker type on Charpy absorbed energy has been extensively investigated in the past, and clear evidence has been published showing that when using 8 mm strikers, absorbed energy (KV) tends to increase for specimens with KV ≥ 200 J. In this paper, we investigate how striking edge radius affects certified values and uncertainties for National Institute of Standards and Technology (NIST) low-energy and high-energy verification specimens. Test data from two low-energy and two high-energy Charpy lots, analyzed in a statistically rigorous manner, were somewhat contradictory and led to the decision to separately certify low-energy and high-energy lots for use with 2 mm and 8 mm strikers. This agrees with previous findings by other NIST researchers, who recommended individual certifications for the two strikers at all energy levels.

scholarly journals The emerging technology of biohybrid micro-robots: a review

2021 ◽  
Author(s):  
Zening Lin ◽  
Tao Jiang ◽  
Jianzhong Shang
Keyword(s):  
Self Assembly ◽  
Degrees Of Freedom ◽  
High Energy ◽  
Living Cells ◽  
Multiple Degrees Of Freedom ◽  
The Past ◽  
Great Prevalence ◽  
Performance Decline ◽  
High Energy Efficiency ◽  
Living Tissues

Abstract In the past few decades, robotics research has witnessed an increasingly high interest in miniaturized, intelligent, and integrated robots. The imperative component of a robot is the actuator that determines its performance. Although traditional rigid drives such as motors and gas engines have shown great prevalence in most macroscale circumstances, the reduction of these drives to the millimeter or even lower scale results in a significant increase in manufacturing difficulty accompanied by a remarkable performance decline. Biohybrid robots driven by living cells can be a potential solution to overcome these drawbacks by benefiting from the intrinsic microscale self-assembly of living tissues and high energy efficiency, which, among other unprecedented properties, also feature flexibility, self-repair, and even multiple degrees of freedom. This paper systematically reviews the development of biohybrid robots. First, the development of biological flexible drivers is introduced while emphasizing on their advantages over traditional drivers. Second, up-to-date works regarding biohybrid robots are reviewed in detail from three aspects: biological driving sources, actuator materials, and structures with associated control methodologies. Finally, the potential future applications and major challenges of biohybrid robots are explored. Graphic abstract

Predicting ductile fracture of cracked pipes using small punch test data

2021 ◽  
Vol 87 ◽  
pp. 104211
Author(s):  
Jong-Min Lee ◽  
Jin-Ha Hwang ◽  
Yun-Jae Kim ◽  
Jin-Weon Kim
Keyword(s):  
Ductile Fracture ◽  
Test Data ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test

scholarly journals Chlorine-free synthesis: An overview

2012 ◽  
Vol 84 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Pietro Tundo
Keyword(s):  
Climate Change ◽  
Industrial Revolution ◽  
High Energy ◽  
Special Topic ◽  
Ozone Layer Depletion ◽  
The Past ◽  
Process Chemistry ◽  
End Products ◽  
Chemical Strategies ◽  
Topic Issue

Since the Industrial Revolution, chlorine has featured as an iconic molecule in process chemistry even though its production by electrolysis of sodium chloride is very energy-intensive. Owing to its high energy and reactivity, chlorine allows the manufacture of chlorinated derivatives in a very easy way: AlCl3, SnCl4, TiCl4, SiCl4, ZnCl2, PCl3, PCl5, POCl3, COCl2, etc. in turn are pillar intermediates in the production of numerous everyday goods. This kind of chloride chemistry is widely used because the energy is transferred to these intermediates, making further syntheses easy. The environmental and health constraints (toxicity and eco-toxicity, ozone layer depletion) and the growing need for energy (energy efficiency, climate change) force us to take advantage from available knowledge to develop new chemical strategies. Substitution of chlorine in end products in compounds where “chlorine is used in the making” means that we avoid electrolysis as primary energetic source; this makes chemistry “without chlorine” considerably more difficult and illustrates why it has not found favor in the past. The rationale behind this Special Topic issue is to seek useful and industrially relevant examples for alternatives to chlorine in synthesis, so as to facilitate the development of industrially relevant and implementable breakthrough technologies.

scholarly journals Determination of Constraint-Modified J-R Curves for Carbon Steel Storage Tanks

2002 ◽  
Author(s):  
P.-S. Lam ◽  
Y. J. Chao ◽  
X.-K. Zhu ◽  
Y. Kim ◽  
R. L. Sindelar
Keyword(s):  
Carbon Steel ◽  
Test Data ◽  
Storage Tank ◽  
Closed Form Solution ◽  
Crack Tip ◽  
Form Solution ◽  
Fracture Parameter ◽  
Element Analysis ◽  
Crack Tip Constraint ◽  
Senb Specimen

Mechanical testing of A285 carbon steel, a storage tank material, was performed to develop fracture properties based on the constraint theory of fracture mechanics. A series of single edge-notched bend (SENB) specimen designs with various levels of crack tip constraint were used. The variation of crack tip constraint was achieved by changing the ratio of the initial crack length to the specimen depth. The test data show that the J-R curves are specimen-design-dependent, which is known as the constraint effect. A two-parameter fracture methodology is adopted to construct a constraint-modified J-R curve, which is a function of the constraint parameter, A2, while J remains the loading parameter. This additional fracture parameter is derived from a closed form solution and can be extracted from the finite element analysis for a specific crack configuration. Using this set of SENB test data, a mathematical expression representing a family of the J-R curves for A285 carbon steel can be developed. It is shown that the predicted J-R curves match well with the SENB data over an extensive amount of crack growth. In addition, this expression is used to predict the J-R curve of a compact tension specimen (CT), and reasonable agreement to the actual test data is achieved. To demonstrate its application in a flaw stability evaluation, a generic A285 storage tank with a postulated axial flaw is used. For a flaw length of 10% of the tank height, the predicted J-R curve is found to be similar to that for a SENB specimen with a short notch, which is in a state of low constraint. This implies that the use of a J-R curve from the ASTM (American Society for Testing and Materials) standard designs, which typically are high constraint specimens, may be overly conservative for analysis of fracture resistance of large structures.

scholarly journals RECENT ADVANCES IN SODIUM INTERCALATION POSITIVE ELECTRODE MATERIALS FOR SODIUM ION BATTERIES

2013 ◽  
Vol 06 (01) ◽  
pp. 1330001 ◽  
Author(s):  
JING XU ◽  
DAE HOE LEE ◽  
YING SHIRLEY MENG
Keyword(s):  
Electrode Materials ◽  
High Energy ◽  
Positive Electrode ◽  
Sodium Ion ◽  
Sodium Ion Batteries ◽  
Significant Progress ◽  
Layered Oxides ◽  
Solid State Physics ◽  
The Past ◽  
Positive Electrode Materials

Significant progress has been achieved in the research on sodium intercalation compounds as positive electrode materials for Na-ion batteries. This paper presents an overview of the breakthroughs in the past decade for developing high energy and high power cathode materials. Two major classes, layered oxides and polyanion compounds, are covered. Their electrochemical performance and the related crystal structure, solid state physics and chemistry are summarized and compared.

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