Development of Damage-Tolerant and Fracture-Resistant Materials by Utilizing the Material Inhomogeneity Effect

2019 ◽  
Vol 86 (11) ◽  
Author(s):  
O. Kolednik ◽  
R. Kasberger ◽  
M. Sistaninia ◽  
J. Predan ◽  
M. Kegl
Keyword(s):  
High Strength ◽  
Crack Arrest ◽  
Basic Mechanism ◽  
Hot Press ◽  
Crack Driving Force ◽  
Material Inhomogeneity ◽  
Interface Delamination ◽  
Press Bonding ◽  
Damage Tolerant ◽  
Force Concept

Abstract The improvement of fracture strength by insertion of thin, soft interlayers is a strategy observed in biological materials such as deep-see sponges. The basic mechanism is a reduction of the crack driving force due to the spatial variation of yield strength and/or Young's modulus. The application of this “material inhomogeneity effect” is demonstrated in this paper. The effectiveness of various interlayer configurations is investigated by numerical simulations under application of the configurational force concept. Laminated composites, made of high-strength tool steels as matrix materials and low-strength deep-drawing steel as interlayer material, were manufactured by hot press bonding. The number of interlayers and the interlayer thickness were varied. Fracture mechanics experiments show crack arrest in the first interlayer and significant improvements in fracture toughness, even without the occurrence of other toughening mechanisms, such as interface delamination. The application of the material inhomogeneity effect for different types of matrix materials is discussed.

scholarly journals Failure Analysis on a Collapsed Flat Cover of an Adjustable Ballast Tank Used in Deep-Sea Submersibles

2019 ◽  
Vol 9 (23) ◽  
pp. 5258
Author(s):  
Fang Wang ◽  
Mian Wu ◽  
Genqi Tian ◽  
Zhe Jiang ◽  
Shun Zhang ◽  
...  
Keyword(s):  
Deep Sea ◽  
Material Selection ◽  
High Strength ◽  
External Pressure ◽  
Element Analysis ◽  
Ballast Tank ◽  
Material Inhomogeneity ◽  
Comprehensive Properties ◽  
Ultimate Cause ◽  
Flat Cover

A flat cover of an adjustable ballast tank made of high-strength maraging steel used in deep-sea submersibles collapsed during the loading process of external pressure in the high-pressure chamber. The pressure was high, which was the trigger of the collapse, but still considerably below the design limit of the adjustable ballast tank. The failure may have been caused by material properties that may be defective, the possible stress concentration resulting from design/processing, or inappropriate installation method. The present paper focuses on the visual inspections of the material inhomogeneity, ultimate cause of the collapse of the flat cover in pressure testing, and finite element analysis. Special attention is paid to the toughness characteristics of the material. The present study demonstrates the importance of material selection for engineering components based on the comprehensive properties of the materials.

Crack Arrest Toughness of Two High Strength Steels (AISI 4140 and AISI 4340)

1982 ◽  
Vol 13 (4) ◽  
pp. 657-664 ◽  
Author(s):  
E. J. Ripling ◽  
J. H. Mulherin ◽  
P. B. Crosley
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Aisi 4140 ◽  
Arrest Toughness ◽  
Aisi 4340

Short Crack Propagation Model Applied to Shot Peened Aluminium Alloys

2009 ◽  
Vol 65 ◽  
pp. 53-61 ◽  
Author(s):  
J. Solis ◽  
J. Oseguera-Peña ◽  
I. Betancourt
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Crack Propagation ◽  
Aluminium Alloys ◽  
Micromechanical Model ◽  
High Strength ◽  
Crack Arrest ◽  
Propagation Model ◽  
Safe Load ◽  
Compressive Residual Stresses

The Navarro-Rios micromechanical model was used to assess the bounds of two different damage zones: crack arrest region and crack propagation region of controlled shot peening (CSP) of high strength aluminium alloys. Performance of CSP in terms of fatigue resistance was investigated. This comparison indicated that CSP in terms of fatigue depends on the competition between its beneficial and detrimental products, i.e. surface roughness and compressive residual stresses respectively. The gathered information can be used for safe load determinations in design.

Reliability of Burst Limit States for Damaged and Corroded High Strength Pipelines

2006 ◽  
Author(s):  
Marc A. Maes ◽  
Mamdouh M. Salama ◽  
Markus Dann
Keyword(s):  
Limit State ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Limit States ◽  
Lower Strain ◽  
Margin Of Safety ◽  
Normal Strength ◽  
The Impact

High strength steels (X100 and X120) that are being considered for high pressure gas pipelines differ from conventional steels by exhibiting lower work hardening capacity, lower strain to failure and softening of their HAZ. These differences impact burst limit state and tensile limit state, in addition to crack arrest. In this paper, the impact of the variations in mechanical properties on the reliability of pipe limit states involving ductile burst of damaged or corroded pipe is examined. The paper presents the results of burst limit state analysis using state-of-the-art plastic burst models of strain hardening pipe and considering all the uncertainties that impact the margin of safety of pipes subject to internal pressure. Intact pipes, corroded pipes and externally damaged pipes are considered. A case study comparing the differences between normal strength (X60) pipeline and high strength (X100) pipeline is also presented.

Fabrication of high strength bond of Ti-17 alloy using press bonding under a high bonding pressure

2013 ◽  
Vol 108 ◽  
pp. 212-214 ◽  
Author(s):  
H. Li ◽  
H.B. Liu ◽  
W.X. Yu ◽  
M.Q. Li
Keyword(s):  
High Strength ◽  
Bonding Pressure ◽  
Press Bonding

Steady-State Crack Propagation in Pressurized Pipelines

1977 ◽  
Vol 99 (1) ◽  
pp. 112-121 ◽  
Author(s):  
C. Popelar ◽  
A. R. Rosenfield ◽  
M. F. Kanninen
Keyword(s):  
Steady State ◽  
Crack Propagation ◽  
Driving Force ◽  
Crack Arrest ◽  
Operating Conditions ◽  
Unstable Crack ◽  
Crack Driving Force ◽  
Plastic Yield ◽  
Pressurized Pipelines ◽  
Full Scale Tests

Previous work at Battelle-Columbus on the development of a theoretical model for unstable crack propagation and crack arrest in a pressurized pipeline is extended in this paper by including the effect of backfill. The approach being developed involves four essential aspects of crack propagation in pipelines. These four components of the problem are: 1 – a shell theory characterization of the dynamic deformation of a pipe with a plastic yield-hinge behind an axially propagating crack, 2 – a fluid-mechanics treatment of the axial variations in the gas pressure acting on the pipe walls, 3 – an energy-based dynamic fracture mechanics formulation for the crack-driving force, and 4 – measured values of the dynamic energy absorption rate for pipeline steels. Comparisons given in the paper show that the steady-state crack speeds predicted by the model are in reasonably good agreement with the crack speeds measured in full-scale tests, both with and without backfill. The analysis further reveals the existence of a maximum steady-state crack-driving force as a function of the basic mechanical properties of the pipe steel and the pipeline goemetry and operating conditions. Quantitative estimates of this quantity provided by the model offer a basis for comparison with the empirical crack-arrest design criteria for pipelines developed by AISI, the American Gas Association, the British Gas Council, and British Steel. These are also shown to be in substantial agreement with the predictions of the model developed in this paper.

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