Critical Fracture Processes in Army Cannons: A Review

2003 ◽  
Vol 125 (3) ◽  
pp. 287-292 ◽  
Author(s):  
John H. Underwood ◽  
Edward Troiano
Keyword(s):  
Residual Stress ◽  
Thermal Damage ◽  
High Strength ◽  
Crack Size ◽  
Initial Crack ◽  
Fatigue Tests ◽  
Material Strength ◽  
Strain Fracture ◽  
Factor Modeling ◽  
Coating Fracture

Fast fracture in cannons can be well described using elastic-plastic fracture toughness, in combination with comparisons of cannon section size relative to the size required to maintain plane strain fracture. Fatigue fracture of cannon tubes is modeled from results of full-size fatigue tests that simulate cannon firing. These tests are also the basis of fatigue-intensity-factor modeling of fatigue life, which incorporates material strength, initial crack size and Bauschinger-modified autofrettage residual stress into life predictions. Environment-assisted fracture in the thermally damaged near-bore region of fired cannons is shown to be controlled by hydrogen. High strength cannon steels are susceptible to hydrogen; cannon propellant gases provide the hydrogen; and the source of sustained tensile stress is the near-bore thermal damage and compressive yielding. A thermo-mechanical model predicts tensile residual stress of similar depth to that of observed hydrogen cracks. Coating fracture in the thermal-damage region of fired cannons is characterized and modeled. The Evans/Hutchinson slip zone concept is extended to calculate in-situ coating fracture strength from observed crack spacing and hardness in the damaged region.

X-ray Fractographic Study on Alumina and Zirconia Ceramics

1990 ◽  
Vol 34 ◽  
pp. 719-727 ◽  
Author(s):  
Sumio Tanaka ◽  
Yukio Hirose ◽  
Keisuke Tanaka
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Surface ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Zirconia Ceramics ◽  
X Ray ◽  
Fractographic Study

The residual stress left on the fracture surface is one of the important parameters in X-ray fractographic study. It has been used to analyze fracture mechanisms in fracture toughness and fatigue tests especially of high strength steels.In this paper, X-ray fractography was applied to brittle fracture of alumina (Al2O3) and zirconia (ZΓO2) ceramics.

Fatigue Performance of High Strength and Large Diameter Mooring Chain in Seawater

2019 ◽  
Author(s):  
Yan-Hui Zhang ◽  
Philip Smedley
Keyword(s):  
Large Diameter ◽  
High Strength ◽  
Crack Size ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Link Failures ◽  
Fatigue Design ◽  
Steel Grades ◽  
Chain Links ◽  
Mooring Chain

Abstract Fatigue design recommendations provided by API RP 2SK, ISO 19901-7 and DNVGL-OS-E301 for studless chain links are based on data of steel grades R3 and R4 and mainly of link diameter of 76mm. Mooring systems utilising larger diameter links and higher strength steels (e.g. grade R5) are now in operation. Consequently, industry expressed a need for fatigue test data in seawater of higher steel grade and larger diameter chain to confirm whether the existing fatigue design guidance is applicable. A joint industry project (JIP) was launched by TWI to investigate fatigue performance of high strength and large diameter mooring chain in free corrosion seawater. A test rig was designed and manufactured which was capable of testing studless mooring chain links up to 127mm link diameter under tension-tension loading. Twenty-three full-scale fatigue tests were conducted on high strength steel grades (R4 and R5) and larger diameter chains (76mm and 127mm) generating 72 link failures. Magnetic particle inspections (MPI) were carried out to characterise the location of cracking, crack size and crack growth rate. This paper describes the results obtained in the JIP.

X-Ray Measurement of Residual Stress Near Fatigue Fracture Surfaces of High Strength Steel

1985 ◽  
Vol 29 ◽  
pp. 265-270 ◽  
Author(s):  
Yukio Hirose ◽  
Keisuke Tanaka
Keyword(s):  
Residual Stress ◽  
Fatigue Fracture ◽  
High Strength Steels ◽  
Diffraction Method ◽  
High Strength ◽  
Fatigue Tests ◽  
Fracture Mechanisms ◽  
Aqueous Environment ◽  
X Ray ◽  
Fracture Surfaces

The residual stress left on the fracture surface is one of the important parameters in X-ray fractography and has been used to analyse fracture mechanisms in fracture toughness, stress corrosion cracking and fatigue tests especially of high strength steels.In this study, the distribution of residual stress near fatigue fracture surfaces made in air and in 3.5% NaCl solution was measured by the X-ray diffraction method. The effect of aqueous environment on the plastic deformation near fatigue fracture surfaces was discussed on the basis of the residual stress distribution.

scholarly journals A Thermodamage Strength Theoretical Model of Ceramic Materials Taking into Account the Effect of Residual Stress

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Weiguo Li ◽  
Ruzhuan Wang ◽  
Dingyu Li ◽  
Daining Fang
Keyword(s):  
Residual Stress ◽  
Particle Size ◽  
Theoretical Model ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Crack Size ◽  
Material Strength ◽  
Temperature Phase ◽  
Particle Volume ◽  
Sic Particle

A thermodamage strength theoretical model taking into account the effect of residual stress was established and applied to each temperature phase based on the study of effects of various physical mechanisms on the fracture strength of ultrahigh-temperature ceramics. The effects of SiC particle size, crack size, and SiC particle volume fraction on strength corresponding to different temperatures were studied in detail. This study showed that when flaw size is not large, the bigger SiC particle size results in the greater effect of tensile residual stress in the matrix grains on strength reduction, and this prediction coincides with experimental results; and the residual stress and the combined effort of particle size and crack size play important roles in controlling material strength.

Subjects on Fatigue Crack Generation in High Strength Alloys for Long-Life Design

2011 ◽  
Vol 685 ◽  
pp. 278-284 ◽  
Author(s):  
Osamu Umezawa ◽  
Satoshi Morooka
Keyword(s):  
Fatigue Crack ◽  
High Strength ◽  
Material Design ◽  
Crack Size ◽  
Cyclic Stress ◽  
Initial Crack ◽  
Localized Deformation ◽  
Crack Generation ◽  
Long Life ◽  
Fatigue Crack Generation

The very localized deformation processes have been found to be decisive for subsurface fatigue crack generation at the lower stress level such as the elastic incompatibility at boundaries where only a very small fraction of plastically deformed grains was detected. The material design and its microstructure modification to achieve higher fatigue resistance in long-life range are needed for the high strength alloys, which is one of the ways developing an ecomaterial. Novel systems have employed to clarify the substance crack generation and growth mechanisms of high strength alloys. The initial crack size highly depends on the maximum cyclic stress range, which implies a threshold of stress intensity range controlling mechanism. Heterogeneous microplasticity due to planar slip and restricted system is considered to play an important role on making the subsurface crack. Then, it should be progressed in the understanding of damage stage in high-cycle fatigue fracture process.

Low-pressure turbine disc fi rtree slots’ life and reliability enhancement by ultrasonic surface hardening

2020 ◽  
pp. 491-495
Author(s):  
A.M. Tomashevich ◽  
G.G. Shirvan’yants ◽  
D.A. Teryaev
Keyword(s):  
Residual Stress ◽  
Low Pressure ◽  
Fatigue Tests ◽  
Compression Stress ◽  
Cycle Basis ◽  
Low Pressure Turbine ◽  
Working Stress ◽  
Turbine Disc ◽  
Axial Residual Stress ◽  
Reliability Enhancement

The possibility of life and reliability enhancing of AL-31F low pressure turbine disc’s fir-tree slots by ultrasonic hardening is considered. Having disc’s material properties studied, working stress derivation is executed which was further used for following comparative fatigue tests. Also, Davidenkov method residual stress analysis is carried out which showed 95.3 % change to compression stress for circumferential residual stress and 80.9 % change to compression stress for axial residual stress which proves possibility of fir-tree slots’ life and reliability enhancement by ultrasonic hardening. Comparative fatigue tests with N = 4•10 5 cycles basis showed that the hardened samples standing out the cycle basis during higher oscillatory amplitudes (and, thus, affecting loads) than the non-hardened basic ones.

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