The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Zhenduo Guan - One of the best experts on this subject based on the ideXlab platform.
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Strength characteristics of toughened ceramics containing contact-induced small surface Cracks
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002Co-Authors: Jianghong Gong, Zhenduo GuanAbstract:Based on an assumption that the R-curve behavior of toughened ceramics can be described with an exponential function, a numerical simulation procedure was designed and performed in this paper to examine the strength characteristics of toughened ceramics containing contact-induced small surface Cracks. Some useful relations among fracture strength, Initial Crack Size, Weibull modulus and the R-curve characteristics were deduced and discussed briefly based on the physical meanings of the parameters included in the exponential R-curve equation.
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Weibull modulus of fracture strength of toughened ceramics subjected to small-scale contacts
Journal of Materials Science, 2001Co-Authors: Jianghong Gong, Zhenduo GuanAbstract:The Weibull modulus of toughened ceramics was evaluated. The fracture of the toughened ceramics was assumed to be initiated by surface Cracks induced during small-scale contacts such as grinding and polishing and an exponential function was selected to describe the R-curve behavior. Based on a brief theoretical analysis, a numerical simulation procedure was designed to predict the fracture strength for toughened ceramics with different R-curve characteristics. The Weibull modulus of each toughened ceramic was estimated and compared with that of the un-toughened base material. It was concluded that an increase in Weibull modulus can always result from toughening. The increase in Weibull modulus was found to be related directly to the relative Crack tolerance, i.e., the ratio of the Initial Crack Size to the critical Crack Size. This suggests that the improvement in Crack stability due to toughening is the main reason for the increased Weibull modulus.
E. Smith - One of the best experts on this subject based on the ideXlab platform.
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The criterion for the attainment of maximum load for a Cracked elastic-softening solid
Journal of Materials Science, 1993Co-Authors: E. SmithAbstract:This paper focuses on the criterion for the attainment of maximum load for a Cracked brittle solid where the material is of the elastic-softening variety. Theoretical analysis of a simple model clearly shows that, as the Initial Crack Size decreases, there is an increasing potential for the maximum load to be attained prior to the attainment of a fully developed softening zone.
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Limiting toughness of a ligament toughened brittle material: Crack Size and loading effect
Theoretical and Applied Fracture Mechanics, 1993Co-Authors: E. SmithAbstract:Abstract Many brittle materials have the characteristic that the Crack tip stress intensity increases during Crack growth; a ligament zone forms behind the Crack tip and the restraining stresses due to the Crack-bridging elements within this zone impede the Crack extension process. The present paper's theoretical analysis shows that the Initial Crack Size and loading condition both have a marked effect on the limiting toughness associated with the full development of a ligament zone.
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use of the reflectionless stress intensity factor procedure to predict Crack arrest during a hypothetical pressurized thermal shock event the effect of Initial Crack Size
International Journal of Pressure Vessels and Piping, 1992Co-Authors: E. SmithAbstract:Abstract A dynamic methodology based on the reflectionless stress intensity factor concept is used to examine the combined effects of pressure and thermal loads on Crack arrest in a nuclear reactor pressure vessel that is subjected to a hypothetical pressurized thermal shock event. Earlier work, for the case of an Initially infinitesimally shallow Crack, has shown that the currently accepted ASME Code procedure is overly conservative in its arrest predictions when applied to the arrest of a Crack deep in the vessel thickness. The present paper shows that this conclusion is also applicable to the case where the Initial Crack is not necessarily infinitesimally shallow.
Jianghong Gong - One of the best experts on this subject based on the ideXlab platform.
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Strength characteristics of toughened ceramics containing contact-induced small surface Cracks
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002Co-Authors: Jianghong Gong, Zhenduo GuanAbstract:Based on an assumption that the R-curve behavior of toughened ceramics can be described with an exponential function, a numerical simulation procedure was designed and performed in this paper to examine the strength characteristics of toughened ceramics containing contact-induced small surface Cracks. Some useful relations among fracture strength, Initial Crack Size, Weibull modulus and the R-curve characteristics were deduced and discussed briefly based on the physical meanings of the parameters included in the exponential R-curve equation.
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Weibull modulus of fracture strength of toughened ceramics subjected to small-scale contacts
Journal of Materials Science, 2001Co-Authors: Jianghong Gong, Zhenduo GuanAbstract:The Weibull modulus of toughened ceramics was evaluated. The fracture of the toughened ceramics was assumed to be initiated by surface Cracks induced during small-scale contacts such as grinding and polishing and an exponential function was selected to describe the R-curve behavior. Based on a brief theoretical analysis, a numerical simulation procedure was designed to predict the fracture strength for toughened ceramics with different R-curve characteristics. The Weibull modulus of each toughened ceramic was estimated and compared with that of the un-toughened base material. It was concluded that an increase in Weibull modulus can always result from toughening. The increase in Weibull modulus was found to be related directly to the relative Crack tolerance, i.e., the ratio of the Initial Crack Size to the critical Crack Size. This suggests that the improvement in Crack stability due to toughening is the main reason for the increased Weibull modulus.
Jian Wang - One of the best experts on this subject based on the ideXlab platform.
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Fatigue behavior of uncorroded non-load-carrying bridge weathering steel Q345qDNH fillet welded joints
Journal of Constructional Steel Research, 2020Co-Authors: Jian WangAbstract:Abstract Bridge weathering steel produced in China is being increasingly employed in bridges worldwide, Q345qNH is among the most commonly used steel grades. Fatigue behavior of uncorroded non-load-carrying fillet welded joints made of bridge weathering steel Q345qNH was explored in this paper. Fatigue tests were conducted on 10 specimens which were under 7 stress ranges, S–N curve and its lower bound of 95% survival probability were established. It was observed that the design S–N curve for non-load-carrying fillet welded joint in Eurocode 3 is suitable to evaluate fatigue behavior of this batch of specimens and offers a considerable safety margin. The influences of Initial Crack Size, Initial Crack shape, Initial Crack location and misalignment of attachments on fatigue behavior of non-load-carrying fillet welded joints were explored, the relationship between fatigue life and Initial Crack Size was derived. Furthermore, it is recommended to adopt a semi-elliptical Crack with Initial Crack depth of 0.075 mm for numerical simulation when Initial Crack Size is unknown. The fatigue test results provide reference for fatigue design of steel bridges made of coated weathering steel and serve as control to analyze deterioration of fatigue behavior caused by corrosion for corroded non-load-carrying fillet welded joints made of uncoated weathering steel.
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Fatigue behavior of uncorroded butt welded joints made of bridge weathering steel
Structures, 2020Co-Authors: Jian WangAbstract:Abstract Bridge weathering steel produced in China has been employed in bridges worldwide, among them Q345qNH is the most commonly used steel grade. Fatigue behavior of uncorroded butt welded joints made of bridge weathering steel Q345qNH was explored in this paper. Fatigue tests were conducted on 13 specimens involving 9 stress ranges, S-N curve and its lower bound of 95% survival probability were established. It was observed that the design S-N curve for butt welded joint in Eurocode 3 is suitable for fatigue assessment of this batch of specimens and provides a considerable safety margin. Numerical simulation of mixed-mode fatigue Crack propagation and analytical investigation of fatigue Crack propagation were conducted, it was found that numerical simulation is preferred since it considers the variation in stress due to Crack propagation. The influences of Initial Crack Size, Initial Crack shape, Initial Crack location and angular misalignment of plates on fatigue behavior of butt welded joints were investigated, the expression between fatigue life and Initial Crack Size was derived. Additionally, it is recommended that a semi-elliptical Crack with Initial Crack depth of 0.2 mm and Initial aspect ratio of 1/4 to be adopted when information on Initial Crack is unavailable. The fatigue test results provide reference for fatigue design of steel bridges made of coated weathering steel and serve as control for analysis of deterioration of fatigue behavior due to corrosion for corroded butt welded joints made of uncoated weathering steel.
John P. Gyekenyesi - One of the best experts on this subject based on the ideXlab platform.
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Slow Crack Growth Analysis of Brittle Materials with Finite Thickness Subjected to Constant Stress-Rate Flexural Loading
Journal of Materials Science, 1999Co-Authors: Sung R. Choi, John P. GyekenyesiAbstract:A two-dimensional, numerical analysis of slow Crack growth (SCG) was performed for brittle materials with finite thickness subjected to constant stress-rate (“dynamic fatigue”) loading in flexure. The numerical solution showed that the conventional, simple, one-dimensional analytical solution can be used with a maximum error of about 5% in determining the SCG parameters of a brittle material with the conditions of a normalized thickness (a ratio of specimen thickness to Initial Crack Size) T > 3.3 and of a SCG parameter n ≥ 10. The change in Crack shape from semicircular to elliptical configurations was significant particularly at both low stress rate and low T, attributed to predominant difference in stress intensity factor along the Crack front. The numerical solution of SCG parameters was supported within the experimental range by the data obtained from constant stress-rate flexural testing for soda-lime glass microslides at ambient temperature.