Prediction of the Temperature Dependence on Fracture Toughness by New Stress Distribution Scaling Method

2017 ◽  
Author(s):  
Kenichi Ishihara ◽  
Takeshi Hamada ◽  
Toshiyuki Meshii
Keyword(s):  
Fracture Toughness ◽  
Stress Distribution ◽  
Temperature Dependence ◽  
Temperature Region ◽  
Tensile Tests ◽  
Fracture Load ◽  
Small Scale ◽  
Scaling Method ◽  
Element Analysis ◽  
Scale Yielding

In this paper, a new method for scaling the crack tip stress distribution under small scale yielding condition was proposed and named as T-scaling method. This method enables to identify the different stress distributions for materials with different tensile properties but identical load in terms of stress intensity factor (K) or J-integral (J). Then, a method to predict the fracture load at an arbitrary temperature from the already known fracture load at a reference temperature was proposed by assuming that the temperature dependence of a material is represented as the stress-strain relationship temperature dependence. This method was combined with the T-scaling method and the knowledge “fracture stress for slip induced cleavage fracture is temperature independent.” Once the fracture load is predicted, fracture toughness Jc at the temperature under consideration can be evaluated by running elastic-plastic finite element analysis. Finally, the above-mentioned framework to predict the Jc temperature dependency of a material in the ductile-to-brittle temperature region was validated for 0.55 % carbon steel JIS S55C. The proposed framework seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests.

Application of the T-Scaling Method to Predict Fracture Toughness Under Compressive Residual Stress in the Transition Temperature Region

2018 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Kenichi Ishihara
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Transition Temperature ◽  
Stress Distribution ◽  
Temperature Dependence ◽  
Temperature Region ◽  
Compressive Residual Stress ◽  
Crack Tip ◽  
Scaling Method ◽  
Crack Tip Stress

The fracture toughness Jc of a material in the ductile-to-brittle transition temperature region shows a test specimen thickness (TST) effect and temperature dependence, and apparently increases when a compressive residual stress is applied. Many models to explain these phenomena have been proposed that can also consider the large scatter of Jc. On the contrary, the authors have focused on the mean Jc and have demonstrated that the TST effect on Jc and temperature dependence of Jc are due to “the loss of the one-to-one correspondence between J and the crack-tip stress distribution” and that the “scaled” crack-tip stress distribution at fracture is independent of the TST effect on Jc or temperature. The T-scaling method was proposed and validated for this purpose. In this study, the fracture prediction of a specimen with compressive residual stress was performed using the T-scaling method, and its validity was confirmed for high-strength steel of 780-MPa class and 0.45 % carbon steel JIS S45C.

Application of SDS Method to Predict Fracture Toughness Temperature Dependency of A533B Steel

2017 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Kenichi Ishihara ◽  
Hiroki Nakano
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Tensile Tests ◽  
Fracture Load ◽  
Reference Temperature ◽  
Small Scale ◽  
Temperature Dependency ◽  
Yielding Condition ◽  
Scale Yielding ◽  
Higher Temperature

Recently, the authors have proposed a new method for scaling the crack tip stress distribution under small scale yielding condition and named it as T-scaling method [1, 2]. This method identifies the different stress loads for materials with different tensile properties but identical in terms of K or J. Then by accepting the knowledge “fracture stress for slip induced cleavage fracture is temperature independent [3],” a framework to predict the fracture load Pc and fracture toughness Jc at an arbitrary temperature from the already known Pcr and Jcr at a reference temperature Tr was proposed and validated for 0.55% carbon steel JIS S55C [1, 2]. This framework was named as SDS method. This paper presents that the SDS method was valid to predict 1TCT Jc temperature dependency of A533B steel [4] in the range of −9 ≤ T-T0 ≤ 27 °C, where T0 is the master curve reference temperature. The SDS method seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests.

scholarly journals Spreadsheet-based method for predicting temperature dependence of fracture toughness in ductile-to-brittle temperature region

2019 ◽  
Vol 11 (8) ◽  
pp. 168781401987089 ◽  
Author(s):  
Toshiyuki Meshii
Keyword(s):  
Fracture Toughness ◽  
Temperature Dependence ◽  
Yield Stress ◽  
High Temperatures ◽  
Test Data ◽  
Temperature Region ◽  
Master Curve ◽  
Fracture Toughness Test ◽  
Scaling Method ◽  
Japan Industrial Standard

A spreadsheet-based simplified and direct toughness scaling method to predict the temperature dependence of fracture toughness Jc in the ductile-to-brittle transition temperature region is proposed. This method uses fracture toughness test data and the Ramberg–Osgood exponent and yield stress at the reference temperature, and yield stress at the temperature in interest to predict Jc. The physical basis of the simplified and direct toughness scaling method is the strong correlation between Jc and yield stress. The simplified and direct toughness scaling method was validated for Cr–Mo steel Japan Industrial Standard SCM440 and 0.55% carbon steel Japan Industrial Standard S55C by comparing the simplified and direct toughness scaling prediction results with the median results of an experiment performed at four temperatures ranging from −55°C to 100°C and at three temperatures ranging from −85°C to 20°C, respectively. The simplified and direct toughness scaling method can predict Jc from both low to high temperatures, and vice versa. Thus, 12 and 6 predictions were made for each material. The prediction discrepancy for these 18 cases ranged from −50.4% to +25.8% and the average absolute discrepancy was 22.1%. These results were acceptable considering the large scatter generally observed with Jc. In particular, in case of predicting Jc at temperatures higher than the lowest temperature of −55°C for SCM440, the simplified and direct toughness scaling method predicted Jc more realistically than the American Society for Testing and Materials E1921 master curve approach. Although the simplified and direct toughness scaling method requires additional tensile test data compared with the master curve approach, the acceptable prediction accuracy at high temperatures seems beneficial because the mass and time required for tensile tests are admissible.

On the Crack Quasi-Static Growth

2019 ◽  
Vol 827 ◽  
pp. 312-317
Author(s):  
Vitalijs Pavelko
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Plastic Material ◽  
Small Scale ◽  
Invariant Equation ◽  
Practical Applications ◽  
Wide Range ◽  
Scale Yielding ◽  
Elastic Plastic Material ◽  
Principal Assumption

The theoretical model of quasi-static crack growth in the elastic-plastic material under load variation in a wide range. Small-scale yielding is principal assumption and main restriction of proposed theory. The model of crack growth provides for continues and interrelated both the crack propagation and plastic deformation development. The nonlinear first-order differential equation describes the quasi-static process of crack growth. In dimensionless form this equation invariant in respect to geometrical configuration and material. The critical size of the plastic zone is proposed as the characteristics of material resistance which is directly connected with the fracture toughness, but more convenient in practical applications of invariant equation. The demonstration of solution is performed for the double cantilever beam that widely used as the standard (DCB) sample for measurement of the mode-I interlaminar fracture toughness. he short analysis of some properties of solution of the invariant equation and its application is done.

Dynamic Crack Growth in a Power Hardening Viscoplastic Material

1994 ◽  
Vol 116 (4) ◽  
pp. 465-470 ◽  
Author(s):  
Vijay B. Shenoy ◽  
R. Krishna Kumar
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Plastic Material ◽  
Dynamic Stress Intensity Factor ◽  
High Rate ◽  
Small Scale ◽  
Dynamic Crack ◽  
Viscoplastic Material ◽  
Element Analysis ◽  
Dynamic Crack Growth

In this paper a finite element analysis of steady-state dynamic crack growth under mode I plane strain small scale yielding conditions has been performed in a power law hardening rate dependent plastic material, characterized by the Perzyna over stress model. A modified version of the rate tangent modulus method has been used to update the stress. The main objective of the work is to obtain a quantitative relationship between dynamic fracture toughness ratio (K/Kss) and crack speed. A plastic strain criteria proposed by McClintock (1968) has been applied to obtain this relationship. It is found that dynamic stress intensity factor increases with velocity for all values of βˆ (a normalized viscosity parameter). At a low value of βˆ, which corresponds to high rate sensitivity, the fracture toughness ratio (K/Kss) increases with hardening. On the other hand, at a higher βˆ, the ratio increases initially and falls subsequently, with increasing hardening.

Small Scale Yielding at a Crack Normal to the Interface Between an Elastic and a Yielding Material

1991 ◽  
Vol 239 ◽  
Author(s):  
Ming Y. He ◽  
R. M. McMeeking ◽  
Ning T. Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Brittle Material ◽  
Crack Tip ◽  
Asymptotic Solutions ◽  
Ductile Material ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Element Analysis ◽  
Scale Yielding

ABSTRACTBy using the elastic singular field as a prescribed loading condition, small scale yielding solutions are obtained for a crack normal to the interface between a brittle and a ductile material. Results for both a crack in the brittle material and one in the ductile material are obtained by finite element analysis. The crack tip fields obtained by the finite element analysis are compared with the asymptotic solutions. It is found that near the tip the stress fields approach the asymptotic solutions. If the crack is in the brittle material, the high triaxial stresses are developed near the interface ahead of the crack tip.

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