• Journal of Welding and Joining
• /
• v.15 no.4
• /
• pp.178-186
• /
• 1997

The purpose of this study is to evaluate the J-R curve characteristics for the 5083 aluminum alloy weldment by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agrees well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The exponential correlation of the J-R curve for the 5083 aluminum alloy base metal by the load ratio analysis is J = 93.88 ${\Delta}{\alpha}^{0.375}$. That for the weld metal and HAZ is J = 69.87 ${\Delta}{\alpha}^{0.389}$ and J = 70.59 ${\Delta}{\alpha}^{0.359}$ respectively. The J-R curve obtained by the ASTM unloading compliance method is overpredicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load displacement curve without particular crack measurement equipment.

• Journal of Power System Engineering
• /
• v.1 no.1
• /
• pp.80-90
• /
• 1997

The purpose of this study is to evaluate the validity examination of the J-R curve characteristics for the nuclear reactor pressure vessel steels and Al alloys by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agree well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The J-R curve obtained by the ASTM unloading compliance method is over-predicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load-displacement curve without particular crack measurement equipment.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.812-815
• /
• 2002

The shape of K-R curve for an ideally brittle material is flat because the surface energy is an unvaried material property. However, the K-R curve can take on a variety of shapes when nonlinear material behavior accompanies fracture. By the way, a general metallic material is nonlinear, structural steel is such. Therefore, the J-R curve form J-integral value instead of K parameters can be used to evaluate elastic-plastic materials with flaws in terms of ductile fracture that can be significant to design. In this paper, R-curve behaviors form K and J parameter is considered for the precise assessment of fracture analysis, in case of JS-SS400 steels.

• Journal of Ocean Engineering and Technology
• /
• v.12 no.1
• /
• pp.65-75
• /
• 1998

The fracture resistance curve is one of most important and design techniques employed in nuclear pressure vessel structures. This study is to evaluate the J-R curve characteristics for the SA508C-3 by the unloading compliance method and load rato analysis. The effect of strain aging for the exponential correlation of the J-R curve in this metal are investigated at room temperature, 20$0^{\circ}C$ and 30$0^{\circ}C$. The load ratio analysis method can evaluate the J-R curve by using the simple tension load-displacement curve only without the repeat of the unloading and loading. Therefore, the analysis by the proposed load ratio method has a merit, in comparison with the unloading compliance method, which can measure the crack length without the precision measurement equipment.

• Proceedings of the KWS Conference
• /
• 1997.05a
• /
• pp.91-98
• /
• 1997

This research is to evaluate of the J-R curve characteristic in 5083 aluminum alloy weldment by utilizing the load ratio analysis. This analysis method can be evaluated the J-R curve only with load-displacement curve without any particular precision instrument equipment in CT specimen. For validity, the results of the load ratio analysis are compared with the those of the J-R curve, which are obtained by the ASTM standard unloading compliance method. The calculated crack length of the load ratio analysis is well appropriate that the measured final crack length. And the J-R curve slope estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method.

• Journal of Ocean Engineering and Technology
• /
• v.12 no.3 s.29
• /
• pp.60-67
• /
• 1998

In this study, the J-Resistance Curve and material tearing modulus of SA508-C3 steel, which is one of the used nuclear pressure vessel steel, are measured ar room temperature, $200^{circ}C$ and $300^{circ}C$ according to load ratio analysis and ASTM E813, ASTM E1152, respectively. It is observed that J-R curve and Tmat value decrease as the temperature level increase. Applicability of $T_j$ proposed by Paris et al as instability parameter for ductile material is investigated. It is concluded that results are the $T_j$ parameter may be used as a crack instability parameter.

• Journal of the Korean Society for Precision Engineering
• /
• v.6 no.3
• /
• pp.78-89
• /
• 1989

Applicability of tearing modulus based on J-integral proposed by Paris et al is investigated using compact tension specimens of strutural alloy steel (SCM4). Both general fracture test and instability fracture test are performed. The applied tearing modulus, ( $T_{j}$)app estimated from the real load vs. crack growth curve measured from experiments are compared with that estimated from the limit load vs. crack growth curve. The results are : (1) the $T_{j}$parameter could be applied to predict crack growth instability : (2) The use of ( $T_{j}$)app estimated from the load vs. crack growth curve, proposed in this study could be well predicted crack growth instability instead of that estimated form the limit load vs. crack growth curve.e.

• Journal of Korea Port Economic Association
• /
• v.27 no.3
• /
• pp.1-12
• /
• 2011

The effect of real exchange rate changes on trade balance is called the J-curve effect. That is, after real depreciation, the trade balance will deteriorate in the short run and improve in the long run. Specially, import and export prices respond with little or no decline in volume. Assuming a zero initial trade balance and dominance of the exporter currency in invoicing trade contracts, the trade balance continues to deteriorate in the medium term. Over time, the relative price-induced volume effect comes to dominate the price effect and the trade balance improves. This pattern of the trade balance adjustment is commonly referred to as the J-curve effect. This study examines the effects of changes in the exchange rate on the Korean port trade balance to China. The empirical results indicate that whilst there is J-curve effect in the short-run, but in the long-run, the real depreciation of the Korean won has positive impact on port trade balance to China.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.9
• /
• pp.930-937
• /
• 2009

The estimation method of the fracture resistance curve for the pipe specimen was proposed using the load ratio method for the standard specimen. For this, the calculation method of the load - CMOD curve for the pipe specimen with the common format equation(CFE) was proposed by using data of the CT specimen. The proposed method agreed well with experimental data. The J-integral value and the crack extension were calculated from the estimated load - CMOD data. The fracture resistance curve was estimated from the calculated J-integral and the crack extension. From these results, it have been seen that the proposed method is reliable to estimate the J-R curve of the pipe specimen.

• Journal of the Korean Society of Safety
• /
• v.12 no.3
• /
• pp.45-51
• /
• 1997

To evaluate the elastic-plastic fracture toughness by this modified offset method, the origin of J-R curve is set with drawing the blunting line on the maximum point of the negative crack growth and R curve is modified by adding the blunting factor of the experimented point on the R curve. The elastic-plastic fracture toughness $J_{IC]$ of A5083-H112 material by the modified offset method we 44kN/m on the smooth CT specimens.