An analytic procedure for determination of fracture toughness of paper materials

2012 ◽  
Vol 27 (2) ◽  
pp. 352-360 ◽  
Author(s):  
Petri Mäkelä ◽  
Christer Fellers
Keyword(s):  
Fracture Toughness ◽  
Closed Form ◽  
Test Data ◽  
Material Model ◽  
Fracture Toughness Test ◽  
Element Analysis ◽  
Analytic Procedure ◽  
Analytic Expressions ◽  
Commercial Paper

Abstract The aim of the present work was to develop an analytic procedure for determination of the fracture toughness of paper materials based on laboratory material test data. Isotropic deformation theory of plasticity was used to model the tensile material behaviour of six different commercial paper grades. Closed-form analytic expressions for calibrating the material model based on tensile test data were developed. The analytically calibrated material model was shown to predict the non-linear tensile stress-strain behaviour of the investigated paper grades excellently. A closed-form analytic expression for determination of fracture toughness was developed based on the used material model and J-integral theory. The fracture toughness of the investigated paper grades was determined analytically based on laboratory fracture toughness test data. The suggested analytic procedure for determination of the fracture toughness was shown to be in excellent agreement with determinations of fracture toughness based on finite element analysis.

Determination of Fracture Toughness and K-R Curve for 2524-T3 Aluminum Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1039-1042
Author(s):  
Wei Xie ◽  
Shao Wei Tu ◽  
Qi Qing Huang ◽  
Ya Zhi Li
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Stress Fracture ◽  
Test Data ◽  
Plane Stress ◽  
Crack Extension ◽  
Room Temperature ◽  
Mode I ◽  
Average Value

In the present work, the resistance to crack extension of 2524-T3 aluminum alloy under Mode I loading was studied by using the middle-cracked tension M (T) specimens. The curve, plane-stress fracture toughness and apparent plane-stress fracture toughness were calculated by test data. The average value of measured fracture toughness at room temperature was 161 MPam1/2. The results and conclusions can be referred in airplane skin design.

Evaluation of Fracture Toughness Test Data for Multilayer Dissimilar Joint Welds Using a Weibull Stress Model

2012 ◽  
pp. 357-376
Author(s):  
Yasuhito Takashima ◽  
Mitsuru Ohata ◽  
Masaru Seto ◽  
Yoshitomi Okazaki ◽  
Fumiyoshi Minami
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Dissimilar Joint ◽  
Fracture Toughness Test ◽  
Stress Model ◽  
Toughness Test ◽  
Weibull Stress

Ductile Tearing Simulation of Circumferential Cracked Pipe Under Cyclic Loading Using Damage Criteria Determined by Monotonic Pipe Test Data

2018 ◽  
Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Naoki Miura ◽  
Yun-Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Ductile Fracture ◽  
Test Data ◽  
Strain Energy ◽  
Fracture Strain ◽  
Damage Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Damage Criteria

To evaluate the structural integrity of nuclear power plant piping, it is important to predict ductile tearing of circumferential cracked pipe from the view point of Leak-Before-Break concept under seismic conditions. CRIEPI (Central Research Institute of Electric Power Industry) conducted fracture test on Japanese carbon steel (STS410) circumferential through-wall cracked pipes under monotonic or cyclic bending load in room temperature. Cyclic loading test conducted variable experimental conditions considering effect of stress ratio and amplitude. In the previous study, monotonic fracture pipe test was simulated by modified stress-strain ductile damage model determined by C(T) specimen fracture toughness test. And, ductile fracture of pipe under cyclic loading simulated using damage criteria based on fracture strain energy from C(T) specimen test data. In this study, monotonic pipe test result is applied to determination of damage model based on fracture strain energy, using finite element analysis, without C(T) specimen fracture toughness test. Ductile fracture of pipe under variable cyclic loading conditions simulates using determined fracture energy damage model from monotonic pipe test.

Scaling of Pop-Ins During Brittle Fracture Testing

2019 ◽  
Author(s):  
O. J. Coppejans ◽  
C. L. Walters
Keyword(s):  
Fracture Toughness ◽  
Analytical Method ◽  
Offshore Structures ◽  
Specimen Size ◽  
Small Scale ◽  
Unstable Fracture ◽  
Displacement Curve ◽  
Fracture Toughness Test ◽  
Key Factor

Abstract Measurement of the fracture toughness of steel is important for the assurance of the safety of ships and offshore structures, especially when these structures are made of thick sections and/or applied in cold environments. One key factor that will affect the determination of the fracture toughness is a pop-in, which is a short event in which unstable fracture is initiated and then self-arrests. If the pop-in is large enough, it will be used to calculate the fracture toughness. Pop-ins are believed to be the products of local brittle zones, which occur randomly at crack tips and have finite sizes. Fracture toughness testing codes have ways of determining whether a pop-in is critical (thus, identifying the maximum force and displacement to be used in the determination of the toughness of the material) or not important (thus, allowing for the test to proceed). In an ongoing project on the use of small-scale fracture specimens to predict standard fracture toughness test results, we would like to know how pop-in acceptance criteria should be scaled for specimen size. It is expected that the physical size of the brittle zones that cause pop-ins is invariant of specimen size, meaning that the contribution of the pop-in will be proportionally more important for smaller specimens. An analytical method for relating the pop-ins on one specimen size to another specimen size is developed. This method is partially verified by observations on the size of a local brittle zone observed on a fracture surface and the effect of that pop-in on the force-displacement curve during a CTOD test. The analytical method showed that an equivalent pop-in for a small-scale specimen is indeed larger, but that the effect was subtle.

Determination of Material Fracture Toughness by Circular Pre-Cracked Small Punch Test Specimens

2019 ◽  
Vol 795 ◽  
pp. 165-171
Author(s):  
Wu Lin Wang ◽  
Du Wei Wang ◽  
Kai Shu Guan
Keyword(s):  
Fracture Toughness ◽  
Empirical Correlation ◽  
Fracture Toughness Test ◽  
J Integral ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Determination Procedure ◽  
Material Fracture

Fracture toughness empirical correlation between SPT(Small Punch Test) with non-crack sample and standard fracture toughness test has been established in recent years. In order to compensate the imperfection of empirical correlation, such as absence theoretical basis, poor repeatability and universality, in this paper, an O-type pre-cracked sample was adopted to evaluate fracture toughness. The mechanical model of the sample is in compliance with plane strain condition in the direction of crack propagation. In this paper a determination procedure was studied and established, and the J-integral of steel Q345R was calculated using the procedure.

Limit Plastic Collapse on Remaining Ligament of Flawed Welds for ECA Application

2014 ◽  
Author(s):  
Antonio Carlucci ◽  
Kamel Mcirdi
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Mechanical Strain ◽  
Plastic Collapse ◽  
Fracture Toughness Test ◽  
Element Analysis ◽  
Critical Fracture ◽  
Failure Assessment ◽  
The One ◽  
Girth Welds

Engineering Critical Assessments (ECAs) are routinely used to provide defect acceptance criteria for pipelines girth welds. The Failure Assessment Diagram (FAD) concept is the most widely used methodology for elastic-plastic fracture mechanics analysis of structural components and adopted by standards/documents including BS7910 [1], API579-1/ASME FFS-1 [2], R6 [3]. It is defined by two criterion Kr and Lr which describe the interaction between brittle fracture and fully ductile rupture: Kr measures the proximity to brittle fracture whereas Lr reflects the closeness to plastic collapse. The BS7910 FAD level 2B is the most employed for assessment of flaws under mechanical strain lower than 0.4%, the FAD associated is material-specific and it based on single toughness value obtained from CTOD test, the latter-on gives no information about the tearing initiation. The objective of this paper is to propose an approach for determination of the critical fracture toughness (associated to zero-tearing: JΔa=0). This approach is based on the comparison between the load-CMOD curve provided from a fracture toughness test to the one obtained by Finite Element Analysis (FEA). The goals is to propose a conservative guidance on how to identify a remote strain level below which it may be considered guaranteed the integrity of the remaining ligament.

Determination of critical angle of circumferential throughwall crack for structurally distorted 90° pipe bends under bending moment with and without internal pressure

2017 ◽  
Vol 233 (5) ◽  
pp. 817-830 ◽  
Author(s):  
S Sumesh ◽  
AR Veerappan ◽  
S Shanmugam
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Closed Form ◽  
Bending Moment ◽  
External Loading ◽  
Element Analysis ◽  
Critical Crack ◽  
Structural Distortions ◽  
Internal Pressures

Throughwall circumferential cracks (TWC) in elbows can considerably minimize its collapse load when subjected to in-plane bending moment. The existing closed-form collapse moment equations do not adequately quantify critical crack angles for structurally distorted cracked pipe bends subjected to external loading. Therefore, the present study has been conducted to examine utilizing elastic-plastic finite element analysis, the influence of structural distortions on the variation of critical TWC of 90° pipe bends under in-plane closing bending moment without and with internal pressure. With a mean radius ( r) of 50 mm, cracked pipe bends were modeled for three different wall thickness, t (for pipe ratios of r/ t = 5,10,20), each with two different bend radius, R (for bend ratios of R/r = 2,3) and with varying degrees of ovality and thinning (0 to 20% with increments of 5%). Finite element analyses were performed for two loading cases namely pure in-plane closing moment and in-plane closing bending with internal pressure. Normalized internal pressures of 0.2, 0.4, and 0.6 were applied. Results indicate the modification in the critical crack angle due to the pronounced effect of ovality compared to thinning on the plastic loads of pipe bends. From the finite element results, improved closed-form equations are proposed to evaluate plastic collapse moment of throughwall circumferential cracked pipe bends under the two loading conditions.

Plastic-Factor for the Fracture Toughness Test of the SA508Cl.1a Narrow-Gap Welding Part

2007 ◽  
Vol 353-358 ◽  
pp. 146-149
Author(s):  
Yong Huh ◽  
Sung Keun Cho ◽  
Hyung Ick Kim ◽  
Chang Sung Seok
Keyword(s):  
Fracture Toughness ◽  
Nuclear Power ◽  
Piping System ◽  
Fracture Toughness Test ◽  
Narrow Gap ◽  
Narrow Gap Welding ◽  
Element Analysis ◽  
Testing Method ◽  
Toughness Test ◽  
Welding Part

In this study, the plastic η -factors of the SA508Cl.1a narrow-gap welding part, which is used for the primary piping system in a nuclear power plant were obtained by using finite element analysis and the modified fracture toughness testing method was suggested for the narrow-gap welding part. Also, we have performed the fracture toughness test for the SA508Cl.1a narrow-gap welding part by applying the new testing method and then we compared the results with those from the ASTM fracture toughness test.

J Resistance Curve Estimation of Inhomogeneous CT Specimen

2002 ◽  
Author(s):  
Kiminobu Hojo ◽  
Kazutoshi Ohoto ◽  
Itaru Muroya
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Stress Condition ◽  
Estimation Method ◽  
Fe Analysis ◽  
Fracture Toughness Test ◽  
Plane Stress Condition ◽  
Element Analysis ◽  
Curve Estimation ◽  
The Finite Element Analysis

In order to obtain the fracture toughness curve of inhomogeneous CT specimens, a simplified J-R curve estimation method has been proposed. To verify the applicability of this method, the fracture toughness test and the finite element analysis has been conducted. In overmatching case (mismatch ratio M = 2.2), the conventional ASTM standard’s J-R curve exceeded the J-R curve from the FE analysis in the plane strain condition by over 20%. On the other hand, the simplified J-R curve was located between J-R curves from the FE analyses in plane strain and plane stress condition. In undermatching case (M = 0.5), experimental J-R curves with and without the inhomogeneity effect were almost same and the conventional standard is applicable.

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