A Study on the Lower Flanges Fracture of Endplate Bolted Connection

2006 ◽  
Vol 326-328 ◽  
pp. 983-986
Author(s):  
Hong Wei Ma ◽  
Chong Du Cho ◽  
Qiang Pan ◽  
Hyeon Gyu Beom
Keyword(s):  
Crack Length ◽  
High Stress ◽  
Transverse Load ◽  
Stress Fields ◽  
Finite Element Models ◽  
J Integral ◽  
Bolted Connection ◽  
Static Tests ◽  
Opening Mode ◽  
Set Up

The quasi-static tests on the endplate bolted connections of the new structure system consisting of SCC beam and CCSHRC column are briefly introduced in this paper. Meanwhile, the 3-D solid finite element models of the connections with pre-existing cracks in the lower flange’s high stress fields are set up by ANSYS. The material nonlinearities of concrete, steel and bars, together with the contact between the endplate and column surface are all considered in the model. With the transverse load applied on top of columns, the fracture parameters are calculated by APDL. The results indicate that the opening mode crack will happen mainly. When the pre-existing crack length is 2.50mm and the inter-storey drift is less than 6mm, the stress intensity factor values agree well with the converting values derived from J-integral and the crack tip fields are in elastic state. The J values are highly influenced by the pre-existing crack length, while seldom influenced by the concrete compression strength. Moreover, the J-integral have the trend to sharply increase when the pre-existing crack length is larger than 0.61mm, and the pre-existing crack will grow during loading when its length is larger than 1.35mm.

Determination of Stress Intensity Factors for Gradient Stress Fields

1977 ◽  
Vol 99 (3) ◽  
pp. 477-484 ◽  
Author(s):  
J. M. Bloom ◽  
W. A. Van Der Sluys
Keyword(s):  
Stress Intensity ◽  
Crack Length ◽  
Stress Intensity Factors ◽  
Maximum Stress ◽  
Nuclear Industry ◽  
Stress Fields ◽  
Polynomial Method ◽  
Intensity Factors ◽  
Asme Code ◽  
Linear Envelope

This paper evaluates eight different analytical procedures used in determining elastic stress intensity factors for gradient or nonlinear stress fields. From a fracture viewpoint, the main interest in this problem comes from the nuclear industry where the safety of the nuclear system is of concern. A fracture mechanics analysis is then required to demonstrate the vessel integrity under these postulated accident conditions. The geometry chosen for his study is that of a 10-in. thick flawed plate with nonuniform stress distribution through the thickness. Two loading conditions are evaluated, both nonlinear and both defined by polynomials. The assumed cracks are infinitely long surface defects. Eight methods are used to find the stress intensity factor: 1–maximum stress, 2–linear envelope, 3–linearization over the crack length from ASME Code, Section XI, 4–equivalent linear moment from ASME Code, Section III, Appendix G for thermal loadings, 5–integration method from WRC 175, Appendix 4 for thermal loadings, 6–8-node singularity (quarter-point) isoparametric element in conjunction with the displacement method, 7–polynomial method, and 8–semi-infinite edge crack linear distribution over crack. Comparisons are made between all eight procedures with the finding that the methods can be ranked in order of decreasing conservatism and ease of application as follows: 1–maximum stress, 2–linear envelope, 3–linearization over the crack length, 4–polynomial method, and 5–singularity element method. Good agreement is found between the last three of these methods. The remaining three methods produce nonconservative results.

Crack extension forces in elasto-plastic stress fields

1977 ◽  
Vol 12 (4) ◽  
pp. 305-309 ◽  
Author(s):  
M F Light ◽  
A R Luxmoore
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Plane Strain ◽  
Crack Extension ◽  
Stress Fields ◽  
J Integral ◽  
Thick Section ◽  
Bend Specimen ◽  
Significant Discrepancy ◽  
Fracture Specimens

A finite-element method has been used to calculate crack extension forces for experimental fracture specimens which failed after general yield. The results are compared with the values of the J-integral for the same specimens, and a significant discrepancy is noted. The crack extension forces at failure for a centre-notch and bend specimen of the same material were found to be almost identical, but did not agree with the plane strain GIC value reported for thick-section specimens.

Method for validating CT length measurement of cracks inside solder joints

2016 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Tamás Garami ◽  
Oliver Krammer ◽  
Gábor Harsányi ◽  
Péter Martinek
Keyword(s):  
High Resolution ◽  
Crack Length ◽  
Solder Joints ◽  
Life Time ◽  
Percentage Error ◽  
Content Type ◽  
Lack Of Information ◽  
Length Measurements ◽  
Set Up ◽  
Ct Measurement

Purpose – This paper aims to develop a method to measure the length of cracks inside solder joints, which enables the validation of computed tomography (CT) crack length measurements. Design/methodology/approach – Cracks were formed inside solder joints intentionally by aging solder joints of 0603 size resistors with thermal shock (TS) test (−40 to +140°C, 2,000 cycles), and CT images were captured about them with different rotational increment (1/4, 1/2 and 1°) of sample projection. The length of cracks was also measured with our method, which is based on capturing high-resolution radiography X-ray images about the cracks in two perpendicular projection planes. The radiography results were compared to the CT measurements. The percentage error for the different CT rotational increment settings was calculated, and the optimal CT settings have been determined. Findings – The results have proven that reducing the rotational increment increases the sharpness of the captured images and the accuracy of crack length measurements. Nevertheless, the accuracy compared to high-resolution radiography measurements is only slightly better at 1/4° rotational increment than in the case of 1/2° rotational increment. It should be also noted that the 1/4° increment requires twice as much time for capturing the images as the 1/2° increment. So, the 1/2° rotational increment of sample projection is the optimal setting in our investigated case for measuring crack lengths. Practical implications – The developed method is applicable to find the optimal settings for CT crack length measurements, which provides faster analysation of large quantity samples used, e.g. at life-time tests. Originality/value – There is a lack of information in the literature regarding the optimisation of CT measurement set-up, e.g. a slightly larger value of the sample rotational increment can provide acceptable resolution with much faster processing time. Thus, the authors developed a method and performed research about optimising CT measurement parameters.

Modeling of Steel Bolted T-Stub Connection under Large Deformation Condition

2014 ◽  
Vol 1049-1050 ◽  
pp. 479-482
Author(s):  
Jin Fan Zhang ◽  
Zhen Yu Wang ◽  
Jian Qun Jiang
Keyword(s):  
Large Deformation ◽  
Deformation Behaviour ◽  
Model Fit ◽  
Component Model ◽  
Deformation Condition ◽  
Finite Element Models ◽  
Design Codes ◽  
Spring Model ◽  
Proposed Model ◽  
Set Up

Based on the component method of EuroCode3, a new component model to evaluate properties of T-stub connections under large deformation condition has been proposed in this paper. Firstly, the T-stub connection was breakdown into several components. And then those components was equivalent to bilinear springs. Finally the multi-spring model of T-stub connection was set up to describe its load deformation behaviour. With the purpose of verifying and calibrating the proposed model, a series of case studies were carried out and corresponding finite element models has also been set up. Results of FEM and multi-spring model fit well each other. And the applicability of the proposed model can be testified by the parametric study. The method of this paper can describe the behaviour of T-stub connections under large deformation condition, which can be a useful improvement to conventional design codes.

Engineering Applications of Synchrotron X-Rays and Neutrons and the FaME38 Project

2004 ◽  
Author(s):  
P. J. Webster ◽  
Z. Chen ◽  
D. J. Hughes ◽  
A. Steuwer ◽  
B. Malard ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Strain ◽  
Stress Fields ◽  
Diagnostic Tools ◽  
X Rays ◽  
X Ray ◽  
Engineering Research ◽  
Materials Engineering ◽  
Set Up ◽  
Non Destructive

Large Central Scientific Facilities such as the ESRF (the European Synchrotron Radiation Facility) and ILL (the European centre for neutron research), were set up to provide scientists with the advanced facilities they need to exploit neutron and synchrotron X-ray beams for scientific research. Engineers also conduct research at these Facilities, but this is less common as most practicing engineers generally have little or no knowledge of neutron or X-ray scattering, or of their considerable potential for engineering research, model validation, material development and for fatigue and failure analysis. FaME38 is the new joint support Facility for Materials Engineering, located at ILL-ESRF, set up to encourage and to facilitate engineering research by engineers at these facilities. It provides a technical and knowledge centre, a materials support laboratory, and the additional equipment and resources that academic and industrial engineers need for materials engineering research to become practicable, efficient and routine. It enables engineers to add the most advanced scientific diffraction and imaging facilities to their portfolio of diagnostic tools. These include non-destructive internal and through-surface strain scanning, phase analysis, radiography and tomography of engineering components. Synchrotron X-ray and neutron diffraction strain mapping is particularly suited for the rigorous experimental, non-destructive, validation of Finite Element and other computer model codes used to predict residual stress fields that are critical to the performance and lifetimes of engineering components. This paper discusses the FaME38 facility and demonstrates its utility in gaining fundamental insight into mechanical engineering problems through examples, including studies of railway rails, welds and peened surfaces that demonstrate the potential of neutron of synchrotron X-ray strain scanning for the determination of residual stress fields in a variety of engineering materials and critical components.

A Study on the Normalized Load Function for J-R Curve Testing Using Normalization Method

2014 ◽  
Author(s):  
Kuk-cheol Kim ◽  
Young-wha Ma
Keyword(s):  
Compact Tension ◽  
Normalization Method ◽  
Piping System ◽  
J Integral ◽  
Function Type ◽  
Curve Estimation ◽  
Load Function ◽  
Crack Stability ◽  
Set Up ◽  
Leak Before Break

The purpose of this study is to suggest a more appropriate normalized load G-function for normalization method of J-R curve testing in the ASTM 1820 standard. For leak before break (LBB) design of reactor coolant piping system, J-R curve testing is required to verify the crack stability integration using J-T analysis. The normalization method of J-R curve testing is an excellent candidate testing method for dynamic J-R curve testing. In the normalization function, the load value is normalized by the G-function based on the plastic η factor. The normalized load function, G-function is important because the resultant J-R curve depends on the normalized function type used. However, for existing J-R curve calculation using the G-function in ASME standards, there exists a mismatch of estimated J integral values between the two different J-integral calculation approaches: the standard method in ASTM 1820, and the approach based on a J-integral physical concept with energy release rate. This problem is caused by the G-function type. To set up a more appropriate G-function, finite element (FE) analysis has been performed for compact tension specimens with various a/W and strain hardening index n. Also, application of the newly proposed G-function to J-R curve estimation is discussed.

Fracture-mechanics Parameters of the Composite-Enamel Bond

1990 ◽  
Vol 69 (1) ◽  
pp. 31-35 ◽  
Author(s):  
R. De Groot ◽  
H.C. Van Elst ◽  
M.C.R.B. Peters
Keyword(s):  
Fracture Mechanics ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Resin Composite ◽  
Strain Energy Release ◽  
Critical Values ◽  
J Integral ◽  
Single Edge ◽  
Opening Mode ◽  
Mode Stress

In a previous study, the critical values of the opening mode stress intensity factor (K1 ), its equivalent, the strain energy-release rate (G1 ), and the J integral (J1 ) (in the elastic case being equal to that of G1 ) were determined for resin composite. In this study, the strength of the composite-tooth interface was investigated. The critical values of K1 and J1 were measured with single-edge notched-bend (SENB) specimens of resin composite bonded to enamel, with the notch at midspan at the bonded interface. Due to enamel's anisotropy, the values of K1c and J1c to be used in a fracture-mechanics application for failure prediction of a structure depend on the enamel prism orientation relative to the adhesive interface. Where interfacial failure is to be expected, the following values for J 1c and K1c can be used: Silux, J1c = 145 ± 35 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 163 ± 13 Jm-2 and K1c = 1.02 ± 0.07 MNm-3/2. Where enamel failure is expected or where the failure mode cannot be predicted, the following values can be applied: Silux, J 1c = 89 ± 15 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 89 ± 15 Jm-2 and K 1c = 0.75 ± 0.10 MNm-3/2.

Formulation for Stress Intensity Factors and J-Integral Calculation by Eddy Current Testing

2015 ◽  
Vol 660 ◽  
pp. 225-230 ◽  
Author(s):  
Salaheddine Harzallah ◽  
Mohamed Chabaat ◽  
Sekoura Benissad
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Eddy Current ◽  
Eddy Currents ◽  
J Integral ◽  
Intensity Factors ◽  
Magnetic Vector ◽  
Current Testing ◽  
Set Up

In this paper, we present a method for computing the Stress Intensity Factor (SIF) and J-Integral, by measuring and testing related Eddy currents. In the process, we provide a magnetic vector based formulations for the theoretical set up. Furthermore, we provide relevant applications having theory consistent results.

scholarly journals Influence of Pressure and Thermal Parameters on Stresses Analysis of Pressurized and Cracked Pipes

2019 ◽  
Vol 35 (6) ◽  
pp. 1640-1646
Author(s):  
Abdullah K. Okab ◽  
Khalid A. Mohammed ◽  
Abdurahman A. Gatta
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
J Integral ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Modeling Process ◽  
Oil Gas ◽  
Pressurized Cylinder

Due to the dangerous alarm for many engineering applications such as energy generating systems and pipelines transporting oil, gas and its derivatives under high-pressure, a study of the effect of thermal and mechanical loading on the cracked materials and pipes at high-temperature environments is required. In this work, the influence of the thermal loadings on stresses analysis of pressurized and cracked pressurized pipes has been solved numerically where the mode I crack's type has been considered. The modeling process mainly aims to find the stress intensity factor, J-integral calculations and the stress distributions. The accuracy of the results has been compared with analytical solutions of a pressurized cylinder. The mesh around the crack have been modeled in a careful way to obtain accurate stress distributions. It was found that the surface’s temperature has a significant effect on stress distributions, for example, the stresses increased by 50% with increasing the temperature differences between the inner and outer pipe’s diameter. Additionally, the stress intensity factor and the J-integrals values were calculated for different crack length ratios and temperature differences. It is found at the crack length ratio of 0.6 the stress intensity factors increased up to 50% from 45 to 76 and J-integral increased by 77% from 250 kN/m to 430 kN/m. Also, the influence of fluid’s temperature investigated, and the result showed that by increasing the fluid’s temperature without cracks, the stresses decreased by 33%. Also, it was found that for different crack length ratios the J-integral and stress intensity reduces when the fluid’s temperature increases.

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