Complex Crack Stability in Dissimilar Metal Welds: Background and Test Plan

2011 ◽  
Author(s):  
D. Rudland ◽  
P. Scott ◽  
R. Olson ◽  
A. Cox
Keyword(s):  
Experimental Data ◽  
Base Metal ◽  
Carrying Capacity ◽  
Nuclear Industry ◽  
Load Carrying Capacity ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
Crack Stability ◽  
Complex Crack ◽  
The Stability

Typically in flaw evaluation procedures, idealized flaw shapes are assumed for both subcritical crack growth and critical crack stability analyses. Past NRC-sponsored research have developed estimation schemes for predicting the load-carrying capacity of idealized flaws in nuclear grade piping and similar metal welds at the operating conditions of nuclear power reactors. However, recent analyses have shown that growth of primary water stress corrosion cracks (PWSCC) in dissimilar metal (DM) welds is not ideal; in fact, very unusual complex crack shapes may form, i.e., a very long surface crack that has a finite length through-wall crack in the same plane. Even though some experimental data on base metal cracks exist to demonstrate that complex shaped cracks in high toughness materials fail under limit load conditions, other experiments demonstrate that the tearing resistance is significantly reduced. At this point, no experimental data exists for complex cracks in DM welds. In addition, it is unclear whether the idealized estimation schemes developed can be used to predict the load carrying capacity of these complex-shaped flaws, even though they have been used in past analyses by the nuclear industry. Finally, it is unclear what material strength data should be used to assess the stability of a crack in a DM weld. The NRC Office of Nuclear Regulatory Research (RES), with their contractor Battelle Memorial Institute, has begun an experimental program to confirm the stability behavior of these complex shaped flaws in DM welds. A combination of thirteen full-scale pipe experiments and a variety of laboratory experiments are planned. This paper will summarize the past base metal complex-cracked pipe experiments, and the current idealized flaw load carrying capacity estimation schemes. In addition, the DM weld complex cracked pipe experimental test matrix will be presented. Finally, plans for using these results to confirm the applicability of idealized flaw stability procedures are discussed.

Dissimilar Metal Weld Pipe Fracture Testing: Analysis of Results and Their Implications

2012 ◽  
Author(s):  
D. Rudland ◽  
R. Lukes ◽  
P. Scott ◽  
R. Olson ◽  
A. Cox ◽  
...  
Keyword(s):  
Experimental Data ◽  
Carrying Capacity ◽  
Nuclear Industry ◽  
Load Carrying Capacity ◽  
Base Metals ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
Estimation Scheme ◽  
The Stability ◽  
J Estimation

Typically in flaw evaluation procedures, idealized crack shapes are assumed for both subcritical and critical crack analyses. Past NRC-sponsored research have developed estimation schemes for predicting the load-carrying capacity of idealized cracks in nuclear grade piping and similar metal welds at the operating conditions of nuclear power reactors. However, recent analyses have shown that growth of primary water stress corrosion cracks (PWSCC) in dissimilar metal (DM) welds is not ideal; in fact, very unusual complex crack shapes may form, i.e., a very long surface crack that has a finite length through-wall crack in the same plane. Even though some experimental data on base metals exists to demonstrate that complex shaped cracks in high toughness materials fail under limit load conditions, other experiments demonstrate that the tearing resistance is significantly reduced. At this point, no experimental data exists for complex cracks in DM welds. In addition, it is unclear whether the idealized estimation schemes developed can be used to predict the load-carrying capacity of these complex-shaped cracks, even though they have been used in past analyses by the nuclear industry. Finally, it is unclear what material strength data should be used to assess the stability of a crack in a DM weld. The NRC Office of Nuclear Regulatory Research, with their contractor Battelle Memorial Institute, has concluded an experimental program to confirm the stability behavior of complex shaped circumferential cracks in DM welds. A combination of full-scale pipe experiments and a variety of laboratory experiments were conducted. A description of the pipe test experimental results is given in a companion paper. This paper describes the ongoing analyses of those results, and the prediction of the load-carrying capacity of the circumferential cracked pipe using a variety of J-estimation scheme procedures. Discussions include the effects of constraint, appropriate base metal material properties, effects of crack location relative to the dissimilar base metals, and the limitations of the currently available J-estimation scheme procedures. This paper concludes with plans for further development of J-estimation scheme procedures for circumferential complex cracks in DM welds.

Fracture Toughness Behavior of Complex Cracks in Dissimilar Metal Welds

2014 ◽  
Author(s):  
D. Rudland ◽  
M. Benson ◽  
D.-J. Shim
Keyword(s):  
Fracture Toughness ◽  
Carrying Capacity ◽  
Material Strength ◽  
Load Carrying Capacity ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
Estimation Scheme ◽  
Complex Crack ◽  
Η Factor ◽  
J Estimation

Currently, J-estimation scheme procedures to predict the load-carrying capacity of idealized circumferential through-wall cracks in nuclear grade piping materials employ analytical or numerical procedures coupled with the fracture toughness of the material to predict the pipe response. However, with the advent of primary water stress corrosion cracking (PWSCC), complex-shaped cracks occur in dissimilar metal (DM) welds. These welds consist of a nickel-based weld joining stainless steel and carbon steel base metals. The NRC Office of Nuclear Regulatory Research (RES) is conducting a program to investigate the behavior of circumferential through-wall and complex cracks in DM welds. In a prior paper, a series of full-scale pipe bend and laboratory-sized fracture experiments were documented. Initial analyses of those test results suggest that reasonable prediction of through-wall crack response is obtained from typical J-estimation scheme procedures using the weld toughness from a compact tension (CT) specimen and the appropriate material strength. In addition, the J-R curves from the through-wall cracked pipe tests, calculated using published η-factor solutions and numerical techniques, were very similar to the CT J-R curves. In this paper, the fracture toughness for the circumferential complex cracked experiments, which was developed from a modified η-factor solution, is presented. These results are compared to the CT and through-wall crack pipe J-R curve results. In addition, predictions of load carrying capacity using the complex crack J-R curve and through-wall crack J-estimation schemes are presented and illustrate the need for the development of a complex crack J-estimation scheme. To support this development, a net-section collapse solution and a modified K-solution is presented. Finally, the need for additional work to generalize the elastic solution and its incorporation into a closed-form J-estimation scheme is discussed.

Development of Z-Factor for Circumferential Part-Through Surface Cracks in Dissimilar Metal Welds

2008 ◽  
Author(s):  
D.-J. Shim ◽  
G. M. Wilkowski ◽  
D. L. Rudland ◽  
F. W. Brust ◽  
Kazuo Ogawa
Keyword(s):  
Correction Factor ◽  
Carrying Capacity ◽  
Limit Load ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Surface Cracks ◽  
Crack Driving Force ◽  
Dissimilar Metal ◽  
Load Carrying ◽  
J Estimation

Section XI of the ASME Code allows the users to conduct flaw evaluation analyses by using limit-load equations with a simple correction factor to account elastic-plastic fracture conditions. This correction factor is called a Z-factor, and is simply the ratio of the limit-load to elastic-plastic fracture mechanics (EPFM) maximum-load predictions for a flaw in a pipe. The past ASME Section XI Z-factors were based on a circumferential through-wall crack in a pipe rather than a surface crack. Past analyses and pipe tests with circumferential through-wall cracks in monolithic welds showed that the simplified EPFM analyses (called J-estimation schemes) could give good predictions by using the toughness, i.e., J-R curve, of the weld metal and the strength of the base metal. The determination of the Z-factor for a dissimilar metal weld (DMW) is more complicated because of the different strength base metals on either side of the weld. This strength difference can affect the maximum load-carrying capacity of the flawed pipe by more than the weld toughness. Recent work by the authors for circumferential through-wall cracks in DMWs has shown that an equivalent stress-strain curve is needed in order for the typical J-estimation schemes to correctly predict the load carrying capacity in a cracked DMW. In this paper, the Z-factors for circumferential surface cracks in DMW were determined. For this purpose, a material property correction factor was determined by comparing the crack driving force calculated from the J-estimation schemes to detailed finite element (FE) analyses. The effect of crack size and pipe geometry on the material correction factor was investigated. Using the determined crack-driving force and the appropriate toughness of the weld metal, the Z-factors were calculated for various crack sizes and pipe geometries. In these calculations, a ‘reference’ limit-load was determined by using the lower strength base metal flow stress. Furthermore, the effect of J-R curve on the Z-factor was investigated. Finally, the Z-factors developed in the present work were compared to those developed earlier for through-wall cracks in DMWs.

Structural Behaviour of Precast Lightweight Foamed Concrete Sandwich Panel (PLFP) with Double Shear Truss Connectors under Axial Load: Preliminary Result

2013 ◽  
Vol 795 ◽  
pp. 190-194
Author(s):  
S. Samsuddin ◽  
I. Ahmad ◽  
W.I. Goh ◽  
N. Mohamad ◽  
Abdul Aziz Abdul Samad ◽  
...  
Keyword(s):  
Experimental Data ◽  
Carrying Capacity ◽  
Ultimate Load ◽  
Axial Loading ◽  
Load Carrying Capacity ◽  
Structural Behaviour ◽  
Double Shear ◽  
Load Carrying ◽  
Foamed Concrete ◽  
Ultimate Load Carrying Capacity

This report provides experimental data on the development of PLFP for building construction. An innovative concept was used in the design of this system and the use of lightweight foamed concrete was discussed. Preliminary result of PLFP with double shear truss connectors was analysed and presented. PLFP was tested to determine its ultimate load carrying capacity under axial loading. Ultimate load carrying capacity, load deflection profile, surface strains and crack pattern were recorded and analysed. Test results were compared with calculated values based on classical formulas that developed by previous researchers and experimental data from previous researchers on its compositeness in between wythes. Results shown that PLFP with double shear truss connectors achieved higher compositeness in between wythes and have adequate ultimate load carrying capacity.

Theoretical Analysis of Externally Pressurized Air Journal Bearing

1970 ◽  
Vol 12 (2) ◽  
pp. 123-129 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Experimental Data ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Dimensional Parameters ◽  
Bearing Design

A theoretical investigation is made to predict the performance of an externally pressurized air journal bearing having several pressure sources. The pressure distribution, which leads to the determination of load-carrying capacity and flow requirement, is obtained by solving Reynolds equation numerically. The load and flow, expressed in non-dimensional parameters, are presented for different bearing design parameters (dimensionless). The results predicted by this method are compared with others' experimental data.

scholarly journals Effect of Grouted Granular Column on the Load Carrying Capacity of the Expansive soil

2019 ◽  
Vol 8 (3) ◽  
pp. 2606-2612
Keyword(s):  
Carrying Capacity ◽  
Urban Areas ◽  
Expansive Soil ◽  
Engineering Properties ◽  
Load Carrying Capacity ◽  
Loose Soil ◽  
Load Carrying ◽  
The Stability ◽  
Lateral Reinforcement ◽  
Granular Column

Due to the scarcity of land for the construction of industrial, commercial, and transportation structures for development in urban areas, it is very necessary to use the places which have weak strata. This has become very mandatory to use the land which has poor engineering properties due to the unavailability of land. In the recent years granular columns have come under the extensive use for increasing the load carrying capacity and reducing the settlement in the expansive soil and loose sand. Nowadays to increase the stability of the foundation, granular columns are being widely used. Traditional columns are driven into the weak expansive soil stratum and maintain its stability from lateral confinement, which is generally due to the reaction from the surrounding stiffened expansive soil. However, this is not so easy to support loose soil, an additional lateral support may have to be provided to stabilize it and reduce its settlements. This study aims to overcome this weakness in soil by wrapping the granular column in geotextile layer to enhance the lateral reinforcement. In the present paper the discussion is about the variation in load carrying capacity and settlement characteristics of granular column (made up of cement fly ash and sand in a definite proportion instead of aggregates and stones) and analyzing its effect on the expansive soil by comparing its results with geotextile encased columns. In this process the study investigates the improvement of load carrying capacity of a single granular column encased with geotextile through model test.

On the Combined Effects of Lubricant Inertia and Viscous Dissipation in Long Bearings

1997 ◽  
Vol 119 (1) ◽  
pp. 76-84 ◽  
Author(s):  
E. Kim ◽  
A. Z. Szeri
Keyword(s):  
Carrying Capacity ◽  
Journal Bearings ◽  
Isothermal Flow ◽  
Nonisothermal Flow ◽  
Combined Effects ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Bearing Load ◽  
The Stability ◽  
Rate Of Dissipation

We have demonstrated earlier that for laminar, isothermal flow of the lubricant in the non-cavitating film of long journal bearings, inertia has negligible effect on the load-carrying capacity and influences only the stability characteristics of the bearing. The question we pose in the present paper is: “will these conclusions remain valid for nonisothermal flow, or will lubricant inertia and dissipation interact and result in significant changes in bearing performance?” The results obtained here assert that the effect of lubricant inertia on load-carrying capacity remains negligible, irrespective of the rate of dissipation. The stability of the bearing is, however, affected by lubricant inertia. These results, although obtained here for long bearings and noncavitating films, are believed to be applicable to some practical bearing operations and suggest that for these, bearing load may be calculated from classical, i.e., noninertial theory.

scholarly journals Evaluation of Talud Technical Planning on River Regency of Aceh Singkil

2018 ◽  
Vol 7 (2.13) ◽  
pp. 372
Author(s):  
Darlina Tanjung ◽  
Jupriah Sarifah ◽  
Bangun Pasaribu ◽  
Marwan Lubis ◽  
Anisah Lukman ◽  
...  
Keyword(s):  
Safety Factor ◽  
Carrying Capacity ◽  
Retaining Wall ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Increase In Productivity ◽  
Technical Planning ◽  
The Stability ◽  
The City ◽  
Physical Manifestation

Dynamics that occur in the city of Singkil impact on the development of the city both on socioeconomic aspects as well as in the physical manifestation of talud facilities, which can spur an increase in productivity of a region and the functioning of infrastructure of a city well and smooth. Effect of retaining wall against cliff reinforcement that can protect embankment or beach. By knowing the magnitude of the effect of the safety factor due to the slip, bolster, and the decrease due to the consolidation of the clay layer and the load of the embankment as well as the amount of time of the decline. The crumbling factor (FS guling = 14.97) is greater than the safety factor, for the stability of the slip where the maximum force, where the only force of thrust causing the active horizontal force component (Pa = 0.333) results in a FS (slip) greater than the safety factor of stability to the carrying capacity, the eccentricity value (e = - 0.081) more than 1/6 then the qmin value becomes positive, since the value of e <1/6, and the FS yield of soil bearing capacity (FS (carrying capacity) = 162.122) this value is greater than FS security means the talud safely holds load carrying capacity, safe against bolsters and slip. 

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