bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental and Analytical Study on Local Failure of Structure Subjected to High Temperature and Pressure
Authors: Tsunemoto Yoshiki , Sakaguchi Takashi , Sato Takuya , Kasahara Naoto 
Published: November 2019

Abstract
In our past paper, the new fracture surface was proposed considering the effects of hydrostatic stress in an elastic-plastic region and in a creep region. In this paper, the mechanism the dominant factors of local failure were studied in an elastic-plastic region. Experimental and analytical study were made using circular plate specimens with a nozzle. The material was a lead alloy (99% Pb-1% Sb). The fracture test was performed in an elastic-plastic region at room temperature. Both ductile fracture and local failure were observed at structural discontinuities, based on the stiffness differences between attached nozzles and plates. In this study, the proposed fracture surface in an elastic-plastic region showed the fracture location accurately, for the both failure modes. It was concluded that the proposed fracture surface is available and useful in order to predict the failure mode and the failure location.
Elastic-Plastic Analysis of Pipe Structure by Transfer Matrix Method
Authors: Arai Masayuki , Kuroda Shoichi , Ito Kiyohiro 
Published: November 2019

Abstract
Pipe systems have been widely used in industrial plants such as power stations. In these systems, it is often required to predict the displacement and stress distribution. Analytical and numerical methods such as the finite element method (FEM), boundary element method (BEM), and frame structure method (FSM) are typically adopted to predict the displacement and stress distribution. The analytical methods are solved based on the Timoshenko beam theory, but the problem that can be solved is limited to simple geometry under simple boundary conditions. Both FEM and BEM can be applied to more complicated problems, although this usually involves a large number of degrees of freedom in a stiffness matrix. The structure is modeled by a beam element in FSM. However, the stiffness matrix still becomes large, as does the matrix size constructed in FEM and BEM. In this study, the transfer matrix method (TMM) is studied to effectively solve complicated problems such as a pipe structure under a small size of the stiffness matrix. The fundamental formula is extended to apply to an elastic-plastic problem. The efficiency and simplicity of this method is demonstrated to solve a space-curved pipe system that involves elbows. The results are compared with those obtained by FEM to verify this method.
Effect of Internal Pressure on Gasket Stress and Leakage Rate of Bolted Flanged Joint During the Long Term Service at High Temperature
Authors: Xue Jilin , Chen Xuedong , Fan Zhichao , Wang Lu 
Published: November 2019

Abstract
Bolted flange joints (BFJs) are very common in the process industries, and they play an important role in equipment connection. A lot of BFJs are working at high temperature. The temperature and internal pressure will lead to gasket stress redistribution, and then affect time-dependent leakage rate of BFJs. In this paper, the effect of internal pressure on gasket stress and leakage rate of BFJ during the long term service at high temperature was discussed. The time-dependent gasket stresses of BFJ during the long term service at high temperature under two tightness levels and three internal pressures were calculated by using the finite element method. And then, based on the leakage rate prediction model of BFJ during the long term service at high temperature proposed, the corresponding time-dependent leakage rates of BFJ during the long term service at high temperature were acquired. The results showed that the internal pressure had a significant impact on the time-dependent gasket stresses and time-dependent leakage rates of BFJ during the long term service at high temperature. This research will help the engineers and technicians to understand the role of the internal pressure on the time-dependent gasket stresses and time-dependent leakage rates of BFJ during the long term service at high temperature.
Failure Assessment Using XFEM for the Austenitic Stainless Steel Pipe With the Circumferential Crack Subjected to Bending and Torque
Authors: Ono Yohei , Sakai Michiya 
Published: November 2019

Abstract
Failure assessment of a pipe with a circumferential crack in a nuclear power plant has to conform to the Rules on Fitness for Service for Nuclear Power Plants published by JSME (The Japan Society of Mechanical Engineering) [1] in Japan. Based on the rules, the applied stresses considered in the failure assessment of the pipe using limit load assessment are membrane, bending, and thermal stresses. The failure assessment focuses only on mode I. In actual plants, depending on the piping system, there is a possibility that torsional stress [2] is applied to the pipe, in addition to membrane, bending, and thermal stresses. Under such a load condition, the crack opening mode will be mixed-mode. In ASME Boiler & Pressure Vessel Code section XI, the bending and torsional moment are considered in failure assessment of the pipe. Therefore, it is important to establish the failure assessment method for the pipe with the crack under mixed-mode. In this study, the XFEM (extended Finite Element Method) [3][4] was applied to assess failure of the austenitic stainless steel pipe (Type 304) with a circumferential crack subjected to bending and torsional moment. XFEM does not require elemental division considering the crack shape and its propagation path. Therefore, the time and cost for developing the analysis model can be reduced compared with conventional FEA (Finite Element Analysis). Fracture test results conducted under two conditions were used the analysis (Specimen No. TP1 and TP2) for determining the energy release rate for crack propagation and verifying the analysis results. The difference between the two tests was the ratio of torsional moment to bending moment. The ratios in TP1 and TP 2 were 0.6 and 1.2, respectively. A parametric analysis was conducted to determine the critical equivalent strain energy release rate required for crack initiation and propagation by comparison with TP1 results. The determined critical equivalent strain energy release rate was verified by comparison with TP2 results. In response to the above considerations, the decreasing load due to crack propagation in the fracture tests under mixed-mode condition was simulated by XFEM, and the maximum load, bending moment, and torsional moment were predicted within the margin of error of 6.1%.
Unsteady Fluid Force and Random Excitation Force Measurement of Triangular Array Tube Bundle in Steam-Water Two Phase Flow
Authors: Nishida Shingo , Kawakami Ryoichi , Hirota Kazuo , Morita Hideyuki , Kondo Yoshiyuki , Utsumi Seiho 
Published: November 2019

Abstract
The in-plane (stream-wise) fluid-elastic instability of triangular tube arrays caused tube-to-tube wear indications as observed in the U-bend regions of tube the bundles of San Onofre Unit-3 steam generators. To understand the in-plane FEI characteristics, stability analysis using unsteady fluid forces is quite helpful. However, taking measurements of unsteady fluid forces in the in-plane direction is quite challenging as the fluid coupling forces of the surrounding tubes must be measured simultaneously for the in-plane stability analysis. In particular, taking measurements under a high pressure and high temperature steam-water conditions, similar to an SG operating condition, is extremely difficult. Recently we have been able to successfully measure unsteady fluid force using a specially designed test equipment. In the meantime, random excitation forces acting on heat transfer tubes were also measured. We calculated the stability boundary of the in-plane FEI using the unsteady fluid force measurement with this special equipment.
Model and Experimental Analysis of the Fiber-Reinforced Pultrusion Composite Under Tension and Shear
Authors: Zhang Qian , Zhang Yanting , Jiang Wenchun 
Published: November 2019

Abstract
This paper proposed a homogenization model, and compiled a VUMAT subroutine to simulate the tension and shear of fiber-reinforced pultrusion composite (FRPC). Experiments were also performed to verify the accuracy of the homogenization model. The results show that, the simulation results agree well with the experiment data. The stiffness and strength increase with the increase of the diameter of the carbon composite part. The limit shear load and the horizontal shear strength decrease with the increase of the span. When FRPC is under shear with smaller span, the matrix tensile damage initiates first and it is the dominate failure mode, then the matrix and fiber compression damage occur at where the indenters contact. However, with the increase of the span, the delamination damage between the wound glass-fiber reinforced composite and pultrusion glass-fiber reinforced composite occurs and becomes the dominate failure mode for FRPC shear.
Evaluation of the Transportable Detonation Chamber for Processing Recovered Munitions
Authors: Tribble Megan K. , Stofleth Jerome H. 
Published: November 2019

Abstract
Sandia National Laboratories was tasked by the United States Army Recovered Chemical Materiel Directorate with evaluating the fitness of the Transportable Detonation Chamber for use in demilitarization of chemical munitions. The chamber was instrumented with strain, pressure, and acceleration sensors to study its behavior during explosive tests ranging from 1.25 to 20 lb of explosive charge weight. The structural response of the chamber and techniques recommended by the manufacturer — use of water bags and sand-filled walls — were assessed. Through this testing, it was found that the two techniques did not significantly affect the chamber’s response. It was also discovered that the structural integrity of the chamber (and, therefore, its suitability for use with chemical agents) was compromised, as some welds failed. Sandia does not recommend using this vessel for chemical munition demilitarization. This chamber is suitable, however, for demilitarization of conventional munitions, in which fragments and overpressure are the primary concern.
Development of Creep Test Method for Thermoplastic Fiber-Reinforced Polymer Composite Tubes Under Pure Hoop Loading Condition
Authors: Doan Hai G. M. , Ashrafizadeh Hossein , Mertiny Pierre 
Published: November 2019

Abstract
Piping made from thermoplastic fiber reinforced polymer composites (TP-FRPCs) is receiving increasing attention in the oil and gas industry. Creep and time-dependent behavior is one of the main factors defining the service life of TP-FRPC structures. The lifetime and time-dependent behavior of TP-FRPC structures can be predicted using simulation tools, such as finite element analysis, to aid in the design optimization by modeling the long-term behavior of the material. Composite material time-dependent properties are required inputs for such models. While there is previous research available on creep testing of TP-FRPCs in laminate geometry, such tests may not enable accurate determination of the composite properties due to edge effects. On the other hand, coupons with tubular geometry not only provide improved load distribution between the fibers and matrix with minimal end effects, they also enable certain loading conditions experienced during typical piping operations such as internal pressure. In this study, a testing method to capture the creep behavior of tubular TP-FRPC specimens subjected to multi-axial loading conditions was developed. Tubular coupons were prototyped by an automated tape placement process. Strain was measure using digital image correlation technique and strain gauges. The development of the test setup forms the foundation for further testing of tubular TP-FRPC coupons at different multi-axial loading conditions. As a preliminary test, the creep behavior of a TP-FRPC tube subjected to pure hoop stress condition was evaluated using the developed testing process.
Resilience Calculation of Process Plants Under Seismic Loading: A Case Study
Authors: Kalemi Bledar , Caputo Antonio C. , Paolacci Fabrizio 
Published: November 2019

Abstract
Earthquakes causes approximately 8% of total accidents in industrial facilities. Although there are several researches in literature pertaining to industrial resilience, none of them provides a modelling framework to quantify the seismic resilience of process plants. This paper presents a methodology for providing a quantitative measure of resilience and business economic losses for the process plants in case of a seismic event. The two main parameters which have utmost influence on the resilience of a process plant are operational capacity and recovery time, so they must be evaluated in proper way. Plant mapping and components vulnerability are the key modelling parameters of plant operational capacity. Exact recovery step functions are introduced based on General Reconstruction Activity Network (GRAN), considering interdependencies between plant components. In order to illustrate the discussed method, a nitric acid plant is set up as a case study. “PRIAMUS” software is used to generate the most probable damage scenarios, assuming the plant is located in seismic region of South Italy, Sicily. Ultimately, recovery curves are constructed for each damaged scenario, and business economic losses are calculated according to direct cost and business interruption. In short, this methodology provides a good estimation of the most critical components and economic losses of a process plant in case of a seismic event.
Re-Evaluation of Stress Rupture Factors for Grade 91 Weldments Based on the Extended Database With the Data Collected in Japan
Authors: Kimura Kazuhiro , Yaguchi Masatsugu 
Published: November 2019

Abstract
Stress rupture factors and weld strength reduction factors for Grade 91 steel weldments in the codes and literatures have been reviewed. Stress rupture factors for weld metals proposed for Code Case N-47 in the mid 1980’s was defined as a ratio of average rupture strength of the deposited filler metal to the average rupture strength of the base metal. Remarkable drop in creep rupture strength of weldments is significant issue of Grade 91, especially in the low-stress and long-term regime. A premature failure of Grade 91 steel weldments in the long-term, however, is caused by Type IV failure which takes place in the fine grain heat affected zone (FG-HAZ), rather than fracture in the deposited weld metal. The stress rupture factor of the Grade 91 steel, therefore, was based on the creep rupture strength of cross weld test specimens. Creep rupture data of Grade 91 steel weldments reported in the publication of ASME STP-PT-077 was incorporated in the creep database collected in Japan which was used for the previous study. Time and temperature dependent stress rupture factors for Grade 91 steel have been re-evaluated based on the extended database as a ratio of average creep rupture strength of cross weld test specimen to the average creep rupture strength of base metal.
Vibration Suppression in Frame-Structural Tower With Fluid Viscous Dampers
Authors: Fan Xiantao , Du Yian , Tan Wei 
Published: November 2019

Abstract
Flexible and skyscraping frame-structural tower is sensitive to dynamic loads, that might oscillate intensely under seismic and wind loads. Thus, vibration suppression system is required and fluid viscous damper (FVD) is implemented to suppress such vibration in this study. The vibration behavior of frame-structural tower with FVD (F-FVD) is investigated by an equivalent model combined with experiment under seismic and wind loads, respectively, and the vibration suppression effect is evaluated by the displacement and energy distribution. The equivalent model of the frame-structural tower with FVD is primarily established, of which FVD is considered through Kelvin model. The parameters of FVD are supplemented to the damping term through a time-dependent damping matrix based in Rayleigh damping, and to the stiffness term through a stiffness matrix based in stiffness-equivalent simply-supported beam. Van der Pol wake oscillator is considered as the wind force term. Several conventional numerical integration methods for solving the equivalent model which belongs to the nonlinear system are compared and Newmark-β algorithm is adopted. The vibration suppression regularity of normalized stiffness coefficient Kr, damping coefficient Cr and velocity exponent α is analyzed via the equivalent model. There is a balance between the stiffness effect and energy dissipation effect of FVD, and the sensitiveness to α depends on excitation and stiffness of F-FVD system. The optimal parameters of fluid viscous damper, Kr = 1.30∼2.0, Cr = 1.65∼3.30 and α = 0.4∼0.8, are obtained eventually. It is indicated that the vibration suppression by fluid viscous damper is effective. And this study can be conducive to vibration suppression design of such flexible and skyscraping frame-structural tower.
Estimation of Impact Energy for Seat Seals in Spring-Operated Pressure Relief Valves During the Reseating Process Under Compressible Fluid Service Conditions
Authors: Schimanowski Alex , Schlattmann Josef 
Published: November 2019

Abstract
Spring operated pressure relief valves (SOPRVs) are used in many industrial fields for hazardous applications in order to protect people and environment as well as to reduce the risks of containment loss. Since SOPRVs are essential elements of safety systems, they are subject to strict functional and reliability requirements, which demand not only a proper disk lift but also give regulations concerning the maximum allowable valve tightness. However, despite the high practical importance of SOPRVs tightness through the whole life cycle, only initial tightness is considered in the literature and regulations. Therefore, in the present contribution we make an attempt to quantify the impact energy of the valve disk during the reseating of the valve, which is assumed to be the most relevant factor for repeated valve tightness. First, we present three different methods of increasing complexity for disk impact energy estimation. Subsequently, we demonstrate the application of these methods on the example of a SOPRV Type API 526 1E2 and discuss the findings. Finally, we consider a set of selected common used soft sealing materials and give implications for their usage within a range of set pressures and maximum disk lifts based on findings for the presented use case.
Investigation on Fluidelastic Instability Accompanied by Wake Shedding With a Time-Domain Model
Authors: Guo Kai , Wang Yipeng , Su Tong , Liu Liyan , Jia Zhanbin , Tan Wei 
Published: November 2019

Abstract
As the most dangerous flow-induced vibration (FIV) mechanism, fluid-elastic instability is always accompanied by the wake shedding. If both of the two FIV mechanisms are considered, fluid forces in this condition can be quite complex. In this paper, a time-domain model based on unsteady flow theory was used to investigate the fluid-elastic instability in a rotated triangular tube array. The vortex shedding forces were simplified as harmonic forces. Computational fluid dynamics (CFD) was used to get the fluid force coefficients with vortex shedding. The model was established by a finite element code with MATLAB software and simulation results agreed with the experiment results. The results showed the critical instability velocity can be influenced by vortex shedding forces, and double peaks can be found in the frequency spectrum of displacements of tubes. The time-domain displacements showed the phases had been impacted by the shedding and periodic characteristic was found in the displacements results. The model can also be adopted in fluid-elastic instability analysis in other tube arrangements and flow conditions.
Mechanical Enhancement and Strain Sensing of Electrofusion Joint With Carbon-Fiber-Reinforced Polyethylene
Authors: Yao Riwu , Shi Jianfeng , Zheng Jinyang 
Published: November 2019

Abstract
Electrofusion (EF) technology is widely used for connecting plastic pipes or composite pipes. For these pipes used in natural gas transportation and nuclear power plant, the higher and higher operation pressure makes the strength of EF joint a limitation in the pressure pipeline systems. In this paper, high density polyethylene (HDPE) filled with different contents of short-cut carbon fiber (CF) was prepared by melt mixing and injection molding. Scanning electron microscopy imagines indicated a good dispersion of CF in HDPE matrix. Experiments were carried out to evaluate the mechanical and electrical properties of the HDPE-CF composite. The addition of CF improved the elastic modulus and yield stress of the composite compared with neat HDPE. The enhanced mechanical properties of HDPE-CF composite can improve the strength of EF joints, and bursting tests revealed a burst pressure of 8.11 MPa, which is 41.8% higher than that of neat HDPE EF joint. Based on the improved electrical conductivity, the electrical resistance of EF joint induced by the strain under internal pressure can be monitored for structural health monitoring of the pipeline. Thus, the combination of mechanical enhancement and strain sensing of EF joint with carbon-fiber-reinforced polyethylene can improve the strength and reliability of pressure pipeline.
Fitness for Service Assessment of Carbon Steel Vessel With Localized Deformation During PWHT
Authors: Shah Utkarsh , Prasad Piyush 
Published: November 2019

Abstract
Post weld heat treatment (PWHT) is applied to welded pressure vessels and piping to relieve residual stress built up during welding. During the PWHT, pressure vessel made of carbon steel is heated up to a minimum temperature of 595 °C for a holding period as required based on the thickness (Refer ASME Section VIII, Division 1, UCS 56) [1]. However, for equipment susceptible to carbonate stress corrosion cracking, PWHT is required irrespective of thickness at a temperature range of 649 °C to 663 °C as per WRC 452 [2].
A process column built in 1983 and operating in carbonate stress corrosion cracking environment was observed to have widespread corrosion under insulation at reboiler supports. Material of construction for the column was SM41B (Japanese Industry Standards Carbon Steel). Four Insert plates of various sizes were welded at same circumferential band during turnaround. The insert plate repair sizes were relatively large. Local PWHT was required to be performed with the equipment in vertical condition. Due to risk of uneven temperature distribution and resultant local thermal stresses, spot PWHT or Bulls-eye method of PWHT was not considered. Full circumferential local PWHT was considered for this equipment. During the actual PWHT process, localized overheating occurred, and some areas of deformation were observed in the equipment.
A multi discipline review was performed to understand the root cause of the localized overheating and subsequent deformation. This paper describes the methodology and results of the fitness-for-service (FFS) assessments that were performed based on API 579-1/ ASME FFS-1, 2016 [3] to assess the integrity of the column. Based on the assessment performed, the equipment was found to be fit for service and continued safe operations.
Seismic Test Results of Air-Operated Valve Actuators for Nuclear Power Plants (Air-Operated Globe Valve (Cylinder Type))
Authors: Kubota Ryo , Tsutsumi Yoshitaka , Matsubara Yoshinao , Suzuki Shigeki , Kumagai Shin 
Published: November 2019

Abstract
It is believed that air-operated globe valves are able to operate during and after earthquakes, leading to maximum accelerations beyond the existing allowable acceleration for nuclear power plants in Japan (6 × 9.8 m/s2). In this work, this assumption is verified using a resonance shaking table for seismic testing at acceleration levels of 20 × 9.8 m/s2 (see Ref. [1]). Results show that the active components used in existing air-operated globe valve designs remain operable at 22 × 9.8 m/s2 (horizontal (X and Y) and vertical (Z) directions).