Creep–fatigue evaluation of stainless steel welded joints in FBR class 1 components

Asayama, Tai

doi:10.1016/s0029-5493(99)00275-7

Cited by 10 publications

(4 citation statements)

References 4 publications

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“…Rapid solidification processing in HAZ leads to a metastable phase formation, solid solution, or dispersion strengthened alloys and intermetallics, and the whole physical phenomenon is at the origin of defects formation located in welded joints [13], [14]. It has been demonstrated that metallic alloy creep fatigue is related to the defect rate located in welded joints considered as a metallic alloy zones [15]. In particular, a model based on molecular dynamics calculations, developed by Vazquez, has discussed on isotropic and anisotropic relaxation phenomenon from simulations of lattice relaxation of metallic alloys considering the sudden appearance of vacancy or an interstitial site in the crystal [16].…”

Section: Results Of Thermomechanical Simulationsmentioning

confidence: 99%

Simulations of Thermomechanical Stresses and Optical Misalignment in 1550-nm Transmitter Optoelectronic Modules Using FEM and Process Dispersions

Deshayes

Béchou

Verdier

et al. 2008

IEEE Trans. Comp. Packag. Technol.

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Expertise of packaging for optoelectronic components requires the solution of optical, mechanical, and electrical problems in the same way. The purpose of this paper is to present three-dimensional simulations using finite-element method (FEM) of thermomechanical stresses and strains in 1550-nm laser modules induced by Nd:YAG crystal laser welds and thermal cycles on main subassembly laser submount. Nonlinear FEM computations, taking into account of experimental ( ) measured curves, show that thew laser welding process can induce high level of strains in columns of the laser platform, bearing the laser diode, responsible of an optical axis shift and a gradual drop of the optical power in relation with relaxation of accumulated stresses in the subassembly (W. M. Sherry et al., "High performance optoelectronic packaging for 2.5 and 10 Gb/s laser modules," in Proc. Electron. Compon. Technol. Conf., 1996, pp. 620-627). Typical stresses are close to 160 MPa with drift about 5 MPa with the dispersion of energy level of the laser Nd: YAG beam. The introduction of both material and process dispersion in order to evaluate their impact on product lifetime distribution has been taking into account. In the case of thermal cycles, stresses can occur on elements sensitive to coefficient of thermal expansion mismatches such as solder joints between the laser platform and thermoelectric cooler and as fiber glued into the pigtail leading to crack propagation with sudden drop of optical power. A previous paper demonstrated that laser submount is the most sensitive part of optical system (Deshayes, et al., "Three-dimensional FEM simulations of thermal mechanical stresses in 1.55 m laser modules," Microelectron. Rel., vol. 43, no. 7, pp. 1125-1136, Jul. 2003). Experimental analyses were also conducted to correlate simulation results and monitor the output optical power of laser modules after 500 thermal cycles ( 40 C + 85 C VRT). Index Terms-Distributed feedback (DFB), finite-element model (FEM), laser YAG, neodymium-doped yttrium aluminium garnet (NdYAG), optical module, reliability, welding.

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Section: Results Of Thermomechanical Simulationsmentioning

confidence: 99%

Simulations of Thermomechanical Stresses and Optical Misalignment in 1550-nm Transmitter Optoelectronic Modules Using FEM and Process Dispersions

Deshayes

Béchou

Verdier

et al. 2008

IEEE Trans. Comp. Packag. Technol.

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“…In an iterative manner, Δ𝜀 !" $ is calculated by minimizing the function in Equation (1). Assuming l is the number of load instances considered, and k is the number of sub-cycles required to reach convergence.…”

Section: The Creep-fatigue Damage Assessment Proceduresmentioning

confidence: 99%

“…The presence of welds further complicates the structural response. Considering both the economic and safety aspects, the life assessment of welds under creep-fatigue loading is a critical issue in reactors [1].…”

Section: Introductionmentioning

confidence: 99%

Creep–Cyclic Plasticity and Damage Assessment of an SS304 Weldolet

Puliyaneth

Chen

2021

Journal of Pressure Vessel Technology

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Creep-fatigue and creep-ratcheting life assessment of an SS304 weldolet considering full creep-cyclic plasticity interaction is investigated using the extended Direct Steady Cycle Analysis (eDSCA) within the Linear Matching Method Framework (LMMF). The creep behaviour is modelled using the Norton relationship, which is modified by the Arrhenius rule to account for the temperature variation within the weldolet. The introduction of a creep dwell increases the reverse plasticity resulting from the creep relaxation. This leads to both creep-fatigue and creep-ratcheting damage mechanisms at different regions within the weldment. For thermal load dominated loading combinations, creep ratcheting due to both cyclically enhanced creep and creep enhanced plasticity are observed based on the dwell period. The effect of dwell period, load and temperature on the creep-fatigue and creep-ratcheting interaction of a weldolet are presented. The simultaneous presence of various damage mechanisms at different locations within the weldment highlights the importance and requirement of the proposed creep-cyclic plasticity investigations at weld locations.

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“…Most of the online (Samavatian et al., 2018) and offline (Asayama, 2000; Chen et al., 2012; Gorash and Chen, 2013) creep-fatigue life evaluation methods only consider the creep damage when stress and temperature are unvarying, which is extremely unlikely during in-service operating conditions. But from the view of visco-plasticity theory, creep also occurs during fluctuating loading conditions (Besson et al., 2010; Ottosen and Ristinmaa, 2005), which means that creep strain accumulates under these conditions, as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

An online monitoring method for creep-fatigue life consumption with real-time damage accumulation

Hong

Cai

Wang

et al. 2021

International Journal of Damage Mechanics

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Online damage evaluation based on monitored complex cyclic loadings has become an important technique for reliability assessment, especially in high-temperature environments where creep occurs in addition to fatigue. Accuracy and rapidity of calculation are basic requirements for online damage evaluation methods. However, current creep damage evaluation methods seldom consider the fluctuation in stress, which leads to inaccuracy in life-consumption estimates. In addition, traditional cycle-counting methods are not applicable to online use. In this study, an online creep-fatigue damage evaluation method is proposed that accounts for the creep behavior that occurs under fluctuating loads. The cycle-counting method is modified from a rainflow-counting algorithm; it broadens the counting of half-cycles and adopts a new equivalent temperature in the stress-strain response calculation. The proposed method is explained in detail and demonstrated with a case study. The application of this method to a high-temperature, high-pressure pipe demonstrates its online applicability and accuracy. A time-matching algorithm is developed to display the damage evolution in real time, thus revealing the link between the incremental damage and the current load conditions, and yielding an intuitive demonstration of a given component’s state of health.

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Creep–fatigue evaluation of stainless steel welded joints in FBR class 1 components

Cited by 10 publications

References 4 publications

Simulations of Thermomechanical Stresses and Optical Misalignment in 1550-nm Transmitter Optoelectronic Modules Using FEM and Process Dispersions

Simulations of Thermomechanical Stresses and Optical Misalignment in 1550-nm Transmitter Optoelectronic Modules Using FEM and Process Dispersions

Creep–Cyclic Plasticity and Damage Assessment of an SS304 Weldolet

An online monitoring method for creep-fatigue life consumption with real-time damage accumulation

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