Continuation Report: Creep-fatigue Behavior and Damage Accumulation of a Candidate Structural Material for Concentrating Solar Thermal Receiver

Creep–fatigue experiments were performed at 850℃ on bare and salt-coated directionally solidified Ni-based superalloy DZ125. Experimental test results showed that the salt-coated sample exhibited lower lifetime than that of the bare sample under all stress conditions. This reduction is found to correlate directly with the higher probability of crack initiation, due to surface micro-structural degradation and higher actual stress as a result of the decrease in effective bearing area. A modified damage accumulation model considering the creep, fatigue, and hot-corrosion interaction effect was proposed to predict the corrosion–creep–fatigue lifetime. In this model, a critical high-temperature hot-corrosion exposure time was proposed and was introduced using the Miller linear damage accumulation model. The predicted lifetimes correspond remarkably well with the experimental results.

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Fatigue of Unidirectional Cord-Rubber Composites

Tire Science and Technology ◽

10.2346/1.2135975 ◽

1999 ◽

Vol 27 (1) ◽

pp. 48-57 ◽

Cited By ~ 5

Author(s):

Y. Liu ◽

Z. Wan ◽

Z. Tian ◽

X. Du ◽

J. Jiang ◽

...

Keyword(s):

Damage Accumulation ◽

Fatigue Testing ◽

Fatigue Behavior ◽

Constant Load ◽

Testing System ◽

Rubber Composites ◽

Cycle Frequency ◽

Periodic Loading ◽

Fatigue Damage Accumulation ◽

Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

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Component Low Cycle Fatigue Behavior Based on Standard Calculation Procedure and Non-Linear FEA

Volume 3B: Design and Analysis ◽

10.1115/pvp2017-66071 ◽

2017 ◽

Author(s):

Jürgen Rudolph ◽

Adrian Willuweit ◽

Steffen Bergholz ◽

Christian Philippek ◽

Jevgenij Kobzarev

Keyword(s):

Power Plants ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Hybrid Approach ◽

Combined Cycle ◽

Cycle Fatigue ◽

Element Analysis ◽

Constitutive Material Model ◽

Standard Design ◽

Creep Fatigue

Components of conventional power plants are subject to potential damage mechanisms such as creep, fatigue and their combination. These mechanisms have to be considered in the mechanical design process. Against this general background — as an example — the paper focusses on the low cycle fatigue behavior of a main steam shut off valve. The first design check based on standard design rules and linear Finite Element Analysis (FEA) identifies fatigue sensitive locations and potentially high fatigue usage. This will often occur in the context of flexible operational modes of combined cycle power plants which are a characteristic of the current demands of energy supply. In such a case a margin analysis constitutes a logical second step. It may comprise the identification of a more realistic description of the real operational loads and load-time histories and a refinement of the (creep-) fatigue assessment methods. This constitutes the basis of an advanced component design and assessment. In this work, nonlinear FEA is applied based on a nonlinear kinematic constitutive material model, in order to simulate the thermo-mechanical behavior of the high-Cr steel component mentioned above. The required material parameters are identified based on data of the accessible reference literature and data from an own test series. The accompanying testing campaign was successfully concluded by a series of uniaxial thermo-mechanical fatigue (TMF) tests simulating the most critical load case of the component. This detailed and hybrid approach proved to be appropriate for ensuring the required lifetime period of the component.

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Life Estimation of Pressurized-Air Solar-Thermal Receiver Tubes

Journal of Solar Energy Engineering ◽

10.1115/1.4007686 ◽

2012 ◽

Vol 134 (4) ◽

Cited By ~ 14

Author(s):

David K. Fork ◽

John Fitch ◽

Shawn Ziaei ◽

Robert I. Jetter

Keyword(s):

Large Body ◽

Inelastic Strain ◽

Current Data ◽

Solar Thermal ◽

Estimation Methods ◽

Inlet Temperature ◽

Operational Conditions ◽

Thermal Receiver ◽

Cyclic Operation ◽

Strain Model

The operational conditions of the solar-thermal receiver for a Brayton cycle engine are challenging, and lack a large body of operational data unlike steam plants. We explore the receiver's fundamental element, a pressurized tube in time varying solar flux for a series of 30 yr service missions based on hypothetical power plant designs. We developed and compared two estimation methods to predict the receiver tube lifetime based on available creep life and fatigue data for alloy 617. We show that the choice of inelastic strain model and the level of conservatism applied through design rules will vary the lifetime predictions by orders of magnitude. Based on current data and methods, a turbine inlet temperature of 1120 K is a necessary 30-yr-life-design condition for our receiver. We also showed that even though the time at operating temperature is about three times longer for fossil fuel powered (steady) operation, the damage is always lower than cyclic operation using solar power.

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