Experimental and Computational Study of Ultra-Low-Cycle Fatigue of Fabric-Reinforced GFRP

2021 ◽  
Vol 410 ◽  
pp. 649-655
Author(s):  
Egor V. Leshkov ◽  
Sergey B. Sapozhnikov ◽  
Oleg A. Kudryavtsev
Keyword(s):  
Deformation Process ◽  
Structural Model ◽  
Computational Study ◽  
Low Cycle Fatigue ◽  
Element Model ◽  
Model Parameters ◽  
Cycle Fatigue ◽  
Cyclic Tests ◽  
Noticeable Effect ◽  
Microdamage Accumulation

The development of weight-efficient reusable launch systems has increased the urgency of problems associated with ultra-low-cycle fatigue. In this paper, one-sided three-point bending cyclic tests of GFRP specimens were performed. Parallel to the cyclic tests, registration of acoustic emission signals has been performed to identify the main damage mechanisms underlying ultra-low-cycle fatigue of fabric-reinforced composites. The obtained displacement-time diagrams showed a noticeable effect of creep on the deformation process. It was found that fiber fracture is the main mechanism of microdamage accumulation. A phenomenological three-element model based on the Norton-Bailey law and the Masing structural model was proposed. The model allowed describing both the deformation process of the specimens in time and their durability at different load levels. An optimization algorithm based on the deformable polyhedron method was used to find the optimal set of the model parameters.

Short Crack Initiation during Low-Cycle Fatigue in SAF 2507 Duplex Stainless Steel

2007 ◽  
Vol 345-346 ◽  
pp. 343-346 ◽  
Author(s):  
M.C. Marinelli ◽  
Suzanne Degallaix ◽  
I. Alvarez-Armas
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Surface Strain ◽  
The Other ◽  
Cycle Fatigue ◽  
Cyclic Tests ◽  
Characteristic Microstructure

In this work, the formation of fatigue cracks is considered as a nucleation process due to the development of a characteristic microstructure formed just beneath the specimen surface. Strain controlled cyclic tests were carried out at room temperature at total strain ranges εt = 0.8 and 1.2% in flat specimens of SAF 2507 Duplex Stainless Steel (DSS). The results show that for this DSS, at εt = 0.8%, the correlation between phases (Kurdjumov-Sacks crystallographic relation) plays an important role in the formation of microcracks. On the other hand, at εt = 1.2%, microcracks initiate in the ferritic phase and the K-S relation does not seem to affect the formation of the cracks.

The Effect of Number of Cycles on Microdamage Accumulation in Bovine Trabecular Bone

2001 ◽  
Author(s):  
Tara L. Arthur Moore ◽  
Lorna J. Gibson
Keyword(s):  
Trabecular Bone ◽  
Bone Remodeling ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Repetitive Motion ◽  
Microdamage Accumulation ◽  
Lower Load ◽  
Small Cracks ◽  
Number Of Cycles ◽  
Fatigue Microdamage

Abstract Microdamage, in the form of small cracks, exists in healthy bone. Microdamage can be created by an overload or by repetitive motion (fatigue) during daily activities. Usually, microdamage is repaired during bone remodeling and a steady state is maintained. However, in cases of excessive microdamage creation or slowed bone remodeling, microdamage can coalesce to create a fracture. Our previous work [1,2] has investigated microdamage accumulation with increasing strain in bovine trabecular bone loaded in monotonic compression and compressive fatigue. Specimens fatigued at relatively high load levels fail after a few loading cycles, while specimens fatigued at lower load levels may undergo thousands of cycles before failure. During high cycle fatigue, microdamage may accumulate by the growth of pre-existing microcracks, as well as by the crack initiation seen in low cycle fatigue.

Proposal of a new low-cycle fatigue life model for cast iron with room temperature calibration involving mean stress and high-temperature effects

2019 ◽  
Vol 233 (14) ◽  
pp. 5056-5073 ◽  
Author(s):  
Cristiana Delprete ◽  
Raffaella Sesana
Keyword(s):  
Finite Element ◽  
Cast Iron ◽  
High Temperature ◽  
Finite Element Model ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Element Model ◽  
Mean Stress ◽  
Exhaust Manifold ◽  
Cycle Fatigue

The paper presents and discusses a low-cycle fatigue life prediction energy-based model. The model was applied to a commercial cast iron automotive exhaust manifold. The total expended energy until fracture proposed by the Skelton model was modified by means of two coefficients which take into account of the effects of mean stress and/or mean strain, and the presence of high temperature. The model was calibrated by means of experimental tests developed on Fe–2.4C–4.6Si–0.7Mo–1.2Cr high-temperature-resistant ductile cast iron. The thermostructural transient analysis was developed on a finite element model built to overtake confidentiality industrial restrictions. In addition to the commercial exhaust manifold, the finite element model considers the bolts, the gasket, and a cylinder head simulacrum to consider the corresponding thermal and mechanical boundary conditions. The life assessment performance of the energy-based model with respect the cast iron specimens was compared with the corresponding Basquin–Manson–Coffin and Skelton models. The model prediction fits the experimental data with a good agreement, which is comparable with both the literature models and it shows a better fitting at high temperature. The life estimations computed with respect the exhaust manifold finite element model were compared with different multiaxial literature life models and literature data to evaluate the life prediction capability of the proposed energy-based model.

Prediction of Low Cycle Fatigue Life Using Cycles Jumping Integration Scheme

2015 ◽  
Vol 784 ◽  
pp. 308-316 ◽  
Author(s):  
Carl Labergere ◽  
Khemais Saanouni ◽  
Zhi Dan Sun ◽  
Mohamed Ali Dhifallah ◽  
Yisa Li ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Mesh Size ◽  
Loading Path ◽  
Integration Scheme ◽  
Model Parameters ◽  
Cycle Fatigue ◽  
316L Steel ◽  
Fully Coupled ◽  
Full Loading

In this paper, cycles jumping scheme integration is used to numerically integrate fully coupled constitutive equations in order to predict the low cycle fatigue life under cyclic loading. This procedure avoids the calculation of the full loading cycles (some millions of loading cycles) while considering the transient stages due to the hardening (at the beginning) and the high damage-induced softening during the last tens of loading cycles. The model parameters have been identified using the results obtained from a 316L steel cylindrical specimen subject to symmetric tension-compression loading path. The effects of the specimen size as well as the mesh size on the fatigue life prediction are investigated.

Model of the Deformation Process under Thermo-Mechanical Fatigue Conditions

2012 ◽  
Vol 726 ◽  
pp. 143-149
Author(s):  
Jerzy Okrajni ◽  
Grzegorz Junak
Keyword(s):  
Deformation Process ◽  
Low Cycle Fatigue ◽  
Hysteresis Loops ◽  
Fatigue Tests ◽  
Mathematical Representation ◽  
Deformation Characteristics ◽  
Cycle Fatigue ◽  
Calculation Algorithm ◽  
Mechanical Fatigue

The paper focuses on the development of a mathematical representation of deformation characteristics under the conditions of an elevated changeable temperature and mechanical loads. The method proposed in the paper is based on the use of characteristics determined in low-cycle fatigue tests at constant temperatures. Hysteresis loops reflecting the behaviour of a material under the conditions of low-cycle loads at an elevated temperature were primarily used. The effect of relaxation on the course of the hysteresis loop was taken into account. The steady state of the material is referred to in the proposed representation. A calculation algorithm was developed to enable the determination of the stress value for subsequent increases of strain over time. The results obtained were compared with experimentally determined characteristics.

Probabilistic Low Cycle Fatigue Life Prediction Using an Energy-Based Damage Parameter and Accounting for Model Uncertainty

2011 ◽  
Vol 21 (8) ◽  
pp. 1128-1153 ◽  
Author(s):  
Shun-Peng Zhu ◽  
Hong-Zhong Huang ◽  
Victor Ontiveros ◽  
Li-Ping He ◽  
Mohammad Modarres
Keyword(s):  
Fatigue Life ◽  
Model Uncertainty ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Damage Parameter ◽  
Model Parameters ◽  
Cycle Fatigue ◽  
Plastic Strain Energy

Probabilistic methods have been widely used to account for uncertainty of various sources in predicting fatigue life for components or materials. The Bayesian approach can potentially give more complete estimates by combining test data with technological knowledge available from theoretical analyses and/or previous experimental results, and provides for uncertainty quantification and the ability to update predictions based on new data, which can save time and money. The aim of the present article is to develop a probabilistic methodology for low cycle fatigue life prediction using an energy-based damage parameter with Bayes’ theorem and to demonstrate the use of an efficient probabilistic method, moreover, to quantify model uncertainty resulting from creation of different deterministic model parameters. For most high-temperature structures, more than one model was created to represent the complicated behaviors of materials at high temperature. The uncertainty involved in selecting the best model from among all the possible models should not be ignored. Accordingly, a black-box approach is used to quantify the model uncertainty for three damage parameters (the generalized damage parameter, Smith–Watson–Topper and plastic strain energy density) using measured differences between experimental data and model predictions under a Bayesian inference framework. The verification cases were based on experimental data in the literature for the Ni-base superalloy GH4133 tested at various temperatures. Based on the experimentally determined distributions of material properties and model parameters, the predicted distributions of fatigue life agree with the experimental results. The results show that the uncertainty bounds using the generalized damage parameter for life prediction are tighter than that of Smith–Watson–Topper and plastic strain energy density methods based on the same available knowledge.

Low Cycle Fatigue of Internally Pressurized Corroded Pipes Under Cyclic Bending

2009 ◽  
Author(s):  
Marcos Andre´ Baeta ◽  
Marcelo Igor Lourenc¸o ◽  
Theodoro A. Netto
Keyword(s):  
Cyclic Load ◽  
Low Cycle Fatigue ◽  
Numerical Models ◽  
Experimental Tests ◽  
Small Scale ◽  
Cycle Fatigue ◽  
Cyclic Tests ◽  
Operational Conditions ◽  
Oil Transportation ◽  
Operational Load

Corroded pipes for oil transportation can eventually experience low cycle fatigue failure after some years of operation. The evaluation of the defects caused by corrosion in these pipes is important when deciding for the repair of the line or continuity in operation. Under normal operational conditions, these pipes are subject to constant internal pressure and cyclic load due to bending and/or tension. Under such loading conditions, the region in the pipes with thickness reduction due to corrosion could experience the phenomenon known as ratcheting. The objective of this paper is to present a revision of the available numerical models to treat the ratcheting phenomenon. Experimental tests were developed allowing the evaluation of occurrence of ratcheting in corroded pipes under typical operational load conditions as well as small-scale cyclic tests to obtain the material parameters. Numerical and experimental tests results are compared.

The Thermo-Mechanical Behaviour of Alloy 600 and Alloy 82 Materials

2018 ◽  
Author(s):  
Vasileios Akrivos ◽  
Mike C. Smith
Keyword(s):  
Weld Metal ◽  
Low Cycle Fatigue ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Parent Material ◽  
Model Parameters ◽  
Alloy 600 ◽  
Cycle Fatigue ◽  
Chaboche Model ◽  
Different Temperatures

Isothermal uniaxial low cycle fatigue tests have been performed at two different total strain ranges (1.5% and 2.5%) and at different temperatures (20, 200, 400 and 600°C) for Alloy 600 and Inconel 82 materials. The materials hardening behaviour has been fitted using the Lemaitre Chaboche formulations using different fitting strategies. Thermo mechanical tests have been performed using a Gleeble machine on both parent material and weld metal. In these tests thermal cycles were applied to a constrained specimen simulating the welding conditions in both the heat affected zone and a weld bead when subsequent beads are deposited alongside. The tests were modelled using two different FE codes, namely Code_Aster and Abaqus. This allowed the validation of the Lemaitre-Chaboche model parameters when the material is subjected to realistic thermo-mechanical cycles. Simulations were conducted using both annealing and/or viscous recovery features to examine their impact on the predicted response.

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