Derivation of a fatigue damage law for an adhesive from in-situ bending tests

An experimental methodology was developed for estimating a very high cycle fatigue (VHCF) life of the aluminum alloy AMG-6 subjected to preliminary deformation. The analysis of fatigue damage staging is based on the measurement of elastic modulus decrement according to “in situ” data of nonlinear dynamics of free-end specimen vibrations at the VHCF test. The correlation of fatigue damage staging and fracture surface morphology was studied to establish the scaling properties and kinetic equations for damage localization, “fish-eye” nucleation, and transition to the Paris crack kinetics. These equations, based on empirical parameters related to the structure of the material, allows us to estimate the number of cycles for the nucleation and advance of fatigue crack.

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In-situ observation on the twinning boundary movement of pure zirconium during three-point bending tests

Materials Science and Engineering A ◽

10.1016/j.msea.2021.142361 ◽

2021 ◽

pp. 142361

Author(s):

Jie Ren ◽

Geping Li ◽

Fusen Yuan ◽

Fuzhou Han ◽

Muhammad Ali ◽

...

Keyword(s):

In Situ Observation ◽

Bending Tests ◽

Three Point Bending ◽

Boundary Movement ◽

Pure Zirconium

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Effect of High-Temperature Pavement Paving on Fatigue Durability of Bearing-Supported Steel Decks

Applied Sciences ◽

10.3390/app10207196 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7196

Author(s):

Qiudong Wang ◽

Bohai Ji ◽

Zhongqiu Fu ◽

Hao Wang

Keyword(s):

High Temperature ◽

Fatigue Damage ◽

Temperature Stress ◽

Damage Accumulation ◽

Considerable Effect ◽

In Situ Monitoring ◽

Fatigue Durability ◽

Residual Temperature ◽

Fatigue Damage Accumulation

Orthotropic steel deck (OSD) is a better choice for urban bridges and the replacement of damaged concrete slabs. Gussasphalt concrete (GAC) is usually adopted as the asphalt surfacing; however, the paving temperature of GAC is high, which will affect the fatigue durability of fatigable welds in OSD. In this study, such influence of high-temperature pavement paving was comprehensively investigated based on in-situ monitoring and numerical analysis. The temperature of OSD and displacement of bearings were investigated based on the monitored data and numerical results. After that, the deformation and residual temperature stress of OSD during the paving process were analyzed. On this basis, the effect of residual temperature stress on fatigue damage accumulation of OSD was investigated and discussed. Results show that the uplift and expanded deformation of OSD arise during the paving process, leading to the displacement of bearings. Residual displacement of bearings, as well as the residual temperature stress at fatigable details of OSD, is observed. The residual temperature stress has considerable effect on fatigue damage accumulation at rib-deck weld. A fatigue damage amplification factor of 1.1 is recommended for taking into consideration of the adverse effect of high-temperature pavement paving.

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Estimation of Creep-Fatigue Damage Through Indentation Test Method

Volume 3: Design and Manufacturing ◽

10.1115/imece2011-63445 ◽

2011 ◽

Author(s):

Raghu V. Prakash

Keyword(s):

Tensile Properties ◽

Fatigue Damage ◽

Indentation Test ◽

Creep Damage ◽

Test Method ◽

Specimen Preparation ◽

Creep Fatigue ◽

Critical Components ◽

The Cost

Creep, creep-fatigue damage is often estimated through in-situ metallography, tensile testing of specimens. However, these methods require specimen preparation which includes specimen extraction from critical components. Automated ball indentation testing has been used as an effective tool to determine the mechanical properties of metallic materials. In this work, the tensile properties of materials subjected to controlled levels of damage in creep, creep-fatigue is studied. It is found that the tensile properties such as yield strength and UTS deteriorates with creep damage, whereas the same specimens show an improved UTS values (at the cost of ductility) when subjected to creep-fatigue interactions.

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Damage Assessment on Low Cycle Fatigue Properties of Cyclic Pre-Strained Austenitic Stainless Steel

ASME 2011 Pressure Vessels and Piping Conference: Volume 1 ◽

10.1115/pvp2011-57832 ◽

2011 ◽

Cited By ~ 4

Author(s):

Nao Fujimura ◽

Hiroyuki Oguma ◽

Takashi Nakamura

Keyword(s):

Surface Roughness ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Fatigue Damage ◽

Low Cycle Fatigue ◽

Strain Ratio ◽

Fatigue Properties ◽

Cycle Fatigue ◽

Damage Law ◽

Number Of Cycles

The effects of cyclic pre-strain on low cycle fatigue properties of austenitic stainless steel were investigated, and the fatigue damage was assessed based on several parameters such as the full width at half maximum (FWHM) of diffracted X-ray profile and surface roughness of specimens. The strain-controlled tests were conducted under strain ratio Rε = −1 and various constant total strain ranges. Also the change in remnant fatigue lives were investigated when the cyclic pre-strain were applied to the specimens under the different number of cycles which were determined with reference to the usage factor UFpre ranged from 0.2 to 0.8. As a result, the remnant fatigue life of the pre-strained samples became shorter than that of the sample without pre-strain as the UFpre increased. The relationship between the pre-strain damage expressed in UFpre and the remnant fatigue damage in UFpost was roughly described by the cumulative linear damage law: UFpre + UFpost = 1. Namely, the cyclic pre-strain affected the remnant fatigue lives. In order to evaluate the effects of cyclic pre-strain on fatigue lives more precisely, the damage in the cyclic pre-straining processes was estimated by using FWHM and surface roughness. The FWHM of the specimens with pre-strain once decreased with increase in UFpre, and then increased after showing a minimum value. The surface roughness of specimens increased linearly with an increase of the number of pre-straining cycles. These results suggested that the damage due to pre-strain can be assessed by means of FWHM and surface roughness of specimens.

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Non-Destructive Tests and Bending Tests on Chestnut Structural Timber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.778.167 ◽

2013 ◽

Vol 778 ◽

pp. 167-174 ◽

Cited By ~ 3

Author(s):

Beatrice Faggiano ◽

Maria Rosaria Grippa ◽

Bruno Calderoni

Keyword(s):

Research Study ◽

Timber Structures ◽

Structural Elements ◽

Bending Tests ◽

Experimental Activity ◽

Collapse Mechanisms ◽

Regression Approach ◽

Non Destructive ◽

Non Destructive Techniques

In the context of a more wide research study for in situ mechanical identification of ancient timber structures by non-destructive techniques, the paper illustrates the experimental activity developed on structural elements made of old chestnut timber, 4x4x76 cm size: 24 squared specimens were extracted by six elements in actual dimensions, already used in a previous tests campaign. Non-destructive (ND: hygrometric, sclerometric and resistographic) and destructive (D: bending) tests were performed, the latter according to UNI EN 408 (2004) standard, in order to assess the mechanical properties and the collapse mechanisms of chestnut timber. Data gathered are presented in detail and, NDT-DT correlations, obtained through a linear regression approach, are provided to predict wood density, strength and modulus of elasticity of the tested members.

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