Micro-cantilever bending tests for understanding size effect in gradient elasticity

The diffusion influence of seawater on the static and interlayer cracking properties of a polyvinyl chloride foam sandwich structure is investigated in this study. After soaking specimens in seawater for various durations, various comparison tests are performed to investigate the effects of seawater. Compression tests for H60 and H200 polyvinyl chloride foam specimens are conducted to study strength and modulus degradation, and the results show that immerging time and temperature have significant effects on polyvinyl chloride foam properties. Tensile tests for glass-fibre-reinforced plastic panels, four-point bending tests and double cantilever bending tests for polyvinyl chloride foam sandwich specimens are also performed. The results show that seawater immerging treatment has a noticeable influence on glass-fibre-reinforced plastic tensile properties and interlayer critical energy release rate values, but has almost no effect on bending properties of foam sandwich specimen. Furthermore, a rate-dependent phenomenon is observed in double cantilever bending tests, in which higher loading rate will lead to larger critical energy release values. Numerical simulation is also performed to illustrate the cracking process of double cantilever bending tests and shows a certain accuracy. The simulation also demonstrates that the viscoelasticity of foam material after immerging treatment results in the rate-dependent characterization of double cantilever bending tests.

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Gradient elasticity and size effect for the borehole problem

Acta Mechanica ◽

10.1007/s00707-018-2109-3 ◽

2018 ◽

Vol 229 (8) ◽

pp. 3305-3318 ◽

Cited By ~ 4

Author(s):

Haoxiang Chen ◽

Chengzhi Qi ◽

G. Efremidis ◽

M. Dorogov ◽

E. C. Aifantis

Keyword(s):

Size Effect ◽

Gradient Elasticity

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A new Timoshenko beam model based on modified gradient elasticity: Shearing effect and size effect of micro-beam

Composite Structures ◽

10.1016/j.compstruct.2019.110946 ◽

2019 ◽

Vol 223 ◽

pp. 110946 ◽

Cited By ~ 4

Author(s):

Bing Zhao ◽

Jian Chen ◽

Tao Liu ◽

Wenhao Song ◽

Jianren Zhang

Keyword(s):

Size Effect ◽

Timoshenko Beam ◽

Gradient Elasticity ◽

Beam Model ◽

Timoshenko Beam Model ◽

Model Based

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Prediction of steel resistance to stress corrosion cracking in seawater based on accelerated tests and structural studies

E3S Web of Conferences ◽

10.1051/e3sconf/201912104009 ◽

2019 ◽

Vol 121 ◽

pp. 04009

Author(s):

Svetlana Mushnikova ◽

Oleg Kharkov

Keyword(s):

Structural Phase ◽

Real Life ◽

Austenitic Stainless Steels ◽

Test Results ◽

Mechanical Fracture ◽

Bending Tests ◽

Laboratory Test Results ◽

Resistance To Stress ◽

Concentrated Solution ◽

Cantilever Bending

The paper presents the tests results of resistance of various structural steel classes to SCC in chloride solutions. The experiments were performed using cantilever bending tests developed by NRC “Kurchatov Institute” – CRISM “Prometey” with stepwise increasing load of Charpy-type precracking specimens. The criterion estimation of resistance to SCC when β = σSCC/σC > 0.85 was confirmed by the laboratory test results compared with the case studies of corrosion-mechanical fracture of shipbuilding structures in real life service conditions. A new approach of SCC susceptibility of austenitic stainless steels in marine conditions is proposed. It is based on estimation of the critical temperature of SCC when testing for SSRT in a concentrated solution of calcium chloride at temperatures from 20°C to 100°C. Specific features of the structural-phase composition of steels that detrimentally affect the resistance to SCC were discovered during the complex testing.

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1D HERMITE ELEMENTS FOR C1-CONTINUOUS SOLUTIONS IN SECOND GRADIENT ELASTICITY

Acta Polytechnica CTU Proceedings ◽

10.14311/app.2017.7.0033 ◽

2016 ◽

Vol 7 ◽

pp. 33-37 ◽

Cited By ~ 1

Author(s):

Christian Liebold ◽

Wolfgang H. Müller

Keyword(s):

Finite Element ◽

Size Effect ◽

Numerical Solution ◽

Stiffness Matrix ◽

Gradient Elasticity ◽

Theory Of Elasticity ◽

Strain Gradient Theory ◽

Gradient Theory ◽

Additional Material ◽

Hermite Finite Elements

We present a modified strain gradient theory of elasticity for linear isotropic materials in order to account for the so-called size effect. Additional material length scale parameters are introduced and the problem of static beam bending is analyzed. A numerical solution is derived by means of a finite element approach. A global C1-continuous displacement field is applied in finite element solutions because the higher-order strain energy density additionally depends on second gradients of displacements. So-called Hermite finite elements are used that allow for merging gradients between elements. The element stiffness matrix as well as the global stiffness matrix of the problem is developed. Convergence, C1-continuity and the size effect in the numerical solution is shown. Experiments on bending stiffnesses of different sized micro beams made of the polymer SU-8 are performed by using an atomic force microscope and the results are compared to the numerical solution.

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