scholarly journals Modelling of Size Effect with Regularised Continua

10.14311/612 ◽  
2004 ◽  
Vol 44 (5-6) ◽  
Author(s):  
H. Askes ◽  
A. Simone ◽  
L. J. Sluys
Keyword(s):  
Finite Element ◽  
Size Effect ◽  
Size Effects ◽  
Finite Element Simulations ◽  
Nonlocal Damage ◽  
Three Point Bending ◽  
Nominal Strength ◽  
Model Size ◽  
Numerical Finite Element

A nonlocal damage continuum and a viscoplastic damage continuum are used to model size effects. Three-point bending specimens are analysed, whereby a distinction is made between unnotched specimens, specimens with a constant notch and specimens with a proportionally scaled notch. Numerical finite element simulations have been performed for specimen sizes in a range of 1:64. Size effects are established in terms of nominal strength and compared to existing size effect models from the literature. 

scholarly journals Size Effect in Fracture of Sandwich Structure Components: Foam and Laminate

2001 ◽  
Author(s):  
Zdeněk P. Bažant ◽  
Yong Zhou ◽  
Drahomír Novák ◽  
Isaac M. Daniel
Keyword(s):  
Size Effect ◽  
Size Effects ◽  
Sandwich Structure ◽  
Maximum Load ◽  
Material Strength ◽  
Large Structures ◽  
Nominal Strength ◽  
Sandwich Plates And Shells ◽  
Extensive Test ◽  
Plates And Shells

Abstract In the design of sandwich plates and shells for very large structures, such as ships in the range of 100 m length, it is very important to take the size effect on the nominal strength into account, and do so in a realistic, physically justified, manner. Before the size effect is addressed for a sandwich structure, it must be understood for its components — the foam core and the laminate skins. In the current practice, the size effects are automatically attributed to the randomness of material strength, as described by the Weibull theory. The purpose of this paper is to show that in both the foam and the laminate there are deterministic size effects, which are generally more pronounced. They are caused by stress redistribution and energy release due to the growth of large fractures or large cracking zones prior to attaining the maximum load. This deterministic size effect is verified and calibrated by new tests of notched specimens of rigid close-cell vinyl foam. A combined deterministic-probabilistic theory of size effect of the laminates is proposed and verified by extensive test data.

Universal size effect of concrete specimens and effect of notch depth

2017 ◽  
Vol 3 (1) ◽  
pp. 47 ◽  
Author(s):  
Sıddık Şener ◽  
Kadir Can Şener
Keyword(s):  
Size Effect ◽  
Crack Length ◽  
Asymptotic Properties ◽  
Experimental Program ◽  
Three Point Bending ◽  
Large Size ◽  
Nominal Strength ◽  
Notch Length ◽  
Point Bend

The universal size effect law of concrete is a law that describes the dependence of nominal strength of specimens or structure on both its size and the crack (or notch) length, over the entire of interest, and exhibits the correct small and large size asymptotic properties as required. The main difficulty has been the transition of crack length from 0, in which case the size effect mode is Type 1, to deep cracks (or notches), in which case the size effect mode is Type 2 and fundamentally different from Type 1. The current study is based on recently obtained comprehensive fracture test data from three-point bending beams tested under identical conditions. In this test, the experimental program consisted of 80 three-point bend beams with 4 different depths 40, 93, 215 and 500mm, corresponding to a size range of 1:12.5. Five different relative notch lengths, a/D = 0, 0.02, 0.075, 0.15, 0.30 were cut into the beams. A total of 20 different geometries (family of beams) were tested. The present paper will use these data to analyze the effects of size, crack length. This paper presents a studying to improve the existing universal size effect law, named by Bazant, using the experimentally obtained beam strengths for various different specimen sizes and all notch depths. The updated universal size effect law is shown to fit the comprehensive data quite well.

scholarly journals Estimates for the elastic moduli of 2D hexagonal-shape orthorhombic crystals with in-plane random crystalline orientations

2019 ◽  
Author(s):  
Vuong Thi My Hanh ◽  
Pham Duc Chinh ◽  
Vu Lam Dong ◽  
Le Hoai Chau
Keyword(s):  
Finite Element ◽  
Elastic Moduli ◽  
Finite Element Simulations ◽  
Orthorhombic Symmetry ◽  
Homogenization Problem ◽  
Hexagonal Shape ◽  
Random Aggregate ◽  
Orthorhombic Crystals ◽  
Numerical Finite Element

Numerical finite element simulations on the homogenization problem for large random-aggregate samples of a particular 2D hexagonal-shape-geometry random polycrystals from the base crystals of orthorhombic symmetry have been performed. At sufficiently large random-aggregate samples, the scatter intervals converge toward the Voigt-Reuss-Hill bounds, and then our recently constructed bounds, which have been specified for the aggregates.

scholarly journals Extended Finite Element Numerical Analysis of Scale Effect in Notched Glass Fiber Reinforced Epoxy Composite

2015 ◽  
Vol 62 (2) ◽  
pp. 217-236 ◽  
Author(s):  
Mohammed Y. Abdellah ◽  
Mohammad S. Alsoufi ◽  
Mohamed K. Hassan ◽  
Hamza A. Ghulman ◽  
Ahmed F. Mohamed
Keyword(s):  
Finite Element ◽  
Size Effect ◽  
Glass Fiber ◽  
Scale Effect ◽  
Fracture Process ◽  
Fiber Reinforced ◽  
Extended Finite Element ◽  
Glass Fiber Reinforced ◽  
Nominal Strength ◽  
Good Agreement

Abstract Nominal strength reduction in cross ply laminates of [0/90]2s is observed in tensile tests of glass fiber composite laminates having central open hole of diameters varying from 2 to 10 mm. This is well known as the size effect. The extended finite element method (XFEM) is implemented to simulate the fracture process and size effect (scale effect) in the glass fiber reinforced polymer laminates weakened by holes or notches. The analysis shows that XFEM results are in good agreement with the experimental results specifying nominal strength and in good agreement with the analytical results based on the cohesive zone model specifying crack opening displacement and the fracture process zone length

Bending Properties of Laser Welded Web-Core Steel Sandwich Plates

2014 ◽  
Vol 936 ◽  
pp. 1451-1455 ◽  
Author(s):  
Xiao Xia Jiang ◽  
Liang Zhu ◽  
Ji Sen Qiao ◽  
Yi Xiong Wu ◽  
Zhu Guo Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Sandwich Plate ◽  
Finite Element Simulations ◽  
Bending Test ◽  
Sandwich Plates ◽  
Bending Properties ◽  
Three Point Bending ◽  
Weld Width ◽  
The Core ◽  
Good Agreement

This paper presents a detailed discussion of the bending properties of laser welded web-core steel sandwich plates and the influence of weld width on stiffness and strength. The over-hanging three point bending test was conducted on the laser welded web-core steel sandwich plates with various welds width by self-designed device, together with the finite element simulations. A good agreement is obtained between the 2D FE analyses and experiment results. The stiffness and strength of the sandwich plates increased with the increasing of weld width, especially for the weld width lower than 60% thickness of the core plate. It is necessary to consider the weld width in the design and evaluation of the stiffness and strength of the laser welded web-core sandwich plate. Base on the results, the FEM is the priority to analysis bending properties of laser welded web-core steel sandwich plates.

UNIVERSAL SIZE EFFECT STUDIES USING THREE POINT BEAM TESTS

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Siddik Şener ◽  
Kadir Can Şener
Keyword(s):  
Size Effect ◽  
Asymptotic Properties ◽  
Main Difficulty ◽  
Fracture Test ◽  
Three Point Bending ◽  
Large Size ◽  
Nominal Strength ◽  
Notch Length

The universal size effect law for concrete is a law that describes the dependence of nominal strength of specimen or structure on both its size and the crack (or notch) length, over the entire of interest, and exhibits the correct small and large size asymptotic properties as required. The main difficulty has been the transition of crack length from 0, in which case the size effect mode is Type 1, to deep cracks (or notches), in which case the size effect mode is Type 2 and fundamentally different from Type 1. The current study is based on recently obtained comprehensive fracture test data from three-point bending beams tested under identical conditions. This paper presents a studying to improve the existing universal size effect law using the experimentally obtained beam strengths for various different specimen sizes and all notch depths. The updated universal size effect law is shown to fit the comprehensive data quite well.

Nonlocal Damage Modeling of Solder Joint Failure Under Thermomechanical Cyclic Loading

2021 ◽  
Author(s):  
Youssef Maniar ◽  
Alexander Kabakchiev ◽  
Marta Kuczynska ◽  
Masoomeh Bazrafshan ◽  
Peter Binkele ◽  
...  
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Solder Joint ◽  
End Of Life ◽  
Damage Evolution ◽  
Life Prediction ◽  
Finite Element Simulations ◽  
Automotive Electronics ◽  
Localization Algorithm ◽  
Nonlocal Damage

Abstract The increasing electrified mobility poses a challenge on reliability prediction of automotive electronics, especially when safety systems are concerned. The use of finite element simulation for accurate end-of-life prediction of automotive electronic devices under harsh environmental loading condition is getting increasingly significant. In particular, solder interconnection failure is in focus when subjected to thermomechanical loads. During cyclic loading, the initial deformation behavior and subsequent solder degradation can be modeled within finite element simulations using material damage coupled deformation models. Such models employ the calculation of an internal damage state variable at integration point level as functions of time, temperature and governing stress-strain state. In this work, a thermodynamic consistent implicit nonlocal damage formulation is presented. This modeling approach allows absolute end-of-life prediction of different solder joint geometries under thermomechanical cyclic loading within finite element simulations. The presented nonlocal damage model consists of damage evolution with strain and stress state dependencies, such as stress multiaxiality. Furthermore, a numerical de-localization algorithm is proposed, in order to avoid instability of damage evolution caused by finite element mesh dependency. Finally, the advantages and implications of the nonlocal damage approach are discussed based on simulations of damage evolution in multiple solder joints of a QFN48 package under combined cyclic thermal and mechanical 4-point bending loading.

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