Size Effects in Scaled Fiber Composites Under Four-Point Flexure Loading

Johnson, David P.; Morton, J.; Kellas, Sotiris; Jackson, Karen E.

doi:10.2514/2.1066

Cited by 12 publications

(4 citation statements)

References 7 publications

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“…from Bažant et al [42] study of the data of Jackson [43] and Johnson et al [44], for laminates, or by comparing the results of Bažant and Novák [39] with those of Zech and Wittmann [49], for concrete).…”

Section: Transition Of Statistical Distribution Between Small and Larmentioning

confidence: 99%

Probability distribution of energetic-statistical size effect in quasibrittle fracture

Bažant

2004

Probabilistic Engineering Mechanics

109

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The physical sources of randomness in quasibrittle fracture described by the cohesive crack model are discussed and theoretical arguments for the basic form of the probability distribution are presented. The probability distribution of the size effect on the nominal strength of structures made of heterogeneous quasibrittle materials is derived, under certain simplifying assumptions, from the nonlocal generalization of Weibull theory. Attention is limited to structures of positive geometry failing at the initiation of macroscopic crack growth from a zone of distributed cracking. It is shown that, for small structures, which do not dwarf the fracture process zone (FPZ), the mean size effect is deterministic, agreeing with the energetic size effect theory, which describes the size effect due to stress redistribution and the associated energy release caused by finite size of the FPZ formed before failure. Material randomness governs the statistical distribution of the nominal strength of structure and, for very large structure sizes, also the mean. The large-size and small-size asymptotic properties of size effect are determined, and the reasons for the existence of intermediate asymptotics are pointed out. Asymptotic matching is then used to obtain an approximate closed-form analytical expression for the probability distribution of failure load for any structure size. For large sizes, the probability distribution converges to the Weibull distribution for the weakest link model, and for small sizes, it converges to the Gaussian distribution justified by Daniels' fiber bundle model. Comparisons with experimental data on the size-dependence of the modulus of rupture of concrete and laminates are shown. Monte Carlo simulations with finite elements are the subject of ongoing studies by Pang at Northwestern University to be reported later. q

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Section: Transition Of Statistical Distribution Between Small and Larmentioning

confidence: 99%

Probability distribution of energetic-statistical size effect in quasibrittle fracture

Bažant

2004

Probabilistic Engineering Mechanics

109

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“…Many articles [33,[68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87] showed that stacking sequence is a key parameter in scaling composite materials. There are three scaling approaches, namely ply level scaling ( Fig.…”

Section: Applications Of Similitude Methodsmentioning

confidence: 99%

“…The choice of the scaling strategy has significant consequences on the response of the composite specimen. This choice is studied in many works [68][69][70][71][72] in which it is demonstrated that ply level scaling applied only to the thickness or to all the geometric dimensions (also known as one-and three-dimensional scaling, respectively) leads to a decreasing tensile strength with increasing size. Such behavior is due to the increased severity of edge delamination and debonding, creating stress concentrations that lower the strength of hybrid materials.…”

Section: Applications Of Similitude Methodsmentioning

confidence: 99%

A Review of Similitude Methods for Structural Engineering

Casaburo

Petrone

Franco

et al. 2019

Applied Mechanics Reviews

126

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Similitude theory allows engineers, through a set of tools known as similitude methods, to establish the necessary conditions to design a scaled (up or down) model of a full-scale prototype structure. In recent years, to overcome the obstacles associated with full-scale testing, such as cost and setup, research on similitude methods has grown and their application has expanded into many branches of engineering. The aim of this paper is to provide as comprehensive a review as possible about similitude methods applied to structural engineering and their limitations due to size effects, rate sensitivity phenomena, etc. After a brief historical introduction and a more in-depth analysis of the main methods, the paper focuses on similitude applications classified, first, by test article, then by engineering fields.

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“…In recent years, many experimental studies have been conducted on the mechanical scaling behavior of composites. Most studies have used two main approaches for scaling composites [9,10,11,12,13,14]. The first is ply-level scaling, which involves simply increasing the number of layers for each angular ply orientation.…”

Section: Introductionmentioning

confidence: 99%

Scale Effect on Impact Performance of Unidirectional Glass Fiber Reinforced Epoxy Composite Laminates

Shen

Jiang

2019

Materials

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As a result of the increasing use of glass fiber reinforced plastic (GFRP) composites in engineering fields, the investigation of scale effect on impact performance for this kind of composite is essential for large scale structure design. The effects of scaling on the impact response of simply supported unidirectional GFRP were investigated through drop weight impact (DWI) tests in this study. Impact tests were undertaken over a wide range of energies to generate damages between barely visible and initiated penetration on four scale size GFRP laminates. The main impact responses including impact force, contact duration, displacement, energy absorption and damage area of scaled specimens were normalized to compare with the full-size specimen. It was found that the impact response of large sample with elastic deformation and small area of delamination can be predicted accurately according to a geometrical similar scaling law. Scale effect was found in the damage threshold force and absorbed energy of the laminates when significant internal damage occurs due to the microstructural effect becoming important in resisting impact force and absorbing impact energy. Moreover, the energy partition and effective stiffness were calculated according to the energy balance model to reveal the contribution of different modes of deformations on energy absorption for the GFRP laminates.

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Size Effects in Scaled Fiber Composites Under Four-Point Flexure Loading

Cited by 12 publications

References 7 publications

Probability distribution of energetic-statistical size effect in quasibrittle fracture

Probability distribution of energetic-statistical size effect in quasibrittle fracture

A Review of Similitude Methods for Structural Engineering

Scale Effect on Impact Performance of Unidirectional Glass Fiber Reinforced Epoxy Composite Laminates

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