Viscoelastic behaviour investigation and new developed laboratory slamming test on foam core sandwich

In the first part of this paper, a viscoelastic model is used to numerically study the cellular foam core fatigue behaviour. Material’s temperature evolution is quantified with a numerical/experimental confrontation. In the second part, the slamming phenomenon is discussed by measuring the panel flexural strain on a racing sailboat during navigation. Making use of these results, a new slamming test rig was developed to evaluate the fatigue of sandwich structure under realistic loading. Four-point bending and slamming tests were performed on sandwich beams in order to compare their fatigue life and to discuss the physical parameters.

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Evaluating the Fatigue Resistance of the Innovative Modified-Reinforced Composite Asphalt Mixture

Advances in Civil Engineering ◽

10.1155/2020/8845647 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Gholamali Shafabakhsh ◽

Mahdi Akbari ◽

Hossein Bahrami

Keyword(s):

Fatigue Life ◽

Asphalt Binder ◽

Asphalt Mixture ◽

Fatigue Behaviour ◽

Road Asphalt ◽

The Road ◽

Road Pavement ◽

Four Point Bending ◽

Reinforced Composite ◽

Traffic Loads

Fatigue failure is regarded as one of the most common failures in the road pavement and necessitates spending huge cost annually to maintain the road. Asphalt binder modification and asphalt mixture reinforcement are among the commonly used methods to increase the pavement resistance to a failure caused by fatigue. By proposing a modified-reinforced composite hot mix asphalt (MRC-HMA), the present study aimed to examine the fatigue life of this mixture with one of the most traditional methods (i.e., four-point bending beam fatigue test) and compare it at constant strain conditions and the strain levels of 500, 700, and 900 μ ε and a temperature of 20 ± 0.8 ° C to that of the other three specimens, including control specimens, geogrid-reinforced (GR-HMA) specimens, and nanosilica-modified (NSM-HMA) specimens with 5% nanosilica. In all experiments, the condition to reach the failure stage was assumed equivalent to a 50% reduction in the stiffness coefficient in each load repetition, and the load was applied semisinusoidal at a frequency of 10 Hz without rest. The results showed that the MRC-HMA mixture improved the fatigue life at the strain level of 500 μ s by about 701, 172.5, and 156.4% compared to the control, NSM-HMA, and GR-HMA specimens, respectively. Based on the results, the use of GR-HMA specimens has almost the same results as NSM-HMA ones, but the use of the MRC-HMA mixture can significantly increase the fatigue life of MRC-HMA in all three levels of strain compared to all specimens studied in the present study. Thus, the introduced mixture can be a proper choice for pavements with heavy or light (with a large amount) traffic loads, which usually have a vast adverse effect on the fatigue behaviour of asphalt mixtures.

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Failure of Composite Sandwich Beams

Advanced Composites Letters ◽

10.1177/096369350201100301 ◽

2002 ◽

Vol 11 (3) ◽

pp. 096369350201100 ◽

Cited By ~ 6

Author(s):

I. M. Daniel ◽

E. E. Gdoutos ◽

K.-A. Wang

Keyword(s):

Failure Modes ◽

Foam Core ◽

Sandwich Beams ◽

Composite Sandwich ◽

Four Point Bending ◽

Constituent Material ◽

Closed Cell ◽

Failure Envelopes ◽

Geometrical Dimensions ◽

Cell Foam

A thorough investigation of failure behaviour of composite sandwich beams under three- and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterised and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. The initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions.

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Improving four-point bending performance of marine composite sandwich beams by core modification

Journal of Composite Materials ◽

10.1177/0021998319874502 ◽

2020 ◽

Vol 54 (8) ◽

pp. 1049-1066

Author(s):

F Balıkoğlu ◽

N Arslan ◽

TK Demircioğlu ◽

O İnal ◽

M İren ◽

...

Keyword(s):

Bending Strength ◽

Mechanical Performance ◽

Composite Beams ◽

Bending Stiffness ◽

Bending Test ◽

Sandwich Composite ◽

Foam Core ◽

Sandwich Beams ◽

Bending Performance ◽

Four Point Bending

The aim of this study was to improve four-point bending performance of foam core sandwich composite beams by applying various core machining configurations. Sandwich composites have been manufactured using perforated and grooved foam cores by vacuum-assisted resin transfer moulding method with vinyl-ester resin system. The influence of grooves and perforations on the mechanical performance of marine sandwich composite beams was investigated under four-point bending test considering the weight gain. Bending strength and effective bending stiffness increased up to 34% and 61%, respectively, in comparison to a control beam without core modification. Analytical equations were utilised for calculating the mid-span deflection, equivalent bending stiffness and ultimate bending strength of the sandwich beams. Finite element analysis was also performed to analyse the flexural response of the specimens taking into account the combined effect of orthotropic linear elasticity of the face sheet and the non-linear behaviour of the foam core.

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Finite Element Analysis of Centrally-Debonded Composite Sandwich Beam under Four Point Bending

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.335-336.351 ◽

2011 ◽

Vol 335-336 ◽

pp. 351-354 ◽

Cited By ~ 2

Author(s):

Meng Kao Yeh ◽

Yu Wen Chiu

Keyword(s):

Finite Element ◽

Composite Structures ◽

Sandwich Structure ◽

Sandwich Beam ◽

Core Material ◽

Sandwich Beams ◽

Element Analysis ◽

Specific Strength ◽

Composite Sandwich ◽

Four Point Bending

Sandwich structure, with high specific strength, high specific stiffness facesheet and light-weighted core material bonded together, is one of commonly used composite structures. During the manufacturing process, it is possible to have debonding between facesheet and core. This facesheet/core debonding affects the mechanical property and strength of sandwich structure. In this study, sandwich beams are made of graphite/epoxy laminate as facesheet and MWNTs/epoxy nanocomposites as core material. The composite sandwich beam, with a central facesheet/core debond and under four point bending, was analyzed by the finite element method. The length of the debonding layer, the fiber orientation of the facesheet laminate and MWNTs content in core were varied to assess their effects on the bending behavior and the strengths of the centrally-debonded sandwich beams.

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Failure behaviour of preloaded API line pipe threaded connections

International Journal Sustainable Construction & Design ◽

10.21825/scad.v2i3.20539 ◽

2011 ◽

Vol 2 (3) ◽

pp. 407-415

Author(s):

Jonas Seys ◽

Koenraad Roeygens ◽

Jeroen Van Wittenberghe ◽

Timothy Galle ◽

Patrick De Baets ◽

...

Keyword(s):

Fatigue Life ◽

Fatigue Behaviour ◽

Bending Test ◽

Specific Test ◽

Line Pipe ◽

Four Point Bending ◽

Sealing Capacity ◽

Threaded Connections ◽

Thin Walled ◽

Future Work

This paper reports on numerical and experimental work concerning the fatigue behaviour andsealing capacity of threaded pipe connections (1” API Line Pipe). Numerical simulations are performedusing Abaqus®in combination with ThreadGen©. The fatigue life of a thick-walled standard coupling isdetermined using a four-point bending test. The corresponding S-N curve is compared to results of previouswork on thin-walled specimens. It can be concluded that the standard thick-walled connection has a higherfatigue life than thin-walled ones. In future work, the prediction of fatigue life using established multi-axialcriteria will be evaluated. Further, the sealing capacity of several couplings will be investigated bysubmitting them to different combinations of internal pressure and axial force. Hereto, a specific test setupis designed. The results will then be presented as a test load envelope

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Failure modes of composite sandwich beams

Theoretical and Applied Mechanics ◽

10.2298/tam0803105g ◽

2008 ◽

Vol 35 (1-3) ◽

pp. 105-118 ◽

Cited By ~ 22

Author(s):

E. Gdoutos ◽

I.M. Daniel

Keyword(s):

Failure Modes ◽

Failure Behavior ◽

Foam Core ◽

Sandwich Beams ◽

Composite Sandwich ◽

Four Point Bending ◽

Constituent Material ◽

Closed Cell ◽

Failure Envelopes ◽

Geometrical Dimensions

A thorough investigation of failure behavior of composite sandwich beams under three-and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterized and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. The initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions.

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