Repeated Slamming of Sandwich Composite Panels on Water

Charca, Samuel; Shafiq, Basir; Just, Frederick

doi:10.1177/1099636209103169

Cited by 43 publications

(34 citation statements)

References 17 publications

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“…Contrary to the results reported on foamfilled honeycomb core sandwich composites [8], there was disappointingly little evidence of accumulated damage when the slammed specimens were tested under static flexure, as indicated in Figure 5. However, curiously when the repeatedly slammed specimens were subjected to fatigue testing, a substantial reduction in life was observed as compared with nonslammed specimens (Figure 6).…”

Section: Resultscontrasting

confidence: 62%

Damage Assessment Due to Repeated Slamming of Foam Core Sandwich Composites

Charca

Shafiq

2009

Jnl of Sandwich Structures & Materials

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Foam core sandwich composite panels repeatedly slammed onto the body of calm water indicate greater accumulation and progression of damage accompanied by lower lifetimes as a function of increasing slamming energy or lower deadrise angle. E-N (slamming energy vs. lifetime) curves showed an exponentially decreasing trend with extensive scatter in the data. E-N curves also differed dramatically when compared with the conventional S-N fatigue life curve. A significant reduction observed in fatigue life of slammed specimens as compared with the nonslammed specimens was used as a basis for the development of a life assessment methodology. Catastrophic failure under slamming resulted from a major crack formation near the chine or the keel depending on the deadrise angle, however, during post-slamming fatigue, failure always occurred near the keel. Core tearing along the interface and core shear were observed to be the dominant modes of failure, while facesheet damage activity was largely absent prior to catastrophic failure.

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Section: Resultscontrasting

confidence: 62%

Damage Assessment Due to Repeated Slamming of Foam Core Sandwich Composites

Charca

Shafiq

2009

Jnl of Sandwich Structures & Materials

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“…[8][9][10][11] Notwithstanding the complexity of hull slamming during sailing and maneuvering of marine vessels, 12 experimental studies on the water entry of wedges are largely limited to impacts that are symmetric with respect to the water surface. 8,9,[13][14][15][16][17] As such, the problem of asymmetric water entry is relatively untapped. Following Judge et al, 18 asymmetry can be categorized into: kinematic asymmetry, in which the initial velocity is not orthogonal to the water surface, so-called "oblique," [19][20][21][22] or geometric asymmetry, in which the symmetry plane of the wedge is not perpendicular to the water surface.…”

Section: Introductionmentioning

confidence: 99%

Experiments on the water entry of asymmetric wedges using particle image velocimetry

2015

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In this work, we experimentally characterize the water entry of an asymmetric wedge into a quiescent fluid through particle image velocimetry (PIV). The wedge enters the water surface with an orthogonal velocity falling from a fixed height. We systematically vary the heel angle to elucidate the effect of asymmetric impact on the flow physics and on the fluid-structure interaction. The pressure field in the fluid is reconstructed from PIV data by integrating the Poisson equation. We find that the impact configuration significantly influences both the velocity and the pressure field, ultimately, regulating the hydrodynamic loading on the wedge. Specifically, as the heel angle increases, the location of maximum velocity of the flow moves from the pile-up region to the keel. At the same time, the pressure field significantly decreases in the vicinity of the keel, reaching values smaller than the atmospheric pressure. The spatiotemporal evolution of the hydrodynamic loading is thus controlled by the heel angle, with larger heel angles resulting into more rapid and sustained impacts. C 2015 AIP Publishing LLC. [http://dx.

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“…Only few efforts have documented a direct measurement of the hydrodynamic loading at selected locations on the impacting structure through pressure gauges (Charca et al, 2009;Battley and Allen, 2011;Stenius et al, 2013). Recently, a non-invasive contactless experimental methodology based on particle image velocimetry (PIV) (Raffel et al, 1998;Van Oudheusden, 2013) has been proposed to experimentally reconstruct the pressure field in water entry problems (Panciroli and Porfiri, 2013;Nila et al, 2013;Panciroli et al, 2015;Shams et al, 2015;Jalalisendi et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Assessment of PIV-based analysis of water entry problems through synthetic numerical datasets

Facci

Ubertini

Porfiri

2015

Journal of Fluids and Structures

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a b s t r a c tThe phenomenon of hull-slamming, that is, the sudden impact of a solid body on the water surface, is critical in the design of naval structures. Thus, the development and validation of schemes to predict the slamming load and elucidate energy exchange during water entry are of fundamental importance in a wide range of engineering applications. Recent studies have demonstrated the possibility of using direct flow measurements from particle image velocimetry (PIV) to investigate the kinetics of water entry. Specifically, these efforts have contributed a first characterization of the hydrodynamic loading on impacting wedges and of the energy imparted to the water pile-up and the spray jets. Here, we seek to provide a thorough assessment of such a PIV-based approach through synthetic datasets, in which PIV parameters, such as the camera acquisition rate and the size of the interrogation area, are systematically varied, without experimental confounds. We implement a direct computational framework to study the two-dimensional flow physics generated during the water entry of a rigid wedge. Water and air are treated as immiscible phases and their relative motion is utilized to track the free surface dynamics. Our results show that the PIV-based methodology allows for an accurate reconstruction of the pressure field from the measured velocity field, except for early stages of the impact and for a small region close to the free surface. We also demonstrate that the reconstruction is only marginally affected by the spatial resolution, while a sufficiently high acquisition frequency is required to correctly predict the pressure field in the pile-up region. The proposed computational framework can also find application in the analysis of less studied aspects of water entry problems, such as cycling loading, flow transitions and separation, and formation of spray jets.

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Repeated Slamming of Sandwich Composite Panels on Water

Cited by 43 publications

References 17 publications

Damage Assessment Due to Repeated Slamming of Foam Core Sandwich Composites

Damage Assessment Due to Repeated Slamming of Foam Core Sandwich Composites

Experiments on the water entry of asymmetric wedges using particle image velocimetry

Assessment of PIV-based analysis of water entry problems through synthetic numerical datasets

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