Bending of curved sandwich beams

Smidt, Sture

doi:10.1016/0263-8223(95)00119-0

Cited by 20 publications

(20 citation statements)

References 2 publications

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“…The Young's modulus of the core E c is on the other hand a very large quantity, often in the order of 10 8 -10 9 Pa, so if the change of thickness w t À w b is significant then the first term of the equation above will be dominating over the other. This is the case if there is a global bending moment resultant, because this will tend to stretch or compress the transverse core, as was reported by Smidt [14], who used the terms opening or closing moments because of this.…”

Section: Transverse Normal Stressesmentioning

confidence: 77%

High Order Analysis of Junction Between Straight and Curved Sandwich Panels

Lyckegaard¹,

Thomsen

2004

Jnl of Sandwich Structures & Materials

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When curved and straight sandwich panels are joined, localized bending effects arise in the vicinity of the curvature discontinuity. To investigate this the problem is analyzed using a high order sandwich beam theory. This, however, is not straight forward because the continuity conditions at a junction cannot be fulfilled in an exact sense. Instead an averaging scheme is suggested and used to obtain a set of approximate continuity conditions. The accuracy of these approximate continuity conditions is estimated and a numerical example is conducted and compared with finite element analyses. The results prove to be within the estimates of the inaccuracy. A parametric study is conducted to identify possible ways to reduce the localized bending effects.

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Section: Transverse Normal Stressesmentioning

confidence: 77%

High Order Analysis of Junction Between Straight and Curved Sandwich Panels

Lyckegaard¹,

Thomsen

2004

Jnl of Sandwich Structures & Materials

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“…The failure occurred by fracture of the core near the outer F/C interface. Stress analysis of curved monolithic and sandwich beams [1,3,5,6] loaded by opening bending moments reveals that the curved region will be subject to a radial tension ( r > 0). Sandwich beams with a weak foam core are prone to fail due to through-thickness tension in the core, or at the F/C interface if this is the weak link.…”

Section: Flexure Test Resultsmentioning

confidence: 99%

“…ANDREW M. LAYNE AND LEIF A. CARLSSON minimizes radial stress concentrations at the junctions between the straight and curved regions of the beam [3].…”

mentioning

confidence: 99%

Flexural Strength of Curved Sandwich Beams with Face/Core Debond

Layne

Carlsson

2002

Jnl of Sandwich Structures & Materials

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The influence of a face/core (F/C) debond on the flexural stiffness and strength of curved sandwich beams under opening bending moments has been experimentally examined. The sandwich beams consisted of glass/polyester face sheets over a PVC foam core. Debonds of various sizes were defined by inserting thin non-stick Teflon films at the outer F/C interface in the curved region of the beam prior to processing. The beams were tested in flexure in a specially designed fourpoint bend test fixture. The load versus displacement and surface strains at the apex of the beam were recorded to examine the response. It was observed that the debonded face sheet lifted off of the core and underwent a bifurcation associated with strain reversal. Beam failure occurred by propagation of the debond. It was observed that the beams suffered marginal reductions in stiffness, but substantial reductions in strength due to the presence of a debond. Linear finite element analysis was performed to examine the initial response of the beams.

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“…Librescu et al (1994 for buckling and post buckling problems of sandwich shells subjected to thermal induced deformations, Vaswani et al (1988) for vibration problems, Di Sciuva and Carrera (1990) and Rao and Meyer-Piening (1990) for buckling of sandwich shells. In addition, Hildebrand (1991), Smidt (1995), Tolf (1983) and Kant and Kommineni (1992) used FE models adopting the Reissner-Mindlin hypothesis, and Kuhhorn and Schoop (1992) adopted displacements distributions (third and second order polynomial) derived for flat sandwich panels, for the analysis of sandwich shells. The effects of the radial (transverse) flexibility of the core on the local and overall behaviour of the curved sandwich panels have been implemented through the use of the high-order sandwich panel theory (HSAPT) for curved panels assuming geometrical linearity, see Frostig (1999) and others.…”

Section: Introductionmentioning

confidence: 99%

Non-linear thermo-mechanical behaviour of delaminated curved sandwich panels with a compliant core

Frostig

Thomsen

2011

International Journal of Solids and Structures

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a b s t r a c tA non-linear analysis of a delaminated curved sandwich panel with a compliant core, and a delamination (debond) at one of the face-core interfaces, and subjected to a thermal field and a mechanical loading or combined is presented. The mathematical formulation outlines the governing equations along with the stress and displacements fields for the cases where the core properties are either temperature independent (TI) or temperature dependent (TD). A variational formulation is used following the principles of the high-order sandwich panel theory (HSAPT) to derive the field equations along with the appropriate continuity conditions. The non-linear analysis includes geometrical non-linearities in the face sheets caused by rotation of the face cross sections, and high-order effects that are the result of the radially (transversely) flexible (or compliant) core. The core stress and displacements fields with temperaturedependent (TD) mechanical properties are determined in closed form using an equivalent polynomial description of the varying properties. The numerical study describes the non-linear response of delaminated curved sandwich panels subjected to mechanical concentrated loads, thermally induced deformations and simultaneous thermal and mechanical loads. In the combined loading case the mechanical loads are below the limit point load level of the mechanical response, and the imposed temperature field is varied. The results are displayed in terms of plots of various structural quantities along the sandwich panel length (circumference), equilibrium curves and strain energy release rate curves. It is shown that the combined thermo-mechanical response shifts the linear or non-linear responses,observed for the separate cases of either temperature induced deformations or mechanical loading, into a strongly non-linear response with limit point behaviour and large stresses in vicinity of supports, loads and tips of delaminated zone.

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Bending of curved sandwich beams

Cited by 20 publications

References 2 publications

High Order Analysis of Junction Between Straight and Curved Sandwich Panels

High Order Analysis of Junction Between Straight and Curved Sandwich Panels

Flexural Strength of Curved Sandwich Beams with Face/Core Debond

Non-linear thermo-mechanical behaviour of delaminated curved sandwich panels with a compliant core

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