A method is proposed that allows for the concurrent optimization of core topology and face sheet thickness of a sandwich beam under compliance constraints. The problem is solved using a novel mixed...

This study presents experimental results and analysis of failure of sandwich beams with steel face sheets and polyurethane core tested in three-point bending. Firstly, a series of experiences are conducted in order to obtain the mechanical properties of the metallic face sheets and the foam core. To model the foam behavior, quasi-cyclic tests were performed by increasing the punch stroke. An exponential model is proposed describing the variation of the elastic modulus as a function of the strain. Secondly, the quasi-static and quasi-cyclic bending tests are carried out leading to failure of the sandwich beam. The results of the quasi-cyclic bending show that the behavior of the sandwich beam is similar to the foam behavior in quasi-cyclic compression. Thirdly, a Finite Element Analysis (FEA) is performed in order to predict the observed foam fracture in bending test using a shear damage criterion for the foam core. The comparisons show a satisfactory agreement between the experimental results and the FEA predictions.

Honeycomb materials are commonly used as cores for sandwich panels. While empirical evidence exists showing that the transverse shear strength of a honeycomb core is affected by its thickness, the ...

As an aircraft or spacecraft ascends, the atmospheric pressure drops. If the internal pressure is not released, a pressure differential develops on the facesheet. With an in-plane load from vehicle...

An open-hole compression test method has been developed to assess the notch sensitivity of sandwich composites under compression loading. This test method, in the process of being standardized by ASTM International, utilizes end loading as well as knife-edge side supports to provide out-of-plane restraint to specimen buckling. Finite element analyses focused on identifying a sandwich specimen geometry that minimized finite-width and finite-length effects on the stress concentration produced by the centrally-located through-hole. Geometric variables included the specimen width-to-hole diameter (w/D) and length-to-hole diameter (l/D) ratios. The sandwich configurations investigated consisted of a Nomex honeycomb core and carbon/epoxy facesheet laminates with a range of material orthotropy ratios. Numerical results were used to identify a candidate sandwich specimen geometry and optimal strain gage placements for use in specimen alignment. A series of mechanical tests were performed to evaluate the proposed specimen design, the proposed test fixture, and the recommended test procedure. The first set of experiments were performed using specimens with different hole diameters but the same specimen width and length. A second set of experiments used specimens with different lengths but with the same specimen width and open-hole. In addition, the use of specimen end potting of the core region was investigated to prevent facesheet separation and end brooming.

Glass fibre reinforced composite facings on PVC (poly(vinyl chloride)) foam cores are widely used sandwich materials in boat structures, but life cycle analysis suggests that alternative materials ...

To investigate a new type of bionic energy-saving sandwich plate—the beetle elytron plate (BEP), the compressive mechanical properties of short basalt fiber reinforced epoxy resin composite BEPs an...

Bionic and gradient designs offer promising applications in honeycomb structures. The intersection unit of the beetle elytra is extracted as to enhance regular hexagonal honeycomb (RHH), and severa...

This study proposes a honeycomb with a sine waveform to increase the impact resistance against bird strike on the vertical stabilizer leading edge. A 2-stage comparison was made using the experimen...

A steel-concrete-steel sandwich panel with prestressed reinforcement was developed, named prestressed steel-concrete–steel sandwich panel. Nine specimens where the loading mode, top steel plate thi...

In this study, various structural configurations such plain core, two-core, epoxy columns in the core, core stitched, and facesheet stitched were designed in the foam core sandwich composite with the aim to increase the absorbed energy and to decrease core/facesheet debonding area due to low-velocity impact. Glass fiber/epoxy and PVC foam were used as a facesheet material and a core material, respectively. The impact energy values were selected considering to penetration and perforation cases. The core stitching effect on low velocity impact behavior of sandwich composites were compared to facesheet stitching and it has been determined that the core stitching process can be an alternative to the facesheet stitching process in terms of the absorbed energy value. Impacted sandwich composites are investigated for core/facesheet debonding; the modifications through the thickness increased the failure path for core/facesheet debonding initiation and the results show that a significant decrease in the core/facesheet debonding area has been achieved.

Foldcore sandwich structure has promising applications for load-bearing, and in this study, M-type foldcore sandwiches are prepared through a molding and pressing process with fiberglass. To be spe...

This study investigates the effect of viscoelastic properties in the numerical modeling of foam-filled sandwich panels when their composite facesheets are exposed to low-velocity impact loading. A ...

As for high resolution satellite application field, novel C/SiC honeycomb sandwich structure is the first to propose and develop on account of such many attractive properties as excellent ultrahigh...

Detecting disbonds in honeycomb sandwich structures using ultrasonics is challenging due to the complex wave propagation. This paper investigates the method for disbond quantification in honeycomb ...

The present study investigates the influence of initial geometric imperfections on large amplitude vibration of shallow sandwich shells with functionally graded graphene nanoplatelets reinforced po...

Although the best configuration of the joints used to connect a common GFRP sandwich panel with the main structures is the adhesively bonded one, that permit high static and fatigue performances as...

Sandwich composites in marine vessels are frequently exposed to impulsive hydrodynamic loading during operation in extreme environments. The response of sandwich composites to impulsive hydrodynami...

A metamaterial plate with multi bandgaps is proposed for vibration suppression by integrating membrane-mass structures that can be used as locally resonant metastructure into a honeycomb sandwich s...

In conventional sandwich construction, the core component is typically made of Nomex honeycomb and sandwiched between two facesheets, a lower and an upper facesheet. To enhance the load-bearing cap...