A Methodology for Obtaining Material Properties of Polymeric Foam at Elevated Temperatures

Zhang, S.; Dulieu-Barton, J.M.; Fruehmann, R.K.; Thomsen, Ole Thybo

doi:10.1007/s11340-011-9519-7

Cited by 48 publications

(63 citation statements)

References 14 publications

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“…The fibre layers introduced inside the peel stopper and placed at the peel stopper/core interface in C3 are made from the same E-glass fabric that was used for the face sheet. The material properties of the sandwich constituent materials are listed in Table 1 [5,15]. The sandwich panel that incorporates the peel stopper was manufactured in a single shot resin infusion process using Prime 20 LV epoxy resin by Gurit.…”

Section: Test Specimensmentioning

confidence: 99%

Fracture behaviour at tri-material junctions of crack stoppers in sandwich structures

Wang

Martakos

Dulieu-Barton

et al. 2015

Composite Structures

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Abstract:Inspired by a previously published peel stopper design for foam cored composite sandwich structures, three novel markedly lighter peel stoppers were evaluated with respect to their ability to deflect and arrest propagating face debond cracks. Of the three novel peel stopper configurations, C1, C2 and C3, C1 was similar to the previous design, whereas C2 and C3 were modified with layers of glass fibre fabric extending from the peel stopper tip into the face sheet (C2) or into the face sheet/core interface (C3). The previous peel stopper was validated under mode II dominated conditions, but the novel designs were investigated under mode I dominated crack propagation conditions, which are of higher practical relevance. Both quasi-static and fatigue loading scenarios were investigated. The mechanisms controlling crack propagation at the internal peel stopper tip were studied using Thermoelastic Stress analysis (TSA) and Finite Element (FE) analysis. The TSA has revealed significant new information about the local stress fields in the vicinity of the tri-material junction (peel stopper tip) as well as the fracture process zone. Configuration C1 was unable to deflect debond cracks consistently, albeit it did so in most cases, whereas it was incapable of achieving crack arrest. C2 and C3 both performed better in that they consistently demonstrated the ability to deflect propagating cracks, whereas only C2 could arrest the cracks consistently as well. Detailed fracture mechanics analyses confirmed and explained the experimental observations.

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Section: Test Specimensmentioning

confidence: 99%

Fracture behaviour at tri-material junctions of crack stoppers in sandwich structures

Wang

Martakos

Dulieu-Barton

et al. 2015

Composite Structures

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“…Similar 178 analyses were conducted for tensile and compressive specimens, and correction factors were 179 computed from the FE results to scale the average surface strain in the gauge (the quantity 180 measured by DIC) to the average through-thickness gauge strain, as described by Taher, et al 181 [25]. This methodology has been shown to compensate for errors associated with non-uniform 182 strain distributions arising from the specimen geometry [30]. Specimen dimensions that are not 183 sufficiently large compared to the cell size are another potential source of experimental error in 184 evaluating the elastic moduli of foams, but the specimens in this work are sufficiently large to 185 avoid this effect according to Tekog~lu et al [31] and given the cell sizes presented in Table 2.…”

Section: Mechanical Testing 150mentioning

confidence: 99%

Evaluation of the anisotropic mechanical properties of reinforced polyurethane foams

Hamilton

Thomsen

Madaleno

et al. 2013

Composites Science and Technology

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“…Divinycell H100 132 [19] 59 [19] 32 [20] 0.40 [19] 35 x10 -6 [24] CTE is the coefficient of linear thermal expansion.…”

mentioning

confidence: 99%

Influence of thermomechanical interaction effects on the failure behaviour of polymer foam cored sandwich panels

Palleti

Zhang

Fruehmann

et al. 2015

Jnl of Sandwich Structures & Materials

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The paper presents an experimentally based and numerically supported investigation of the collapse behaviour of polymer foam cored sandwich beams subjected to combined mechanical and thermal loading. Recent analytical and numerical modelling results available in the literature have ascertained that collapse may be due to loss of stability induced by nonlinear interactions between mechanical loads and thermally induced deformations, when accounting for the reduction of the polymer foam core mechanical properties with increasing temperature. In the paper, experiments are devised whereby a thermal gradient is introduced into a sandwich beam specimen loaded in three point bending. The experiments cover a range of temperatures where one face sheet is heated from room temperature (25°C) to just below the glass transition temperature of the polymer foam core (70°C) and the other face sheet remains at room temperature. Digital image correlation (DIC) is used to obtain the local displacement field of the sandwich beam and its temperature is monitored using an infrared detector and thermocouples. The experimental results are compared with the predictions of both a generally nonlinear finite element model and an analytical so-called high-order sandwich panel theory (HSAPT) model. It is important to note that the HSAPT model has clear limitations as it takes into account only the geometric nonlinearity and thermal degradation of the foam core elastic properties, and it further assumes that the sandwich constituents are linear elastic with infinite straining capability. The HSAPT model predicts the occurrence of a strongly nonlinear load response leading to loss of stability (limit point Palleti, H.N.K.T., Zhang, S., Dulieu-Barton, J.M., Fruehmann, R.K. and Thomsen, O.T., "Influence of thermomechanical interaction effects on the failure behaviour of polymer foam cored sandwich panels", Journal of Sandwich Structures and Materials, 17, 2015, 308-331. DOI: 10.1177/1099636214567602. 2 behaviour). However, the experiments show that for the investigated sandwich beam configuration it is necessary to include the nonlinear material properties in the modelling, as the nonlinear beam response leading to failure and collapse is significantly influenced by plastic deformations in the constituent materials. Thus, core indentation and extensive plasticity precedes the transition to loss of stability driven by geometric nonlinearity and thermomechanical interaction effects. Finite element analyses that include both geometric and material nonlinearities provide results that correlate closely with the experimental observations. The work presented lays the foundations of a methodology for validating complex thermomechanical behaviour in sandwich structures using non-contact full-field measurement systems, and it demonstrates that analytical or numerical models based on the assumption of linear elastic material behaviour (such as the HSAPT model referenced in the paper) generally cannot adequately describe the thermomechanical be...

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A Methodology for Obtaining Material Properties of Polymeric Foam at Elevated Temperatures

Abstract: A new methodology to characterise the elastic properties of polymeric foam core materials at elevated temperatures is proposed.

Cited by 48 publications

References 14 publications

Fracture behaviour at tri-material junctions of crack stoppers in sandwich structures

Fracture behaviour at tri-material junctions of crack stoppers in sandwich structures

Evaluation of the anisotropic mechanical properties of reinforced polyurethane foams

Influence of thermomechanical interaction effects on the failure behaviour of polymer foam cored sandwich panels

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