Shear and mode II fracture of PUR foams

Marșavina, Liviu; Constantinescu, Dan Mihai; Linul, Emanoil; Voiconi, Tudor; Apostol, Dragoş Alexandru

doi:10.1016/j.engfailanal.2015.05.021

Cited by 65 publications

(30 citation statements)

References 23 publications

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“…In contrast, because it is difficult to set the LVDT in the AFPB test to measure the shear strain in the gauge region, which corresponds to the region between the notch roots, an alternative method for measuring shear strain was required. Optical methods, such as digital image correlation (DIC) and virtual fields method (VFM), are promising in measuring the strain induced in a material with low stiffness, such as foam and paper materials [15][16][17][18]20,28]. In the preliminary tests, it was examined whether the shear strain could be accurately measured using a high-speed digital image sensor (Keyence CV-5000SO, Keyence Corporation, Osaka, Japan), which was effective for measuring the elongation induced during a tensile test of the paper material [29].…”

Section: Tension and Compression Tests For The Strain Gauge Calibrationmentioning

confidence: 99%

“…Several methods are considered to measure both the shear modulus and the shear strength values of foam materials. Among them, the in-plane shear (IPS), Arcan, and Iosipescu shear tests are often conducted for several foam materials [15][16][17][18][19][20]. Nevertheless, these methods are not always convenient, because a pair of metallic plates must be bonded or connected to the facings of the foam sample to apply a shearing force.…”

Section: Introductionmentioning

confidence: 99%

“…However, the measurement of the shear strain is indirect, despite the effectiveness in using the strain gauge. To improve the accuracy in measuring the shear modulus, the aforementioned alternative techniques, such as the digital image correlation (DIC) and virtual field method (VFM), should be adopted for the AFPB test in place of the strain gauge [15][16][17][18]20]. Further research should be performed on this topic.…”

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confidence: 99%

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Measurement of the Shear Properties of Extruded Polystyrene Foam by In-Plane Shear and Asymmetric Four-Point Bending Tests

Yoshihara

Maruta

2019

Polymers

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The shear modulus and shear strength of extruded polystyrene foam were obtained by the in-plane shear and asymmetric four-point bending tests. In addition, the test data were numerically analysed, and the effectiveness of these tests was examined. The numerical and experimental results suggest that the shear modulus and shear strength obtained from the in-plane shear test are significantly smaller than those obtained from the asymmetric four-point bending test because the influence of the stress concentration was less significant. Although the in-plane shear test is standardised in ASTM C273/C273M-11, it is considerable to adopt the asymmetric four-point bending test as another candidate for obtaining the shear properties of extruded polystyrene foam.

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Section: Tension and Compression Tests For The Strain Gauge Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Measurement of the Shear Properties of Extruded Polystyrene Foam by In-Plane Shear and Asymmetric Four-Point Bending Tests

Yoshihara

Maruta

2019

Polymers

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“…The cellular structure of low‐density foams results in lightweight materials with excellent stiffness‐to‐weight ratio, high ability to absorb impact energy, good shear and fracture strength, exceptional heat transfer ability, which recommends them for a wide range of applications, from packaging materials in the form of paper‐based honeycomb cardboard up to sport, automotive, marine and aerospace industries.…”

Section: Introductionmentioning

confidence: 99%

Low‐cycle fatigue behaviour of ductile closed‐cell aluminium alloy foams

Linul

Şerban

Marșavina

et al. 2016

Fatigue Fract Eng Mat Struct

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This work investigates the fatigue response of a class of ductile closed‐cell aluminium alloy foams, known by their commercial name Alulight M8. In order to determine the yield stress of the used foams, preliminary experimental tests were performed, at room temperature, in monotonic compression on cylindrical specimens of 25 mm diameter and 25 mm height, with a loading speed of 10 mm/min. Fatigue tests were performed in uniaxial compression on cylindrical specimens (25 mm × 25 mm) with a stress ratio of R = 0.1, at a frequency of 10 Hz. The peak stress was varied from 110 to 135% of the yield stress in compression. Tested specimens were cut from the same cylindrical bar, and the density of the investigated material was 500 kg/m3 ± 10%, or a total of 18 specimens being investigated. With the gathered experimental data, S–N curve was generated, and the effect of cellular structure (e.g. structure irregularity–the number and the size of cells) being investigated and discussed.

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“…It should be noted that this unit cell is axisymmetric. The anisotropy of polyurethane foams and its impact on their mechanical properties has been extensively studied [8,[15][16][17][18][19][20]. However, significant differences and variability of the foam and the obtained results are expected between these studies and the case of PU pre-insulated pipes, due to:…”

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confidence: 99%

Anisotropy in Polyurethane Pre-Insulated Pipes

2019

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The polyurethane foam in district heating pre-insulated pipes has a critical role to play both as thermal insulation and as load bearing element, as it serves as bond between the medium pipe and the casing. Hence, knowledge on how the foam behaves under multiaxial stresses is of great importance for the design as well as for aging predictions of the network. It is known that cell shape anisotropy in polymeric foams leads to anisotropy in its mechanical properties. In this study, we evaluate and quantify the microstructural anisotropy of PU foam from pre-insulated pipes as well as its mechanical behaviour under compression in the three orthogonal directions. We cover rigid and flexible PU foam, batch and continuous manufacturing, and different pipe diameters. The results were compared with those predicted by available rectangular and Kelvin cell shape models. We have found that PU from pre-insulated pipes is orthotropic and present stronger anisotropy than that typically found in PU slabs. The traditional bonded pipes under consideration behaved in a similar way. However, when comparing the two flexible pipes in this study, despite no significant differences in cell shape anisotropy were found, a significantly different behaviour for the E modulus ratio was observed. This shows that while the manufacturing process exerts the main influence on cell shape anisotropy, to explain the difference in stiffness behaviour other factors need to be taken into consideration, such as cell size and cell size variability.

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Shear and mode II fracture of PUR foams

Cited by 65 publications

References 23 publications

Measurement of the Shear Properties of Extruded Polystyrene Foam by In-Plane Shear and Asymmetric Four-Point Bending Tests

Measurement of the Shear Properties of Extruded Polystyrene Foam by In-Plane Shear and Asymmetric Four-Point Bending Tests

Low‐cycle fatigue behaviour of ductile closed‐cell aluminium alloy foams

Anisotropy in Polyurethane Pre-Insulated Pipes

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