Residual stress in polyethylene pipes

Poduška, Jan; Hutař, Pavel; Kučera, Jaroslav; Frank, Andreas; Sadílek, Jiří; Pinter, Gerald; Náhlík, Luboš

doi:10.1016/j.polymertesting.2016.07.017

Cited by 32 publications

(21 citation statements)

References 20 publications

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“…According to the literature, the lower the mold temperature, the higher is the expected residual 14 International Journal of Polymer Science stress level [53,54] and for Tenac, the lower is the observed fatigue fracture performance. Hence, it is interpreted that there is an inverse proportionality between the fatigue fracture performance and the residual stress level, which is consistent with the effect of residual stresses on the tensile properties [55] and on the slow crack growth behavior of polymeric pipes [56,57]. For Delrin, the insensitivity of the fatigue fracture curves to the mold temperature is, as described above, related to the nucleation of the material, which is expected to lead to a rather uniform residual stress level for the processing conditions examined.…”

supporting

confidence: 75%

Fatigue Fracture Properties and Morphology of Polyoxymethylene (POM) Plates Produced under Moderate Processing Conditions

Berer

Halb

Feuchter

et al. 2018

International Journal of Polymer Science

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The present study was inspired by different industry projects in which a strong dependence of the fatigue fracture performance of POM on the processing conditions was observed. To examine the relationships under more reproducible conditions, plates of two different POM homopolymer resins (one significantly nucleated) were produced by compression molding and by injection molding under moderate conditions. For the injection molding, three different mold temperatures were used. At specific locations, the plates were analyzed concerning their hierarchical structure on the micro- and nanolevel and concerning their fatigue fracture performance. For the fatigue fracture performance, the dependence on the processing conditions was rather small for the nucleated resin but much more significant for the other resins. This dependence could not be related to morphological effects only, and thus, a combined effect of morphology and residual stresses was assumed.

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supporting

confidence: 75%

Fatigue Fracture Properties and Morphology of Polyoxymethylene (POM) Plates Produced under Moderate Processing Conditions

Berer

Halb

Feuchter

et al. 2018

International Journal of Polymer Science

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“…In order to get an idea about material resistance to crack propagation, it has been shown that the difference between fracture toughness values (JIC; kJ/m²) for the two layers can reach up to 25% in favor of the outer layer. Again, the variations are attributed to changes in internal stresses and microstructure [5,6,9].…”

Section: Resultsmentioning

confidence: 99%

“…When studying different pipe cooling rates, thermal gradients caused the spherulites to grow from the outer towards the inner layers creating an orientation across the wall and concluding to a lower resistance to slow crack growth (SCG) [2,3]. To predict plastic pipe lifetime under SCG mode, it is compulsory to consider the residual stress distribution imparted by the extrusion process [4][5][6][7]. The important part of residual stresses lays in the circumferential direction as it is in direct relation with SCG in plastic pipes.…”

Section: Introductionmentioning

confidence: 99%

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An Investigation Into Property Variances Between Outer and Inner Hdpe Pipe Layers

Ghabeche

Chaoui

2019

mech

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NomenclatureAO -antioxidants; CB -% carbon black; DSC -differencial scanning calorimetry; E -Young's modulus, MPa; HDPE -highdensity polyethylene; HS -Shore hardness; IL -inner layer; JIC -critical energy release rate, kJ/m²; KIC -fracture toughness, MPa.√m; La -most probable amorphous layer thickness, nm; Lc -most probable crystalline layer thickness, nm; Lp -long period of the lamellar stacking, nm; MDPE -mediumdensity polyethylene; MFI -melt flow index; OD -outer diameter, mm; OL -outer layer; OIT -oxidation induction time; PE -polyethylene; PP -polypropylene; Ra -arithmetical mean roughness, µm; Rq -root mean square roughness, µm; Rz -average maximum height of the profile, µm; SCG -slow crack growth, SDR -standard dimension ratio; Xc -crystallinity, %; XRD -X rays diffraction; εf -failure strain, %; σf -failure stress, MPa; σy -yield stress, MPa.

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“…An investigation of the residual stress state in a PE pipe 160 SDR11 (outer diameter 160 mm, wall thickness 14.6 mm) was carried out. The results have already been published in [10]. The residual stress was determined by measuring deformation of slit ringspipe was cut into several rings.…”

Section: Fig 1: Scheme Of the Experiments (A) And The Results For Thementioning

confidence: 99%

Soil Load on Plastic Pipe and its Influence on Lifetime

Poduška

Hutař

Frank

et al. 2019

Strojnícky Časopis - Journal of Mechanical Engineering

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Lifetime of plastic pipes can be estimated by integration of a power law describing the crack kinetics. However, this procedure requires an FEM (finite element method) calculation of the possible crack propagation in the pipe to obtain stress intensity factor dependency on the crack length. It is very important for the simulation to consider every possible load that is acting on the pipe. This contribution deals with FEM modelling of a pipe that is loaded by internal pressure, residual stresses and soil loads. Comparison of the factors and pipe lifetime estimation is carried out.

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Residual stress in polyethylene pipes

Cited by 32 publications

References 20 publications

Fatigue Fracture Properties and Morphology of Polyoxymethylene (POM) Plates Produced under Moderate Processing Conditions

Fatigue Fracture Properties and Morphology of Polyoxymethylene (POM) Plates Produced under Moderate Processing Conditions

An Investigation Into Property Variances Between Outer and Inner Hdpe Pipe Layers

Soil Load on Plastic Pipe and its Influence on Lifetime

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