Review on lifetime predictions of polyethylene pipes: Limitations and trends

Zha, Sixi; Lan, Huiqing; Huang, Hui

doi:10.1016/j.ijpvp.2022.104663

Cited by 28 publications

(15 citation statements)

References 116 publications

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“…Equations ( 8) and ( 9) are ordinary differential equations involving the unknown function σ v (t) and its derivatives with respect to time t. Matlab was applied to solve these ordinary differential equations. To solve these ordinary differential equations using Matlab, function "Ode15i" in Matlab was used to determine these four parameters in the Parallel model, based on Equation (8), as this equation is a fully implicit differential equation which can be solved using "Ode15i" [45]. For the Series model, on the other hand, the four parameters were determined using the function "Ode45" in Matlab, as this function is designed to solve a nonstiff differential equation like Equation ( 9) [46].…”

Section: Case Study 1: Comparison Of Three Models Depicted Abovementioning

confidence: 99%

“…Equation ( 8) was used for the simulation of relaxation phase and the last three data points in the loading phase before the relaxation phase. Equation (8) was first applied to fit the relaxation phase, to determine values for E v . δ 0E,1 , E v .…”

Section: Case Study 2: Determination Of Activation Energies For the E...mentioning

confidence: 99%

“…With the significant improvement in PE’s performance, its applications to engineering structures have steadily increased in recent years [ 6 , 7 ]. A total of 95% of the plastic pipes in the United States are PE pipes [ 8 ]. PE pipes are increasingly applied to water and gas transportation [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Polyethylene Using a New Test Method Based on Stress Response to Relaxation and Recovery

Shi

Jar

2022

Polymers

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A novel multi-relaxation-recovery (RR) test was proposed based on cyclic stages of stress relaxation and stress recovery. Three nonlinear visco-elastic models, that is, the standard model and two models with two dashpots connected either in parallel or in series, were examined for the analysis of the test results. Each model contains a time-dependent, viscous branch and a time-independent, quasi-static branch. The examination suggests that the standard model can determine the long-term, load-carrying performance of polyethylene (PE) and identify a transition point for the onset of plastic deformation in the crystalline phase, but the models with two dashpots connected either in parallel or in series are needed to provide a close simulation of the experimentally measured stress response in both relaxation and recovery stages of the RR test. In this work, the mechanical performance of two PEs was compared based on RR test results at room temperature. The RR tests were also conducted at elevated temperatures to explore the possibility of quantifying the activation energies for deformation of the dashpots at the relaxation stage. It was found the RR test has the advantage of separating the time-dependent and time-independent components of stiffness of the materials. The study concludes that the RR test can provide data for determining parameters in Eyring’s model in order to characterize the contribution of time-dependent and time-independent components of the stress response to PE’s deformation.

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Section: Case Study 1: Comparison Of Three Models Depicted Abovementioning

confidence: 99%

Section: Case Study 2: Determination Of Activation Energies For the E...mentioning

confidence: 99%

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Characterization of Polyethylene Using a New Test Method Based on Stress Response to Relaxation and Recovery

Shi

Jar

2022

Polymers

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“…The lifetime assessment and predictions of the long-term response of these materials under creep and fatigue conditions have attracted noticeable attention in the past few decades [ 1 , 2 , 3 , 4 ]. These issues are of essential importance for polyethylene pipes, whose failure is driven by the viscoplastic flow and damage accumulation in both the amorphous and crystalline phases [ 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

“…(i) They are valid at the first stage of creep only (before changes in microstructure driven by slow growth of microcracks become noticeable [ 7 ]).…”

Section: Introductionmentioning

confidence: 99%

Lifetime Predictions for High-Density Polyethylene under Creep: Experiments and Modeling

2023

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Observations are reported in uniaxial tensile tests with various strain rates, tensile relaxation tests with various strains, and tensile creep tests with various stresses on high-density polyethylene (HDPE) at room temperature. Constitutive equations are developed for the viscoelastoplastic response of semicrystalline polymers. The model involves seven material parameters. Four of them are found by fitting observations in relaxation tests, while the others are determined by matching experimental creep curves. The predictive ability of the model is confirmed by comparing observations in independent short- and medium-term creep tests (with the duration up to several days) with the results of numerical analysis. The governing relations are applied to evaluate the lifetime of HDPE under creep conditions. An advantage of the proposed approach is that it predicts the stress-time-to-failure diagrams with account for the creep endurance limit.

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Thermo‐mechanical properties of polyethylene composites filled with soapstone waste

de Sousa,

Kalantar Mehrjerdi,

Skrifvars

et al. 2023

J of Applied Polymer Sci

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In this study, soapstone waste originated from craftsmanship activities was used as an alternative filler (0–30 wt%) for a high‐density polyethylene (PE) matrix. The aim of this paper is to understand the effect of the filler particles on crystallinity, thermal stability and thermo‐mechanical properties of this newly developed composite material. Physico‐chemical characterization was performed by x‐ray diffraction (XRD) and Fourier‐transform infrared (FTIR) spectroscopy. Thermogravimetric analysis (TGA), oxidation induction time (OIT) and dynamic mechanical thermal analysis (DMA) were performed to assess the effect of the filler on the themo‐mechanical properties of PE. Thermal stability, measured by TGA, was enhanced, while OIT values reduced with filler content. A significant increase on the storage modulus of the composites (up to 148% in comparison with unfilled PE) was observed and this reinforcing effect was even more prominent at higher temperatures. XRD analysis revealed that the degree of crystallinity improved significantly with soapstone loading, which explains the substantial increase in stiffness observed. Increased crystallinity is also associated with higher strength, reduced residual stress, and better dimensional stability of end products, which can be particularly attractive for pressure pipe applications.

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Review on lifetime predictions of polyethylene pipes: Limitations and trends

Cited by 28 publications

References 116 publications

Characterization of Polyethylene Using a New Test Method Based on Stress Response to Relaxation and Recovery

Characterization of Polyethylene Using a New Test Method Based on Stress Response to Relaxation and Recovery

Lifetime Predictions for High-Density Polyethylene under Creep: Experiments and Modeling

Thermo‐mechanical properties of polyethylene composites filled with soapstone waste

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