Characterization and Constitutive Modelling of Nonlinear Creep of PE100 Grade Gas Pipe Material

doi:10.19491/j.issn.1001-9278.2021.11.014

Abstract

Abstract:

Polyethylene （PE） has been widely used in pressure pipeline engineering due to its excellent corrosion resistance. Long-term service behavior of a pipe is predominated by the creep property of its raw material. It is of great significance to study the creep behavior of PE at room temperature for the safety and integrity evaluation of PE pressure pipelines. In this paper， the room temperature creep tests of PE100 grade gas pipe material were conducted under various stresses ranging from 2.4 MPa to 9.6 MPa. The results indicated that there was a stress independency of creep comp?liance of the material when the stress does not exceed 5.4 MPa， indicating linear viscoelastic behavior. However， a stress dependency occurred and showed nonlinear viscoelastic creep when the applied stress was higher than 5.4 MPa. Based on the single integral nonlinear viscoelastic constitutive theory， the Findley model was used to analyze the creep behavior of PE100 grade gas pipe material by comparison with the Struik empirical model. It was found that both the Findley model and the Struik model well described the creep behavior of the pipe material， but the Findley model was more accurate than the Struik one for modeling the nonlinear creep behavior under high stresses.

Key words: polyethylene, gas pipe, creep, nonlinear viscoelasticity, creep compliance, constitutive model

CLC Number:

TQ 322.2

LI Maodong, LI Yan, YANG Bo, WANG Zhigang, LUO Wenbo. Characterization and Constitutive Modelling of Nonlinear Creep of PE100 Grade Gas Pipe Material[J]. China Plastics, 2021, 35(11): 91-96.

Figures/Tables 10

Fig.1. Schematic diagram of PE100 creep specimens and its cutting orientation on pipes

Fig.2. Zwick/Roell Z020 tensile test machine for creep tests

Fig.3. Stress?time and strain?time curves of tensile creep tests

Fig.4. Creep compliance vs time curves under different stresses

Fig.5. Initial instantaneous elastic strain under different creep stresses

Fig.6. Stress dependent factor h0(σ) for initial instantaneous elastic responses

Fig.7. Stress dependent factor h1(σ) for transient response

Fig.8. Creep behavior of PE100： Findley model prediction vs tests

Fig. 9. Variation of average retardation time of Struik model with stress

Fig.10. Creep behavior of PE 100： Struik model prediction vs tests

References 17

1	EN： Plastics Piping and Ducting Systems⁃Determination of the Long⁃term Hydrostatic Strength of Thermoplastics Materials in Pipe Form by Extrapolation［S］. BSI Standards Limited，British， 2012.
2	VAKILI⁃TAHAMI F， ADIBEIG M R. Using Developed Creep Constitutive Model for Optimum Design of PE⁃HD pipes［J］. Polymer Testing， 2017， 63： 392⁃397.
3	SCHAPERY R A. Nonlinear Viscoelastic Solids［J］. International Journal of Solids and Structures， 2000， 37： 359⁃366.
4	杨挺青，罗文波，徐平，等. 黏弹性理论与应用［M］. 北京：科学出版社： 2004：25⁃26.
5	LUO W， WANG C， HU X， et al. Long⁃term Creep Assessment of Viscoelastic Polymer by Time⁃temperature⁃stress Superposition［J］. Acta Mechanica Solida Sinica， 2012， 25（6）： 571⁃578.
6	KOLAŘÍK J， PEGORETTI A. Proposal of the Boltzmann⁃like Superposition Principle for Nonlinear Tensile Creep of Thermoplastics［J］. Polymer Testing， 2008，27（5）：596⁃606.
7	LAI J， BAKKER A. Analysis of the Non⁃linear Creep of High⁃density Polyethylene［J］. Polymer， 1995，36（1）： 93⁃99.
8	LUO W， YANG T， AN Q. Time⁃temperature⁃stress Equi⁃valence and Its Application to Nonlinear Viscoelastic Materials［J］. Acta Mechanica Solida Sinica， 2001， 14：195⁃199.
9	LIU H， POLAK M A， PENLIDIS A. A Practical Approach to Modeling Time⁃dependent Nonlinear Creep Behavior of Polyethylene for Structural Applications［J］. Polymer Engineering and Science， 2008， 48（1）：159–167.
10	ZHANG C， MOORE I D. Nonlinear Mechanical Response of High Density Polyethylene［J］. Part II： Unia⁃xial Constitutive Modeling. Polymer Engineering and Science，1997， 37（2）：414⁃420.
11	KUHL A， MUNOZ⁃ROJAS P A. Application of a Master Curve and the Modified Superposition Principle for Modeling Creep and Loading Rate Effects at Small Strains in High⁃density Polyethylene［J］. Mechanics of Advanced Materials and Structures， 2019， 1605008.
12	SCHAPERY R A. An Engineering Theory of Nonlinear Viscoelasticity with Applications［J］. International Journal of Solids and Structures， 1966，（2）：407⁃425.
13	SCHAPERY R A. On the Characterization of Nonlinear Viscoelastic Materials［J］. Polymer Enginerring and Science， 1969，（9）：295⁃ 310.
14	FINDLEY W N， LAI J S， ONARAN K. Creep and Relaxation of Nonlinear Viscoelastic Materials［M］. Dover Publications， New York， 1976：221⁃225.
15	STRUIK L C E. Physical Aging in Amorphous Polymers and Other Materials［M］. Amsterdam： Elsevier， 1978：38⁃39.
16	TOMLINS P E. Comparison of Different Functions for Modelling the Creep and Physical Aging Effects in Plastics［J］. Polymer， 1996， 37（17）：3 907⁃3 913.
17	TOMLINS P E， READ B E. Creep and Physical Ageing of Polypropylene： a Comparison of Models［J］. Polymer， 1998， 39（2）：355⁃367.

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