Dr. Abdul Monaim Jesry, Eng. Yaser Alewe

Syria-Aleppo city (Aleppo university) - Email:yaseralewe@gmail.com

Abstract: The parallel plate test (ISO 9969 & EN 1446) is a standardized test for insuring that the ring stiffness and flexibility of thermoplastic pipe meets specified levels of performance. Traditional calculation of ring stiffness depend on study of the elasticity of the material and neglect the role of its plasticity and viscosity. Nowadays scientific revolution in engineering programs and finite element analysis was helpful in complex studies and we could use it in simulation of real world conditions and optimize the profile shape which achieve decrease in cost of experiments and manufacturing. This work presents the results of a series of parallel plate tests and finite element simulations those tests conducted on corrugated HDPE plastic pipe to investigate the role of material and geometry on the behavior of the pipe during the test. Specifically, the work considers parallel plate tests on 400 mm diameter pipe, and its finite element simulation. ISO 9969 & EN 1446 uses the test to assure that corrugated HDPE pipe has required minimum pipe stiffness at 3% deflection (i.e. 3% reduction in diameter), and no buckling or loss of load before 30% deflection. After a series of experiments and comparing between them and theoretical study we find a great correspondence.

Keywords: Corrugated ;Plastic; simulation; ISO 9969; EN1446.

1. Introduction

HDPE corrugated plastic pipes is classified by its ring stiffness into Sn4, Sn8, Sn16 and it is the value of external load per squared meter kN/m2 [1]. The parallel plate test (ISO 9969 & EN 1446) is a standardized test for insuring that the ring stiffness and flexibility of thermoplastic pipe meets specified levels of performance. ISO 9969 & EN 1446 uses the test to assure that corrugated HDPE pipe has required minimum pipe stiffness at 3% deflection (i.e. 3% reduction in diameter), and no buckling or loss of load before 30% deflection which achieve the Syrian Standard Specifications 3062/2005[2]. The 3% stiffness criterion relates to handling and installation while the 30% deflection criterion provides necessary ultimate capacity as its shown in fig.1. Fig.1 vertical deflection of buried corrugated plastic pipes

2.Our research value and its objectives

Ring stiffness is decided theoretically by Eq.(1):

[pic](1)

E – Young's modulus (kN/m2).

Dm- internal diameter of the pipe (m).

I-inertia momentum of the pipe per length unit (m4/m).

And it is decided experimentally by a specimen has a specified length as it is mentioned in ISO 9969 and applying a load with a specified velocity until 3% of vertical deflection so we got the load value and by using Eq.(2) we will know the ring stiffness: [pic](2)

SR- ring stiffness (N/m2).

L- specimen length (mm).

y- vertical deflection of the pipe (mm)

F- applied force (N)

Test method is shown in fig.2

[pic]

Fig.2 test method of ring stiffness according to ISO 9969

Flexibility stiffness is decided by applying a load with a specified velocity until 30% of vertical deflection according to EN1446 standard. Eq.(1) which gives us theoretical ring stiffness considers the role of material elasticity E and neglects the role of material plasticity and viscosity so it is valid for small strains, but for large strains we can't neglect material plasticity and viscosity. Now by using engineering programs which include FEA method [3] and considers all material properties we could simulate parallel plate testing of corrugated plastic pipes according to ISO 9969 & EN 1446.

3.Plan of the research

We will use appropriate engineering programs to simulate parallel plate testing of corrugated plastic pipes according to ISO 9969 & EN 1446 and assure correspondence of simulation results with test results which...