Stress Distribution and Fracture Toughness of Underground Reinforced Plastic Pipe Composite

Abstract

Reinforced composite materials have many applications in the aerospace, marine, and petroleum industries. Glass fiber-reinforced pipes are of considerable importance as pressurized vessels, infrastructure materials, and petroleum wastewater pipelines. The stress intensity factor due to through-thickness discontinuities is a major parameter in fracture mechanics to understand the failure mechanisms in glass fiber-composite pipes. The stress intensity factor is calculated for a composite cylinder subjected to internal pressure using the linear extended finite element method based on the law of energy release evaluation of surface damage. The analytical model needs two material properties; they are the tensile strength and the fracture toughness; therefore, a standard tensile test was carried out on a standard specimen taken from the pipe’s wall thickness. Moreover, the compact tension test specimen was manufactured from the pipe’s wall thickness to obtain the fracture toughness. The average tensile strength was measured as 21.5 MPa with a standard deviation of 5.59 MPa, moreover, the average Young’s modulus was measured as 32.75 GPa with a standard deviation of 6.64 GPa. The fracture toughness was measured as 2322 (MPa √m) with a standard deviation of 142.5 (MPa √m), whereas the average surface release energy (GIC) was 153.6 kJ/m2 with a standard deviation of 22.53 kJ/m2. A valuable design equation was extracted from the finite element model to measure the effect of cracks on the hoop stress of the cylinder wall thickness based on a nonlinear model. Moreover, an acceptable equation was used to calculate the correction and shape factor of a cylinder with movable and unmovable through-thickness cracks. This study provides useful tools and guidance for the design and analysis of composite cylinders.

Investigation of Erosion/Corrosion Behavior of GRP under Harsh Operating Conditions

“…In the current study, glass-fiber-reinforced polymer pipes with a heterogeneous structure of random mats, roving, unsaturated polyester resin and sand were used according to the values shown in Figure 1. Additional details are provided in [23,39,40]. Unsaturated polyester resin binds the fibers in the pipe structure and is resistant to chemicals and the environment.…”

“…In the petroleum industry, these pipes are used in chemical waste pipelines. The elastic properties of the composite glass fiber pipes (GRP) are provided in [23,39,40]. The pipes used for this study were in service for a period of time and then removed from their original location.…”

“…This circuit is a closed system. The samples were cut from the wall of a cylinder using a diamond cutter to avoid delamination and damage to the samples, as recommended in papers [15,23,39]. The samples were rectangular in shape with average dimensions of Polymers 2022, 14, 5388 5 of 15 17 × 14 mm 2 .…”

“…An effective method for determining the failure processes of carbon-fiber-reinforced pipes was developed using progressive continuum mechanics and experimental findings. In another study by Abdellah et al [39], analytical and numerical FE models were developed to predict the ring stress and stress intensity factors in cylindrical tubes made with GFRP.…”

A thermal conductivity computation model of the carbon fiber reinforced polymer/aramid fiber reinforced polymer laminate considering the bi‐material composite interfaces

“…For engineering application with different thermal requirements, bi-material fiber reinforced composites show significant advantages in design flexibility of thermal response, such as heating-required deep-sea oil pipeline, [1,2] where good thermal conductivity was necessary in inner wall of the pipeline and good thermal insulation was needed in outer wall.…”