PSI - Issue 47

A. Khtibari et al. / Procedia Structural Integrity 47 (2023) 855–862 Abderrahim Khtibari et al./ Structural Integrity Procedia 00 (2023) 000–000

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used nowadays is chlorinated polyvinyl chloride (CPVC) Chen et al. (2021). It is product by a post-chlorination process that increases the chlorine content from 57.4 % in PVC to 70 % Liu et al. (2012). This modification is to raise the glass transition temperature Tg of the base resin from 95 °C to the 115–135°C and improves mechanical properties at elevated temperatures Merah et al. (2003). It’s has been widely used of industries aiming at water, wastewater, and gas transportation. The CPVC is a more durable and efficient material than traditional PVC, as it is more resistant to corrosion, higher temperature ratings, and increased pressure ratings Safi et al. (2017). It is also more cost-effective than other materials, such as metal. For this reason, studying the mechanical properties and damage of this material is essential. The knowledge gained from these studies can be used to improve the service life and maintenance of CPVC materials, as well as the safety of their use Yu et al. (2021). Many efforts have been devoted to study the main parameters that affect the mechanical behaviors of the PVC and CPVC. Hitt and Gilbert (1992) have researched the tensile characteristics of PVC (polyvinyl chloride) at around temperatures ranging from 25 to 180 °C. So, it was eventually found that the level of stress at the proper break went down progressively as the temperature went up, whereas elongation at the break clearly revealed a maximum between 80 and 90 °C and also a minimum between 130 and 170°C. This comportment is indicative of the presence of the lattice crystallites, which begins to disintegrate at 90 ◦ C. There is finally enough, lattice breakdown to allow viscous flow to occur. Hussein et al. (2018) are reported that the PVC pipe lost 50 % of its elongation at break within a year to 16 months at Dhahran and more than two years in Florida during outdoor exposure. Merah et al. (2008) studied the impact of the strain rate and the temperature on mechanical properties of CPVC specimens. They found that the Yong’s modulus and yield stress increased as the strain rate increased at different temperatures and decreased as the temperature increased at different strain rates. This paper aims to characterize the mechanical behavior of the chlorinated polyvinyl chloride (CPVC), based on a series tensile test on specimens at 6.10 -4 s -1 strain rates and under a wide range of temperatures (-10, 0, 10, 25, 50, 70, and 90°C). Moreover, two damage models are employed, one of which was generated through static damage and the other is obtained through a modified version of unified theory. Both models are constructed on the stress. The results obtained from these two models, enables us to describe the mechanical behavior and damage evolution of this material. Therefore, we can predict the safety and maintenance intervals for CPVC polymer. Nomenclature β life fraction σ u the ultimate stress σ ur the residual ultimate stress σ a the applied stress T0 lowest temperature Ti instantaneous temperature Tf the highest temperature. γ a loading level D damage Ds static damage m = 0.98 constant for CPVC material 2.Materials and Experimental Methods The samples for the tensile tests were made from 100 mm schedule 80 injection molded couplings that are readily accessible in the market. 50 mm (wide rings) were cut on the sides of the fittings. After that we straightened and slit the rings between metal plates after heating during 60 min at 120 ◦ C in an electric oven. As shown in Fig.1. and Table 1, the samples' size and shape are provided in accordance with ASTM D638 Lin et al. (2004). For these tests, we used an Instron 8501 material testing frame (load capacity ±100 kN). The machine was outfitted with a hydraulically actuated self-aligning gripping system. During the test, specially machined inserts were used to ensure the specimen's vertical alignment. Tree tensile tests were conducted at each of these temperatures. The results of these tests are presented and discussed in the section that follows.