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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CPVC material is more likely to occur at higher temperatures due to the increased mobility of the molecules, further reducing the yield stress. The evolution of Yong’s modulus (E) of CPVC with strain rate obtained in the present work for various temperatures is displayed in Fig. 4. The average value of this parameter decreases with the increasing temperatures. We can also observe the existence of three zones on the graph. The first zone is the brittle zone, in which the Young's Modulus is relatively high and the material is still very strong and is easy to be damaged. The second zone is the semi-ductile zone, in this zone the Young's Modulus begins to decrease, indicating that the material is becoming ductile behavior and the brittle behavior. The third zone is the ductile zone, in which the Young's Modulus is very low, indicating that the material is very deformable and can stretch extensively without breaking. This behaviour is due to thermal expansion, which causes the molecules in the CPVC material to vibrate more, leading to an overall decrease in stiffness Abdel-Wahab et al. (2017).

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Fig. 2. Evolution of the stress-strain of Chlorinated Polyvinyl Chloride with various temperature.

3.2. Static damage in accordance with life fraction Damage is a physical process that may be quantified and qualified through the measurement of specific physical properties, most notably mechanical characteristics such as Young's modulus yield stress, and ultimate stress. The static damage concept, which is largely based upon stress, was designed to forecast the evolution of damage. In our case, the objective of this concept is to estimate the evolution of damage to the chlorinated polyvinyl chloride (CVPC) material versus the fraction life. The static damage concept, namely (DS), is presented as the following expression Majid and ELGhorba (2017): 1 σ u Ds= σ a 1 σ u The curve from Fig. 5 depicts the evolution of static damage based on ultimate stress according to life fraction   1 σ ur