The Stress Triaxiality Effect under Large Plastic Deformation of a Polybutylene Terephthalate (PBT)

Abstract

In this work, we focus on a new generation of polymer named Polybutylene terephthalate (PBT). In order to analyse and determine true behaviour of this polymer, a special experimental method was used. Hence, the true stress/strain responses are investigated under a large plastic deformation in different stress triaxiality frameworks with a particular attention on the volumetric strain evolution, with their decomposition to an elastic volumetric strain, plastic volumetric strain and the pure shear. Moreover, the effect of stress triaxiality on the plastic instability and the fracture strain is also examined. With the plastic instability analysis, it was found that plastic strain hardening increases gradually with the triaxiality. Finally, in order to evaluate the damage of this polymer, a theoretical damage formula is proposed.

Thermal Effect of Bobbin Tool Friction Stir Welding on the Mechanical Behavior of High Density Polyethylene Sheets: Experimental Study

“…Various experimental and numerical techniques were developed to measure the different mechanical properties, the stress intensity factor, the J-integral, and the CTOD (Crack Tip Opening Displacement) to determine the strength of the materials welded joint [8][9][10][11]. Generally, during the shaping process of solid materials, the phenomena of plastic instability often control the appearance and performance of the finished product [12][13][14][15][16]. It is therefore essential to understand the mechanisms of plastic instability in order to know how to control its comportment .The stresses' triaxiality effect on several cases of polymers such as PBT (polybutylene terephthalate), PVC (polyvinyl chloride), TPC (thermoplastic copolyetherester) and PEHD (high-density polyethylene) under high plastic stress have been studied by these authors.…”

Effect of Tool Design on the Mechanical Properties of Bobbin Friction Stir Welded High-Density Polyethylene Sheets: Experimental Study

“…The failure behavior of HDPE pipes is related to the loading conditions, the shape and the position of the crack in the pipe wall. Generally, during the shaping process of solid materials, the phenomena of plastic instability often control the appearance and performance of the finished product [6][7][8][9]. Moulay Ali et al [6], Khellafi et al [7] and Zaim et al [8,9] have studied the stresses triaxiality effect on several cases of polymers such as PVC (polyvinyl chloride), PBT (polybutylene terephthalate) and TPC (thermoplastic copolyetherester) under high plastic stress.…”