Plane strain compression testing of polyoxymethylene at varying strain rates and elevated temperatures

Abstract

In this paper, the behaviour of three grades of polyoxymethylene (POM) in plane strain compression (PSC) has been studied at temperatures ranging from 120 to 160uC and strain rates ranging from 10 23 to 10 21 s 21 in order to provide material property data for modelling solid state orientation processes. All materials showed a similar stress-strain response characterised by an initial short linear viscoelastic region with a rounded yield point followed by an extended plastic regime with an approximately constant positive slope, indicative of linear strain hardening. It was demonstrated that the deformation behaviour of POM is strongly dependent on both temperature and strain rate. In addition, the plastic flow stress was found to be a linear function of the equivalent strain rate, suggesting an Eyring type thermally activated process. Finally, a simplified finite element material model was developed and shown to give good predictions of the PSC test data.

Development of elastic and plastic properties of polyoxymethylene during bending fatigue

“…[1][2][3] Because of the advantageous properties, POM is used extensively in applications ranging from conventional injection-molded or extruded components to microscale devices. [4][5][6][7] Expanding applications have resulted in engineering requirements for greater plastic and viscoelastic property stability over longer product lifetimes. Accordingly, a more complete understanding of the development of mechanical and dynamic properties and degradative phenomena is essential.…”

“…Various researchers have linked polymer mechanical behavior under various macroscale deformation conditions to the mechanisms of molecular motion. [6][7][8][9][10][11] Under low strain, the main mechanism is the movement of the lamellae relative to one another, known as interlamellar sliding. As the strain is increased, the lamellae begin to separate.…”

“…These structures are composed of radially arranged lamellae connected by chain‐entangled amorphous regions. Various researchers have linked polymer mechanical behavior under various macroscale deformation conditions to the mechanisms of molecular motion . Under low strain, the main mechanism is the movement of the lamellae relative to one another, known as interlamellar sliding.…”

“…Polyoxymethylene (POM), a polyacetal resin, is a common engineering thermoplastic with excellent toughness, moldability, and dimensional stability . Because of the advantageous properties, POM is used extensively in applications ranging from conventional injection‐molded or extruded components to microscale devices . Expanding applications have resulted in engineering requirements for greater plastic and viscoelastic property stability over longer product lifetimes.…”