Material modeling and solid phase forming of polycarbonate sheet

Abstract

The Maxwell‐Voigt type mechanical model proposed by Haward and Thackray was further modified to describe the strain rate dependent stress‐strain behavior of polycarbonate under the uniaxial loading condition. Major modifications included effects associated with different hardening components of inelastic resistance and the related temperature dependent material behavior. The modified analytical model was shown to describe some of the important features of the stress‐strain behavior of polycarbonate specimens tested over the range of strain rates and temperatures. Using the stress‐strain relationship as input data; several finite element analyses were made to predict the behavior of polycarbonate sheets under a simple solid phase cup forming process. The computed strain distributions agreed reasonably with the measured values obtained from the gridded polycarbonate sheet that was formed at an elevated temperature. Some of the key assumptions that were used in the analysis are discussed.

Modeling the uniaxial rate and temperature dependent behavior of amorphous and semicrystalline polymers

“…52. The validity of the hourglass technique was first reported by Lee and Luken (5) and subsequently elaborated on by Vest, Amoedo, and Lee (53) by comparing with experimental data reported by Nied and Stokes (54).…”

“…Haward and Thackray (4) proposed a mechanical model using the viscosity theory of Eyring (31) to approximate the behavior of cellulose polymers, with limited success. Lee (5) in a later study modified this model by replacing the more complex Langevin (22) expression with the Rivlin-Mooney rubber elasticity (43,44) element in order to better describe the orientation hardening effects observed in polycarbonate (45). Yeh (46), on the other hand, proposed a folded-chain fringed micellar grain model by considering the solid state be composed of random and ordered regions separated by a grain boundary.…”

“…To model the uniaxial response of both polycarbonate and polypropylene, a simple onedimensional mechanical analog, shown in FYg. 5, is introduced to help explain the different deformation mechanisms that give rise to the polymer deformation behavior.…”

“…eformation behavior of polymers has been the D subject of extensive research over the past three decades (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The majority of these research efforts have relied on experimental techniques in order to understand specific mechanisms of polymer deformation behavior (2,3,(10)(11)(12)(13)(14)(15)(16).…”

Deep drawing self‐reinforced thermoplastic sheet

“…strain curve at the particular conditions of strain rate and temperature of the drawing process is measured experimentally and inserted into Eq 6. Attempts have also been made to model the material properties a priori (22). Equation 6 is valid for materials with planar isotropy but may be extended to represent materials with normal anisotropy by suitably modifying the material yield criterion.…”