An experimental study on uniaxial ratcheting of polycarbonate polymers with different molecular weights

Experimental Observation on the Pure Torsional Ratchetting of Polycarbonate Polymer at Room Temperature

“…Figure 3(a) illustrates the equivalent shear stress-strain curves obtained in the monotonic torsional tests under the torsional angle-controlled condition and at load rates of 0.1°/s and 2°/s, respectively; the evolution of equivalent shear strain field in the analysis zone of specimen is also provided in the figure for the load case at lower load rate (i.e., 0.1°/s). It is seen in Figure 3(b) that, similar to the monotonic tensile stress-strain curves discussed in [21,22] for other PCs, apparent nonlinear stressstrain response occurs before the macroscopic yielding and the pure torsional deformation behavior of the PC also is rate-dependent; however, the stress-strain responses at yielding point and beyond the yielding (i.e., at the stage of softening) in monotonic torsional tests are different from Advances in Materials Science and Engineering those in the tensile ones. In the monotonic torsional cases (Figure 3(a)), a yielding plateau is observed, and the strain softening after the yielding is not as remarkable as that in the monotonic tensile ones (Figure 3(b)).…”

“…It can be seen that the equivalent shear strain increases quickly at the beginning of creep tests, but its increasing rate (i.e., creep rate) decreases with the creep time; after certain creep times, the creep rate becomes constant, and a stable creep occurs as shown in Figure 4(a). Generally, a higher shear stress results in a larger torsional creep strain, which is similar to the tensile creep of the PCs conducted by Xi et al [21] and Jiang et al [22]. Moreover, Figure 4(a) illustrates that the residual shear strain after the unloading from the creep tests will be partially recovered during the subsequent zero stress hold due to the viscoelasticity of the PC; however, the recovery rate at the first beginning of recovering is much higher than that at the end of recovering.…”

Ratcheting response of nylon fiber reinforced natural rubber/styrene butadiene rubber composites under uniaxial stress cycles: Experimental studies

“…17 Lu et al 12 performed ratcheting tests on polycarbonate polymers and showed great dependency of ratcheting deformation on the loading spectrum. The influence of molecular weight on ratcheting response of polycarbonate polymer samples was further studied by Xi et al 13 Temperature-dependent compressive ratcheting deformation of polytetrafluoroethylene (PTFE) was confirmed by Zheng et al 14 Kang and coworkers 15 examined glass fiber reinforced polyester resin under various asymmetric stress histories with various stress rates and peak stress hold to examine the ratchetting evolution of the continuous and short glass fiber reinforced resin matrix composites. They reported that as glass fiber volume fraction increased, both ratchetting deformation time-dependency response diminished.…”

Ratcheting effect of reinforced graphite sheet with stainless steel insert (RGSWSSI) under cyclic compression at elevated temperature

“…The ratcheting effect is an key index to assess the shakedown behaviour of eigineering structures . Moreover, temperature‐dependent and time‐dependent ratcheting behaviours of nonmetallic material, such as PTFE, polycarbonate polymers, polyacetal, PVDF, PEEK, and nonasbestos fibre, have also been investigated widely. Recently, micromechanisms and macromechanisms of compression and recovery behaviour of flexible graphite have been investigated by Toda et al Results present that the microscopic compression/recovery behaviour of flexible graphite is impacted by the highly localized deformation of thin expanded graphite discs, while its macroscopic deformation is induced by the combined effect of bending and thickness reduction of the discs.…”