Uniaxial time‐dependent ratcheting behavior of bronze powder filled polytetrafluoroethylene at room and high temperature

Abstract

A series of tensile and ratcheting experiments for cold compaction polytetrafluoroethylene (PTFE) and bronze filled PTFE (PTFE/bronze) were conducted with Dynamic Mechanical Analyzer (DMA‐Q800) at room and high temperature (473 K). The effects of peak stress‐holding time, creep, recovery, mean stress history, stress‐rate history, and pretension on the ratcheting behavior of PTFE/bronze were investigated. It is found that longer peak stress‐holding time leads to larger ratcheting strain accumulation. In the meantime, the ratcheting strain accumulates more rapidly at high temperature and the influence of temperature is more obvious than that of the additive fraction of bronze. Creep strain produced during the uploading and the stress‐holding time only partially recovers in the unloading process. Moreover, prior lower stress rate enhances the deformation resistance and restrains the ratcheting of subsequent cycling at higher stress rate. The ratcheting strain in the subsequent cyclic loading at lower mean stress is also restrained by previous cyclic loading at higher mean stress. Finally, the elastic modulus increases and the ratcheting strain is restrained apparently after the pretension. In addition, the elastic modulus and ratcheting strain of the PTFE/bronze with both pretension and recovery are smaller than those with pretension but without recovery. POLYM. ENG. SCI., 54:1571–1578, 2014. © 2013 Society of Plastics Engineers

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

“…7), it is concluded that: (1) the ratcheting of the PC-7030PJ and PC-7020PJ polymers is significantly time-dependent, and the ratcheting strains produced in the load cases with a longer hold-time at peak stress points and at a lower stress rate are larger than those with a shorter hold-time and at a higher stress rate, respectively. The time-dependent ratcheting of PC-7030PJ and PC-7020PJ polymers is similar to that observed for other materials [13,18]. (2) The time-dependent ratcheting of the PC-7030PJ polymer with a larger molecular weight is more remarkable than that of the PC-7020PJ polymer with a smaller molecular weight, as shown in Figs.…”

“…3, it is seen that: (1) apparent ratcheting occurs during the cyclic tests of both the PC-7030PJ and PC-7020PJ polymers. The ratcheting strain increases with the number of cycles in the direction of tensile mean stress, while the ratcheting strain rate decreases rapidly in the first beginning of cyclic loading and a stable ratcheting with a constant ratcheting strain rate is reached after certain cycles, which is similar to that observed in the cyclic tests of other polymer materials [13][14][15][16][17][18].…”

“…Xu et al [13] temperatures, and the effects of peak stress hold-time, mean stress, stress rate, and pretension on the ratcheting were discussed. Li et al [14] studied the uniaxial ratcheting of cerium oxide filled vulcanized natural rubber.…”

Thermal cycling aging effects on the ratcheting behavior of anisotropic conductive film

“…For example, Chen et al investigated the uniaxial ratcheting behavior of PTFE under cyclic compression and constructed a simple constitutive model with stress rate effects (Chen and Hui, 2005;Zhang et al, 2008). Other polymer materials have also been investigated by various authors (Yu et al, 2008;Wang et al, 2010;Shariati et al, 2012;Avanzini, 2008;Liu et al, 2008;Li et al, 2013;Xu et al, 2014). The effect of thermal cycling aging on materials and structures has been adequately documented to improve the stability and reliability of the components Pang et al, 2001;Chiu et al, 2002;Jang et al, 2012).…”