Composites with different levels of hydroxyapatite (HA) content and ultra-high molecular weight polyethylene (UHMWPE) were prepared in this work. Mechanical properties of the composites were examined here, and to evaluate the effect of HA particles on the time-dependent behavior of the pure matrix, the creep and recovery performance of composites at various stress levels were also researched. As expected, the addition of HA influenced the time-dependent response of the UHMWPE and the effect had a strong dependence on the HA content. The creep and recovery strain of the composites significantly decreased with increasing HA content, and tensile properties were also impaired, which was due to the concentration of HA fillers. The mechanism and effect of HA dispersed into the UHMWPE matrix were examined by scanning electron microscopy. Additionally, since variations in the adjusted parameters revealed the impact of HA on the creep behavior of the UHMWPE matrix, Findley’s model was employed. The results indicated that the analytical model was accurate for the prediction of creep of the pure matrix and its composites.

•Pseudoelastic behavior occurred due to cyclic loading-unloading.•The apparent elastic modulus and anelastic strain nonlinear varied with the stress or strain.•Mechanical properties of Mg ZEK 100 significantly deteriorated after precorrosion.Magnesium alloys, which possess excellent mechanical properties and unique biocompatibility and biodegradability, are newly developed as load-bearing orthopedic implant biomaterials. This paper focuses on the pseudoelasticity of Mg ZEK100 alloy under cyclic tensile loading–unloading at a fixed cyclically incremental strain as well as the effect of precorrosion times on the mechanical response of the material. The results show that under cyclic loading–unloading, Mg ZEK100 alloy exhibits an obvious pseudoelastic behavior. The effect of increasing stress or plastic strain on the apparent elastic modulus and anelastic strain is nonlinear and nonmonotonic. After corrosion, the mechanical properties deteriorate significantly.

•The fatigue life and electrical property of COG assembly undergoing coupled loads were studied.•Different salt-spray corrosion time seriously influences the relative resistance change.•Fatigue life decreases with corrosion time under the coupled loads.•Miner's linear damage rules was used to define damage caused by salt-spray corrosion.It is well-known that chip-on-glass (COG) assembly working in the coastal areas is often subjected to the coupled effects of salt-spray corrosion, electrical current and cyclic mechanical loading in service. Therefore, the fatigue life and electrical property of COG assembly undergoing the coupled loads of salt-spray corrosion, electrical current and cyclic mechanical loading have been studied in the present work. It is found that the relative resistance of COG assembly increases with the increase of salt-spray corrosion time. Moreover, the salt-spray corrosion time has a great influence on the resistance variation during the fatigue process. Simultaneously, the fatigue life of the COG assembly decreases with the increasing corrosion time. Finally, Miner's linear damage rules could be used to define the damage of COG assembly caused by the salt-spray corrosion.

This work reports the uniaxial ratcheting and fatigue behavior of a duplex Mg-Li-Al alloy under the influence of phosphate-buffered solution corrosion. Microstructural observations reveal pitting and filament corrosion defects, which impair the load-bearing capacity of the alloy and cause stress concentration, thus leading to an accelerated accumulation of ratcheting strain and shortened fatigue life under the same nominal loading conditions. Comparing Smith model, Smith-Watson-Topper model, and Paul-Sivaprasad-Dhar model, a ratcheting fatigue life prediction model based on the Broberg damage rule and the Paul-Sivaprasad-Dhar model was proposed, and the model yielded a superior prediction for the studied magnesium alloy.

•The coupling loads of temperature–electric–hygrothermal stress for COG assembly were built.•Different hygrothermal aging time seriously influences the relative resistance change.•Fatigue life decreases with aging time under loads of temperature–electric–hygrothermal stress.•The relation of hygrothermal aging time and the damage factor was obtained.The present work deals with studying fatigue life and electrical properties of chip-on-glass (COG) assemblies undergoing the coupling loads of temperature, electrical current and hygrothermal stress by shear fatigue tests. Firstly, as the COG assemblies are exposed in hygrothermal environment, an increased hygrothermal aging time leads to an increased relative resistance of COG assemblies. Secondly, during the fatigue experiments, the fatigue life of COG assemblies decreases with an increase of hygrothermal aging time. The change of relative resistance displays different trends under different aging degrees. When the hygrothermal aging time is less than 96 h, the relative resistance increases rapidly in the initial stage, then the rate of rise decreases subsequently, and finally the relative resistance falls to a stable value suddenly. By contrast, the relative resistance of COG assemblies having more than 168 h hygrothermal aging increases rapidly with increasing fatigue cycles. Owing to the effects of hygrothermal aging and fatigue on the change of assemblies’ resistance, the total of relative resistance increases with increasing hygrothermal aging time. Finally, the hygrothermal aging damage defined as life reduction after degradation aggravates exponentially with aging time on the basis of the Miner’s linear damage rule. The fatigue life prediction model based on the Miner’s linear damage rule and the Basquin’s equation is proposed and yielded to good prediction for the COG assemblies undergoing hygrothermal aging.

A series of uniaxial ratcheting experiments on anisotropic conductive adhesive film (ACF) were conducted under stress-control at elevated temperature using a DMA-Q800. The ratcheting behavior of ACF specimens with different hygrothermal aging times was investigated at room temperature and 120 °C. The effects of loading rate, mean stress and stress amplitude on the ratcheting behavior of unaged and aged specimens were compared. The results show that the ratcheting strains of aged specimens are smaller than those of unaged specimens under the same experimental conditions. The cycling stability of aged specimens is increased by hygrothermal aging. At room temperature, with the increase of aging time, the ratcheting strains of aged specimens increase with hygrothermal aging time when it is less than or equal to 96 h but, however, decrease when it exceeds 96 h. At 120 °C the ratcheting strains of ACF only decrease with the increase of hygrothermal aging time. Additionally, the effects of loading rate, mean stress and stress amplitude on the ratcheting behavior of unaged and aged ACF are different and their effects are weakened by hygrothermal aging.

A series of tensile and ratcheting experiments for compacted polytetrafluoroethylene (PTFE) and bronze filled PTFE (PTFE/bronze) were conducted on dynamic mechanical analyzer (DMA-Q800). The effects of mean stress, stress amplitude and temperature on the ratcheting behaviors of PTFE and PTFE/bronze were investigated. It is found that the stress-strain response of PTFE/bronze is nonlinear and its elastic modulus is higher than that of pure PTFE. For uniaxial ratcheting test, the dissipation strain energy density (DSED) decreases rapidly in the first 10 cycles and approaches a constant after 20 cycles. The ratcheting strain and the DSED corresponding to 100 cycles increase with increasing mean stress, stress amplitude and temperature. Additionally, the DSED and ratcheting strain of PTFE/bronze are much lower than those of pure PTFE under the same experimental conditions. It is also found that both pure PTFE and PTFE/bronze present cyclic hardening characteristics. Above all, the addition of bronze can improve both the uniaxial tensile property and the cyclic property of PTFE.

A series of uniaxial ratcheting experiments on anisotropic conductive adhesive films (ACFs) were conducted under stress-control at elevated temperature using DMA (DMA-Q800). The effects of mean stress, stress amplitude, applied temperature and loading history on the uniaxial ratcheting behavior of ACF were investigated. The results show that Young’s modulus of the ACF declines rapidly with increasing temperature. The ratcheting strain increases as the mean stress, stress amplitude and temperature increased. Especially, when the temperature was over 80 °C, the ratcheting strain accumulated rapidly. There are significant differences in the uniaxial ratcheting behavior of ACF at 80 °C and 120 °C. The ratcheting strain rate at 120 °C is nearly twenty times that at 80 °C. The ratcheting strain decreases with increasing stress rate. Furthermore, the loading history also plays an important role in the progress of ratcheting. Previous cycling with higher stress amplitude greatly reduces ratcheting strain of subsequent cycling at lower stresses.