Papers by Keyword: PPS

Abstract: Rolling Contact Fatigue (RCF) caused crack propagation, flaking, and wear. We focused on the wear in the present study because in recent years it was found that PPS thrust bearings under the RCF in water caused wear. The RCF test was performed under a thrust load of 2300 N in water to investigate the effect of the number of cycles on surface roughness in detail. We obtained the experimental results that R_a and R_z values decrease with the number of cycles. This means the bottom surface is worn down at the early stage of wear fatigue.

Abstract: Rolling bearings are important mechanical parts. They are used for the transmission of rotational motion. In this study, we focused on surface roughness of the polymer thrust bearing under rolling contact fatigue. Surface roughness of the groove bottom was measured when small pitting around shoulder and crack occurred. Thrust bearings were loaded with thrust loads of 2300 N, 2400 N, 2500 N, and 2600 N. The surface in the rolling contact area was worn during the rolling contact fatigue test. We concluded that surface roughness values ranged from 0.49 μm to 0.18 μm, under thrust loads of 2300 N, 2400 N, 2500 N, and 2600 N when small pitting occurred.

Abstract: In this study, in order to evaluate the progress of internal cracks in PPS thrust bearings under rolling contact fatigue in water, cracks were observed by a full-cross-section observation method using a lathe machining. “Main subsurface crack” initiated at the surface toward the inside, then grew in a direction parallel to the surface. They connected with many “Semi-circular cracks” initiating at the surface from the opposite side to the inside, to from a semi-ellipsoidal flaking damage. It was found that the “Semi-circular cracks” and the “Main subsurface crack” dominated the flaking destruction.

Abstract: In the present study, Rolling Contact Fatigue (RCF) tests of Poly-phenylene-sulfide (PPS) thrust bearings under dry condition were carried out and the relationship between fatigue life of bearings and temperature was studied. Furthermore, in order to investigate maximum temperature of PPS thrust bearings in service, in order to obtain the calibration data, the temperatures of rolling contact element and Infrared (IR) temperature on the side of top race were measured and correlated. It is concluded that the contact temperature of failure PPS bearing was higher than the glass transition point but lower than a melting point of PPS.

Abstract: In this study, crack propagation in PPS thrust bearings under rolling contact fatigue (RCF) in water was observed in order to investigate the relation between cracks and flakings. RCF tests in water under loads of 700 N and 900 N were performed. The semi-circular cracks propagated in a direction perpendicular to the rolling direction were observed under a load of 700 N. The line cracks propagated in a direction parallel to the rolling direction at periphery of contact area and the semi-circular cracks were observed under a load of 900 N. To study the subsurface cracks, full section of rolling contact area was observed. It is concluded that the flaking mechanism in PPS thrust bearing has three features as follows: Initiation and propagation of surface cracks depend on the load; When load is 700N, the semi-circular cracks growing from the surface and the cracks branching from the main subsurface cracks join to form the flaking; When load is 900N the line cracks and the semi-circular cracks growing from the surface join to form the flaking.

Abstract: In this study, crack propagation in PPS thrust bearings under rolling contact fatigue (RCF) in water was observed, and relation between subsurface crack and internal shear stress parallel to the surface was investigated. It was found the cause of flaking was subsurface crack. They were evaluated in terms of contact stress and friction between their faces. It was discovered that subsurface cracks distributed around shear stress peak, and flaking failure was dominated by subsurface shear stress.

Abstract: Model-based quality control has the potential to reduce the reject rate in the production of fiber-reinforced plastics (FRP) components. After all the cross-market establishment of FRP, undesirable quality deviations often occur with new materials or component shapes. The quality control uses the component quality (e.g. component angle, crystallinity, fiber orientation, pore content) as the control variable. As a key component of the control, a process model is developed to link the process parameters (press pressure, press duration and tool temperature) with the quality parameters. Knowledge of the process-determining cause-effect relationships is necessary to ensure that different quality parameters are in the target value at the same time. Based on experimental tests, these interrelationships are determined using methods of statistical test planning and serve as the basis for model-based quality control. As a result, it has been shown that the targeted control of the component angle is possible in a range of about ±1° by using the control parameters, tool temperature and pressure, which have a significant influence on the quality. In the next step, further quality characteristics are included in the control system in order to demonstrate the ability to control the quality of complex component specifications. Model-based quality control is particularly promising for the reduction of the process run-in phase and thus for the reduction of the reject rate.

Abstract: In present work, the influences of TiO₂ nanoparticles addition on the tribological and mechanical behavior of polyphenylene sulfide (PPS) were investigated. The composites samples containing TiO₂ nanoparticles at various percentages (0, 1, 3, and 6 wt. %) were prepared by melt mixing process using single screw extruder at 325 °C and 20 rpm. A pin-on-disc sliding test machine was used for measurement of wear volume and the friction coefficient. The counterface was made of steel carbide with roughness 0.1 μm Ra. The tests were run at a sliding speed of 0.4 m/s and 1 m/s, the contact pressure 0.65 Mpa with different sliding distances (5, 10, 15 and 20 km). Mechanical properties of PPS nanocomposites were studied to evaluate the influence of the nanoparticles addition, as well as examined the relation between the tribological and mechanical behavior. It was found that nanoparticles could further enhance the tribological properties. The lowest wear volume and friction coefficient was observed at 1 m/s was PPS+1wt. %, and for 0.4 m/s was observed in PPS+6wt. %. The results indicate that the mechanical of PPS nanocomposites have been improved, the impact strength and hardness increased with the incorporation of TiO₂ nanoparticles. The density was also increased with TiO₂ nanoparticles.

Abstract: The interlaminar properties of a bond joint of stacked layers in a carbon fibre-reinforced composite with a thermoplastic matrix were evaluated under static loading. The un-precracked tension specimen with an external reinforcing layer was analysed in detail in the area of a bond joint. A detailed finite element method (FEM) analysis was performed to evaluate the influence of the bond joint shape on the interlaminar cohesive forces, which are simulated using the cohesive zone model (CZM). Simple lap and tapered joints were analysed. Continuum and shell elements were utilized in the FEM analysis, and the delamination results obtained using both solutions were compared to each other; however, no significant influence of the bond joint shape on the delamination onset was observed. The FEM analysis was supported using an experimental test on an un-precracked specimen made from prepreg with a carbon fibre fabric and a polyphenylene sulphide (PPS) matrix.

Abstract: Based on their properties, PPS fibers are a promising material for reinforcing elastomeric components that are subjected to high mechanical and thermal loads. The use of this material is at present hindered because of the low adhesion between the fiber and matrix. Atmospheric pressure plasma treatments based on the dielectric barrier discharge were performed on PPS fibers using air as reactive gas for different treatment durations in order to improve the adhesion. The effects of these treatments have been characterized by determining the surface energy, and the residual tensile strength as well as by analyzing the surface chemistry. Required conditions for an improved wetting behavior and a significant increase in the polar component of the surface energy could then be identified.