•Lubricated and dry sliding tests were conducted on AA5083/AISI-52100 material pair.•The effect of initial surface topography on the wear and friction behavior was discussed.•RS approach was applied ...to correlate crater area, cycle number and mean absolute profile slope.•The formation of BUL improve contact condition and provokes transition in wear mechanisms.•Analysis of crater area contributes for controlling friction and wear when sliding dry.
This paper discusses the effect of surface topography and lubrication on the tribological behavior of AA5083 alloy for wide range of average roughness, Ra. Reciprocating sliding tests were conducted under lubricated and dry regimes over different pre-textured surfaces using AISI-52100 steel ball under two contact pressures. Scanning Electron Microscope (SEM) and profilometer were employed for characterizing wear land and type. Particularly, the effect of the mean absolute profile slope Δa of AA5083 plates on friction and wear was investigated within an early repetitive sliding stage. Experimental results show that a close correlation was found between the tribological behavior and the mean absolute slope, Δa, contrary to the average roughness, Ra, which shows a partial link. From SEM inspections, dry sliding correlates with the generation of ploughing over aluminum topographies, and with the formation of Built-Up Layer (BUL) due to adhesion over steel ball. However, lubrication, transforms material removal process over the ball from adhesion to abrasion which affects inevitably the initial topography. The evolution of crater area S − reflects high sensitivity to Δa. In order to predict the wear evolution, a mathematical model taking into account the impact of Δa and the number of sliding cycles (N) was developed using Response Surface Method (RSM).
Predicted crater area vs. the number of cycles and mean absolute profile slope obtained using RS approach. (a) Smooth, and, (b) rough surfaces at dry conditions, and, (c) Smooth, and, (d) rough surfaces at lubricated conditions. Display omitted
In this study, the micromechanical scratch behavior of unidirectional glass fiber reinforced polyester (GFRP) using several wear conditions was highlighted. Single-indenter scratch tests (SSTs) were ...carried out on GFRP composite material perpendicular (SST
) and parallel (SST
) to fiber direction. Damage modes dominating the material removal process (MRP) and friction exhibit significant sensitivity to both attack angle and normal load. From findings, damage modes and apparent friction coefficient substantially accentuate when increasing the attack angle. The inspections of the damage state at different testing conditions using a scanning electron microscope (SEM) reveal the dominating modes governing the MRP through the different phases. The response surface methodology (RSM) was adopted to develop a mathematical model based on the measured data. The RSM approach was found very promoting for predicting friction evolution versus attack angle and normal load. The proposed model reveals good ability not only in predicting apparent friction coefficient but also in detecting separately its ploughing and adhesive component. To emphasize the correlation between friction coefficient and MRP, the wear maps have been drawn up.
This study investigates the tribological behavior of talc-filled polypropylene (PP-talc) via reciprocating sliding tests. These tests are realized in dry conditions and at room temperature. The ...cyclic sliding tests were realized using a spherical steel slider with a speed of 30 mm/s under the normal load of 10 N and along a distance of 15 mm. The maximal number of cycles was 15000. Four proportions of talc were utilized: 0 % (neat PP), 5 %, 10 %, and 50 %. Both friction coefficient (COF) and wear rate (Wr) were determined and discussed as a function of talc proportions and the number of sliding cycles. Furthermore, these findings were discussed regarding the induced damage patterns examined via Scanning Electronic Microscopy (SEM). The findings show that the low talc proportion, less than 10 %, leads to lower and stabilized COF with nearly the same value and also to a lower wear rate, Wr, relative to the high talc proportion. The COF evolution during the friction was generally occasioned by the stick-slip phenomenon, which is accentuated by the talc proportion. Nevertheless, noticeable high values of these tribological parameters were obtained when using a high talc proportion of 50 %. The SEM analyses of the worn surface after 15000 cycles revealed different damage forms: material displacement, chip formation, rolls, and delamination wear. The formation and displacement of chips within the groove are accentuated by increasing the talc proportion.
Display omitted
Unsuitable surface quality is frequently observed in the machining of composites due to their heterogeneity and anisotropic properties. Thus, minimizing the machining damages requires a thorough ...understanding of the machining process. In this study, two different finite element models were developed using Abaqus/Explicit to simulate the cutting process of unidirectional carbon fiber-reinforced polymer: (i) a macromechanical model based on the homogenization approach and (ii) a micromechanical model in which the composite constituents were treated separately. The effects of CFRP mechanical properties, the energy of breaking and hourglass control were analyzed using a macromechanical model. The results revealed that CFRP properties and the numerical parameters highly influenced the cutting process. A comparative study was also performed between the macromechanical and the micromechanical models to study the mechanisms of chip formation. It was demonstrated that the material removal mechanisms for both models are in good agreement with the experimental observations for different fiber orientation angles.
Tribological behavior of five different surfaces patterns, bioinspired from maize leaf skin, shark skin, snakeskin, pitcher’s structure and lizard skin, was investigated. Bioinspired surfaces have ...been printed using Fused Deposition Modelling (FDM) technology from a marked Poly Lactic Acid (PLA). Tribological tests were carried out using a reciprocating sliding device under dry conditions at room temperature. Particular interest was given to the investigation of the friction anisotropy as well as the wear mechanisms. The correlation between the apparent friction coefficient and the test conditions, particularly, the 3D printed bioinspired surface patterns and the number of cycles, was emphasized via the friction maps.
Drilling is the most widely used machining process in manufacturing holes in many industrial applications. Optimizing the drilling process is a key to improve the hole quality. Therefore, numerical ...modeling is an effective method that gives an idea about the cutting process to optimize the drilling parameters. This paper emphasizes the sensitivity of the thrust force, the torque and the machining-induced damage to the hole saw tool geometry using a 3D Finite Element (FE) model developed using ABAQUS/Explicit. A Johnson cook model associated with a ductile damage law is used to predict the failure mechanism of a random chopped glass fiber reinforced polyester. It is found that the thrust force, the torque and the damage around the hole obtained from the FE model are in good agreement with the experimental data. Differences of about 2% for the thrust force, 2.4% for the torque and 3% for the damage around the hole are observed. The results of the numerical model also indicated that the thrust force as well as the drilled workpiece quality are improved by choosing the suitable rake angle. A decrease of about 61% in the thrust force is observed when varying the rake angle from 0° to 20°. However, the latter has an insignificant effect on the thrust force. Furthermore, it can be concluded that this parameter highly influences the material removal process.
Short glass fiber composites, particularly sheet molding compound (SMC) materials, are becoming increasingly important alternative in various contemporary aerospace, automotive, and electronic ...applications. For these manufacturing industries, the quality of the machined SMC composite is still a challenging target. The article proposes a new tool design with an offset between teeth to minimize friction, limit damage and promote chip removal when drilling composite materials. The effects of the tool's geometric parameters, especially the rake, the inclination and the complementary side cutting edge angles on the material removal process, as well as the cutting and thrust forces, are investigated. A 3D finite element model of a representative multi-tooth tool is developed using the ABAQUS\Explicit code. The results show that fine-tuning the geometric parameters of the tool reduces the induced machining damage and enhances the chip removal and the flow evolution. The rake angle has a significant influence on the cutting and thrust forces. However, both forces are insensitive to the inclination angle. The complementary side cutting edge angle influences only the thrust force. The presented outcomes not only give insights into the cutting process, but also improve the SMC machinability.
In the interest of developing a comprehensive understanding of the drilling process using the hole saw tool, this article aims to build a three-dimensional (3D) micromechanical model representing the ...orthogonal cutting of CFRP using one tooth of the hole saw tool. For this purpose, a finite element model is developed using Abaqus Explicit code. The influence of various drilling parameters like rake angle, inclination angle and cutting-edge radius on the drilling quality is explored. Especially, chip formation mechanisms, cutting force and lateral damage are analyzed. Through finite element simulations and computational analyses, it is found that these outputs results are highly influenced by drilling parameters. When the fiber orientation angle is set to 0°, increasing the rake angle results in a change in the chip formation mechanism from buckling to bending. In contrast, with a fiber orientation angle of 90°, bending and shear governs the chip formation process, irrespective of the rake angle. In both cases, whether the fiber orientation angle is 0° or 90°, chips tend to fragment more favorably with increasing the inclination angle. Regarding the cutting-edge radius, when the fiber orientation angle is 0°, an increase in the cutting-edge radius leads to a transition in the chip-forming mechanism from buckling to bending. However, for a fiber orientation angle of 90°, the chip formation remains governed by bending even as the cutting-edge radius changes. Decreasing the rake angle, the inclination angle, and the cutting-edge radius contribute to a reduction of the cutting force. As the inclination angle and the cutting-edge radius increase, the lateral damage increases, while the rake angle has showed a negligible impact on the damage. These results provide a guidance on the appropriate hole saw tool parameters for a good drilling quality namely, a rake angle of 20°, an inclination angle of 5° and a cutting-edge radius of 0.03 mm.
This attempt proposes a Finite Element Approach (FEA) to investigate the tribological behavior of glass fiber reinforced polyester composite. The 3D finite element model was developed upon ...ABAQUS/Explicit. The Johnson-Cook criteria were considered for describing the material behavior and damage of both fiber and matrix phases. The fiber/matrix interface behavior was, however, modeled using a thin cohesive zone (CZ). A mixed-mode loading concept was specially adopted to predict delamination propagation within the interface. The prevailing wear mechanisms owing to Multi-Scratch Test (MST) were inspected at variable load and attack angle, using scanning electron microscope (SEM). Wear maps were built to highlight the correlation between friction coefficient and wear mechanisms. Predictions of both elementary and interacting mechanisms showed excellent correlation with observations. It was revealed that material removal process varies sensitively with the dominating failure mode. The proposed approach exhibits good ability not only in predicting active mechanisms but also in detecting damage sequences governing the surface integrity during scratching.
