This paper aims at investigating the production of high quality briquettes from olive mill solid waste (OMSW) mixed with corn starch as a binder for energy production. For this purpose, different ...mass percentages of OMSW and binder were considered; 100%-0%, 90%-10%, 85%-15%, and 70%-30%, respectively. The briquetting process of the raw mixtures was carried out based on high pressures. Physico-chemical and mechanical characterizations were performed in order to select the best conditions for the briquettes production. It was observed that during the densification process, the optimal applied pressure increases notably the unit density, the bulk density, and the compressive strength. Mechanical characterization shows that the prepared sample with 15% of corn starch shows the best mechanical properties. Moreover, the corn starch binder affects quietly the high heating value (HHV) which increases from 16.36 MJ/Kg for the 100%-0% sample to 16.92 MJ/Kg for the 85%-15% sample. In addition, the kinetic study shows that the binder agent does not affect negatively the thermal degradation of the briquettes. Finally, the briquettes characterization shows that the studied samples with particles size less than 100 μm and blended with 15% of corn starch binder are promising biofuels either for household or industrial plants use.
•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.
•The fatigue life behaviour of one component polyurethane adhesive was investigated.•Normalized tests are used to determine the S–N curves.•Fracture mechanisms scenarios are proposed and correlated ...with the fracture fatigue life of specimens.
Over the years, using adhesive joints in structural applications widespread all industrial domain, achieving an amazing current usage. This is due to the benefits that this technology is capable of providing to complex-shaped structures, both in aerospace and automotive applications. Indeed, new polyurethane adhesives are a recently fastening method. This newest adhesive types bid great advantages especially on damping, impact and fatigue which are critical characteristics in the transportation industry. Besides, the current bus manufactures use this adhesive kind to join doors' structures aluminium assembly. As like, the Tunisian automotive industry ICAR uses a one-component polyurethane for doors' structure assembly. Crack problems due to fatigue are evident in those areas since they are continuously stressed. Thereby, working on more understanding polyurethane fatigue performance we investigate over this work, the response of the assembly aluminium-alloy polyurethane adhesive joints using SLJ with two design's parameters sorted from a static study under five distinct load levels. To achieve this purpose, substrates' surfaces roughness with an arithmetic average of surface heights Ra ≈ 0.6 µm, was used. Bonded specimens with 1 mm adhesive thicknesses were manufactured and examined using cyclic fatigue testing. Furthermore, the obtained results are also compared with others from literature using epoxy adhesives. Worthy results are obtained rising the effectiveness of this adhesive's type in the transport industry.
In the past, several experimental and analytical studies have been conducted aimed towards predicting the critical thrust force responsible for delamination at the hole exit during drilling. Among ...these analytical models, few take into account the coupling between bending and stretching often observed in multi-directional (MD) laminates with an un-symmetrical stacking sequence considering the presence of an elliptical crack. In addition, in these analytical models, the tool/composite contact region is modeled without taking into account the chisel edge effect. In the present study, a unique analytical model for critical thrust force prediction has been proposed that explicitly accounts for the effect of the chisel and cutting edges. The interaction zone (composite/chisel edge and composite/principal cutting edge) has been modeled using classical lamination plate theory (CLPT) and linear elastic fracture mechanics (LEFM) principles. In addition, a comparison between the proposed analytical model predictions and experimental results from quasi-static punch tests accompanied with different X-ray tomography observations led to choosing the accurate loading profile developed during drilling.
Hard body Armors are often deployed in ballistic applications to enhance resistance to Armor Piercing projectiles (AP). The main challenge for body armor designers is to find a best compromise ...between strength and weight to ensure a given level of protection. This paper investigates the effect of layer arrangement order, ceramic layer thickness, composite backing layer thickness and impact velocity on body armor performance using a numerical experimental design. In addition, the influence of bullet diameter on target damage and bullet erosion is examined. A finite element model (FEM) is evolved through Abaqus explicit software to simulate the ballistic impact of an ogival‐nosed projectile against body armor composed of a ceramic forward layer and a composite rear layer. The results revealed that the layout of the ceramic layer on the front side, that is, directly in contact with the projectile, and the composite layer on the rear side provides better ballistic performance than the opposite case. Furthermore, it is found that the thickness of ceramic and composite plates has a considerable impact on the ballistic performance of body armor. The ceramic thickness has a greater influence on the residual velocity than the composite one. Moreover, the full penetration and nonpenetration zones of the projectile have been highlighted according to the thicknesses of the ceramic and composite layers and using two impact velocities.
Highlights
Development of a numerical model simulating ballistic impact.
Study the ceramic and composite thicknesses effect on ballistic performance.
Analysis of target and projectile damage as a function of projectile diameter.
Identification of full penetration and nonpenetration zones of the projectile.
Effect of target thickness on ballistic performance based on numerical modeling
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.
Surface treatment before adhesive bonding is vital for improving both strength and durability of adhesively bonded joints by modifying surface characteristics. This article reviews the effect of ...surface texture on the strength of adhesive-bonded joints. It starts with a presentation of different adhesion mechanisms. Afterwards, the surface texture is classified into stochastic and structured surfaces, the effect of these textures on the wettability is then discussed. The influence of surface texture on quasi-static strength and fatigue behaviour of adhesively bonded joints is reviewed with a focus on the effect of structured surface parameters. This paper provides also an overview of the manufacturing process of structured surface texture for adhesive bonding applications. Finally, future trends in this research direction are highlighted and fundamental conclusions are drawn.
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.
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