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The mechanical behavior of aluminum alloy under impact loading using different configurations is described. Perforation tests are referred in this work at wide ranges of specimen using several projectile shapes to analyze their effect on the ballistic curve VR -V0 (conical, hemispherical and blunt), with a diameter of 6.mm. A wide range of impact velocities from 40 to 100 m/s has been used. Experimental and numerical analysis have been carried out to predict the mechanical behavior of the studied aluminum alloy. This analysis has been done using a high-pressure gas gun. Specimens have been prepared from standard 1.0 mm and 1.5 mm thick aluminum sheets with 13x13 cm plates. The resistance and the energy absorbed by the aluminum sheets under dynamic load have been obtained by measuring the initial and residual velocities of the projectiles. The experimental and numerical results are presented and compared in terms of ballistic curve VR -V0, and a good correlation is observed between the two types of results.

Composite materials are attracting increasing interest from many industrial sectors, and their use is becoming more widespread. The naval industry, for example, remains a large field of investigation for composite materials due to their mechanical properties, able to reach very interesting performance levels. Composites are often composed of plies arranged according to loading directions and forming structures called laminates; these directions can have a great effect on the structural behavior of the composite. For this, the study carried out in this article, consists in determining orientations and stacking sequences effect on the mechanical performance of a glass/epoxy composite panel, with a thickness of 8 mm containing 12 plies of the same thickness and different orientations, inclined at an angle of 10° and impacting the water at a velocity of V = 8 m/s.

Since carbon nanotubes and carbon fibers were discovered, the number of research works on these composite materials has exploded, and that’s the reason behind using them in this article as reinforcement to improve the mechanical, electrical and thermal behaviors of materials, to enable their use as Nano-sensors in several new applications. This article aims to describe the structure of these materials and their multi-functionality. An analytical estimation of physical properties was presented, using the homogenization technique. Then, a numerical study in Abaqus, to determine thickness and volume fraction effect of CNts on the behavior of composite materials.

Groundwater potential delineation in the Akka basin, southwest Morocco, has been determined through the combination of geospatial techniques and geological data. The geometric average and expected value are two multi-criteria approaches used to integrate a set of factors–data for which the weights of each factor are assigned using the fuzzy logic function, which transforms values of factors influencing groundwater presence in a range of [0, 1]. The efficiency factors used in this study are the lineament density, node density, drainage density, distance from rivers, distance from lineament, permeability, slope, topographic witness index, plan curvature, and profile curvature. Thereafter, the groundwater potential map was generated in a GIS environment. To assess and compare the efficiency of the two models, the well data existing in the basin were used to choose the most efficient model. For that reason, the prediction area (P–A) graph, the normalized density (Nd), and its weight (We) were applied to estimate the capacity of each model to predict the target area. The analysis shows that the expected value model (Nd = 1.86 and We = 0.62) is more efficient than the geometric average model (Nd = 0.96 and We = −0.04). The results of the expected value model can be used in the future planning and management of water resources in the Akka basin.

Ensuring water availability for agriculture and drinking water supply in semi-arid mountainous regions requires control of factors influencing groundwater availability. In most cases, the population draws its water needs from the alluvial aquifers close to villages that are already limited and influenced by current climatic change. In addition, the establishment of deep wells in the hard rock aquifers depletes the aquifer. Hence, understanding the factors influencing water availability is an urgent requirement. The use of geographic information system (GIS), and remote sensing (RS), together with decision-making methods like analytical hierarchy process (AHP) will be of good aid in this regard. In the Tata basin, located in SE Morocco, ten factors were used to explain the groundwater potentiality map (GWPM). Five categories of potential zones were determined: very low (8.67%), low (17.74%), moderate (46.77%), high (19.95%), and very high (6.87%). The efficiency of the AHP model is validated using the ROC curve (receiver operating characteristics) which revealed a good correlation between the high potential groundwater zones and the spatial distribution of high flow wells. Geophysical prospecting, using electrical resistivity profiles, has made it possible to propose new well sites. It corresponds to conductive resistivity zones that coincide with the intersection of hydrogeological lineaments.

The present work describes the mechanical behavior of aluminum alloy under impact loading using different parameters. The work is focused on perforation tests carried out at wide ranges of specimen using three projectile shapes (conical, hemispherical and blunt), with a diameter of 6 and 12 mm. The material used to fabricate the projectile was maraging steel with heat treatment to reach a yield stress of 2.0 GPa. A wide range of impact velocities from 40 to 120 m/s has been used during this study. Experimental, analytical studies have been carried out to analyze in details the perforation process. This analysis has been accomplished using a high pressure gas gun equipped with a thermal chamber. The specimens were prepared from a standard Aluminum sheet of 1.0 mm and 1.5 mm thickness to form 13x13 cm plates. The resistance and the absorbed energy by the aluminum sheet under dynamic loading has been obtained by measuring initial and residual projectile velocities.

Compressed earth blocks (CEB) are a well-established constructional material in the world’s less developed countries. The most common weakness of earthen construction is their high rate of deterioration under water. The aim purpose of this work is to upgrade the behavior of stabilized blocks of earth blocks against water attacks by studying experimentally the properties of the composite that is made from CEB and vegetable wastes in Morocco: Argan nut shell powder (ANS). The water absorption behavior has been estimated for the new bio-composite. The tested natural load contents are: 0%, 2%, 4% and 6%. To examine the effect of chemical stabilization on the new material, dosages of 0%, 5% and 6% of cement was also tested. This work highlights the procedure of soil-stabilization and the contributions of soil’s structure during stabilization. It investigated the quasi-static process of conventional block compaction (slow-applied pressure) and established the effects obtained from the alteration of the components (ANS and cement) and the compaction energy (2 MPa and 4 MPa) on the dry density of CEBs.

Water scarcity affects all continents, with approximately 1.2 billion people living in areas where water is physically lacking. This scarcity is more accentuated in countries with an arid climate, and its impact becomes more threatening when the economy depends mainly on it. The Kingdom of Morocco, with its agricultural vocation, is one of them, especially in its southern regions. Therefore, mapping areas with high groundwater potential based on available geospatial data allows for optimizing the choice of a future well in such areas. Geometric average and fractal models were used to assess and delineate potential groundwater areas in the Tissent basin, Southeast Morocco. Eight factors, including topography, geology, hydrology, and hydrogeology, influencing the distribution of water resources was used. The formation permeability factor presents the most significant impact among the others, although it is directly related to most of them. The areas located in the central and downstream part of the basin are characterized by a high water potentiality due to increased geological formations’ permeability near the drainage system, which constitutes a recharge zone, and a low slope allowing a prolonged water-formation contact time favoring a gradual infiltration of the water towards the deep aquifers. The groundwater potential map has been edited and validated by comparing it with data from 52 wells scattered throughout the basin. The favorable potential sectors cover 15.81% of the basin’s total area. The moderate ones account for 21.36% while the unfavorable areas cover 62.83%. These results aim to provide policymakers and managers with a guide map for groundwater research and reduce hydrogeological investigation costs.

Computational thermodynamic method, such as CALPHAD and the first principle calculation, could be combined and would provide a high throughput thermodynamic investigation method. In the present paper, the thermodynamic properties of the Palladium-Ytterbium binary system were optimized using the CALPHAD approach with the aid of the Thermo-Calc software. The liquid phase and the terminal solid solutions: body-centered cubic for γYb and face-centered cubic for βYb, and (Pd) are described by the substitutional solution model with the exponential (Kaptay model) and linear (Redlich-Kister polynomials) models for the temperature dependence of the excess Gibbs energy. The five intermetallic compounds α-PdYb, β-PdYb, α-Pd5Yb3, β-Pd5Yb3, and Pd3M, which have a homogeneity range, are treated as the phases α-PdM, β-PdM, α-M5Yb3, β-M5Yb3, and Pd3M, respectively, by a two-sublattice model with Yb in M5Yb3 and Pd in PdM and in Pd3M on one sublattice and M on the other, where M is used as an abbreviation for a mixture of Pd and Yb. The other intermetallic compounds, PdYb3, α-Pd2Yb5, β-Pd2Yb5, Pd4Yb3, Pd2Yb, α-Pd21Yb10, β-Pd21Yb10, and Pd7Yb are treated as strict stoichiometric compounds.

International audience; The analysis of the mechanical characteristics and dynamic behavior of fiberglass composite material structure used for perforation tests based on experimental results will be presented. This work is focused on perforation tests carried out at two ranges of temperatures (21 and 60 °C) and high strain rates. By using the specially designed thermal chamber to heat specimens before impact. Based on this experimental series, the ballistic properties of the material impacted by a conical nose shape projectile is studied. The complete energy balance is also reported and the absorbed energy by the composite sheet has been obtained by measuring initial and residual projectile velocities. A wide range of impact velocities from 40 to 123 m/s has been covered during the tests. The projectile has a diameter of 12 mm and the plate has 4 mm thickness. The main objective of this work is to study the behavior of the composite material specimens during the impact. To study the temperature effects, two different temperatures were used material, at room temperature and 60 °C. The time needed to heat the specimen and to stabilize its temperature is 15 min.

International audience; In this paper, perforation experiments were carried out and numerically modelled in order to analyze the response of 2024-T3 aluminum alloy plates under different initial temperatures T0. This alloy has a particular relevance since it is widely used as a structural component in aircrafts, but it is also interesting for other sectors of industry. A gas gun projectile launcher was used to perform impacts within initial velocities V0 from 40 m/s to 120 m/s and at temperatures varying from 293 K to 573 K. A temperature softening of the material was observed which was manifested in the reduction in the ballistic limit by 10% within the temperature range studied. Changes in the material failure mode were also observed at different test conditions. Additionally, a finite element model was developed to predict the material response at high velocities and to confirm the temperature softening that was observed experimentally. An optimization of the failure criterion resulted in a reliable model for such mild aluminum alloys. The results reported here may be used for different applications in the automotive and military sectors.

International audience; A novel single shear specimen (SSS) together with a correction coefficient method is used to study the deformation behavior of a 304 stainless steel under shear loadings. Shear stress-shear strain relations over a wide range of shear strain rates (0.001 to 39000 s−1) at three initial temperatures (77 to 473 K) are obtained experimentally. The effects of strain rate and temperature on the flow stress curves are determined. With increasing strain rate or temperature, the strain hardening rate decreases continuously. At the maximum strain rate of 39000 s−1, negative strain hardening rates are observed. At very high strain rates above 13000 s−1, a sharp increase in flow stress is observed, indicating a rapid rise in strain rate sensitivity. The fracture morphology of post-mortem specimens is analyzed and no well-developed adiabatic shear bands are observed. This may be due to the shear-tension stress state without hydrostatic pressure in the fracture process. Based on the experimentally obtained shear stress-shear strain curves, parameters of a modified Johnson-Cook (MJC) model are determined. A good agreement between experiments and model predictions is found, with an average error of 3.9%. Using finite element analysis, distributions of stress and strain components in the specimen shear zone is analyzed. It is found that the shear stress and shear strain play dominant roles, and a simple shear stress state with low stress triaxiality (0.015) and Lode angle parameter (0.014) is obtained.

The originally performed perforation experiments were extended by compression and tensile dynamic tests reported in this work in order to fully characterize the material tested. Then a numerical model was presented to carry out numerical simulations. The tested material was the common brass alloy. The aim of this numerical study was to observe the behavior of the sample material and to define failure modes under dynamic conditions of impact loading in comparison with the experimental findings. The specimens were rectangular plates perforated within a large range of initial impact velocities V0 from 40 to 120 m/s and in different initial temperatures T0. The temperature range for experiments was T0 = 293 K to 533 K, whereas the numerical analysis covered a wider range of temperatures reaching 923 K. The thermoelasto-viscoplastic behavior of brass alloy was described using the Johnson–Cook constitutive relation. The ductile damage initiation criterion was used with plastic equivalent strain. Both experimental and numerical studies allowed to conclude that the ballistic properties of the structure and the ballistic strength of the sheet plates change with the initial temperature. The results in terms of the ballistic curve VR (residual velocity) versus V0 (initial velocity) showed the temperature effect on the residual kinetic energy and thus on the energy absorbed by the plate. Concerning the failure pattern, the number of petals N was varied depending on the initial impact velocity V0 and initial temperature T0. Preliminary results with regard to temperature increase were recorded. They were obtained using an infrared high-speed camera and were subsequently compared with numerical results.

In fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of a specimen when a critical stress intensity factor is reached. In this paper, stress intensity factors which represents fracture toughness of material, caused by a notch in a volumetric approach has been examined, taking into account the specific conditions of loading by examining various U-notched circular ring specimens, with various geometries and boundary conditions, under a mixed mode I+II. The bend specimens are computed by finite element method (FEM) and the local stress distribution was calculated by the Abaqus/CAE. The results are assessed to determine the evolution of the stress intensity factor of different notches and loading distances from the root of notch. This study shows that the tenacity is not intrinsic to the material for all different geometries notches.

This work aims at characterizing the mechanical behaviour of polymethyl-methacrylate (PMMA) under high velocity impact conditions over a wide range of testing temperatures. To this end, the mechanical response at uniaxial compression is studied for both quasi-static and dynamic conditions covering testing temperatures below, at and above glass transition. A pseudo-brittle to ductile transition in the failure of PMMA is observed at a threshold that depends on testing temperature and strain rate. This analysis allows for the interpretation of the perforation impact tests and to explain the principal deformation and failure mechanisms. To complete the study, the Richeton model to predict yielding is revisited. Finally, we provide a new constitutive model for finite deformations to further identify the deformation mechanisms governing the mechanical behaviour of PMMA and the influence of temperature and strain rate on them. D. Garcia-Gonzalez acknowledges support from the Talent Attraction grant (CM 2018 - 2018-T2/IND-9992) from the Comunidad de Madrid.

International audience; The effect of temperature on perforation behavior of 304 austenitic stainless steel plates was investigated experimentally. Perforation tests have been conducted at velocities from 80 to 180 m/s and temperatures between − 163 and 200 °C. Low temperatures were obtained using a specific designed cooling device and the temperature distribution on the specimens was verified to be uniform. Based on the experimental results, the failure mode, the initial-residual velocity curves, the ballistic limit velocities and the energy absorption capacity under different temperatures were analyzed. It was found that petalling was the main failure mode during the perforation process. The average number of petals was three at 20 °C or 200 °C and was increasing continuously to five at − 163 °C. The ballistic limit velocity Vbl was also affected by the initial temperature. It increased slightly from 93 m/s at 200 °C to 103 m/s at − 20 °C and then remained constant at lower temperatures. The material showed better energy absorption capacity at low temperatures and this came not only from the temperature sensitivity of the material but also from the strain-induced martensitic transformation effect. According to martensite measurement by X-ray diffraction technique, the martensite fractions along the fracture surface of petals were 87.1%, 66.2%, 52.8% and 32.4% respectively for initial temperatures of − 163 °C, − 60 °C, − 20 °C and 20 °C.

In this paper, experimental and numerical results of an aluminum alloy&rsquo, s mechanical behavior are discussed. Over a wide range of strain rates (10&minus, 4 s&minus, 1 &le, έ &le, 103 s&minus, 1) the influence of the loading impact, velocity and temperature on the dynamic response of the material was analyzed. The interface friction effect on the material&rsquo, s dynamic response is examined using a split Hopkinson pressure bar (SHPB) in a high temperature experiment using finite element analysis (FEA). The effect of different friction conditions between the specimen and the transmitted/incident bars in the SHPB system was examined using cylinder bulk specimens and cylinder plates defined with four-layer configurations. The results of these tests alongside the presented numerical simulations allow a better understanding of the phenomenon and reduces (minimizes) errors during compression tests at high and low strain rates with temperatures ranging from 21 to 300 &deg, C.

International audience; Compression test is frequently used to define material behaviour. However, this test may be depending on different effects, for example friction, specimen inertia or local stress triaxiality. For this reason, a new design is proposed to analyse the previous effects and to try to minimize it on quantities measured as macroscopic stress and strain. To have a complete understanding, numerical simulations have been performed using finite element method (Abaqus/Standard and Abaqus/Explicit). It allows one to define the macroscopic behaviour and to have an access to the local values not accessible during experiments for a better understanding of the experimental measurements.

Experimental analysis on standard brass alloy has been carried out using a high pressure gas gun. Perforation tests have been performed for a variety of impact velocities from 40 to 120 m/s in order to study the material behaviour and to define failure modes. The main aim of the study has been to provide results using an innovative thermal chamber that allows to heat specimens before impact. The range of available temperatures is from the room temperature up to 260 ˚C. The experimental study has allowed to discuss the ballistic properties of the structure. The ballistic resistance of sheet plates is strongly dependent on the material behaviour under dynamic loading and changes with temperature. The ballistic properties are also intensely related to interaction between the projectile and thin brass target. The results in terms of the ballistic curve VR (residual velocity) versus V0 (initial velocity) have shown the temperature effect on the residual kinetic energy and thus on the energy absorbed by the plate, revealing a thermal softening of the brass. The ballistic limit corresponding to the maximum impact velocity without complete perforation has decreased by 5-7% for the highest temperature considered. A changing failure pattern is observed. The number of petals varies as a function of impact velocity and temperature. It can be concluded based on experimental observations that thermal softening is a key point on the process of perforation. Preliminary temperature records have been provided using a thermal imaging camera.

The paper describes the mechanical behavior of brass alloy under impact loading. The work is focused on perforation tests carried out at wide range of specimen temperatures. This has been obtained due to application of the specially designed thermal chamber to heat specimens before impact. Based on this experimental series, the ballistic properties of the material impacted by conical nose shape projectile are studied. The experimental investigations have been extended by numerical simulations using a general purpose software Abaqus/Explicit. The phenomenological constitutive relation has been checked coupled with a failure criterion. Finally, good correlation is reached between numerical and experimental results.

Experimental tests were carried out on poly(Methyl Methacrylate) (PMMA) in order to define its mechanical behaviour over a wide range of temperature. To reach high strain rate, perforation tests were performed within a wide range of temperatures using a high-performance oven, from room temperature to 130 °C, above the glass transition temperature Tg. In addition, the results were confronted with compression tests previously obtained. Based on experiments, the temperature transition between fragile and ductile was defined. The material became fully ductile above 118 °C inducing no cracking and debris during the perforation process. The yield stress evolution as function of strain rate for various temperatures was modelled by using the cooperative model. The model predictions were in agreement with experimental data. Two material models developed by Richeton and Nasraoui were analysed, the latter was then implemented into the FE model to simulate perforation tests for a wide range of temperatures and strain rates. It was observed that the coupling strain rate-temperature is a key factor to predict the structure behaviour not only in terms of material behaviour but also in terms of dynamic failure.

The paper describes mechanical behavior of aluminum alloy AW5005 (EN AW5005) un- der impact loading. The work is focused on tensile tests and the process of perforation of aluminum alloy AW5005 sheets. Experimental, analytical and numerical investigations are carried out to analyse in details the perforation process. Based on these approaches, ballistic properties of the structure impacted by a conical nose shape projectile are studied. Different failure criteria are discussed, coupling numerical and experimental analyses for a wide range of strain rates. Optimization method functions are used to identify the parameters of the failure criteria. Finally, good correlation is obtained between the numerical and experimental results for both tension and perforation tests.

The majority of structures contain singularities that cause a high stress concentration on the root of defect which affect the mechanical properties. In this regard, it’s important to take into account that the development process of fracture phenomenon requires a physical volume of elaboration of failure process. The concept of determination of this volume forces us to defineits diameter that called the effective distance. In order to settle this issue, the current paper proposes a new method such as stress triaxiality to define the fracture process zonecaused by aU-notch in a volumetric approach that’s examined under a mixed mode I+II. The bend specimens are computed by finite element method (FEM) and the local stress distribution was calculated by the Abaqus/CAE. The study shows a credibility of the criteria (χ stress gradient and β parameter of triaxiality) to determine the effective distance along the notch. The comparison between the various values shows a good agreement.