Numerical study of bonded composite patch repair in damaged laminate composites

Azzeddine, Nacira,Benkheira, Ameur,Fekih, Sidi Mohamed,Belhouari, Mohamed Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.2

The present study deals with the repair of composite structures by bonding composite patches. The composite structure is a carbon/epoxy laminate with stacking sequence [45/-45/0/90]S. The damaged zone is simulated by a central crack and repaired by bonding symmetrical composite patches. The repair is carried out using composite patches laminated from the same elemental folds as those of the cracked specimen. Three-dimensional finite element method is used to determine the energy release rate along the front of repaired crack. The effects of the repair technique used single or double patch, the stacking sequence of the cracked composite patch and the adhesive properties were highlighted on the variations of the fracture energy in mode I and mixed mode I + II loading.

Effect of long-term natural aging on the microstructural characteristics of an extruded WE54 alloy

Azzeddine Hiba,Baudin Thierry,Brisset Francois 한국물리학회 2023 Current Applied Physics Vol.54 No.-

The microstructure and the corresponding crystallographic texture of the as-extruded WE54 alloy after natural aging for 11 years at room temperature have been characterized by the Electron backscatter diffraction (EBSD) technique. Before natural aging, the as-extruded WE54 exhibited equiaxed microstructure with a strong splitting basal texture and the presence of second particles along the extrusion direction (ED). Unexpectedly, long-term aging led to the formation of elongated deformed grains along ED having {11-20}<10-10> and {0001}<10-10> orientations with a partial development of fine static recrystallized grains by continuous and discontinuous mechanisms. It is believed that the origin of such grain structure development is the residual stored strain during the extrusion processing and the strain field induced from the solute Nd and Y atoms diffusion through the long-term natural aging. Artificial aging at 400 °C for 60 min demonstrated that the elongated deformed grains disappeared and left behind a heterogeneous recrystallized microstructure with a weak basal texture.

Deep Neural Network-based Inverse Analysis with Application to a Rockfill Dam

Gullnaz Shahzadi,Azzeddine Soulaimani 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1

The availability of significant computational resources has played an essential role in developing advanced numerical models for the design and safety evaluation of complex structures such as rockfill dams. Determining the geomechanical parameters is deemed a crucial but challenging task for effective modelling. The general approach involves using in situ or laboratory tests or experimental relationships from the literature to assess these parameters. These measures, however, do not accurately reflect the actual situation. This paper proposes a data driven approach using deep neural networks and non-deterministic optimization algorithms to identify the soil parameters that will lead to displacements that best approximate the measured data. The methodology is applied to a rockfill dam recently built in Quebec, for which some measurements of inclinometer displacements are available. A finite element model (FEM) of two dimensions generates numerical solutions. A comparative study is performed to account for the heterogeneity of the materials by decomposing the computational domain into subdomains. Subsequently, the inverse analysis uses the surrogate model instead of the full FEM model for rapid computations. A suitable objective function is defined to account for large oscillations in the measurement data. Non-intrusive stochastic optimization algorithms such as Genetic algorithm (GA), Particle Swarm Optimization (PSO), and Differential evolution (DE) are evaluated for the minimization problem. Finally, the case study confirms the capability of the proposed methodology to identify the relevant dam parameters, provide some insights into the performance, and compare three optimization algorithms.

Experimental Investigation of Turbulent Cross-flow in a Staggered Tube Bundle with Wavy Cylinders

Morad Belharizi,Tayeb Yahiaoui,Azzeddine Khorsi,Omar Ladjedel,Lahouari Adjlout,OndřejŠikula 한국유체기계학회 2022 International journal of fluid machinery and syste Vol.15 No.3

This paper presents the results of an investigation on the effects of wavy cylindrical tubes on the turbulent cross-flow in a staggered tube bundle arrangement with transverse and longitudinal pitch-to-diameter ratios of 3.8 and 2.1, respectively. Two models of staggered tube bundles equipped with wavy cylinders are tested; the Model-A having a wavelength ratio ( /Dm= 2) corresponding to a wave steepness (a/ = 0.1) and the Model-B having ( /Dm= 1) corresponding to (a/ = 0.2).Experimental measurements were performed using a subsonic wind tunnel to study and compare the flow characteristics of the new configuration of cylindrical tubes with that of a similar arrangement with smooth cylinders for Reynolds numbers ranging from 0.5 104 to 2 104 based on the mean tube diameter and the free stream velocity. Experimental results show that the circumferential minimum pressure coefficients for wavy tube bundles are greater than at the bundle with smooth cylinders. As a result, the lift forces of wavy tube bundles are suppressed and a significant drag reduction is observed up to 20% for both wavy models. This continuous reduction of the drag force becomes larger with the increase of Reynolds number.

Human IL-32 expression protects mice against a hypervirulent strain of <i>Mycobacterium tuberculosis</i>

Bai, Xiyuan,Shang, Shaobin,Henao-Tamayo, Marcela,Basaraba, Randall J.,Ovrutsky, Alida R.,Matsuda, Jennifer L.,Takeda, Katsuyuki,Chan, Mallory M.,Dakhama, Azzeddine,Kinney, William H.,Trostel, Jessica National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.16

<P><B>Significance</B></P><P>Interleukin-32 (IL-32) is induced by IL-1β, Toll-like receptor agonists, and nucleotide oligomerization domain as well as by <I>Mycobacterium tuberculosis</I> (<I>MTB</I>). Expression of human IL-32γ in the lungs of mice reduced the burden of <I>MTB</I> in both the lungs but also in the spleen and was associated with increased survival. Mechanistically, increased numbers of host-protective innate and adaptive immune cells were present in the IL-32 transgenic mice. Alveolar macrophages from the transgenic mice were also better able to control <I>MTB</I> infection and had increased colocalization of <I>MTB</I> with lysosomes. IL-32 expression was increased in the surgically resected lungs of tuberculosis patients, particularly in macrophages, airway epithelial cells, B cells, and T cells. Thus, IL-32 enhances host immunity against <I>MTB</I>.</P><P>Silencing of interleukin-32 (IL-32) in a differentiated human promonocytic cell line impairs killing of <I>Mycobacterium tuberculosis</I> (<I>MTB</I>) but the role of IL-32 in vivo against <I>MTB</I> remains unknown. To study the effects of IL-32 in vivo, a transgenic mouse was generated in which the human <I>IL-32γ</I> gene is expressed using the surfactant protein C promoter (SPC-IL-32γTg). Wild-type and SPC-IL-32γTg mice were infected with a low-dose aerosol of a hypervirulent strain of <I>MTB</I> (W-Beijing HN878). At 30 and 60 d after infection, the transgenic mice had 66% and 85% fewer <I>MTB</I> in the lungs and 49% and 68% fewer <I>MTB</I> in the spleens, respectively; the transgenic mice also exhibited greater survival. Increased numbers of host-protective innate and adaptive immune cells were present in SPC-IL-32γTg mice, including tumor necrosis factor-alpha (TNFα) positive lung macrophages and dendritic cells, and IFN-gamma (IFNγ) and TNFα positive CD4<SUP>+</SUP> and CD8<SUP>+</SUP> T cells in the lungs and mediastinal lymph nodes. Alveolar macrophages from transgenic mice infected with <I>MTB</I> ex vivo had reduced bacterial burden and increased colocalization of green fluorescent protein-labeled <I>MTB</I> with lysosomes. Furthermore, mouse macrophages made to express IL-32γ but not the splice variant IL-32β were better able to limit <I>MTB</I> growth than macrophages capable of producing both. The lungs of patients with tuberculosis showed increased IL-32 expression, particularly in macrophages of granulomas and airway epithelial cells but also B cells and T cells. We conclude that IL-32γ enhances host immunity to <I>MTB</I>.</P>