European Journal of Mechanics - A/Solids

A method coupling experiments and simulations, is developed to characterize the yield stress and strain hardening of several metals loaded at 106 s−1 and < 25 ns, typically involved during Laser Shock Peening. It was applied to four materials: pure aluminum, 2024-T3 and 7175-T7351 aluminum alloys and Ti6Al4V-ELI titanium alloy. Thin foils have been irradiated with high-power laser to induce high-pressure shock wave. Plastic deformation is activated through the thickness up to the rear free-surface of the foils. These experiments have been simulated using three material constitutive equations: Elastic–Perfectly Plastic model considering static yield stress, Johnson–Cook model without strain hardening and Johnson–Cook model with strain hardening. The material parameters of Johnson–Cook law were identified by comparison of the experimental and calculated velocity profiles of the rear-free surface. Results are shown and discussed

Contrasting Effects of Laser Shock Peening on Austenite and Martensite Phase Distribution and Hardness of Nitinol

Laser shock peening of cold rolled Nitinol was carried out at high power density (7 and 9 GW/cm2) and high overlap ratio (90%). Tensile surface residual stresses were generated in the peened material. An enhancement in surface microhardness from 351 for unpeened material to 375 and 394 VHN for the 7 and 9 GW/cm2 samples, respectively, was also observed. However, at a depth of 50 &mu;m, the hardness of the peened material was lower than that of the as-received material. These contrasting observations were attributed to the change in the austenitic phase fraction brought about by laser interactions

Contrasting Effects of Laser Shock Peening on Austenite and Martensite Phase Distribution and Hardness of Nitinol

Laser shock peening of cold rolled Nitinol was carried out at high power density (7 and 9 GW/cm2) and high overlap ratio (90%). Tensile surface residual stresses were generated in the peened material. An enhancement in surface microhardness from 351 for unpeened material to 375 and 394 VHN for the 7 and 9 GW/cm2 samples, respectively, was also observed. However, at a depth of 50 μm, the hardness of the peened material was lower than that of the as-received material. These contrasting observations were attributed to the change in the austenitic phase fraction brought about by laser interactions

Sustainable Environmental-Based ZnO Nanoparticles Derived from <i>Pisonia grandis</i> for Future Biological and Environmental Applications

The bio-synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Pisonia grandis is discussed in this work as an effective ecologically beneficial and straightforward method. This strategy intends to increase ZnO nanoparticle usage in the biomedical and environmental sectors, while reducing the particle of hazardous chemicals in nanoparticle synthesis. In the current study, bio-augmented zinc oxide nanomaterials (ZnO-NPs) were fabricated from Pisonia grandis aqueous leaf extracts. Different methods were used to analyze the ZnO-nanoparticles including X-ray diffraction (XRD), Fourier Transforms Infrared (FT-IR), Ultraviolet (UV) spectroscopy, and Field Emission Scanning Electron Microscopy (FE-SEM) with EDX. The synthesized nanoparticles as spheres were verified by FE-SEM analysis; XRD measurements showed that the particle flakes had an average size of 30.32 nm and were very pure. FT-IR analysis was used to validate the functional moieties in charge of capping and stabilizing ZnO nanoparticles. The antimicrobial, cytotoxic, and photodegradation properties of synthesized nanoparticles were assessed using well diffusion, MTT, and UV visible irradiation techniques. The bio-fabricated nanoparticles were proven to be outstanding cytotoxic and antimicrobial nanomaterials. As a result of the employment of biosynthesized ZnO nanoparticles as photocatalytic agents, 89.2% of the methylene blue dye was degraded in 140 min. ZnO nanoparticles produced from P. grandis can serve as promising substrates in biomedicine and applications of environmental relevance due to their eco-friendliness, nontoxic behavior, and cytocompatibility

Sustainable Environmental-Based ZnO Nanoparticles Derived from Pisonia grandis for Future Biological and Environmental Applications

The bio-synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Pisonia grandis is discussed in this work as an effective ecologically beneficial and straightforward method. This strategy intends to increase ZnO nanoparticle usage in the biomedical and environmental sectors, while reducing the particle of hazardous chemicals in nanoparticle synthesis. In the current study, bio-augmented zinc oxide nanomaterials (ZnO-NPs) were fabricated from Pisonia grandis aqueous leaf extracts. Different methods were used to analyze the ZnO-nanoparticles including X-ray diffraction (XRD), Fourier Transforms Infrared (FT-IR), Ultraviolet (UV) spectroscopy, and Field Emission Scanning Electron Microscopy (FE-SEM) with EDX. The synthesized nanoparticles as spheres were verified by FE-SEM analysis; XRD measurements showed that the particle flakes had an average size of 30.32 nm and were very pure. FT-IR analysis was used to validate the functional moieties in charge of capping and stabilizing ZnO nanoparticles. The antimicrobial, cytotoxic, and photodegradation properties of synthesized nanoparticles were assessed using well diffusion, MTT, and UV visible irradiation techniques. The bio-fabricated nanoparticles were proven to be outstanding cytotoxic and antimicrobial nanomaterials. As a result of the employment of biosynthesized ZnO nanoparticles as photocatalytic agents, 89.2% of the methylene blue dye was degraded in 140 min. ZnO nanoparticles produced from P. grandis can serve as promising substrates in biomedicine and applications of environmental relevance due to their eco-friendliness, nontoxic behavior, and cytocompatibility

Identification of constitutive equations at very high strain rates using shock wave produced by laser

A method coupling experiments and simulations, is developed to characterize the yield stress and strain hardening of several metals loaded at 10⁶ s−ⁱ and < 25 ns, typically involved during Laser Shock Peening. It was applied to four materials: pure aluminum, 2024-T3 and 7175-T7351 aluminum alloys and Ti6Al4V-ELI titanium alloy. Thin foils have been irradiated with high-power laser to induce high-pressure shock wave. Plastic deformation is activated through the thickness up to the rear free-surface of the foils. These experiments have been simulated using three material constitutive equations: Elastic–Perfectly Plastic model considering static yield stress, Johnson–Cook model without strain hardening and Johnson–Cook model with strain hardening. The material parameters of Johnson–Cook law were identified by comparison of the experimental and calculated velocity profiles of the rear-free surface. Results are shown and discussed