Abstract This work presents a model for determining the depth of projectile perforation based on the RBL formula for ballistic impact, validated with microconcrete specimens made with Portland cement and coarse aggregate of granite and basalt. The model was validated with 7.62 x 51 mm FMJ (Full Metal Jacketed) ammunition on specimens with 5 cm of diameter and a height variation of 5.00 - 10.00 cm The transformation of kinetic energy into heat was found to be one of the forms of energy release. Experimental results showed that the calculation model proposed here predicts penetration depth values closer to the experimental values than current models, which is favorable for the safety. impact basalt 762 7 62 7.6 Full Jacketed 500 00 5.0 1000 10 10.0 release models safety 76 6 7. 50 0 5. 100 1 10.

Resumo Este trabalho apresenta um modelo para determinar a profundidade da penetração de um projetil baseado sobre a formula RBL para impactos balísticos, validados com corpos de prova de microconcreto feito em cimento Portland, agregados de granitos grossos e basalto. O modelo foi validado com munição FMJ (revestido totalmente de metal) de 7,62 x 51 mm sobre corpos de prova de 5 cm de diâmetro e alturas variando entre 5 a 10 cm. Foi possível determinar que uma das formas de liberação de energia ocorreu a través da energia cinética em calor. Os resultados experimentais mostram que o modelo calculado aqui predisse valores de profundidade de penetração mais próximos aos valores experimentais usados nos modelos atuais, das quais são favoráveis para a segurança. balísticos Portland basalto revestido metal 762 7 62 7,6 1 calor atuais segurança 76 6 7,

An experimental study on the distribution of residual stresses induced by shot peening on samples of SAE 1020 steel with pre-existing compressive stresses is presented. Two samples with similar geometries were subjected to a heat treatment to relieve stress. Then, one of the samples was subjected to a cementation process to introduce compressive residual stresses. Both samples, with and without cementation, were subjected to the same shot peening treatment. Using X-ray diffraction and electrolytic polishing to remove superficial layers, the depth-resolved residual stress distribution was obtained. It was concluded that the effect of pre-existing compressive stresses should be considered as a factor that influences the final distribution of the residual stresses induced by shot peening, namely the maximum of shot peening induced residual stresses moves closer to the surface in a sample with large initial compressive stresses and its value is greater than the maximum value for a specimen with lower initial compressive stresses. 102 preexisting pre existing presented Then Xray X ray layers depthresolved depth resolved obtained 10 1

Abstract The nanostructured hydroxyapatite (HAp) was synthesized by precipitation from aqueous phase, using hen’s eggshells and different sucrose concentrations. The XRD results confirmed the formation of HAp, with crystallite size of about 15-22 nm. The SEM and TEM characterization showed morphological changes when increasing the amount of sucrose used, with the tendency to form spheroidal particles. The specific surface area increases from 36 to 93 m2.g-1 as the amount of sucrose used increases. Our results indicated that sucrose can be used as a promising additive/template, easy to obtain at low cost. In addition to contributing to the recycling of this biowaste (eggshells), the synthesized HAp has the potential to be used in bone tissue engineering applications, since the samples were no cytotoxicity to dental pulp stem cells in the in vitro assessment by resazurin assay.

Welding is widely used in the manufacture of steel products. Metallurgical processes during welding produce residual stresses in different zones of the welded parts. Welding residual stresses, particularly tensile stresses, can significantly impact the reliability and the integrity of the welded components. Our recent works report the effect of residual stress redistribution in a relatively short, up to two weeks, period after the welding procedure. The hypothesis that the observed stress relaxation phenomenon is associated to the microstructure evolution that occur in the material after the end of the welding procedure was proposed. To prove this hypothesis a physical simulation of the influence of the welding thermal cycles on the base metal with GLEEBLE equipment was performed. Using SEM EBSD, technique the variation of grain boundary misorientation accompanied by the residual stresses redistribution in the first days after welding thermal cycles simulation were observed.