RESUMO
The asymptotic homogenization method is applied to characterize the effective behaviour of periodic multi-laminated micropolar elastic heterogeneous composites under perfect contact conditions. The local problem formulations and the analytical expressions for the effective stiffness and torque coefficients are derived for the centrosymmetric case. One of the main findings in this work is the analysis of the rotations effect of the layers' constitutive properties on the mechanical response of bi-laminated composites. The effects of microstructure and interfacial interactions on the composite's mechanical behaviour are captured through the independent effective moduli. Comparisons with the classical elastic case show the approach validation. Some numerical examples are shown. Furthermore, considering the micropolar media's prevalence in bio-inspired systems, the model's applicability is evaluated for reconstructing bone fractures using multi-laminated biocomposites. An important finding in this bio-inspired simulation is related to the analysis of a periodic bi-laminated micropolar composite whose isotropic constituents are a bioceramic material and a compact bone. This artificial bio-inspired material should integrate with host tissue to support cell growth and be stable and compatible. These characteristics are crucial in the enhancement of the fractured bone.
RESUMO
In a previous work an elastic bar with a groove or notch that presents a doorway state was studied when the system was excited with 20 cycles of harmonic signals. The strength function had a Lorentzian width Γd = 1/πτd, where τd is the decay time of the prompt response. In the present paper, the doorway-state phenomenon is analyzed again for the same harmonic signals but for a very large number of cycles. The strength-function phenomenon is once more obtained, but now with a Lorentzian width Γ' which is larger than Γd. A qualitative and numerical explanation of this fact is given, leading therefore to further understanding of doorway states in elastic systems. The numerical results show a very good agreement with the values measured in the laboratory.
RESUMO
Se evalua el resultado del tratamiento quirurgico en 23 pacientes portadores de liposarcomas. El mayor porcentaje corresponde al sexo masculino, 14 casos (60,8%); con incidencia mayor entre la 4a. y 6a. decadas de la vida. La localizacion mas frecuente fue en el miembro inferior, 12 casos (52,2%). La histologia revelo que la mayoria de los pacientes eran portadores de tumores indiferenciados (17 casos - 74%). El tratamiento efectuado en mayor porcentaje (16 casos - 69,5%), fue la cirugia locorregional ampliada seguida de radioterapia. La sobrevida de 5 anos es de 11 casos (47,9%), comprobandose que los pacientes portadores de neoplasia diferenciada tienen mejor pronostico. En cuanto a los sometidos a cirugia ultrarradical, evolucionaron desfavorablemente en corto plazo
Assuntos
LipossarcomaRESUMO
Se evalua el resultado del tratamiento quirurgico en 23 pacientes portadores de liposarcomas. El mayor porcentaje corresponde al sexo masculino, 14 casos (60,8%); con incidencia mayor entre la 4a. y 6a. decadas de la vida. La localizacion mas frecuente fue en el miembro inferior, 12 casos (52,2%). La histologia revelo que la mayoria de los pacientes eran portadores de tumores indiferenciados (17 casos - 74%). El tratamiento efectuado en mayor porcentaje (16 casos - 69,5%), fue la cirugia locorregional ampliada seguida de radioterapia. La sobrevida de 5 anos es de 11 casos (47,9%), comprobandose que los pacientes portadores de neoplasia diferenciada tienen mejor pronostico. En cuanto a los sometidos a cirugia ultrarradical, evolucionaron desfavorablemente en corto plazo