Avaliação térmica provocada pela furação no tecido ósseo

Este trabalho tem como objetivo avaliar o efeito da temperatura no osso devido ao aquecimento provocado pelo processo de furação. Foram realizadas visitas a duas clínicas para acompanhamento da técnica de implantologia dentária e recolhidas imagens termográficas para a leitura da temperatura gerada na broca após o processo de furação. Na colocação de implantes dentários por exemplo, as variáveis que interferem no processo de furação do osso são: a velocidade, o material, o diâmetro, o comprimento e a geometria da ponta da broca. Com este trabalho pretende-se verificar, experimental e numericamente, as variáveis que interferem no aquecimento da estrutura óssea. Para isso, são utilizados materiais compósitos com características similares ao osso cortical e trabecular. A metodologia apresentada revela-se útil e diferenciadora de outros trabalhos, pois são utilizados materiais com características similares aos materiais in vivo. Os métodos experimentais utilizados em laboratório são baseados nas técnicas de termografia e termopares durante a furação dos diferentes materiais. Paralelamente, são utilizados modelos teóricos numéricos, com o recurso à técnica de elementos finitos, para a discussão de resultados. Após a elaboração do trabalho conclui-se que a temperatura na broca é superior à temperatura no osso e aumenta consoante a estrutura do material, isto é, se o material possuir cavidades na sua estrutura a temperatura na broca não é tão elevada como no material compacto.

Numerical analysis of wooden slabs with perforations under fire conditions

Wood is considered an ideal solution for floors and roofs building construction, due the mechanical and thermal properties, associated with acoustic conditions. These constructions have good sound absorption, heat insulation and relevant architectonic characteristics. They are used in many civil applications: concert and conference halls, auditoriums, ceilings, walls… However, the high vulnerability of wooden elements submitted to fire conditions requires the evaluation of its structural behaviour with accuracy. The main objective of this work is to present a numerical model to assess the fire resistance of wooden cellular slabs with different perforations. Also the thermal behaviour of the wooden slabs will be compared considering different material insulation, with different sizes, inside the cavities. A transient thermal analysis with nonlinear material behaviour will be solved using ANSYS© program. This study allows to verify the fire resistance, the temperature evolution and the char-layer, throughout a wooden cellular slab with perforations and considering the insulation effect inside the cavities.

Fire analysis of car park building structures

The thermal loading of an open car park building structure is going to be analysed, based on different fire scenarios that depend on the type of vehicle (different heat release rate). The compartment is going to be fixed and the thermal effect on beams is going to be analysed, depending on the vehicle position. The result of simple calculation method will be used to determine several temperature-time curves. The simple calculation method (Hasemi method) is also to be compared with the calculations of the Elefir-EN calculation program to analyse the thermal effect of the localized fire on beams.

Axial buckling load of partially encased columns under fire

Partially encased columns have significant fire resistant. However, it is not possible to assess the fire resistance of such members simply by considering the temperature of the steel. The presence of concrete increases the mass and thermal inertia of the member and the variation of temperature within the cross section, in both the steel and concrete components. The annex G of EN1994-1-2 allows to calculate the load carrying capacity of partially encased columns, for a specific fire rating time, considering the balanced summation method. New formulas will be used to calculate the plastic resistance to axial compression and the effective flexural stiffness. These two parameters are used to calculate the buckling resistance. The finite element method is used to compare the results of the elastic critical load for different fire ratings of 30 and 60 minutes. The buckling resistance is also calculated by the finite element method, using an incremental and iterative procedure. This buckling resistance is also compared with the simple calculation method, evaluating the design buckling curve that best fits the results.