Browsing by Author "Oliveira, Fallconny Rodrigues Sensato"
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- Fire performance on the load bearing LSF wallsPublication . Oliveira, Fallconny Rodrigues Sensato; Piloto, P.A.G.; Razuk, Henrique CotaitThis work presents a numerical validation study of a load bearing light steel frame (LSF) wall structure in respect to full scale-test, to obtain the fire resistance of the wall. Three parametric studies were performed to evaluate the influence of the plasterboard’s thickness, plasterboard restriction and steel section in the fire resistance of load bearing LSF wall. Simplified studies were also developed in order to compare with advanced calculation models. The finite element method was done in three stages: (1) simulation at room temperature to obtain the buckling and ultimate loads, (2) simulation of the transient thermal analysis to obtain the temperature distribution and (3) simulation of the thermomechanical analysis to obtain the fire resistance and critical temperature of the load bearing wall under fire. Results showed good agreement at room temperature. In the thermal analysis, the model was able to predict the temperature field with good accuracy, however, for thermomechanical, the model did not show good agreement with test results. In respect to the parametric analysis, plasterboard thickness influenced in the temperature distribution, resulting in a higher critical temperature in the thermomechanical simulation. Plasterboard restriction is affecting the lateral deflection of the wall in thermomechanical simulation. The steel section has a big effect in the load bearing capacity at room temperature, regarding the buckling and ultimate load, it also affects the out of plan displacement in the thermomechanical simulation. Simplified methods have been used to predict the critical temperature results under fire, with good conservative prediction for lower load ratios.
- Stress Concentration on PDMS: An evaluation of three numerical constitutive models using digital image correlationPublication . Sales, Flaminio; Souza, Andrews; Oliveira, Fallconny Rodrigues Sensato; Lima, Rui A.; Ribeiro, J.E.The examination of hyperelastic materials’ behavior, such as polydimethylsiloxane (PDMS), is crucial for applications in areas as biomedicine and electronics. However, the limitations of hyperelastic models for specific stress scenarios, with stress concentration, are not well explored on the literature. To address this, firstly, three constitutive models were evaluated (Neo-Hookean, Mooney-Rivlin, and Ogden) using numerical simulations and Digital Image Correlation (DIC) analysis during a uniaxial tensile test. The samples were made of PDMS with stress concentration geometries (center holes, shoulder fillets, and edge notches). Results of ANOVA analysis showed that any of the three models can be chosen for numerical analysis of PDMS since no significant differences in suitability were found. Finally, the Ogen model was chosen to obtain the stress concentration factors for these geometries, a property which characterize how discontinuities change the maximum stress supported by an element. Our study provides new values for variables needed to analyze and design hyperelastic elements and produce a foundation for understanding PDMS stress-strain behavior.