The knowledge of contact forces in teeth surfaces during mastication or para-functional movements can help to understand processes related to friction and wear of human dental enamel. The development of a numerical model for analysis of the occlusal contact between two antagonistic teeth is proposed, which includes three basic steps: the characterisation of the surface roughness, its homogenisation using an assumed distribution function and the numerical determination of the resulting forces. Finite element strain results for the main different asperities are statistically combined, deriving the predicted macroscopic behaviour of the interface. Axisymmetric and 3D numerical models with an elasto-plastic constitutive law are used to simulate micro-indentations and micro-contacts, respectively. The contact is allowed to occur locally in planes not necessarily parallel to the surface's mean plane, a problem for which there is no analytical solution. The three identified parameters, homogenised surface hardness (3.68 GPa), surface yield stress (3.08 GPa) and static friction coefficient (0.23), agree with the experimental values reported in the literature.

The mathematical and computational modeling of the lubricated contact between bearing surfaces is presented to analyze the sliding friction using a realistic 3D model on a microscopic scale. The fluid–structure interaction model evaluates the effects of lubricant film thickness on friction in hydrodynamic and mixed lubrication regimes. Higher contact pressures are seen at the peaks of asperities, especially during mixed lubrication, in which the fluid volume is smaller. Calculated friction coefficients from a homogenization procedure of shear and normal forces in the hydrodynamic and mixed lubrication, close to 0.0045 and 0.014, respectively, were accurate and within the range specified in the Stribeck curve. Results demonstrate the computational model allows examining the effects of lubrication on contact between rough surfaces.

Concrete is a widespread material all over the world. Due to this material’s heterogeneity and structural complexity, predicting the behavior of concrete structures under extreme environmental conditions is a very challenging task. High temperatures lead to microstructural changes which affect the macrostructural performance. In this context, computational tools that allow the simulation of structures may assist the analysis, by reproducing varied situations of thermal and mechanical loading and boundary conditions. In order to contribute to this scenario, this study proposes a numerical methodology to simulate the thermomechanical behavior of concrete under temperature gradients, through inverse analyses and a user subroutine implemented in Abaqus software. Thermal loading effects were considered as loading data for a damage model. Experimental data available in the literature was adopted for adjustment and validation purposes. The preliminary results presented herein encourage further improvements so as to allow realistic simulations of such an important aspect of concrete’s behavior.

Concrete, a heterogeneous mixture basically composed of cement, coarse aggregate, fine aggregate and water, is amongst the most widely adopted construction materials in the world [¹ 1 P. J. M. Monteiro, S. A. Miller, and A. Horvath, "Towards sustainable concrete," Nat. Mater., vol. 16, pp. 698-699, 2017, http://dx.doi.org/10.1038/nmat4930. http://dx.doi.org/10.1038/nmat4930... ]-[³ 3 E. P. G. Padre, J. C. L. Ribeiro, R. C. S. S. Alvarenga, and R. C. Silva, "Algoritmo computacional para verificação de seções de concreto armado em situação de incêndio," Rev. IBRACON Estrut. Mater., vol. 12, no. 4, pp. 932-955, 2019, https://dx.doi.org/10.1590/S1983-41952019000400012. https://dx.doi.org/10.1590/S1983-4195201... ], with an annual consumption of about 4,7 tons per inhabitant per year [⁴ 4 International Organization for Standardization, Concrete, Reinforced Concrete and Pre-stressed Concrete, ISO/TC 71, 1949, https://www.iso.org/committee/49898.html (accessed Feb. 23, 2022). https://www.iso.org/committee/49898.html... ]. Its intrinsic complexity, especially regarding microstructure changes under extreme situations, such as high temperature, justifies the need for investigation by the scientific community.