Um refinamento h, p e hp adaptativo na análise de flexáo de placas semi-espessas

In this work, the Finite Element Method is used through its h, p and hp adaptive version to solve the Reissner-Mindlin plate elastic bending problem. The object oriented programming philosophy (C++) is employed in order to overcome the natural difficulties of handling information in a self-adaptive finite element code. The Webb and Abouchacra hierarchical basis for triangular e lements, recently proposed in, is employed to discretize the plate domain. The adaptive refinement is done in accordance with the Zienkiewicz and Zhu error estimator. Finally, some numerical results are shown, being compared with analytical solutions, when they are available

A variational framework for a set of hyperelastic-viscoplastic isotropic models

The rate tensor of plastic deformation in elasto-viscoplastic models is usually decomposed in direction and magnitude. In the case of small-strain J2 models, this leads to the well known radial return mapping algorithms in which the flow direction is known a priori at each load step. In the context of the variational large-strain elasto-viscoplastic models, this decomposition between constitutive and cinematic aspects is accomplished by the choice of logarithmic strain measures, exponential integration algorithm and quadratic (Hencky) elastic potentials. The aim of this paper is to show that the mentioned decoupling properties can be extended to a wide set of hyperelastic-plastic isotropic models not restricted to Hencky-type elastic behavior by relaxing the classical decomposition amplitude/direction into the sum of spectral quantities

Torsion test method for mechanical characterization of PLDLA 70/30 ACL interference screws

AbstractThis study developed a test method for determining the mechanical properties of poly-L/D-lactide (PLDLA) 70/30 cannulated bioabsorbable anterior cruciate ligament (ACL) interference screws. We proposed a method that defines three characteristic lengths associated with the screw void space, which was designed to receive the screwdriver during insertion of the implant: (1) the clamping length Lc, (2) the screwdriver insertion length Lb, and (3) the gauge length Lg. We tested twenty completely fabricated and finished screws that had been submitted to different levels of hydrolytic degradation. In torsion tests, the variables measured were stiffness, yield torque, yield torque angle, maximum torque and maximum torque angle. These values were correlated with the fracture surface, numerical simulation and molecular weight. The results of the degradation testing, lasting from 0 to 240 days, show a clear transition in the screws' mechanical behavior from ductile to brittle. We concluded that the proposed torsion testing method is appropriate for determining the mechanical properties of cannulated polymeric screws