Abstract This work addresses the determination of the cohesive law under mode I loading of bovine cortical bone tissue using the Double Cantilever Beam (DCB) test. Direct and inverse methods were proposed to assess the cohesive laws representative of bone fracture under mode I loading. The direct method combines the evolution of the strain energy release rate under mode I loading with the crack tip opening displacement that is monitored by digital image correlation technique. According to this method, the cohesive law is obtained by differentiation of such relation with respect to the crack opening. The inverse procedure is performed through a finite element analysis including cohesive zone modelling, conjointly with a developed optimization algorithm. This identification strategy does not require a pre-established shape of the cohesive law as with the conventional inverse based procedures, which is viewed as a novelty of this work. It was concluded that both methods provide consistent results, being appellative tools concerning systematic and methodical studies dedicated to bone fracture characterization.

Biodegradable polymers such as PLA have been studied for medical applications, human ligament repair is one of such cases. However, these materials can be applied in other sectors as aerospace, aeronautics, automotive, food packaging. PLA presents a relatively brittle on the mode I fracture behavior, being often blend with other biodegradable or non-degradable polymers to improve its fracture energy. For some existing applications, PLA components exhibit accumulated permanent deformation resulting from dynamic mechanical inputs, resulting on failure by laxity of parts. Aiming the improvement of PLA mechanical properties, the inclusion of carbon nanofillers into PLA matrix, in particular, CNT-COOH and GNP have been developed, due to their strong sp2 carbon-carbon bondings and their geometric arrangement that enhance mechanical properties of the polymer matrix. PLA and nanocomposites were produced by melt blending followed by compression moulding in a hot press, with small weight percentages of nanofillers added to the matrix. Nanocomposites dispersion was evaluated by SEM. Quasi static tensile tests were performed on a mechanical testing machine (Instron� ElectroPuls E1000) along with strain field measurements of specimens with centred crack with digital image correlation, revealing strain distribution along specimens.

This paper presents a control process and frequency adjustment based on the Magnetic Core Reactor prototype. For the past decades, there has been significant development in the technologies used in Wireless Power Transfer systems. In the Wireless Power Transfer systems it is essential that the operating frequency of the primary circuit be equal to the resonant frequency of the secondary circuit so there is the maximum energy transfer. The Magnetic Core Reactor allows controlling of the frequencies on both sides of the transmission and reception circuits. In addition, the assembly diagrams and test results are presented.

Fracture characterization of human cortical bone under mode II loading was analyzed using a miniaturized version of the end-notched flexure test. A data reduction scheme based on crack equivalent concept was employed to overcome uncertainties on crack length monitoring during the test. The crack tip shear displacement was experimentally measured using digital image correlation technique to determine the cohesive law that mimics bone fracture behavior under mode II loading. The developed procedure was validated by finite element analysis using cohesive zone modeling considering a trapezoidal with bilinear softening relationship. Experimental load-displacement curves, resistance curves and crack tip shear displacement versus applied displacement were used to validate the numerical procedure. The excellent agreement observed between the numerical and experimental results reveals the appropriateness of the proposed test and procedure to characterize human cortical bone fracture under mode II loading. The proposed methodology can be viewed as a novel valuable tool to be used in parametric and methodical clinical studies regarding features (e.g., age, diseases, drugs) influencing bone shear fracture under mode II loading.