Nuno Viriato

Ligaments’ clamping: a novel solution to prevent soft tissue slippage

The mechanical properties of ligaments are often measured using mounted specimens such as boneligament-bone in a uniaxial tension setup. Numerous experimental studies have been conducted to perform knee ligaments characterization, facing some challenges to reach the ultimate load. The ligaments are soft moist tissues with viscoelastic properties that make its clamping a complex task. Therefore, the main goal was to overcome these difficulties by developing an innovative and functional clamping method. The validation of the proposed solution was done through mechanical characterization of porcine knee ligaments. The design of these customized clamps took into account the soft tissue characteristics. The performance of the clamps was evaluated during mechanical characterization of porcine knee ligaments under tensile loading at three different strain rates. The test results indicated that the cruciate ligaments are the most rigid, whereas the collateral ligaments are the less rigid, in line with published results. In brief, the proposed method and protocol to measure ligaments’ mechanical properties revealed to be effective, reaching the failure load without tissue slippage. DOI: https://doi.org/10.24243/JMEB/2.5.160

An Automated Method for the Measurement of Fatigue Crack Progression

This letter describes the work conducted at our laboratory for the implementation of an automated vision system for fatigue crack growth measurement. The system relies on a dedicated illumination system with grazing incidence and optimized feature extraction by morphological image processing and continuous calculation of the crack growth, for adjustment of the optimal time interval for image registration.

Coherent fringe projector for 3D surface profilometry

Active image processing full field methods for 3D contactless profilometry are amongst the current methods of choice for obtaining point clouds from object surfaces. The fringe projection system plays a decisive role on the entire process, significantly impacting both quality and reliability of the final measurements. Moreover, most every phase measurement profilometer can only be used under laboratory controlled lighting environments. This note describes the ongoing LOME project for a coherent fringe projection system which will enable outdoor measurements by selectively band pass filtering the projected wavelength.