The article is focused on a two-dimensional geometrically nonlinear formulation of a Bernoulli beam element that can accommodate arbitrarily large rotations of cross sections. The formulation is based on the integrated form of equilibrium equations, which are combined with the kinematic equations and generalized material equations, leading to a set of three first-order differential equations. These equations are then discretized by finite differences and the boundary value problem is converted into an initial value problem using a technique inspired by the shooting method. Accuracy of the numerical approximation is conveniently increased by refining the integration scheme on the element level while the number of global degrees of freedom is kept constant, which leads to high computational efficiency. The element has been implemented into an open-source finite element code. Numerical examples show a favorable comparison with standard beam elements formulated in the finite-strain framework and with analytical solutions.

We propose a structural health monitoring (SHM) paradigm based on the simultaneous use of ultrasounds and electromechanical impedance (EMI) to monitor waveguides. Methods based on the propagation of guided ultrasonic waves (GUWs) are increasingly used in all those SHM applications that benefit from built-in transduction, moderately large inspection ranges, and high sensitivity to small flaws. Meantime, impedance-based SHM promises to adequately assess locally the structural integrity of simple waveguides and complex structures such as bolted connections. As both methods utilize piezoelectric transducers bonded or embedded to the structure of interest, this paper describes a unified SHM paradigm where pulse-echo and pitch-catch GUWs as well as EMI are employed simultaneously and are driven by the same sensing/hardware/software. We assess the feasibility of this unified system by monitoring a large flat aluminum plate with two transducers. Damage is simulated by adding small masses to the plate. The results demonstrate that the proposed system is robust and can be developed further to address the challenges associated with the SHM of complex structures

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We propose the electromechanical impedance technique to monitor the stability of dental implants. The technique consists of bonding one wafer-type piezoelectric transducers to the implant system. When subjected to an electric field, the transducer induces structural excitations which, in turn, affect the transducer’s electrical admittance. The hypothesis is that the health of the bone surrounding the implant affects the sensor’s admittance. A three-dimensional finite element model of a transducer bonded to the abutment of a dental implant placed in a host bone site was created to simulate the progress of the tissue healing that occurs after surgery. The healing was modeled by changing the Young’s modulus of the bone–implant interface. It was found that as the Young’s modulus of the interface increases, the electromechanical characteristic of the transducer changes. Then, the model was used to interpret the experimental results relative to a sensor bonded to an abutment screwed to implants secured into bovine bone samples. The results show that the electromechanical impedance technique can be used to monitor the stability of dental implants although more research is warranted to examine the repeatability of the methodology and its advantage with respect to existing commercial systems.