Abstract:In this experimental study, we investigate the nonlinear dynamic response of nanocomposite beams composed of polybutylene terephthalate (PBT) and branched carbon nanotubes (bCNTs). By varying the weight fraction of bCNTs, we obtain frequency response curves for cantilever specimens under harmonic base excitations, measuring the tip displacement via 3D scanning laser vibrometry. Our findings reveal a surprising nonlinear softening trend in the steady-state response of the cantilevers, which gets switched into h… Show more
“…For sensor applications, their ability of specific and stable detections of mechanical and electrochemical properties was extensively explored in the literature: for an up-to-date survey on this, see for instance [44,45]. An experimental and numerical study about the response of such nanostructured materials is given in [46][47][48], where the accuracy of the constitutive modeling here employed was also successfully validated.…”
A nonlinear MEMS multimass sensor is numerically investigated, designed as a single input-single output (SISO) system consisting of an array of nonlinear microcantilevers clamped to a shuttle mass which, in turn, is constrained by a linear spring and a dashpot. The microcantilevers are made of a nanostructured material, a polymeric hosting matrix reinforced by aligned carbon nanotubes (CNT). The linear as well as the nonlinear detection capabilities of the device are explored by computing the shifts of the frequency response peaks caused by the mass deposition onto one or more microcantilever tips. The frequency response curves of the device are obtained by a pathfollowing algorithm applied to the reduced-order model of the system. The microcantilevers are described by a nonlinear Euler-Bernoulli inextensible beam theory, which is enriched by a meso-scale constitutive law of the nanocomposite. In particular, the microcantilever constitutive law depends on the CNT volume fraction suitably used for each cantilever to tune the frequency bandwidth of the whole device. Through an extensive numerical campaign, the mass sensor sensitivity estimated in the linear and nonlinear dynamic range shows that, for relatively large displacements, the accuracy of the added mass detectability can be improved due to the larger nonlinear frequency shifts at resonance (up to 12%).
“…For sensor applications, their ability of specific and stable detections of mechanical and electrochemical properties was extensively explored in the literature: for an up-to-date survey on this, see for instance [44,45]. An experimental and numerical study about the response of such nanostructured materials is given in [46][47][48], where the accuracy of the constitutive modeling here employed was also successfully validated.…”
A nonlinear MEMS multimass sensor is numerically investigated, designed as a single input-single output (SISO) system consisting of an array of nonlinear microcantilevers clamped to a shuttle mass which, in turn, is constrained by a linear spring and a dashpot. The microcantilevers are made of a nanostructured material, a polymeric hosting matrix reinforced by aligned carbon nanotubes (CNT). The linear as well as the nonlinear detection capabilities of the device are explored by computing the shifts of the frequency response peaks caused by the mass deposition onto one or more microcantilever tips. The frequency response curves of the device are obtained by a pathfollowing algorithm applied to the reduced-order model of the system. The microcantilevers are described by a nonlinear Euler-Bernoulli inextensible beam theory, which is enriched by a meso-scale constitutive law of the nanocomposite. In particular, the microcantilever constitutive law depends on the CNT volume fraction suitably used for each cantilever to tune the frequency bandwidth of the whole device. Through an extensive numerical campaign, the mass sensor sensitivity estimated in the linear and nonlinear dynamic range shows that, for relatively large displacements, the accuracy of the added mass detectability can be improved due to the larger nonlinear frequency shifts at resonance (up to 12%).
Polymer nanocomposites exhibiting remarkable mechanical properties are a focus of research for decades in structural applications. However, their practical application faces challenges due to poor interfacial load transfer, nanofiller dispersion, and processing limitations. These issues are critical in achieving stiff, strong, lightweight, and structurally integrated materials. Additionally, they often suffer from predetermined properties, which may not be effective under specific loading conditions. Addressing these challenges, the development of design strategies for mechano‐responsive materials has advanced, enabling self‐adaptive properties that respond to various mechanical stimuli. Drawing inspiration from natural systems, these approaches have been implemented in synthetic material systems, leveraging the design flexibility of nanocomposites as needed. Key focus areas include exploring mechanoradical reactions for dynamic mechano‐responsiveness, as well as utilizing biomimetic mineralization and mechanical training for self‐strengthening. This work also examines multistability, enabling on‐demand deformation of materials and structures. Recent advancements in viscoelastic damping and nonreciprocal materials are discussed, highlighting their potential for directional energy absorption, transmission, and vibration control. Despite the need for significant improvements for real‐world applications, mechano‐responsive polymers and nanocomposites are expected to offer enormous opportunities not only in structural applications but also in other fields such as biomedical engineering, energy harvesting, and soft robotics.
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