Smooth and curved microstructural topologies found in nature—from soap films to trabecular bone—have inspired several mimetic design spaces for architected metamaterials and bio-scaffolds. However, the design approaches so far are ad hoc, raising the challenge: how to systematically and efficiently inverse design such artificial microstructures with targeted topological features? Herein, surface curvature is explored as a design modality and a deep learning framework is presented to produce topologies with as-desired curvature profiles. The inverse design framework can generalize to diverse topological features such as tubular, membranous, and particulate features. Moreover, successful generalization beyond both the design and data space is demonstrated by inverse designing topologies that mimic the curvature profile of trabecular bone, spinodoid topologies, and periodic nodal surfaces for application in bio-scaffolds and implants. Lastly, curvature and mechanics are bridged by showing how topological curvature can be designed to promote mechanically beneficial stretching-dominated deformation over bending-dominated deformation.

Multi-material direct ink writing (DIW) of smart materials opens new possibilities for manufacturing complex-shaped structures with embedded sensing and actuation capabilities. In this study, DIW of UV-curable piezoelectric actuators is developed, which do not require high-temperature sintering, allowing direct integration with structural materials. Through particle size and ink rheology optimization, the highest d₃₃^*g₃₃ piezoelectric constant compared to other DIW fabricated piezo composites is achieved, enabling tunable actuation performance. This is used to fabricate ultrasound transducers by printing piezoelectric vibrating membranes along with their support structures made from a structural ink. The impact of transducer design and scaling up transducer dimensions on the resonance behavior to design millimeter-scale ultrasound transducers with desired out-of-plane displacement is explored. A significant increase in output pressure with increasing membrane dimensions is observed. Finally, a practical application is demonstrated by using the printed transducer for accurate proximity sensing using time of flight measurements. The scalability and flexibility of the reported DIW of piezo composites can open up new advancements in biomedical, human-computer interaction, and aerospace fields.

To accurately analyze the fracture behavior of piezoceramics at small length scales, flexoelectricity must be considered along with piezoelectricity. Due to its dependence on size, flexoelectricity predominates at the micro- and nano-length scales. Additionally, crack tips having the largest strain gradient state cause large flexoelectricity around them. Different approaches are employed in the past to model cracks computationally. However, extended isogeometric analysis (XIGA) is proven to be an accurate and efficient method. C¹ continuity requirements for modeling gradients in flexoelectricity are met by non-uniform rational B-splines (NURBS) basis functions used in XIGA. In this work, XIGA-based computational model is developed and implemented to study the fracture behavior of the piezoelectric-flexoelectric domain. An in-house MATLAB code is developed for the same. Several numerical examples are studied to ensure the efficacy and efficiency of the implemented model, and crack behavior is presented in the form of an electro-mechanical J-integral. The analysis is carried out to investigate how cracks behave for different flexoelectric coefficients under different electrical and mechanical loading combinations. J-integral is also analyzed against crack parameters such as crack orientation and length. It is observed that boundary loads and flexoelectric material constants significantly influence J-integral. Results also show a considerable amount of fracture toughening in the presence of flexoelectricity. The peak value of J-integral is found to be reduced with an increase in the flexoelectric coefficient. A significant reduction in J-integral, as much as 45%, is observed when the flexoelectric constant varied from 0.5 to 2 µCm⁻¹.

Although conventional actuators like piezoelectric and electrostrictive are efficient, but they required hard wiring, which contaminates the control signal and adds to the weight of the structure. The current study presents a wireless control strategy using photostrictive actuators. Owing to the fortunate combination of photovoltaic effect and converse piezoelectric effect, a photostrictive actuator can generate mechanical strain, when irradiated with light intensity. Limited choices of photostrictive material with high electromechanical coupling coefficient give the motivation to design photostrictive composites. The finite element-based formulation incorporating fuzzy logic controller is employed to study the active vibration control response of cantilever structure when equipped with photostrictive composite actuator. A parametric study has been carried out to study the influence of inclusion's volume fraction on wireless active vibration control of the structure. Control merits have been defined to compare the control performance of different composites. It is found that particulate composites are the better choice for lightweight structure and fiber composites are better if there is no weight constraint.

Commercial trucks are not always transporting goods at full capacity, which means that the box-shape trailer is partially occupied or even completely empty on occasions. In this work, we explore foldable trailer design to improve truck efficiency and sustainability. To achieve the folding feature we explore active compliant hinges in origami-inspired design. Active origami engineering relies on two-dimensional smart hinges able to interact in a three-dimensional design without external forces. The truck trailer is envisioned to be able to fold itself into an aerodynamic wedge shape when the trailer is (partially) empty. This design can be made lighter and more environmentally friendly than the original trailer design and the use of such a foldable trailer can reduce fuel consumption. Smart material layered hinges made from dielectric elastomers actuate the plastic faces of the construction to achieve the folding and deploying of the adaptable trailer design. Initial studies of geometry, materials, and actuation power as well as the potential for energy savings are presented. The drag coefficient is reduced by 33.77% when folded into an aerodynamic shape which leads to an annual decrease in fuel consumption of 6.32% for the average truck that drives around empty 20% of the time and 15.8% for one way transport trucks that drive around empty 50% of the time.

A model for numerical homogenization of triply periodic minimal surfaces (TPMS) based on electrostrictive composites is presented. This electrostrictive composite consists of TPMS (a three-dimensional continuous structure) implanted in a soft non-electrostrictive matrix. A representative volume element (RVE)-based approach is used to homogenize the electrostrictive composites and determine all the effective electrostrictive, mechanical, and electrical coefficients. Finite element formulation is employed to solve the nonlinear electrostrictive constitutive equations. Special attention is paid to designing the boundary conditions that permit the fast calculation based on simulations of overall deformation-induced due to mechanical and electrical loads. Interestingly, the value of the effective electrostrictive coefficient of the composite surpasses that of the inclusion Pb (mg_1/3Nb_2/3)O₃-PbTO₃-BaTiO₃ (PMN-PT-BT), even though the matrix is non-electrostrictive due to the additional flexibility imparted by the matrix. This electrostrictive response of TPMS-based composite is independent of the type of TPMS structures used. It is prudent to say that these composites will find their place in practical application owing to their salient features of more flexibility and high electrostrictive coefficient.

Piezoelectric energy harvesting has played a vital role in powering several engineering devices and systems, where conventional power supply is either not possible or not desirable. Another perspective for piezoelectric energy is its utilization as a non-conventional clean energy source, harnessing the ambient mechanical vibrations. With the increasing global population and developing infrastructure, the load from human footsteps can be a source of significant amount of freely available mechanical vibration energy. The piezoelectric tiles are aimed at harnessing this otherwise wasted energy with minimum interference to the regular activities. This article aims to provide a comprehensive review of the technologies and methodologies that have been implemented in the literature. A comprehensive discussion on the various designs and mechanisms utilized in piezoelectric energy harvesting tiles is provided. Electrical circuits, which are crucial for successfully extracting the electrical energy from piezoelectric harvesters in usable form, are also discussed in detail. The feasibility aspects, from economic and energy perspectives, are also presented critically. Lastly, the challenges in the successful implementation of the piezoelectric tiles and their possible solutions are presented.

In this study, a method for the bacterial disinfection of drinking water in the water storage systems based on the electric potential generated from a piezoelectric wind energy harvester is presented. First, an efficient galloping piezoelectric wind energy harvester is designed by adding curve- shaped attachments to the bluff body of the harvester. The simulated output voltage of the harvester is validated by performing different sets of experiments on an open environment. Later, the output voltage of the harvester is enhanced, using copper oxide nanowires (CuONWs) grown perpendicular to the surface of the center copper wire. The enhanced electric field is able to disinfect the bacterial water in a 25 min time period. The bacterial removal log efficiency of 2.33 is obtained with a supplied rms voltage of 0.1 V from the harvester. The findings of this study will help to provide alternate means to water treatment that are efficient, reliable, and also free from disinfection by-products.