Adaptive Parameter Estimation With Convergence Analysis for the Prandtl–Ishlinskii Hysteresis Operator

Hysteresis is a nonlinear characteristic ubiquitously exhibited by smart material sensors and actuators, such as piezoelectric actuators and shape memory alloys. The Prandtl–Ishlinskii (PI) operator is widely used to describe hysteresis of smart material systems due to its simple structure and the existence of analytical inverse. A PI operator consists of a weighted superposition of play (backlash) operators. While adaptive estimation of the weights for PI operators has been reported in the literature, rigorous analysis of parameter convergence is lacking. In this article, we establish persistent excitation and thus parameter convergence for adaptive weight estimation under a rather modest condition on the input to the PI operator. The analysis is further supported via simulation, where a recursive least square (RLS) method is adopted for parameter estimation.

Smart Experience in Fashion Design: A Speculative Analysis of Smart Material Systems Applications

During the last decade, smart materials and systems have increasingly impacted several niches, including ‘one-off/limited edition experimental fashion’. As the traditional boundaries between what is art and what was not supposed to be art are now turning into osmotic membranes, we will speculatively focus on how ‘smart material systems’ are highly contributing to outline a new creative landscape full of interesting and compelling issues. Introducing three different sub-niches of experimental fashion—multi-sensory dresses, empathic dresses, and bio-smart dresses—this article outlines the emergence of a new smart design scenario. Then, we critically discuss some of the implications of the developing research in terms of design thinking and design aesthetics. This paper aims to contribute to the topic of next design scenario, demonstrating how design research is increasingly affecting the extension of human perception, emotions, and the concept of ‘almost-living’ entities, projecting towards the redefinition of relationships with materials and objects.

CO2-Responsive polymer materials

This paper reviews the chemical fundamentals of CO2-responsive polymers as well as the latest reported “smart” material systems switched by CO2.

Uncertainty Quantification for Robust Control Design of Smart Material Systems

The objective in robust control design is to provide mechanisms to achieve tracking or stabilization objectives in the presence of unmodeled dynamics. This is usually achieved by assuming worst case model discrepancies which can significantly degrade control authority if the uncertainty bounds are overly conservative. In this paper, we use uncertainty quantification techniques to construct densities for control outputs that can be used to derive optimal robust control designs. We illustrate the performance of these techniques in the context of systems with smart material actuators and sensors.

Cyclic Viscoplastic-Viscodamage Analysis of Shape Memory Polymers Fibers With Application to Self-Healing Smart Materials

The cold-drawn, programmed shape memory polymer (SMP) fibers show excellent stress recovery property, which promotes their application as mechanical actuators in smart material systems. A full understanding of the thermomechanical-damage responses of these fibers is crucial to minimize the trial-and-error manufacturing processes of these material systems. In this work, a multiscale viscoplastic-viscodamage theory is developed to predict the cyclic mechanical responses of SMP fibers. The proposed viscoplastic theory is based on the governing relations for each of the individual microconstituents and establishes the microscale state of the stress and strain in each of the subphases. These microscale fields are then averaged through the micromechanics framework to demonstrate the macroscale constitutive mechanical behavior. The cyclic loss in the functionality of the SMP fibers is interpreted as the damage process herein, and this cyclic loss of stress recovery property is calibrated to identify the state of the damage. The continuum damage mechanics (CDM) together with a thermodynamic consistent viscodamage theory is incorporated to simulate the damage process. The developed coupled viscoplastic-viscodamage theory provides an excellent correlation between the experimental and simulation results. The cyclic loading-damage analysis in this work relies on the underlying physical facts and accounts for the microstructural changes in each of the micro constituents. The established framework provides a well-structured method to capture the cyclic responses of the SMP fibers, which is of utmost importance for designing the SMP fiber-based smart material systems.