Research projects

Geomaterials encompass a diverse range of materials, typically characterized by brittleness or quasi-brittleness. Examples include rocks, soils, concrete, masonry, and advanced materials like ceramics.

The aim of this research is to formulate constitutive models tailored to this category of materials, employing either classical Theory of Plasticity or non-local methodologies. These models are intended for application in nonlinear Finite Element analysis, facilitating solutions to complex engineering challenges such as geotechnical scenarios or the mechanical simulation of aged masonry structures.

The mechanical behavior of geomaterials often exhibits traits like softening and/or non-associated plastic flow. When employing classical plasticity, these characteristics undermine the ellipticity of the governing PDE system, leading to non-uniqueness of solutions and dependence on mesh resolution, hindering convergence. To address this, non-local models rooted in micropolar or micromorphic continua can restore ellipticity.

Furthermore, from a numerical standpoint, constitutive modeling of these materials poses significant challenges, often impeding successful Finite Element analyses of boundary value problems. In contrast to conventional approaches found in literature, prioritizing numerical efficiency and stability of integration algorithms becomes paramount to ensure the practical applicability of developed models across a broad spectrum of engineering contexts.

The overarching aim of this research project is to pioneer the development of advanced constitutive models capable of effectively accounting for nonlocal effects, also known as gradient effects, in the mechanical behavior of polycrystalline metallic materials undergoing plastic deformation.

When examining the plastic response of metals at the micron scale, it becomes evident that grain boundaries play a pivotal role in constraining the flow of dislocations. This microstructural influence significantly alters the mechanical properties of metallic specimens, particularly when subjected to actions such as bending or torsion. Notably, at this scale, the mechanical behavior is intricately linked to specimen size, presenting marked deviations from observations at the macroscopic level.

Remarkably, as specimen size diminishes, there is a notable enhancement in mechanical properties, characterized by strengthened material behavior and alterations in strain hardening characteristics. However, classical Plasticity Theory falls short in accommodating such phenomena, as it lacks explicit consideration of intrinsic material scales.

In response to this gap, Gradient Plasticity models have emerged as promising alternatives. These models, rooted in nonlinear partial differential equations, explicitly incorporate the spatial gradient of plastic strains. Nonetheless, the numerical integration of these intricate equations using the Finite Element Method poses considerable challenges due to their inherent nonlinearity.

Consequently, this research endeavor is twofold in nature. Firstly, it entails the development and refinement of this class of constitutive models to accurately capture the intricate interplay between microstructural features and mechanical behavior. Secondly, it involves the advancement of numerical techniques essential for seamlessly integrating these models into the simulation of engineering boundary value problems, thereby bridging theoretical advancements with practical applications in the realm of materials science and engineering.

Ionic polymer-metal composites (IPMCs) represent a fascinating class of synthetic composite nanomaterials with the potential to serve as artificial muscles when subjected to an applied voltage or electric field. These composites typically consist of an ionic polymer, often Nafion, whose surfaces are either chemically plated or physically coated with conductive materials such as platinum or gold. Upon the application of a voltage, the migration and redistribution of ions within the IPMC strip lead to a bending deformation, showcasing their remarkable electro-mechanical properties.

The versatility of IPMCs extends beyond mere deformation, positioning them as promising candidates for a wide array of smart device applications, particularly within the medical field. For instance, IPMCs could revolutionize medical procedures by serving as guiding wires and endovascular steerers, facilitating navigation within the intricate human blood vasculature. Moreover, their potential as artificial muscles holds promise for correcting paralysis or assisting weakened cardiac muscles, representing groundbreaking advancements in medical intervention.

In our research, we delve into the electrochemomechanics of IPMCs with the primary objective of developing comprehensive predictive models. These models aim to elucidate and accurately predict the sensing, actuation, and energy harvesting capabilities of IPMCs, thereby paving the way for their widespread utilization in various technological domains, including biomedical engineering, robotics, and beyond. By unraveling the underlying mechanisms governing the behavior of IPMCs, we strive to unlock their full potential and propel innovation in the realm of advanced materials and smart devices.

The primary focus of this research lies in advancing the development of constitutive models tailored specifically for composite materials, with a particular emphasis on syntactic foams. Syntactic foams represent a class of particulate composites wherein a thermoset polymer matrix, often comprising vinyl ester or epoxy resin, is infused with hollow spheres, commonly referred to as balloons. These hollow spheres, crafted from materials such as glass, ceramic, or metal, endow syntactic foams with a distinctive closed-cell microstructure, rendering them invaluable materials for a multitude of applications within aerospace and marine systems.

Central to our research endeavor is the utilization of numerical homogenization techniques to accurately replicate the mechanical behavior exhibited by syntactic foams. This involves conducting Finite Element micromechanical simulations on representative volumes (RVEs) of composite material, enabling a detailed examination of their intricate structural characteristics and mechanical response under various loading conditions.

A pivotal aspect of our analyses revolves around the comprehensive modeling of both the mechanical behavior of the polymeric matrix constituents and the failure mechanisms inherent to the filler materials, which typically exhibit brittle characteristics. By meticulously characterizing the mechanical properties and failure modes of both components within the composite, we aim to formulate robust constitutive models capable of capturing the nuanced interplay between matrix-filler interactions and their collective influence on the overall performance of syntactic foams. Through these efforts, we seek to not only deepen our understanding of the underlying physics governing the behavior of these advanced materials but also pave the way for enhanced design and optimization of syntactic foam-based structures across a diverse array of engineering applications.

The primary objective of this scientific research is to advance the development of constitutive models tailored specifically for metals undergoing large strains, thereby facilitating the accurate simulation of metal forming processes through the Finite Element method. These simulations serve a dual purpose within engineering practice.

Firstly, through the utilization of parametric analyses, the aim is to engineer productive processes that minimize costs while maximizing efficiency. By leveraging computational simulations, engineers can explore a plethora of design parameters and configurations, ultimately identifying optimal process settings that strike a balance between productivity and resource utilization.

Secondly, particularly in the realm of cold forming processes, the simulations enable the thorough examination and optimization of mechanical properties exhibited by the resulting components. This entails the meticulous reproduction of residual stress profiles within the workpieces and the precise modeling of material mechanical behavior, which often undergoes significant loading-unloading cycles characterized by exceedingly large plastic strains. Achieving an accurate numerical representation of these intricate mechanical phenomena is paramount for ensuring the reliability and performance of the produced components.

Furthermore, the constitutive models developed in this research endeavor must also possess the capability to simulate and predict the occurrence of defects, such as chevron cracks or surface irregularities, which may arise due to suboptimal combinations of design parameters or process conditions. By incorporating defect simulation capabilities into the constitutive models, engineers can proactively identify and address potential manufacturing challenges, thereby enhancing product quality and minimizing production setbacks.

Ultimately, the culmination of this research will empower engineers with sophisticated computational tools capable of not only optimizing metal forming processes for cost-effective production but also ensuring the integrity and quality of the resulting components through comprehensive defect analysis and mitigation strategies.

This research project is dedicated to advancing analytical tools for accurately estimating the forces involved in cold drawing wires or rectangular plates. These analytical models must meticulously consider various factors, including die geometries, area reduction, and friction conditions, to provide reliable predictions of the drawing process.

The significance of such analytical models cannot be overstated in the realm of metal forming process design. While numerical analyses offer unparalleled depth and precision in optimizing metal forming processes, real-world industrial applications often necessitate parametric analyses. These analyses require conducting numerous numerical simulations for each combination of process parameters, making them time-consuming and resource-intensive. Consequently, analytical models play a crucial role by providing rapid and efficient initial designs of the process, serving as invaluable aids in decision-making and process optimization.

Furthermore, it's noteworthy that despite advancements in computational techniques, the predominant design procedures for metal forming processes in engineering practice still rely heavily on limit analysis techniques. These techniques offer simplified yet robust methodologies for assessing the structural integrity and feasibility of forming processes, making them indispensable tools in the design engineer's toolkit.

The analytical solutions developed in this research project are rooted in limit analysis techniques, leveraging their proven efficacy in providing practical and reliable insights into the complex phenomena underlying metal forming processes. By refining and enhancing these analytical tools, we aim to empower engineers with efficient and accurate means of designing and optimizing metal forming processes, thereby driving innovation and efficiency in industrial manufacturing.

This research project is centered around the numerical simulation of coupled fluid-structure problems, particularly in the realm of acoustic phenomena, utilizing the Finite Element method.

Specifically, the focus of this scientific inquiry lies in leveraging Finite Element simulations to engineer devices aimed at enhancing the acoustic environment within spaces dedicated to music listening, particularly focusing on mid and low frequencies. By employing advanced numerical techniques, we seek to design and optimize acoustic correction devices capable of effectively manipulating sound waves to achieve optimal listening conditions.

The Finite Element numerical simulations conducted as part of this research endeavor encompass dynamic analyses in both the time and frequency domains. These simulations serve as the cornerstone for developing comprehensive insights into the intricate interplay between acoustic waves and structural components, facilitating the refinement and validation of device designs.

Moreover, the outcomes of these numerical simulations lay the groundwork for the development of simplified analytical models. These analytical models, derived from the detailed numerical simulations, hold immense practical value in engineering applications. They offer engineers efficient tools for designing and optimizing acoustic devices for room correction, enabling the creation of bespoke solutions tailored to specific acoustic environments and listening preferences.

By integrating advanced numerical simulations with analytical modeling techniques, this research project aims to bridge the gap between theoretical insights and practical engineering applications in the realm of acoustic engineering. Ultimately, the goal is to empower engineers with the knowledge and tools necessary to create immersive and optimized listening experiences across a diverse range of environments and applications.