Article
Materials Science, Characterization & Testing
Vincent Dorleans, Remi Delille, Delphine Notta-Cuvier, Franck Lauro, Eric Michau
Summary: The use of thermoplastics in the automotive industry is increasing, requiring the characterization of their thermo-mechanical behavior under various conditions. The time-temperature-superposition principle can be extended to the viscoplastic domain, reducing the number of required tests. A new approach using a limited number of tests enables the characterization of whole thermoplastic behavior with good correlation between numerical simulations and experiments.
Article
Materials Science, Multidisciplinary
Rong Luo, Qiang Hou
Summary: This study developed a time-temperature-humidity superposition principle for asphalt mixtures and demonstrated the significant effect of humidity on the viscoelastic properties. The humidity-dependency of the viscoelastic properties of asphalt mixtures was identified, and the study validated the developed model fit.
MECHANICS OF MATERIALS
(2021)
Article
Polymer Science
Philipp Schroeder, Monika Schoenhoff, Cornelia Cramer
Summary: Complex coacervates of chitosan and gum arabic, two naturally abundant weak polyelectrolytes, were studied using oscillatory shear rheology. The results showed that the shear moduli scaled with temperature, salt concentration, and pH, indicating the applicability of time-temperature superposition (TTSP), time-salt superposition (TSSP), and time-pH superposition (TpHSP). However, a breakdown of superposition occurred in the low-frequency regime at high salt concentrations and pH values near the pK (a) of chitosan. This breakdown was attributed to gelation, likely due to the associative interaction of chitosan chains and the formation of a chitosan network.
Article
Engineering, Mechanical
B. N. V. S. Ganesh K. Gupta, Bhaskar Sen, Mritunjay Maharudrayya Hiremath, Rajesh Kumar Prusty, Bankim Chandra Ray
Summary: This study compares the performance of glass fiber reinforced epoxy-vinyl ester interpenetrating polymer network (GEVIPN) composite with the base materials, GE and GVE composites, through flexural testing and lifetime prediction at different temperatures. The results indicate that the GEVIPN composite exhibits higher creep resistance at lower temperatures and the opposite trend at elevated temperatures.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Chemistry, Physical
Yuyin Xi, Ryan P. Murphy, Qingteng Zhang, Aurora Zemborain, Suresh Narayanan, Junsu Chae, Siyoung Q. Choi, Andrei Fluerasu, Lutz Wiegart, Yun Liu
Summary: Bicontinuous structures have broad applications in various research fields. A new gel called SeedGel has been developed to create reversible bicontinuous channels with tunable particle sizes. The mechanical properties of SeedGel were characterized using temperature-dependent rheology, showing excellent reproducibility and an interesting temperature dependence. The gelation transition and solvent exchange between domains were studied using SANS measurements, while the long-time dynamics of the gel were studied with X-ray Photon Correlation Spectroscopy (XPCS).
Article
Mechanics
Vivek Khare, Sudhir Kamle
Summary: The study investigates the effect of temperature and MWCNT concentration on the nonlinear viscoelastic behavior of -COOH functionalized multi-walled carbon nanotubes reinforced polypropylene nanocomposites. Experimental observations and model fitting show that high temperatures and low concentrations of MWCNT result in higher viscoplastic strain, while strengthening MWCNT up to 1% improves the thermomechanical behavior and viscoelastic recovery, reducing viscoplastic strain. Temperature-dependent compliance behavior of nanocomposites is explored using the Williams-Landel-Ferry and Arrhenius models with the time-temperature superposition principle.
ARCHIVE OF APPLIED MECHANICS
(2021)
Article
Chemistry, Multidisciplinary
Jasim Ahmed
Summary: This work investigates the interaction between chitosan and calcium crosslinked pectin in aqueous solution. The addition of calcium chloride improves the properties of the pectin solution and increases the dynamic moduli. Atomic force microscopy is used to observe the surface morphology of the blended films and reveals the distribution changes of CS and CP particles.
SUSTAINABLE CHEMISTRY AND PHARMACY
(2023)
Article
Multidisciplinary Sciences
Jun Koyanagi, Kodai Hasegawa, Akio Ohtani, Takenobu Sakai, Kenichi Sakaue
Summary: In this study, a non-linear viscoelastic-viscoplastic constitutive equation for polyamide 6 (PA6) is proposed with a new empirical model suggested to accurately predict viscoplastic strain. Creep, recovery, and stress relaxation tests were conducted to evaluate the material's behavior, while the time-temperature superposition principle was applied to consider the effect of elevated temperature on the material's viscoelastic-viscoplastic behavior.
Review
Materials Science, Composites
Loredana Kehrer, Johannes Keursten, Valerian Hirschberg, Thomas Boehlke
Summary: Polyamides are widely used as matrix materials in fiber-reinforced composites in various engineering applications. The influence of environmental conditions, such as temperature and humidity, on the mechanical behavior of these materials is crucial for their performance. This study investigates the thermoviscoelastic behavior of polyamide 6 under different moisture contents and analyzes the effects of humidity on material properties using dynamic mechanical analysis tests. The findings reveal drying effects, increased diffusion activities, and shifts in the glass transition temperature induced by humidity.
JOURNAL OF THERMOPLASTIC COMPOSITE MATERIALS
(2023)
Article
Polymer Science
Cai-hong Zhang, Wei-jie Wang, Hao Huang, Ze-xin Liu, Shu-guang Yang
Summary: In this study, the effect of humidity on the structure and properties of polymer complexes was investigated by constructing hydrogen-bonding complex fibers. The results showed that the increase in humidity led to changes in the morphology and glass-transition temperature of the complex fibers. The mechanical properties of the complex fibers were mainly attributed to the different complexation strengthes, chain structures, and water contents in the systems.
ACTA POLYMERICA SINICA
(2023)
Article
Polymer Science
Can-Qi Li, Horst Henning Winter, Yuan-Qi Fan, Geng-Xin Xu, Xue-Feng Yuan
Summary: This paper presents a robust method, called time-concentration superposition (TCS), for studying the concentration scaling properties of polymer solutions. TCS can not only determine the existence of power law scaling and its concentration range, but also accurately estimate the concentration scaling exponents of linear viscoelastic properties for a range of non-model polymer solutions.
Article
Chemistry, Multidisciplinary
Thi M. Tran, Javier Read de Alaniz
Summary: This paper presents a strategy to synthesize, isolate, and polymerize a well-defined tetracyclopentadiene monomer, and also de-cross-link the network polymer. Mechanical properties, including creep-recovery, shape memory, and tensile behaviors, are investigated. This work provides a versatile platform to access and study new cyclopentadiene-based and better-defined polymer networks with potential applications ranging from shape memory polymers to degradable thermosets.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Polymer Science
Albert Serra-Aguila, Josep Maria Puigoriol-Forcada, Guillermo Reyes, Joaquin Menacho
Summary: A method was developed in this study to predict the tensile moduli of thermoplastic materials under different conditions, saving research time and reducing the number of tests. The method was validated and showed good results, being applicable to thermorheologically simple materials.
Article
Food Science & Technology
Shaoyang Sheng, Aimin Shi, Junjie Xing
Summary: This study systematically investigated the rheological behavior of maize kernel using a dynamic mechanical analyzer. Drying caused a loss in toughness, resulting in changes in relaxation and creep curves. Long relaxation behavior was observed at temperatures above 45 degrees C due to weakening hydrogen bonds. The viscosity of cell walls and polysaccharide tangles affected the rapid relaxation of maize kernel at high temperatures. The results are important for understanding the rheological properties of maize kernel for processing and storage.
Article
Biochemistry & Molecular Biology
Benjamin S. Hanson, Lorna Dougan
Summary: This study computationally investigates the effect of intermediate nanoscale structure on the formation of protein hydrogels, showing how changes in the polymeric building block impact force transmission in the system and provide insights into dynamic network formation processes. The preassembled intermediate structure offers a novel structural coordinate for hierarchical modulation of macroscopic network properties, contributing to a deeper understanding of general dynamics of network formation.
Article
Chemistry, Analytical
Alireza Entezami, Stefano Mariani, Hashem Shariatmadar
Summary: This article proposes a multi-level machine learning method for vibration-based damage detection in civil structures using restricted vibration datasets. The method aims to increase the accuracy and stability of detection through distance calculation, feature normalization, and damage localization decision-making.
Article
Engineering, Mechanical
Giorgio Gobat, Andrea Opreni, Stefania Fresca, Andrea Manzoni, Attilio Frangi
Summary: In this study, the Proper Orthogonal Decomposition (POD) method is applied to efficiently simulate the nonlinear behavior of Micro-Electro-Mechanical-Systems (MEMS) in various scenarios involving geometric and electrostatic nonlinearities. The POD method reduces the polynomial terms up to cubic order associated with large displacements through exact projection onto a low-dimensional subspace spanned by the Proper Orthogonal Modes (POMs). Electrostatic nonlinearities are modeled using precomputed manifolds based on the amplitudes of the electrically active POMs. The reliability of the assumed linear trial space is extensively tested in challenging applications such as resonators, micromirrors, and arches with internal resonances. Comparisons are made between the periodic orbits computed with POD and the invariant manifold approximated with Direct Normal Form approaches, highlighting the reliability and remarkable predictive capabilities of the technique, particularly in terms of estimating the frequency response function of selected output quantities of interest.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Computer Science, Interdisciplinary Applications
Matteo Torzoni, Luca Rosafalco, Andrea Manzoni, Stefano Mariani, Alberto Corigliano
Summary: This paper proposes a data-driven approach for structural damage localization that efficiently utilizes vibration and temperature data to account for the effects of temperature fluctuations on the structural response.
COMPUTERS & STRUCTURES
(2022)
Article
Physics, Applied
Andrea Opreni, Matteo Furlan, Andreea Bursuc, Nicolo Boni, Gianluca Mendicino, Roberto Carminati, Attilio Frangi
Summary: This study presents experimental evidence of resonant modal interaction and the presence of a 1:1 internal resonance in a symmetric resonant micromirror. The authors use a reduced model obtained from finite element discretization, parametrizing the system motion in a low dimensional invariant set of the phase space. Both the model and experimental data show the existence of multiple stable solutions for a given excitation frequency.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Mechanical
Andrea Opreni, Alessandra Vizzaccaro, Cyril Touze, Attilio Frangi
Summary: The direct parametrisation method is used to reduce the model order of forced-damped mechanical structures with geometric nonlinearities. Nonlinear mappings are introduced to convert degrees of freedom to normal coordinates, and arbitrary orders of expansions are considered for the unknown mappings and reduced dynamics. The method is applied to various structures, highlighting the importance of high-order non-autonomous terms and predicting phenomena like parametric excitation and isolas formation. The accuracy and computational performance of the method suggest its potential for predicting nonlinear dynamic responses in a wide range of vibratory systems.
NONLINEAR DYNAMICS
(2023)
Article
Chemistry, Analytical
Tiago Vicentini Ferreira do Valle, Stefano Mariani, Aldo Ghisi, Biagio De Masi, Francesco Rizzini, Gabriele Gattere, Carlo Valzasina
Summary: This paper focuses on the out-of-plane tensile strength of columnar polysilicon and investigates it through a combination of on-chip testing and finite element analyses. The experiments utilize static loading to test the stopper, using electrostatic actuation to move a massive shuttle against it until failure. The observed failure mechanism is captured by numerical simulations, and the data is interpreted using the Weibull theory, leading to an estimated reference out-of-plane strength of polysilicon of approximately 2.8-3.0 GPa, consistent with other literature results.
Article
Engineering, Mechanical
Matteo Torzoni, Andrea Manzoni, Stefano Mariani
Summary: This study proposes a non-intrusive surrogate modeling strategy for real-time structural health monitoring. By using a multi-fidelity framework, datasets characterized by different fidelity levels are blended to alleviate the computational burden of supervised training while ensuring accuracy. The resulting surrogate model provides remarkably accurate approximations.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Engineering, Mechanical
Zhandong Yuan, Shengyang Zhu, Stefano Mariani, Qinglai Zhang, Jiang Wu, Wanming Zhai
Summary: This study proposes a multi-strategy-based domain adaptation method for cross-domain damage detection and localization of steel-spring vibration isolators. The method incorporates domain adversarial training and feature distribution discrepancy regularization. The advantage of the proposed method is that it only requires labeled data from the source domain and does not need labeled data related to the real structure for model training. The effectiveness of the proposed method is validated using an experimental dataset collected during field tests.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Engineering, Geological
Filippo Gatti, Luca Rosafalco, Giorgia Colombera, Stefano Mariani, Alberto Corigliano
Summary: This paper uses adversarial learning technique to generate the transient dynamic response of shear type multi-storey buildings under earthquake ground motion, starting from the relevant undamaged responses. The proposed methodology enables damage classification in shear-type multi-storey buildings and can successfully detect and assess different damage severity levels.
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
(2023)
Article
Chemistry, Analytical
Gianluca Mezzanzanica, Olivier Francais, Stefano Mariani
Summary: Size sorting, line focusing, and isolation of microparticles or cells are essential for disease diagnostic tools in biology and biomedicine. This paper presents a finite element model of a microfluidic surface acoustic wave-based device for microparticle manipulation. Acoustic waves are used to create a standing surface acoustic wave in a microchannel, allowing for non-contact manipulation. The effects of microchannel size on microparticle actuation are discussed using sensitivity analysis and exemplary results.
Article
Engineering, Electrical & Electronic
Daniel Calegaro, Stefano Mariani
Summary: Periodic elastic metamaterials have the ability to block the transmission of elastic waves, creating band gaps. By using active materials, the band gaps can be actively adjusted in real-time, making use of piezoelectricity and instability-induced pattern transformation.
Proceedings Paper
Engineering, Civil
Alireza Entezami, Stefano Mariani, Hashem Shariatmadar
Summary: This paper proposes a multi-stage machine learning method using autoregressive spectra as damage-sensitive features for structural health monitoring. The method successfully addresses the technical and economic challenges of deploying sensor networks over civil structures, and shows promising results in early damage detection under environmental variability.
EUROPEAN WORKSHOP ON STRUCTURAL HEALTH MONITORING (EWSHM 2022), VOL 2
(2023)
Proceedings Paper
Engineering, Civil
Matteo Torzoni, Andrea Manzoni, Stefano Mariani
Summary: This paper presents a methodology for reliable real-time structural health monitoring using a multi-fidelity deep neural network. The proposed approach is able to accurately locate and quantify damage, and can effectively combine datasets with different fidelities without prior assumptions. It provides numerous advantages over single-fidelity based models for structural health monitoring purposes.
EUROPEAN WORKSHOP ON STRUCTURAL HEALTH MONITORING (EWSHM 2022), VOL 2
(2023)
Proceedings Paper
Computer Science, Software Engineering
Roberto Casadei, Stefano Mariani, Danilo Pianini, Mirko Viroli, Franco Zambonelli
Summary: The paper proposes a distributed coordination strategy for spatial estimation through collaborative adaptive sampling. It dynamically partitions space into regions that compete and adapt to pressure forces exerted by the underlying phenomenon, providing an accurate aggregate sampling.
COORDINATION MODELS AND LANGUAGES
(2022)
Proceedings Paper
Biophysics
Jose Pablo Quesada-Molina, Stefano Mariani
Summary: This paper proposes a data-driven multiscale modeling framework for polysilicon micro electromechanical systems, where a tiny convolutional neural network learns the morphological features of the polycrystalline structural film to provide size-dependent solutions, and a neural network-based model learns the effects of microfabrication defects on the performance indices of the entire device.
2022 23RD INTERNATIONAL CONFERENCE ON THERMAL, MECHANICAL AND MULTI-PHYSICS SIMULATION AND EXPERIMENTS IN MICROELECTRONICS AND MICROSYSTEMS (EUROSIME)
(2022)
