Article
Mechanics
Sree Kalyan Patiballa, Girish Krishnan
Summary: This paper presents a two-phase design methodology for the conceptual synthesis of three-dimensional tunable mechanical metamaterials. The first phase involves obtaining a kinematically feasible conceptual topology using a building block-based design approach, while in the second phase, the conceptual topology is refined using shape/size optimization to meet specific elastic properties and manufacturing requirements. The efficacy of the framework is demonstrated through the design of microstructures with negative Poisson's ratios and the ability to achieve isotropic microstructures from a qualitative understanding of the conceptual designs.
MECHANICS BASED DESIGN OF STRUCTURES AND MACHINES
(2022)
Article
Chemistry, Multidisciplinary
Dianwei Gao, Chunwei Zhang, Jianhua Zhang
Summary: This study investigates the Poisson's ratio of 2D and 3D nested helical structures through theoretical analysis and numerical simulations. The results show that impact velocity strongly influences the energy absorption and deformation behavior of the proposed 3D helical structure, increasing the beam radius reduces energy absorption capability, but the yield strength of nodes has minimal effect on energy absorption capability, and impact direction affects the energy absorption performance depending on the crushing strain. These findings can be utilized to optimize the design of the proposed novel 3D helical honeycombs for various applications, such as impact energy absorbers and vibration-resistant dampers.
APPLIED SCIENCES-BASEL
(2023)
Review
Instruments & Instrumentation
Matthew Wallbanks, Muhammad Farhan Khan, Mahdi Bodaghi, Andrew Triantaphyllou, Ahmad Serjouei
Summary: Auxetic metamaterials exhibit the unexpected behavior of negative Poisson's ratio, expanding transversely when stretched longitudinally, which has applications in energy absorption, sensors, smart filters, vibration isolation, and medical fields. The potential of these structures can be further explored through additive manufacturing. There is currently a lack of guidance on the design of these structures, and this paper provides insights into the state-of-the-art and design approaches.
SMART MATERIALS AND STRUCTURES
(2022)
Review
Materials Science, Multidisciplinary
James N. Grima-Cornish, Daphne Attard, Joseph N. Grima, Kenneth E. Evans
Summary: The article explores how ancient symmetrical esthetic artifacts have been transformed into functional auxetics through mechanisms in the field of mechanical metamaterials and architected materials. It focuses on the important role and various implementations of rotating rigid units at different scales of structure.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Chemistry, Physical
Julian Plewa, Malgorzata Plonska, Pawel Lis
Summary: This paper introduces a failsafe mode in structures made of rigid squares, which exhibit a unique expansion laterally instead of contraction upon stretching. A novel solution for connecting the squares is proposed by introducing axes of rotation on the square's surface. Physical models confirm the theoretical relationships and offer new application possibilities.
Article
Chemistry, Multidisciplinary
Oliver Skarsetz, Viacheslav Slesarenko, Andreas Walther
Summary: This study introduces shape morphing of a hydrogel metamaterial by integrating responsive actuating elements to reconfigure the mesoscale unit cell geometry, achieving programmable auxeticity. The ability to programmably change the unit cell angle from 68 degrees to 107 degrees results in negative, zero, or positive Poisson's ratio under tensile strain. Finite element simulation confirms the predicted geometrical reconfiguration and programmable auxeticity.
Article
Materials Science, Multidisciplinary
Kazi Zahir Uddin, Nicholas Pagliocca, Ibnaj Anamika Anni, George Youssef, Behrad Koohbor
Summary: This study investigates the relationships between global and local strain fields in rectangular center-symmetric perforated planar structures, highlighting the role of local morphology on the macroscopic material response.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Engineering, Civil
Yang Pan, Xue Gang Zhang, Dong Han, Wei Li, Lin Fang Xu, Yi Zhang, Wei Jiang, Sai Bao, Xing Chi Teng, Tao Lai, Xin Ren
Summary: This study investigated the out-of-plane mechanical properties and deformation patterns of a recently proposed auxetic structure, the chiral lattice with circular nodes (NCL), under quasi-static uniaxial compression. The results showed that the NCL structure had superior energy absorption capacity in the out-of-plane direction compared to two benchmarks, the truss lattice and traditional chiral lattice (TCL). Parametric studies were also conducted to investigate the effects of geometric parameters and volume fraction on the structural deformation patterns and mechanical properties.
THIN-WALLED STRUCTURES
(2023)
Article
Engineering, Marine
Zhiping Wang, Gang Chen, Xiaofei Cao, Wei Chen, Chun Bao Li, Xiaobin Li, Josko Parunov
Summary: This study investigates the effect of nodal configuration on the mechanical properties of hexachiral honeycombs. It reveals that nodal reinforcement improves the negative Poisson's ratio properties of the honeycomb, and nodal filling plays a significant role in enhancing the specific absorption energy.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Multidisciplinary Sciences
K. K. Dudek, A. Drzewinski, M. Kadic
Summary: The study demonstrates that three-dimensional chiral mechanical metamaterials can self-twist and control global rotation, with the potential for programmable adjustment of rotation extent and promising applications in satellites or telescopes.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Engineering, Mechanical
Yahui Xue, Xiang Zhang
Summary: By deforming a soft mechanical metamaterial with a Poisson's ratio of -1, an underwater acoustic cloak can be automatically achieved, fulfilling the requirement of quasi-conformal mapping for cloak design. This self-adaptive acoustic cloak exhibits a wide frequency and angular bandwidth, providing a convenient avenue for designing various types of acoustic metamaterials.
EXTREME MECHANICS LETTERS
(2021)
Article
Mechanics
Xiang Li, Rong Fan, Zhengjie Fan, Yang Lu
Summary: This paper presents a novel two-dimensional mechanical metamaterial with highly programmable mechanical response by introducing hierarchical rotating structures, which shows multi-step deformation pathways and negative Poisson's ratio. The mechanical behavior of the hierarchical metastructure is highly ordered and can be programmed by constraining angles, offering new insights for creating mechanical metamaterial for flexible devices and crashworthiness applications.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2021)
Review
Materials Science, Multidisciplinary
Ebba Montgomery-Liljeroth, Silvia Schievano, Gaetano Burriesci
Summary: The field of auxetics, which focuses on materials or structures with a negative Poisson's ratio, has gained attention due to their advantageous properties including high indentation and shear resistance. Significant progress has been made in understanding the factors contributing to auxetic behavior, resulting in a wide variety of designed structures. This review provides an overview of identified and designed auxetic structures, discussing their mechanical behavior, structural properties, limitations, and potential applications, with a focus on important works and complementary research.
APPLIED MATERIALS TODAY
(2023)
Article
Mechanics
Luke Mizzi, Andrea Spaggiari
Summary: This study investigates the impact of introducing geometric chiral characteristics on the mechanical properties of Euclidean polygonal tessellations with octahedral or dodecahedral elements. The research discovers three novel auxetic metamaterials with potentially large negative Poisson's ratios and high in-plane isotropy. It further demonstrates the control of auxeticity through tuning the geometric parameters. This work highlights the potential of Euclidean polygonal tessellations in designing innovative auxetic metamaterials and provides insights into the deformation mechanisms and geometric conditions that lead to this anomalous property.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2022)
Article
Mechanics
Zhongyuan Liao, Yingjun Wang, Liang Gao, Zhen-Pei Wang
Summary: The study focuses on the application of deep learning in the inverse design of tetra-chiral auxetic materials, aiming to enhance design efficiency and simplify sensitivity analysis through the development of parameterization methods and surrogate models.
COMPOSITE STRUCTURES
(2022)
Article
Engineering, Chemical
M. Ragni, D. Castagnetti, A. Spaggiari, E. Dragoni, M. Milelli, S. Girlando, P. Borghi
Summary: This research focuses on the shear strength of metal-elastomer bonded joints, which is influenced by manufacturing parameters and working temperature. Through experimental tests, the study identifies the parameters that most affect the shear strength of the joint, helping designers maximize the load-carrying capacity of the joint.
JOURNAL OF ADHESION
(2022)
Article
Engineering, Mechanical
Giovanni Meneghetti, Alberto Campagnolo, Alberto Visentin, Massimiliano Avalle, Matteo Benedetti, Andrea Bighelli, Davide Castagnetti, Andrea Chiocca, Luca Collini, Massimiliano De Agostinis, Alessandro De Luca, Eugenio Dragoni, Stefano Fini, Vigilio Fontanari, Francesco Frendo, Alessandro Greco, Giuseppe Marannano, Fabrizio Moroni, Antonio Pantano, Alessandro Pirondi, Alessandro Rebora, Alessandro Scattina, Raffaele Sepe, Andrea Spaggiari, Bernardo Zuccarello
Summary: This paper presents a Round Robin study among eleven Italian Universities to calibrate the peak stress method (PSM) using seven different commercial FE software packages. The study found that most of the FE software packages had similar PSM parameter values, with the main source of discrepancy being the stress extrapolation method at FE nodes.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
Andrea Sorrentino, Davide Castagnetti
Summary: The study presents a novel bone-mimicking biomaterial for vertebral implants, which shows promising potential after experimental validation. Through finite element analysis and shape optimization, the lattice structure with negative Poisson's ratio demonstrates mechanical properties close to human cancellous bones in terms of Young's modulus.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
Pierre-Sandre Farrugia, Ruben Gatt, Luke Mizzi, Joseph N. Grima
Summary: The deformation behavior of intersecting ligaments forming variants of the square and rectangular grids under mechanical compression was investigated. It was shown that these systems can exhibit a negative incremental Poisson's ratio at relatively large axial compressive strains. The extent of auxeticity depends on the relative offset of successive ligaments, the relative lengths of the ligaments as well as on their thickness. Two distinct modes of deformation were observed, one resembling that of the reentrant hexagonal honeycomb and the other that of the meta-tetrachiral system.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2023)
Article
Mechanics
Luke Mizzi, Andrea Spaggiari
Summary: This study investigates the impact of introducing geometric chiral characteristics on the mechanical properties of Euclidean polygonal tessellations with octahedral or dodecahedral elements. The research discovers three novel auxetic metamaterials with potentially large negative Poisson's ratios and high in-plane isotropy. It further demonstrates the control of auxeticity through tuning the geometric parameters. This work highlights the potential of Euclidean polygonal tessellations in designing innovative auxetic metamaterials and provides insights into the deformation mechanisms and geometric conditions that lead to this anomalous property.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2022)
Article
Instruments & Instrumentation
A. Sorrentino, D. Castagnetti
Summary: The research introduces a novel polyhedral mechanical metamaterial based on rotating triangular prisms connected by their corners, which demonstrates a large negative Poisson's ratio (NPR). Through a kinematic model, the study evaluates the auxeticity of the system by varying the geometrical parameters of the polyhedrons. Experimental results of 3D printed specimens and finite element analyses show excellent agreement with computational predictions, highlighting the highly auxetic property of rotating polyhedral systems.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Instruments & Instrumentation
Luke Mizzi, Seyedeh Farzaneh Hoseini, Marco Formighieri, Andrea Spaggiari
Summary: Shape memory alloys (SMA) are used in a novel SMA-metamaterial actuator to achieve a reversible, global elongation in multiple directions. The actuator consists of an SMA component, a bias component, and a metamaterial geometry that amplify and re-direct the unidirectional SMA actuation. A prototype actuator was tested in different configurations to demonstrate its functionality and reusability. A theoretical model was developed to predict the actuation stroke based on material properties and geometry, and was validated.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
L. Nicolini, A. Sorrentino, D. Castagnetti, A. Spaggiari
Summary: The work focuses on the design and prototyping of a novel end-effector for a collaborative robotic arm that can grab and drag industrial packages without lifting them. The proposed solution is a passive 3D-printed end-effector made of carbon fibre reinforced Onyx material, which has a simple, scalable, and inexpensive structure. It includes three main parts: a thin blade for separating boxes, a rocker arm-rod mechanism for grabbing packages, and a paddle with flexural springs for counterbalancing pushing force. The work presents a low-cost, passive end-effector suitable for collaborative robots, and the final prototype demonstrates its functionality and fabricability through 3D printing.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART L-JOURNAL OF MATERIALS-DESIGN AND APPLICATIONS
(2023)
Article
Mechanics
K. K. Dudek, L. Mizzi, J. A. Iglesias Martinez, A. Spaggiari, G. Ulliac, R. Gatt, J. N. Grima, V. Laude, M. Kadic
Summary: The ability to control Poisson's ratio of functional materials is essential for the development of efficient structures in various fields. This study proposes novel microscopic 2D and 3D functionally-graded mechanical metamaterials that can exhibit a wide range of Poisson's ratio depending on their composition. The research also explores the dynamic properties of these structures, specifically how the variation in composition affects wave propagation velocity. This has significant implications for applications involving wave attenuation or sensors.
COMPOSITE STRUCTURES
(2023)
Article
Instruments & Instrumentation
Lorenzo Nicolini, Andrea Sorrentino, Davide Castagnetti
Summary: This work focuses on studying, developing and validating a soft piezo-polymer that has enhanced piezo-elastic response and can be easily cast into any shape through a single and easy process. By combining polymerizable silicone with a barium titanate ceramic powder, a promising soft piezoelectric elastomer with flexibility, softness, and easy fabrication at ambient temperature was obtained for various sensing applications.
SMART MATERIALS AND STRUCTURES
(2023)
