1,721,125 research outputs found
Materiali strutturali biologici e bioinspirati
Full text linkI materiali sviluppati dall'uomo e utilizzati per applicazioni tecnologiche, in generale non sono multifunzionali, né tolleranti ai difetti, né auto-riparanti, né auto-pulenti, né gerarchici. Il contrario è vero per i materiali naturali, che manifestano queste proprietà nonostante siano "costruiti" usando un numero limitato di componenti di base estremamente comuni. Una comprensione approfondita del perché sia così potrebbe fornire la chiave per accelerare l'avvento di una nuova era basata su nuovi materiali.Questo è l'obiettivo della ricerca sui materiali bioispirati, che è in continua evoluzione e ha già fatto passi significativi verso questa meta
A theoretical-numerical model for the peeling of elastic membranes
Full text linkThe adhesive behavior of biological attachment structures such as spider web anchorages is usually studied using single or multiple peeling models involving “tapes”, i.e. one-dimensional contacts elements. This is an oversimplification for many practical problems, since the actual delamination process requires the modeling of complex two-dimensional adhesive elements. To achieve this, we develop a theoretical-numerical approach to simulate the detachment of an elastic membrane of finite size from a substrate, using a 3D cohesive law. The model is validated using existing analytical results for simple geometries, and then applied in a series of parametric studies. Results show how the pull-off force can be tuned or optimized by varying different geometrical or mechanical parameters in various loading scenarios. The length of the detachment boundary, known as the peeling line, emerges as the key factor to maximize adhesion. The approach presented here can allow a better understanding of the mechanical behavior of biological adhesives with complex geometries or with material anisotropies, highlighting the interaction between the stress distributions at the interface and in the membrane itself
Computational modeling of the mechanics of hierarchical materials
Full text linkStructural hierarchy coupled with material heterogeneity is often identifi ed in natural materials, from the nano- to the macroscale. It combines disparate mechanical properties, such as strength and toughness, and multifunctionality, such as smart adhesion, water repellence, self-cleaning, and self-healing. Hierarchical architectures can be employed in synthetic bioinspired structured materials, also adopting constituents with superior mechanical properties, such as carbon nanotubes or graphene. Advanced computational modeling is essential to understand the complex mechanisms that couple material, structural, and topological hierarchy, merging phenomena of different nature, size, and time scales. Numerical modeling also allows extensive parametric studies for the optimization of material properties and arrangement, avoiding time-consuming and complex experimental trials, and providing guidance in the fabrication of novel advanced materials. Here, we review some of the most promising approaches, with a focus on the methods developed by our group
Systematic numerical investigation of the role of hierarchy in heterogeneous bio-inspired materials
Full text linkIt is well known that hierarchical structure is an important feature in biological materials to optimise various properties, including mechanical ones. It is however still unclear how these hierarchical architectures can improve material characteristics, for example strength. Also, the transposition of these structures from natural to artificial bioinspired materials remains to be perfected. In this paper, we introduce a numerical method to evaluate the strength of fibre-based heterogeneous biological materials and systematically investigate the role of hierarchy. Results show that hierarchy indeed plays an important role and that it is possible to “tune” the strength of bio-inspired materials in a wide range of values, in some cases improving the strength of non-hierarchical structures considerably
Deformation characteristics of composite laminates- Part II: An experimental/numerical study on equivalent single-layer theories
No full textThe influence of substrate roughness, patterning, curvature, and compliance in peeling problems
Full text linkNMP is supported by the European Commission under the Graphene FET Flagship (WP14 'Polymer composites' No. 604391) and FET Proactive 'Neurofibres' grant No. 732344. FB is supported by 'Neurofibres' grant No. 732344
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