scholarly journals Numerical implementation of multiple peeling theory and its application to spider web anchorages

2015 ◽  
Vol 5 (1) ◽  
pp. 20140051 ◽  
Author(s):  
Lucas Brely ◽  
Federico Bosia ◽  
Nicola M. Pugno
Keyword(s):  
Numerical Model ◽  
Numerical Approach ◽  
Complex Structures ◽  
Numerical Implementation ◽  
Spider Web ◽  
Complex Architectures ◽  
Fibrillar Adhesives

Adhesion of spider web anchorages has been studied in recent years, including the specific functionalities achieved through different architectures. To better understand the delamination mechanisms of these and other biological or artificial fibrillar adhesives, and how their adhesion can be optimized, we develop a novel numerical model to simulate the multiple peeling of structures with arbitrary branching and adhesion angles, including complex architectures. The numerical model is based on a recently developed multiple peeling theory, which extends the energy-based single peeling theory of Kendall, and can be applied to arbitrarily complex structures. In particular, we numerically show that a multiple peeling problem can be treated as the superposition of single peeling configurations even for complex structures. Finally, we apply the developed numerical approach to study spider web anchorages, showing how their function is achieved through optimal geometrical configurations.

scholarly journals Competition between delamination and tearing in multiple peeling problems

2019 ◽  
Vol 16 (160) ◽  
pp. 20190388 ◽  
Author(s):  
Lucas Brely ◽  
Federico Bosia ◽  
Stefania Palumbo ◽  
Massimiliano Fraldi ◽  
Ali Dhinojwala ◽  
...  
Keyword(s):  
Numerical Model ◽  
Mechanical Performance ◽  
Dissipated Energy ◽  
Complex Structures ◽  
Adhesive Systems ◽  
Complex Interplay ◽  
Spider Web ◽  
Interface Delamination ◽  
Adhesive Energy ◽  
Parameter Ranges

Adhesive attachment systems consisting of multiple tapes or strands are commonly found in nature, for example in spider web anchorages or in mussel byssal threads, and their structure has been found to be ingeniously architected in order to optimize mechanical properties: in particular, to maximize dissipated energy before full detachment. These properties emerge from the complex interplay between mechanical and geometric parameters, including tape stiffness, adhesive energy, attached and detached lengths and peeling angles, which determine the occurrence of three main mechanisms: elastic deformation, interface delamination and tape fracture. In this paper, we introduce a formalism to evaluate the mechanical performance of multiple tape attachments in different parameter ranges, where an optimal (not maximal) adhesion energy emerges. We also introduce a numerical model to simulate the multiple peeling behaviour of complex structures, illustrating its predictions in the case of the staple-pin architecture. Finally, we present a proof-of-principle experiment to illustrate the predicted behaviour. We expect the presented formalism and the numerical model to provide important tools for the design of bioinspired adhesive systems with tuneable or optimized detachment properties.

Research Regarding the Effects of 120 mm HE Mortar Bombs on Advanced Materials

2021 ◽  
Vol 42 ◽  
pp. 128-134
Author(s):  
Daniela Pintilie ◽  
Iuliana Florina Pană ◽  
Adrian Malciu ◽  
Constantin Puică ◽  
Cristina Pupăză
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Initial Velocity ◽  
High Explosive ◽  
Numerical Approach ◽  
Advanced Materials ◽  
Physical Mechanisms ◽  
Shock Wave Generation ◽  
3D Numerical Model ◽  
Experimental Trials

High Explosive Mortar bombs are used on the battlefield for destroying the manpower, non-armoured equipment and shelters. The paper describes an original experimental and numerical approach regarding the potential threats caused by the detonation of 120 mm HE mortar bombs. The evaluation of the bomb effect presumes the fulfillment of experimental trials that focus on two physical mechanisms which appear after the detonation of the cased high explosive. These mechanisms are the shock wave generation and the fragments propulsion, which were also studied by a numerical model that provides results over the bomb fragmentation mode. The novelty of the paper consists in the calibrated 3D numerical model confirmed by the experimental data, which provides information over the fragmentation process of the case and the initial velocity of its fragments, proving that the main threat of this type of ammunition is the effect through metal fragments. The results of numerical simulation and experimental data are used for their comparative analysis and the assessment of the phenomena.

scholarly journals Intramolecular, Visible Light-Mediated Aza Paternò-Büchi Reactions of Unactivated Alkenes

2021 ◽  
Author(s):  
Corinna Schindler ◽  
Dominique Blackmun ◽  
Stephen Chamness
Keyword(s):  
Visible Light ◽  
Oxidative Metabolism ◽  
Medicinal Chemistry ◽  
Complex Structures ◽  
Complex Architectures ◽  
Further Development

Azetidines are of particular interest in medicinal chemistry for their favorable properties, including increased resistance to oxidative metabolism and lower lipophilicity. The recent development of [2+2] reactions has significantly benefitted the previously limited methods for azetidine synthesis, but access to more complex architectures still requires further development. Herein we report a visible-light enabled intramolecular [2+2] cycloaddition to access tricyclic azetidines with 3D complex structures and high levels of saturation.

scholarly journals Optimal adjustment of FE model of concrete slab exposed to impact loading

2020 ◽  
Vol 313 ◽  
pp. 00024
Author(s):  
Daniel Jindra ◽  
Petr Hradil ◽  
Jiří Kala
Keyword(s):  
Numerical Model ◽  
Impact Loading ◽  
Concrete Slab ◽  
Numerical Approach ◽  
Fe Model ◽  
Model Response ◽  
Optimal Adjustment ◽  
Numerical Solver

Numerical approach using FEM has been used to describe the behaviour of concrete slab exposed to impact loading. 3D parametrical numerical model has been created, and the influence of various parameters values on model response is being investigated. The analyses have been conducted using explicit numerical solver of commercially available software LS-Dyna. The optimal adjustment of the model has been determined.

Development of the Bus Sandwich Roof Experimental and Numerical Approach

2015 ◽  
Vol 732 ◽  
pp. 211-214
Author(s):  
Karel Doubrava ◽  
Ctirad Novotný
Keyword(s):  
Mechanical Properties ◽  
Numerical Model ◽  
Numerical Approach ◽  
Global Structure ◽  
Experimental Results ◽  
Design Verification ◽  
Fem Modelling ◽  
The Future ◽  
Verification Process ◽  
Core Materials

This paper describes the design verification process of a new bus roof. The aim was to obtain a roof with comparable or better mechanical properties and likely dropped weight. The sandwich roof is developed in the framework of the project when properties matching real roof were compared to test samples. Different core materials and faces have been investigated. The experimental results serve to verify the suitability of the proposed FEM modelling for the future use on global structure roof numerical model.

scholarly journals Effects of the soil properties on the sea pressure profile due to seismic motions

2017 ◽  
Vol 56 (4) ◽  
Author(s):  
Alejandro Rodríguez-Castellanos ◽  
Rafael Ávila-Carrera ◽  
Ernesto Pineda-León ◽  
Víctor Martínez-Calzada ◽  
Francisco José Sánchez-Sesma
Keyword(s):  
Boundary Element Method ◽  
Numerical Model ◽  
Soil Properties ◽  
Extreme Values ◽  
Pressure Profile ◽  
Numerical Implementation ◽  
Two Dimensional ◽  
Diffracted Waves ◽  
Huygens Principle ◽  
P And Sv Waves

Large number of earthquakes have epicenters in offshore areas and their effects are a matter of great concern. This paper applies, for two dimensional problems, the Indirect Boundary Element Method to calculate the seismic pressure profile with the water depth due to the incidence of P- and SV-waves on the seabed, which can be characterized using the soil properties. Moreover, seismic amplifications of the seabed are highlighted. Our formulation can be considered as a numerical implementation of the Huygens’ Principle in which the diffracted waves are constructed at the boundary from which they are radiated. Thus mathematically, it is fully equivalent to the classical Somigliana’s representation theorem. Numerical results show the importance of knowing the properties of the marine soil because the pressure profile has an enormous dependence with respect to them. In some cases, pressure amplifications of six times between extreme values of soil materials can be expected. In addition, results from a layered numerical model evince that large seismic amplifications may be found, they can reach values up to 15.57 and 18.36 times the incident P- and SV-waves, respectively.

scholarly journals Numerical approach of the bond stress behavior of steel bars embedded in self-compacting concrete and in ordinary concrete using beam models

2013 ◽  
Vol 6 (3) ◽  
pp. 499-512 ◽  
Author(s):  
F.M. Almeida Filho ◽  
M. K. El Debs ◽  
A.L.H.C. El Debs
Keyword(s):  
Numerical Model ◽  
Constitutive Relations ◽  
Numerical Approach ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Self Compacting Concrete ◽  
Bond Behavior ◽  
Ordinary Concrete ◽  
Steel Bars ◽  
Good Agreement

The present study evaluates the bond behavior between steel bars and concrete by means of a numerical analysis based on Finite Element Method. Results of a previously conducted experimental program on reinforced concrete beams subjected to monotonic loading are also presented. Two concrete types, self-compacting concrete and ordinary concrete, were considered in the study. Non-linear constitutive relations were used to represent concrete and steel in the proposed numerical model, aiming to reproduce the bond behavior observed in the tests. Experimental analysis showed similar results for the bond resistances of self-compacting and ordinary concrete, with self-compacting concrete presenting a better performance in some cases. The results given by the numerical modeling showed a good agreement with the tests for both types of concrete, especially in the pre-peak branch of the load vs. slip and load vs. displacement curves. As a consequence, the proposed numerical model could be used to estimate a reliable development length, allowing a possible reduction of the structure costs.

A Dual-Scale Numerical Model for the Diffusive Behaviour Prediction of Biocomposites Based on Randomly Oriented Fibres

2022 ◽  
Author(s):  
Mustapha Nouri ◽  
Mahfoud Tahlaiti
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Element Model ◽  
Numerical Approach ◽  
Optical Microscope ◽  
Diffusion Problem ◽  
Finite Element Calculation ◽  
Element Calculation ◽  
Calculation Software ◽  
Diffusive Behaviour

This work aims to present a multi-scale numerical approach based on a 2D finite element model to simulate the diffusive behaviour of biocomposites based on randomly dispersed Diss fibres during ageing in water. So, first of all, the diffusive behaviour of each phase (fibres/matrix) as well as of the biocomposite was determined experimentally. Secondly, the microstructure of the biocomposite was observed by optical microscope and scanning electron microscope (SEM), and then regenerated in a Digimat finite element calculation software thanks to its own fibre generator: "Random fibre placement". Finally, the diffusion problem based on Fick's law was solved on the Abaqus finite element calculation software. The results showed an excellent agreement between the experiment and the numerical model. The numerical model has enabled a better understanding of the diffusive behaviour of water within the biocomposite, in particular the effect of the fibre/matrix interface. In terms of durability, the layered structure of this biocomposite has proven to be effective in protecting the plant fibres from hydrothermal transfer, which preserves the durability of the material.

Numerical Model Development and Validation for the WECCCOMP Control Competition

2018 ◽  
Author(s):  
Nathan Tom ◽  
Kelley Ruehl ◽  
Francesco Ferri
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Control Strategies ◽  
Model Development ◽  
Control Algorithms ◽  
Numerical Implementation ◽  
Energy Converter ◽  
Experimental Implementation ◽  
Two Stages ◽  
Development And Validation

This paper details the development and validation of a numerical model of the Wavestar wave energy converter (WEC) developed in WEC-Sim. This numerical model was developed in support of the WEC Control Competition (WECCCOMP), a competition with the objective of maximizing WEC performance over costs through innovative control strategies. WECCCOMP has two stages: numerical implementation of control strategies, and experimental implementation. The work presented in this paper is for support of the numerical implementation, where contestants are provided a WEC-Sim model of the 1:20 scale Wavestar device to develop their control algorithms. This paper details the development of the numerical model in WEC-Sim and of its validation through comparison to experimental data.

Numerical Analysis of Masonry Confined by FRCM

2017 ◽  
Vol 747 ◽  
pp. 558-566 ◽  
Author(s):  
Francesco Saverio Murgo ◽  
Claudio Mazzotti
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Structural Behaviour ◽  
Confined Masonry ◽  
Axial Forces ◽  
Commercial Code ◽  
The University ◽  
Model Approach

In the present paper, structural behaviour of masonry columns strengthened with fiber reinforced cementitious matrix have been investigated; in particular, numerical 3D simulations calibrated on experimental tests have been presented. T hree-dimensional numerical model, realized by using the commercial code MIDAS FEA, based on a macro-model approach, has been used to simulate the nonlinear structural behavior of masonry columns strengthened with FRCM, and two different models for unreinforced and strengthened columns have been adopted. The 3D numerical approach are presented and results discussed to investigate the interaction between masonry columns and reinforcement. The numerical model has been calibrated on a large number of experimental tests on confined masonry columns carried out at the University of Bologna; in particular, columns have been wrapped by FRP and FRCM and with different arrangements (continuous and discontinuous). The comparison of the numerical models with the experimental outcomes shows a good matching in terms of axial forces-strain curves and strength peak.

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