scholarly journals Soft and Stiff Simplex Tensegrity Lattices as Extreme Smart Metamaterials

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 187 ◽  
Author(s):  
Anna Al Sabouni-Zawadzka ◽  
Wojciech Gilewski
Keyword(s):  
Continuum Model ◽  
Theory Of Elasticity ◽  
Structural Members ◽  
Qualitative Properties ◽  
Normal Forces ◽  
Shear Modes ◽  
Actual Configuration ◽  
Deformation Modes ◽  
Extreme Materials

The present paper is dedicated to an evaluation of novel cellular metamaterials based on a tensegrity pattern. The materials are constructed from supercells, each of which consists of a number of simplex modules with different geometrical proportions. Mechanical properties of the metamaterial can be controlled by adjusting the level of self-equilibrated forces or by changing the properties of structural members. A continuum model based on the equivalence of strain energy of the 3D theory of elasticity with a discrete formulation is used to identify the qualitative properties of the considered metamaterials. The model allows the inclusion of nonlinearities related to the equations of equilibrium in actual configuration of the structure with self-equilibrated set of normal forces typical for tensegrities. The lattices are recognised as extreme metamaterials according to the eigensolution of the equivalent elasticity matrices of the continuum model. The six representative deformation modes are defined and discussed: stiff, soft and medium extensional modes and high (double) as well as low shear modes. The lattices are identified as unimode or nearly bimode according to the classification of extreme materials.

scholarly journals Towards Recognition of Scale Effects in a Solid Model of Lattices with Tensegrity-Inspired Microstructure

Solids ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 50-59
Author(s):  
Wojciech Gilewski ◽  
Anna Al Sabouni-Zawadzka
Keyword(s):  
Mechanical Properties ◽  
Continuum Model ◽  
Scale Effects ◽  
Theory Of Elasticity ◽  
Solid Model ◽  
Gradient Theory ◽  
General Description ◽  
Normal Forces ◽  
Second Gradient ◽  
Proposed Model

This paper is dedicated to the extended solid (continuum) model of tensegrity structures or lattices. Tensegrity is defined as a pin-joined truss structure with an infinitesimal mechanism stabilized by a set of self-equilibrated normal forces. The proposed model is inspired by the continuum model that matches the first gradient theory of elasticity. The extension leads to the second- or higher-order gradient formulation. General description is supplemented with examples in 2D and 3D spaces. A detailed form of material coefficients related to the first and second deformation gradients is presented. Substitute mechanical properties of the lattice are dependent on the cable-to-strut stiffness ratio and self-stress. Scale effect as well as coupling of the first and second gradient terms are identified. The extended solid model can be used for the evaluation of unusual mechanical properties of tensegrity lattices.

scholarly journals TOPOLOGICAL CLASSIFICATION OF BLACK HOLES: GENERIC MAXWELL SET AND CREASE SET OF A HORIZON

2011 ◽  
Vol 20 (06) ◽  
pp. 1095-1122 ◽  
Author(s):  
MASARU SIINO ◽  
TATSUHIKO KOIKE
Keyword(s):  
Black Holes ◽  
Smooth Function ◽  
Singularity Theory ◽  
Topological Classification ◽  
Cauchy Horizon ◽  
Qualitative Properties ◽  
Important Object ◽  
Maxwell Set ◽  
Spatial Section

The crease set of an event horizon or a Cauchy horizon is an important object which determines the qualitative properties of the horizon. In particular, it determines the possible topologies of the spatial sections of the horizon. By Fermat's principle in geometric optics, we relate the crease set and the Maxwell set of a smooth function in the context of singularity theory. We thereby give a classification of generic topological structures of the Maxwell sets and the generic topologies of the spatial section of the horizon.

scholarly journals Extreme Mechanical Properties of Regular Tensegrity Unit Cells in 3D Lattice Metamaterials

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4845
Author(s):  
Anna Al Sabouni-Zawadzka
Keyword(s):  
Mechanical Properties ◽  
Continuum Model ◽  
Soft Mode ◽  
Point Of View ◽  
Unit Cells ◽  
Deformation Modes

The study focuses on the identification of extreme mechanical properties of 3D lattice metamaterials based on regular tensegrity modules: 4-strut simplex, 3-strut simplex, expanded octahedron, truncated tetrahedron and X-module. The basis of the analysis is a continuum model which is used to find the equivalent elasticity matrices of the unit cells. For each examined tensegrity module a line of extreme properties is determined, which indicates the occurrence of the soft mode of deformation. Moreover, the eigenvectors corresponding to soft and stiff deformation modes are calculated and presented graphically. The obtained results are promising from the point of view of future creation of tensegrity lattices and metamaterials with extreme mechanical properties. One of the analysed materials is identified as quasi bimode, two as quasi trimodes, another one as a trimode and one more as a unimode.

scholarly journals Intelligent control based on ergatic systems in conditions of incomplete and fuzzy information

2021 ◽  
Vol 2131 (2) ◽  
pp. 022101
Author(s):  
E Prokopenko ◽  
B Martynov ◽  
I Magerramov ◽  
O Popov ◽  
D Fathki
Keyword(s):  
Quality Criteria ◽  
Economic Systems ◽  
Machine Component ◽  
Qualitative Properties ◽  
Management Quality ◽  
Hybrid Intelligence ◽  
Rational Alternative ◽  
Machine Systems ◽  
High Level

Abstract The article deals with the management of human-machine (ergatic) systems in the conditions of digital transformation in relation to their functioning in the presence of NON-factors, such as: uncertainty, complexity, instability, ambiguity. Modern conditions for the formation of the digital economy imply the search and use of a new methodology in the organization of management activities, including the regional level. This process is carried out through the widespread use of human-machine systems with a high level of intellectualization of the machine component, the use of hybrid intelligence and the formation of bionts. We show a variant of classification of ergatic systems, focused on socio-economic systems. We propose a method for choosing a rational alternative to support the management of human-machine systems in the conditions of vagueness and ambiguity of the initial data and approaches to the management quality criteria. A fuzzy approach to a multi-criteria problem is proposed. It leads to a certain combination of fuzzy selection criteria, and to the study of complex systems as a hierarchical structure, with the representation of system elements and its qualitative properties as fuzzy mathematical models, the combination of which will give a mathematical model of the systems.

Effect of Discrete Sectional Bonding of Cellular Core on Impact Performance of Square Tubes: A Finite Element Study

2018 ◽  
Author(s):  
Muhammad Ali ◽  
Eboreime Ohioma ◽  
Khairul Alam
Keyword(s):  
Impact Loading ◽  
Axial Loading ◽  
Deformation Mode ◽  
Displacement Curve ◽  
Structural Members ◽  
Progressive Deformation ◽  
Impact Performance ◽  
Deformation Modes ◽  
Force Displacement ◽  
Passenger Cabin

Thin walled members such as square tubes are commonly used in vehicle’s frontal chassis to provide protection and damage attenuation to the passenger cabin in the case of impact loading. These structural members undergo progressive deformation under axial loading. The type of deformation mode is critical as it defines the overall configuration of force-displacement curve. There are different types of deformation modes for square tube under axial loading. Likewise, cellular structure exhibit distinct deformation modes under in-plane loading. The work presented here investigates the effects of partial or discrete bonding of cellular core structure on deformation modes of square tubes under axial loading. The results show that discrete bonding of cellular core with the tube has significant effect on progressive deformation of tubes and therefore, presents an opportunity to re-configure force-displacement curve for improved protection of automobile structures under impact loading.

Study of Energy Absorption Characteristics of Square Tube With Composite Cellular Core

2018 ◽  
Author(s):  
Muhammad Ali ◽  
Eboreime Ohioma ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Compressive Loading ◽  
Absorption Capacity ◽  
Structural Members ◽  
Tubular Structures ◽  
Tube Material ◽  
Energy Absorption Capacity ◽  
Core Tube ◽  
Energy Absorbing ◽  
Deformation Modes

Square tubes are primarily used in automotive structures to absorb energy in the event of an accident. The energy absorption capacity of these structural members depends on several parameters such as tube material, wall thickness, axial length, deformation modes, locking strain, crushing stress, etc. In this paper, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. Here, the crushing response of composite cellular core tube was numerically studied using ABAQUS/Explicit module. The energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, crushing stroke, and energy curves were discussed. The composite cellular core tube shows promise for improving the crashworthiness of automobiles.

scholarly journals Vertical Lifting Ice Forces Caused by a Rising Water Level, and their Action on a Vertical Slender Structure (PILE) (Abstract only)

1983 ◽  
Vol 4 ◽  
pp. 306
Author(s):  
Per Tryde
Keyword(s):  
Water Level ◽  
Freezing Point ◽  
Theory Of Elasticity ◽  
Water Level Fluctuations ◽  
Normal Forces ◽  
Complete Failure ◽  
Slender Structure ◽  
Ice Force ◽  
Ice Forces ◽  
Uplift Forces

The problem of vertical lifting ice forces caused by a rising water level, and their action on a vertical slender structure (pile), has been studied by use of the classical theory of an elastic plate resting on an elastic support, in order to calculate the moments and normal forces in the sheet that cause rupture and thus produce cracks in the sheet (Nevel 1974). When cracks are formed, the continuous rise of the water level tends to widen them further, and the theory of elasticity is no longer valid. Usually, formation of cracks in structural members results in complete failure, but this may not be the case here. If the temperature of the air is below zero, the water penetrating the cracks will freeze when it meets with the upper part of the ice and with the air, both having a temperature far below the freezing point of water. Thus the cracks will be continuously healed up, as they are widened by the rising water level. A material healing its own cracks along the rupture zone gives a completely changed stress/strain situation during the deformation. This new approach may lead to a theory which is able to predict the uplift forces of ice as a function of time, of frequency and amplitude of water-level fluctuations, and of air temperature. It appears that the pile is lifted only a short distance with each cycle of water-level fluctuation. Since the downward ice force is smaller than the upward force, and the pile has a larger resistance to compression than to pulling, the pile may eventually, in the course of repeated cycles, be lifted several metres.

Sign in / Sign up

Export Citation Format

Share Document