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The impact behaviour of plate-like assemblies made of new interlocking bricks: An experimental study
Abstract
In this paper we study a new type of interlocking brick recently proposed by the authors. The brick has a symmetrical geometry with four concavo-convex side surfaces for the interlocking purpose. Drop weight tests have been conducted to investigate the mechanical response of interlocking assembly plates by applying different levels of impact force and lateral confining load. The results show that, compared with monolithic plates, the new interlocking assembly plates have significantly improved flexural performance in terms of impact energy absorption capacity. The fracture of individual bricks during the impact always occurs along a load transmission path that is determined by the geometrical constraints of the interlocking bricks. Most importantly, the interlocking design of the plate-like assembly can effectively prevent the propagation and spread of the cracks, so that the damage to a single brick will not lead to a catastrophic failure of the entire structure.
... Thus different patterns will be shown on different sides of the assembly plate, which may lead to different impact resisting performance on the two sides. Most recently, the authors of the present paper proposed a new design of interlocking brick [20,21], in which the curved surfaces of the same profile on all sides of the interlocking brick (see Fig. 1b) lead to the symmetrical in-plane behaviour of the assembly plate in the two principal directions. Besides, additional curved side surfaces of the new brick provide more resistance against out-of-plane movements because of increased friction and shear resistance. ...
... However, very limited experimental and numerical investigations can be found from literature on studying the dynamic behaviour of interlocking structures under impact loads [28,29]. The potential applications of these novel structures (assembly plates made of interlocking bricks) can be protective walls in resisting the collision of fragments produced in explosion, or road side crash barrier [20]. In 2012, Khandelwall et al. [29] conducted drop weight tests to study the dynamic behaviour of the topologically interlocked material (TIM) created using identical tetrahedral elements made of brittle base material. ...
... Numerical modelling of the same TIM assembly conducted by Feng et al. [28] demonstrated that TIM could absorb more impact energy than conventional solid plates. Recently, the authors of the present paper carried out a series of drop weight tests on both monolithic plates and the assembly plates made of the newly designed interlocking brick [20,21] under different loading scenarios, i.e., different ...
This paper presents an extensive numerical study on the impact behaviour of plate-like assemblies made of interlocking concrete bricks. In the proposed 3D finite element model, a damage based concrete model is employed with considerations of strain rate effect and concrete failure criteria. Boundary conditions are appropriately defined to simulate various initial loading scenarios. The impact responses of both monolithic and assembly plates are investigated, and the numerical model is validated by comparing the predicted results with experimental data. Compared to the monolithic plate, the structural flexibility, energy absorption capacity and the tolerance to local failure are improved in the assembly plates made of interlocking bricks. A comparative study is also carried out on the assembly plates made of two types of interlocking bricks including osteomorphic brick with two curved side surfaces and newly designed interlocking brick with four curved surfaces. It is found that the plate made by the newly developed interlocking brick exhibits less deflection and absorbs more energy than the existing osteomorphic brick.
... The topologically interlocking method can be used as an innovative way in the design of a hybrid structure. The mechanical properties of segmented structures can be improved by using topologically interlocking elements as structural components [2,[6][7][8][9][10][11][12][13]. One of the aims of topologically interlocking is to improve the damage tolerance of brittle material by pre-fragmenting structures [14]. ...
... Furthermore, topologically interlocking can provide high resistance to the removal of the elements, and maintain structural integrity even when some blocks are missing [18]. In the authors' previous works [13,20], a new design of interlocking brick was proposed. The plate assembled by the new interlocking bricks was found to significantly improve the structural flexibility, energy absorption capacity and the tolerance to local failure compared to the monolithic plate made of the same concrete material under impact loading. ...
... The plate assembled by the new interlocking bricks was found to significantly improve the structural flexibility, energy absorption capacity and the tolerance to local failure compared to the monolithic plate made of the same concrete material under impact loading. More importantly, the propagation and spread of the cracks were effectively restrained by the interfaces of the bricks, so that the damage could be confined within a single brick without causing a catastrophic failure of the entire structure [12,13]. Also, the plate made by the new interlocking bricks showed less deflection and more energy absorption than the plate assembled using the existing osteomorphic bricks [12]. ...
In this study, the mechanical responses of an assembly plate made of topologically interlocking concrete bricks
with rubber as soft interfaces are investigated. The principle of topological interlocking is combined with the concept of hybrid material design. A series of quasi-static tests are conducted to compare the mechanical behaviour
of the hybrid interlocking assembly plate with those obtained from the monolithic plate and the interlocking assembly plate without soft interfaces. The results show that the hybrid assembly plate has a remarkable flexural
compliance with less damage in the bricks compared to the other two. The effect of lateral confining load on
the structural behaviour of the hybrid interlocking assembly plate is also investigated. In addition, a 3D numerical
model is established to predict the overall behaviour, failure mode and the damage distributions of the hybrid assembly plate. Then the hybrid assembly plate under various lateral confining loads and with different friction factors between rubber and bricks is studied numerically. It is found that, although the maximum transverse force is
influenced by the initial confining load and the friction factor, the mechanical behaviour of the hybrid structure is
consistent in large deformation.
... In particular, Dyskin et al. (14) explored how regular, convex polyhedral (platonic) solids can interlock and serve as building blocks for TIMs, with examples including cubes (15,17) and tetrahedra (18,19). Nonplatonic geometries with planar surfaces such as truncated tetrahedra (20)(21)(22) or blocks with nonplanar surfaces (8,(23)(24)(25)(26)(27) have also been proposed. Interestingly the interlocked blocks can still slide, rotate, or separate to some extent, providing a wealth of tunable deformation mechanisms and properties (12,16,28). ...
... For example, the frictional sliding of the blocks on one another can dissipate energy and confer TIMs with very high impact resistance compared with monolithic panels of the same materials, a strategy which can be used to overcome brittleness of glasses and ceramics. However, improvements in impact resistance and energy absorption are achieved at the expense of 40-80% losses in strength (11,20,25,27,29). Despite recent efforts in unifying designs (30)(31)(32) and optimization (33,34), there are still no comprehensive guidelines to select optimum architectures for given applications and requirements. ...
Topologically interlocked materials (TIMs) are an emerging class of architectured materials based on stiff building blocks of well-controlled geometries which can slide, rotate, or interlock collectively providing a wealth of tunable mechanisms, precise structural properties, and functionalities. TIMs are typically 10 times more impact resistant than their monolithic form, but this improvement usually comes at the expense of strength. Here we used 3D printing and replica casting to explore 15 designs of architectured ceramic panels based on platonic shapes and their truncated versions. We tested the panels in quasi-static and impact conditions with stereoimaging, image correlation, and 3D reconstruction to monitor the displacements and rotations of individual blocks. We report a design based on octahedral blocks which is not only tougher (50×) but also stronger (1.2×) than monolithic plates of the same material. This result suggests that there is no upper bound for strength and toughness in TIMs, unveiling their tremendous potential as structural and multifunctional materials. Based on our experiments, we propose a nondimensional "interlocking parameter" which could guide the exploration of future architectured systems.
... The bricks had specially engineered geometries with two curved side surfaces for interlocking purposes. Javan et al. [215] conducted drop-weight tests to investigate the mechanical response of new interlocking assembly plates. The brick used in the plate had a symmetrical geometry with four curved side surfaces that differed from the brick proposed by Djumas [214], as shown in Fig. 31C. ...
... Fig. 31. Bio-inspired structures for civil engineering; (A) building ceramic composite with a nacre-like structure [207]; (B) bricked-wall structure [213]; (C) interlocking concrete mimicking nacre structure [215]; (D) FGC mimicking the structure of sea urchin spines [36]; (E) concrete structure with staggered arrangement of steel wire mesh [221]; (F) Bio-inspired 3D printing concrete [222]. ...
It is widely known that the availability of lightweight structures with excellent energy absorption capacity is essential for numerous engineering applications. Inspired by many biological structures in nature, bio-inspired structures have been proved to exhibit a significant improvement over conventional structures in energy absorption capacity. Therefore, use of the biomimetic approach for designing novel lightweight structures with excellent energy absorption capacity has been increasing in engineering fields in recent years. This paper provides a comprehensive overview of recent advances in the development of bio-inspired structures for energy absorption applications. In particular, we describe the unique features and remarkable mechanical properties of biological structures such as plants and animals, which can be mimicked to design efficient energy absorbers. Next, we review and discuss the structural designs as well as the energy absorption characteristics of current bio-inspired structures with different configurations and structures, including multi-cell tubes, frusta, sandwich panels, composite plates, honeycombs, foams, building structures and lattices. These materials have been used for bio-inspired structures, including but not limited to metals, polymers, fibre-reinforced composites, concrete and glass. We also discussed the manufacturing techniques of bio-inspired structures based on conventional methods, and adaptive manufacturing (3D printing). Finally, contemporary challenges and future directions for bio-inspired structures are presented. This synopsis provides a useful platform for researchers and engineers to create novel designs of bio-inspired structures for energy absorption applications.
... The concept is to separate a monolithic structure 46 into a number of identical elements with special shapes and arrangement that could keep all 47 elements in place through kinematic constraints imposed by neighbouring elements [2]. By 48 using topological interlocking elements, it is possible that a structure is assembled without any 49 binder or connector, which distinguishes itself from the assembly structures made of traditional 50 regular elements [3,4]. Besides, the interlocking assembly structures could undergo a certain 51 degree of relative movements, which is more flexible and can absorb more energy than 52 monolithic structures [5]. ...
... 70 Additionally, the sound absorption ability was found to be enhanced in a plate assembled by 71 the topologically interlocked osteomorphic blocks [19]. Recently, a new type of interlocking 72 brick was proposed as shown in Fig. 1 (d) [4,20], in which all four side surfaces were 73 interlocked, giving better out-of-plane resistance and energy absorption capacity compared 74 to the ostemorphic brick. In this paper, a novel design of non-planar interlocking element is proposed, which can 81 be applied in the tube-shaped structures. ...
In this paper, a novel non-planar interlocking element is developed, which can be used to construct cylindrical structures. The proposed element has a symmetrical geometry with six curved side surfaces to be interlocked with adjacent elements. A tubular structure can be constructed by assembling a number of identical non-planar elements, and the movement of each element is naturally restricted in all directions. To investigate the performance of the proposed system, a 3D finite element model is established to simulate the dynamic response of a concrete tunnel assembled using the new non-planar elements. Compared to the monolithic concrete tunnel and the tunnel constructed of normal concrete segments, the interlocking tunnel has shown a lower peak contact force and a higher energy absorption capacity. Besides, the joint opening and the damage area could be significantly reduced by the interlocking feature. A parametric study is also conducted to investigate effects of the confining load and the initial impact velocity on the performance of the interlocking system.
... Research on topologically interlocked elements has mostly focused on small-scale structures (Brugger et al. 2009;Javan et al. 2017;Zareiyan and Khoshnevis 2017). This research focuses on structural characterization of TeSA shear walls at a building scale for implementation as lateral load-resisting systems. ...
This thesis investigates the structural behavior of tessellated structural-architectural (TeSA) shear wall systems that are made of pre-fabricated concrete tessellated elements (repetitive patterns of similar tiles), and have the ability to localize structural damage. TeSA walls can be used for rapid construction, reconfiguration, disassembly, and reuse, as they are built of repetitive discrete tiles. This study covers topologically interlocking TeSA walls in one and two directions (1D and 2D interlocking), for which the separation of tiles is prevented in one or two directions, respectively, through the interlocking of each piece to neighboring pieces. Finite element analysis is used to understand the fundamental behavior and the capacity of the TeSA walls.
An existing conventional shear wall, for which test data is available, is modeled in a finite element package. Modeling details, material data, and boundary conditions are validated by comparing the numerical model and the test results. The validated modeling technique is then adopted to characterize the behavior of the 1D and 2D TeSA walls.
First, the behavior of the 1D interlocking TeSA walls is studied. 1D TeSA walls have interlocking in one direction, in addition, vertical unbonded post-tensioning (PT) strands provide stability and self-centering. Results of the monotonic pushover analysis show that the 1D interlocking walls with PT are able to offer similar capacities compared to an equivalent conventional wall with no PT. Increasing PT force also increases the initial stiffness of TeSA walls.
This thesis investigates the structural behavior of tessellated structural-architectural
(TeSA) shear wall systems that are made of pre-fabricated concrete tessellated elements
(repetitive patterns of similar tiles), and have the ability to localize structural damage.
TeSA walls can be used for rapid construction, reconfiguration, disassembly, and reuse, as
they are built of repetitive discrete tiles. This study covers topologically interlocking TeSA
walls in one and two directions (1D and 2D interlocking), for which the separation of tiles
is prevented in one or two directions, respectively, through interlocking of each piece to
neighboring pieces. Finite element analysis is used to understand the fundamental behavior
and the capacity of the TeSA walls.
An existing conventional shear wall, for which test data is available, is modeled in
a finite element package. Modeling details, material data, and boundary conditions are
validated by comparing the numerical model and the test results. The validated modeling
technique is then adopted to characterize the behavior of the 1D and 2D TeSA walls.
First, the behavior of the 1D interlocking TeSA walls is studied. 1D TeSA walls
have interlocking in one direction, in addition, vertical unbonded post-tensioning (PT)
strands provide stability and self-centering. Results of the monotonic pushover analysis
show that the 1D interlocking walls with PT are able to offer similar capacities compared
to an equivalent conventional wall with no PT. Increasing PT force also increases initial
stiffness of TeSA walls.
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Next, monotonic push-over analysis of the 2D interlocking TeSA wall is conducted,
and lateral load-displacement behaviors of the conventional and the TeSA walls are
compared. The results indicate that the TeSA wall behavior is affected by the continuity
and the pattern of the tiles along the edge of the wall. Progression of damage in tiles at
different drift ratios is investigated, and the number of damaged tiles that would need
replacement is studied. A comprehensive parametric study is conducted on the 2D
interlocking TeSA walls, which shows that friction coefficient and concrete compression
strength have negligible effect on the lateral load deformation behavior of walls.
Reinforcement ratio has considerable effect on the wall capacity. In addition to finite
element analysis, a simplified analytical method is proposed to estimate the lateral load
capacity of 2D TeSA wall, which provided results close to ones from the numerical
simulations.
... (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) as 3D printing ( Djumas et al., 2017;Feng et al., 2015;Khandelwal et al., 2015;Malik et al., 2017;Slesarenko et al., 2017a ), and casting ( Krause et al., 2012;Mirkhalaf et al., 2018 ) and of variety of shapes such as regular tetrahedral ( Khandelwal et al., 2012( Khandelwal et al., , 2014, osteomorphic ( Autruffe et al., 2007;Dyskin et al., 2003b;Javan et al., 2017 ), regular cubes ( Dugue et al., 2013;Estrin et al., 2004 ), buckyballs ( Dyskin et al., 2003a ), jigsaw , or puzzle-like shapes ( Haldar et al., 2017;Mirkhalaf and Barthelat, 2017 ). These blocks are then assembled through precise methods: manual assembly ( Krause et al., 2012 ), robotic pick and place ( Mather et al., 2012 ), template assisted parallel assembly ( Mather, 2007 ), self-assembly Siegmund et al., 2016 ), or by embedded wires ( Siegmund et al., 2013 ). ...
Precise material architectures and interfaces can generate unusual and attractive combinations of mechanisms and properties. For example, the segmentation into blocks of finite size and well-defined geometries can turn brittle ceramics into tough, deformable and impact resistant material systems. This strategy, while scarcely used in engineering, has been successfully used for millions of years in biological materials such as bone, nacre or tooth enamel. In this work, the precise relationships between architecture, mechanics, and properties in architectured ceramic panels are explored using a combination of mechanical testing with stereo-imaging, 3D reconstruction, and finite-element/analytical modeling. In particular, this work shows that a fine balance of interlocking and block size generates controlled frictional sliding and rotation of blocks, minimizes damage to individual blocks and optimizes performance. These ceramic architectured panels have 1/4 to 1/2 of the strength of monolithic ceramic panels, but they can absorb 5 to 20 times more mechanical energy, making them very attractive for applications where high surface hardness or high resistance to temperature must be combined with resistance to impact and toughness.
... Further block geometries [74] shown in Fig. 15 were also considered. The flexural performance of an assembly of modified, osteomorphic-like concrete blocks, yet with interlocking at four, rather than two contact surfaces, was studied in Ref. [75]. A substantial improvement over the performance of a monolithic plate in terms of bending compliance and impact energy absorption was demonstrated. ...
In this chapter, we present a materials design principle which is based on the use of segmented, rather than monolithic, structures consisting of identical blocks locked within the assembly by virtue of their special geometry and mutual arrangement. First, a brief history of the concept of topological interlocking materials and structures is presented and current trends in research are outlined. Recent work of the authors and colleagues directed at the variation of the shape of interlockable building blocks and the mechanical performance of structures—either assembled from them or 3D printed—are overviewed. Special emphasis is put on materials responsive to external stimuli. Finally, an outlook to possible new designs of topological interlocking materials and their engineering applications is given.
... The results indicated that the assembly panel without soft interfaces showed higher flexural compliance than a monolithic concrete panel, and the sample with soft interfaces suffered less damage. Furthermore, Javan et al. [124,125] carried out a series of experiments to investigate interlocked panels with osteomorphic blocks under low-velocity impact loads. It was found that a smaller number of concrete bricks were damaged under impact. ...
Nature provides examples of resilient materials and structures with optimised morphologies and topologies to achieve excellent mechanical and structural properties and sustainable options for the construction industry. This paper provides an overview of nature-inspired materials applicable to buildings and civil structures. Current research on bio-inspired novel cementitious composites, bacteria-enhanced materials, building envelopes and facade systems, advanced manufacturing processes, and their applications are discussed. Moreover, this paper provides insights for future research on designing and developing bio-inspired building materials and resilient structures.
... Moreover, [23] demonstrated that for certain classes of solid-architecture combination a simultaneous improvement of strength and toughness of the assembled plate relative to the monolithic plate is possible. Such favourable mechanical performance of the assembled plate structures also were found to extend to impact loading by altering the relationship between impact velocity and residual velocity [24] and increased impact energy absorption capacity [25,26,27]. In addition, assembled plate structures can serve as the template for the implementation of adaptive structural configurations [28,29] to control system stiffness, strength and toughness. ...
Topologically interlocked material systems are two-dimensional assemblies of unit elements from which no element can be removed from the assembly without disassembly of the entire system. Consequently, such tile assemblies are able to carry transverse mechanical loads. Archimedean and Laves tilings are investigated as templates for the material system architecture. It is demonstrated under point loads that the architecture significantly affects the force-deflection response. Stiffness, load carrying capacity and toughness varied by a factor of at least three from the system with the poorest performance to the system with the best performance. Across all architectures stiffness, strength and toughness are found to be strongly and linearly correlated. Architecture characterizing parameters and their relationship to the mechanical behavior are investigated. It is shown that the measure of the smallest tile area in an assembly provides the best predictor of mechanical behavior. With small tiles present in the assembly the contact force network structure is well developed and the internal load path is channeled through these stiffest components of the assembly.
... From an ecological view point, the interlocking block construction permits for a huge reduction in the embodied power in comparison to a kiln sintered clay masonry or building with the concrete. As a matter of fact, the massively energy consuming sintering procedure at high temperature of the clay bricks is substituted by a further compaction utilizing a mechanical press [3]. Manufacturing of the traditional bricks and blocks is a considerable contributor to the ecological depletion. ...
The production of the blocks is an essential aspect of the constructional industry. The production process is considerably energy exhausting, contamination emitter, un eco-friendly, and waste generator. The target of this research is to produce an innovative eco-friendly interlocking block made from locally available waste materials like palm oil clinker, palm oil fuel ash, and quarry dust by non-conventional procedure. The modern approach neither exhausts the virgin material of earth nor does it consume energy resources or emit contamination, with remarkable economic and ecological benefits. The properties of the blocks like the compressive strength of the blocks, compressive strength of the prism, and modulus of rupture, water absorption, ultra-sonic pulse velocity, thermal conductivity, and the efflorescence were investigated in this research. Based on the results out coming, the blocks developed in this research can be classified as light weight and thermally efficient. The hybrid interlocking blocks produced wholly from waste materials showed superior properties in comparison to the conventional interlocking blocks and satisfied the relevant thresholds. Thus, they can be used in the building sector as substitute to the conventional blocks.
... In a few cases, the crack propagation started from both the transient regions. Similar crack failure patterns were observed on interlocking bricks during impact loading by Javan et al. (2017). ...
The present study demonstrates the mixing process of lime stabilized fly ash bricks. In India, fly ash bricks are gaining popularity against fired clay bricks due to their green benefits. However, the lack of technical guidelines on mixing methodology, and disproportionate moisture content in raw materials adversely affect the performance and production of fly ash bricks. To mitigate this, dry and powdered form hydrated lime is suggested in place of slaked lime to avoid the excess moisture content. This study experimentally examines the combined effect of two distinct mixing sequences at five different moisture contents on the properties of hydrated lime fly ash (HLF) bricks. Compressive strength, dry bulk density, water absorption, percentage voids, dynamic modulus of elasticity, impact energy, and drying shrinkage were selected as the parameters for comparison of HLF bricks. Bricks with 15% moisture content produced by a two-stage mixing sequence were found to have enhanced mechanical and durability performance. Furthermore, economic and environmental comparisons (in terms of embodied energy and embodied carbon calculations) revealed that HLF bricks are more beneficial compared to fired clay bricks.
... Previous research on topologically-interlocked elements has primarily focused on small-scale structures [20][21][22]. The current research studies the structural characterization of TeSA shear walls at building scale for potential use as lateral load-resisting systems. ...
This paper studies the lateral behavior of a reinforced concrete tessellated structural-architectural (TeSA) shear wall system. TeSA walls are made of prefabricated repetitive tiles and have the ability to localize damage which occurs under extreme loading. A TeSA wall is intended for architectural interest, automated construction, reconfiguration, disassembly, and reuse. This study focuses on TeSA tiles that are topologically interlocking in two directions. Nonlinear finite element analysis is used to study the monotonic pushover behavior of TeSA walls with different edge tile configurations and a comparison is made thereof with a conventional reinforced concrete shear wall. The results indicate that the strength of TeSA walls is not significantly affected by the configuration of edge tiles. Damage progression in tiles and the number of damaged tiles that need to be replaced are also presented at different drift ratios. The study shows that reinforcement ratio substantially affects the wall lateral capacity. Finally, a simplified cross-sectional analysis procedure is proposed to provide a lower and upper bound estimate of the lateral capacity of TeSA walls.
... Later studied the systematization of the TI mechanical behavior, [7][8] [9]. Many cases, research complemented with experimental tests, that established advantages of TI mechanics with brittle materials, such as glass [10], ceramic [11], or even impact with monolithic concrete [12]. The manufacture of interlocking materials has received a considerable increase in alternatives, thanks to the use of additive manufacturing technologies [13]. ...
The modular interlocked blocks in flat structures are known in ancient buildings with pure-compression constructions. Over the last two decades, this structural bond has become relevant, studied by mechanical engineers, and material scientists due to the properties and design freedom that modular structures have. The structural hierarchy existing in topologically interlocked structures enhance the performance, allowing to design and fabricate custom block elements. The main reason to consider this system is that, from the architectural perspective, it is composed by identical modular elements, and it discretizes flat or curved surfaces into elements that work only by contact and compression. This article presents preliminary studies for its application and different approaches for designing discrete interlocked assemblies with a focus on the application for architectural structures: studying the structural performance of contact analysis and introducing the combination of topological interlocking with different structural principles.
Tessellated Structural-Architectural (TeSA) systems are composed of repeated tiles that can interconnect, be designed to have load carrying capacity, and are aesthetically pleasing. TeSA systems may localize damage to few tiles when subjected to extreme loads, may facilitate easier or faster reparability, and contribute to resilience. This research investigates numerical modeling of simply supported TeSA beams. Finite Element (FE) analysis was performed and the results were validated using experiments of TeSA beams made of Medium Density Fiberboard (MDF). The FE analysis incorporated gaps and interaction between tiles. The results showed that contact properties and gap size between tiles affected the calculated load-displacement relationship and strain of the TeSA beam. Contact properties were captured by a pressure-overclosure relationship, which required calibration using the global load-displacement response obtained from testing. Incorporation of geometric nonlinearity did not affect the results significantly. Beams with varying friction coefficient between tiles, load and support bearing width, Poisson's ratio and aspect ratios were analyzed. The results showed that TeSA beams had smaller stiffness than solid beams with similar dimensions. The outcomes of this research provide insights on the behavior and modeling of TeSA structures.
Topologically interlocked material systems are two-dimensional assemblies of unit elements from which no element can be removed from the assembly without disassembly of the entire system. Consequently, such tile assemblies are able to carry transverse mechanical loads. Archimedean and Laves tilings are investigated as templates for the material system architecture. It is demonstrated under point loads that the architecture significantly affects the force-deflection response. Stiffness, load carrying capacity and toughness varied by a factor of at least three from the system with the poorest performance to the system with the best performance. Across all architectures stiffness, strength and toughness are found to be strongly and linearly correlated. Architecture characterizing parameters and their relationship to the mechanical behavior are investigated. It is shown that the measure of the smallest tile area in an assembly provides the best predictor of mechanical behavior. With small tiles present in the assembly the contact force network structure is well developed and the internal load path is channeled through these stiffest components of the assembly.
Campus sustainability intends to minimize the negative effects that impact on their resources, while fulfils the activities of the universities for assisting the society in transition as the sustainable lifestyles. Since the activities of universities require many structures and the construction projects inevitably cause unfriendly effects on the environment, this research aims to investigate the effectiveness of interlocking brick system in reducing the energy consumption. In this research, a single-storey building had been built-up to validate the sustainability of the interlocking brick in constructing the green campus. By implementing the reinforced concrete construction method, it has found that about 1356.28 kg cement is needed to construct the required beams and columns. The invented interlocking brick system has avoided the exhaustion of 1356.28 kg cement and thus, saved 5.425 GI energy depletion, reduced 1.35-ton greenhouse gases emission and eliminated the formwork consumption. Moreover, this system is also proved to be competent in taking the essential role as load-bearing system of a building.
Topologically Interlocked Material (TIM) systems are load-carrying assemblies of unit elements interacting by
contact and friction. TIM assemblies have emerged as a class of architectured materials with mechanical properties not ordinarily found in monolithic solids. These properties include, but are not limited to, high damage tolerance, damage confinement, adaptability and multifunctionality. The review paper provides an overview of recent research findings on TIM manufacturing and TIM mechanics. We review several manufacturing approaches. Assembly manufacturing processes employ the concept of scaffold as a unifying theme. Scaffolds are understood as auxiliary support structures employed in the manufacturing of TIM systems. It is demonstrated that the scaffold can take multiple forms. Alternatively, processes of segmentation are discussed and demonstrated. The review on mechanical property characteristics links the manufacturing approaches to several relevant material configurations and details recent findings on quasistatic and impact loading, and on multifunctional response.
Structural composites inspired by nacre have emerged as prime exemplars for guiding materials design of fracture-resistant, rigid hybrid materials. The intricate microstructure of nacre, which combines a hard majority phase with a small fraction of a soft phase, achieves superior mechanical properties compared to its constituents and has generated much interest. However, replicating the hierarchical microstructure of nacre is very challenging, not to mention improving it. In this article, we propose to alter the geometry of the hard building blocks by introducing the concept of topological interlocking. This design principle has previously been shown to provide an inherently brittle material with a remarkable flexural compliance. We now demonstrate that by combining the basic architecture of nacre with topological interlocking of discrete hard building blocks, hybrid materials of a new type can be produced. By adding a soft phase at the interfaces between topologically interlocked blocks in a single-build additive manufacturing process, further improvement of mechanical properties is achieved. The design of these fabricated hybrid structures has been guided by computational work elucidating the effect of various geometries. To our knowledge, this is the first reported study that combines the advantages of nacre-inspired structures with the benefits of topological interlocking.
The paper investigates mechanical behaviour of structures based on the principle of topological
interlocking. In these structures the constituent elements are held together by their geometry alone, without
any connectors. Only the elements (blocks) at the periphery need to be constrained for the integrity of the
whole structure to be ensured. Two types of plate-like structures with interlocking are considered: an assembly
of tetrahedra arranged in a special way and a masonry-like assembly of blocks with curved surfaces referred
to as osteomorphic blocks. With these shapes, some parts of a block prohibit its displacement in one direction,
while the other parts prevent it from moving in the opposite direction. The behaviour of assemblies of
interlocked elements under indentation is compared for that of a solid plate of the same thickness and of an
assembly of rectangular blocks held together by friction. The topologically interlocking assemblies are found
to be very flexible and tolerant to missing blocks. Their structural integrity is due to the specific geometry of
the constituents, rather than friction at the interfaces. Structures based on topological interlocking possess
high fracture toughness, mainly due to the weakness of the interfaces between the blocks preventing fractures
from spreading from one block to another. The loading curves of plates composed from interlocked elements
exhibit kinks – small drops and rises in the load. Each of these features is attributed to a temporary loss of inter-
block contact due to the action of tensile components of bending stresses in the absence of binding between
the blocks. Being an intrinsic property of topological interlocking, these kinks can serve as indicators
of non-linear stage of deformation and are precursors of ultimate failure.
In this study, concrete specimens, having different shapes and sizes have been studied for two different strength levels cured in air and in water. Compressive strength test was performed on cubic and cylindrical samples, having various sizes. The analyses of this investigation were focused on conversion factors for compressive strengths of different samples. Conversion factors of different specimens against cross sectional area of the same specimens were also plotted and regression analyses were done. It was found that according to the results of analyses, the best fit curves, tend to have different trends at different curing conditions.
The objective of the present study is to provide understanding of potential energy absorption and dissipation mechanisms and benefits of topologically interlocked material (TIM) assemblies under impact loading. The study is motivated by earlier findings that TIMs under low rate loading demonstrated attractive properties including the capability to arrest and localize cracks and to exhibit a quasi-ductile response even when the unit elements are made of brittle materials. It is hypothesized that TIMs due to their modularity would possess advantageous impact characteristics. In order to test this hypothesis, a series of computational experiments on the dynamic loading of TIMs are conducted. Results obtained in this study are presented for a planar TIM configuration based on a dense packing of tetrahedral unit elements to form an energy absorption layer. Finite element models are calibrated on samples fabricated using fused deposition modeling (FDM) additive manufacturing (AM). With employing the Lambert–Jonas formula to interpret the numerical data, it is demonstrated that TIMs can absorb more impact energy than conventional solid plates. An extended Lambert–Jonas model is defined such that accurate description of the impact response of TIMs is obtained.
In the present paper, the force-fit connection of discrete ceramic components by means of geometrically interlocking surfaces is studied. These surfaces possess a concavo-convex topology permitting assembly of structures in which each individual element is kinematically locked by its neighbors. Such structures have a tuneable bending stiffness, allow for large deformations and are tolerant to missing or destroyed elements. These properties of topologically interlocked structures make them particularly attractive in construction with brittle materials. The elements used were produced by freeze gelation of ceramic slurries, leading to near net shape with the coefficient of shrinkage below 3%. It is shown that planar assemblies of interlocked ceramic elements can withstand flexural deflections up to a ten-fold of those a solid plate from the same material can sustain. The response of these structures to concentrated load can be divided into an elastic and a quasi-plastic, i.e., irreversible, part. After the point of maximum load, the interlocked structures investigated were still able to withstand further deformation, whereas solid plates showed brittle failure.
We present a novel approach for combating noise pollution by segmentation of monolithic plates into an assembly of topologically interlocked building blocks. The results of a study of the sound absorption in such segmented structures demonstrate a spectacular increase in the sound absorption coefficient over that in the original material (dental stone GC Fujirock). Measurements of the airflow resistance confirm the primary role of segmentation in imparting high sound absorption capability to the material, notably in the audible frequency range.
Unusual mechanical response of a structure with topologically interlocked elements is discussed. Under point loading, it behaves pseudo-plastically, with a negative stiffness in part of the unloading curve. This effect is inherent in the structure and is attributed to changing contact conditions due to rotation of the elements.
Applications of a newly established principle of topological interlocking to different types of extraterrestrial construction are considered. Topological interlocking arises when elements of special shapes (usually convex or nearly convex, such that no stress concentration develops) are arranged in such a way that neither of them can be removed from the assembly without disturbing the neighbouring elements. Two types of extraterrestrial structures are considered. The first type represents mortar free structures built from specially engineered interlocking bricks, called osteomorphic bricks. The self-adjusting property of these bricks permits erecting structures which tolerate low precision of production and assembly, thus making the proposed method suitable for in situ produced bricks and low cost assembling machinery. The structures of the second type are modular extraterrestrial bases or space ships organised in topologically interlocking assemblies. For an extraterrestrial settlement such an organisation permits easy assembly even if the modules are uploaded on uneven ground. A space ship can be assembled from independent smaller ships interlocked topologically thus becoming a flexible vehicle suitable for both long-distance journeys and simultaneous exploration of extraterrestrial objects clustered in a relative proximity of each other.
We review the concept of topological interlocking of identical elements in single-layer structures on which we have been working over the last decade and outline its advantages over monolithic structures. Multi-layers involving topological interlocking are also introduced and their unusual properties are discussed. In a broader sense interlocking also occurs in living organisms, and a connection of our artificial, geometry-inspired design to some recent observations of interlocking in nature is made.
The proposed assembly of interlocked tetrahedron-shaped elements forms a layer in which each individual block is held in place by neighbouring blocks. The layer is flexible, but can withstand considerable loads even if no binder is used to hold the elements together. Great opportunities are seen in finding processing routes for manufacturing such self-locking structures with different dimensional scales depending on the desired application.
A new concept of assembling layer-like structures from identical convex elements interlocked by virtue of their geometry and spatial arrangement was developed recently. In particular, identical cubes can be arranged in this type of assembly, such that none of them can be removed from the structure. This is achieved through the kinematic constraint imposed by the neighbouring elements, provided that a constraining frame substitutes for neighbours along the periphery of the assembly. We report experimental results and the results of numerical simulation showing that such assemblies exhibit a highly non-linear response to out-of-plane point loads (indentation), in particular a pronounced loading/unloading hysteresis, post-peak softening, a negative stiffness in the stage of unloading and localisation of irreversible rotations. The results of the simulations confirm that the observed unusual mechanical response is an intrinsic, material-independent property of such assemblies.
The influence of the friction coefficient on the indentation behavior of an interlocked material is presented. Ice can be used to provide easily interlocked structures, and that the effect of the friction coefficient can be investigated in this system. Ice block is a good model material to test possible geometries and has the property of providing an easy way of changing the friction coefficients between blocks, simply by changing the testing temperature. This simple analog system will allow in a near future to test innovative geometries. A systematic modeling of the interlocked materials, coupling FEM for the block/block interaction, and a discrete element simulation for the collective behavior, is in progress.
In this brief overview, we present recent work on the novel concept of topological interlocking as a means of designing new materials and structures. Starting from a special self-supporting arrangement of tetrahedron-shaped elements that was discovered first, we proceed with the introduction of other shapes exhibiting topological interlocking. Unusual mechanical properties of assemblies of tetrahedrons that were studied both experimentally and theoretically are discussed. Possible applications can range from large scale mortar free construction in civil engineering to novel advanced materials based on microscale interlocking elements.
Fracture resistant structures based on topological interlocking with non-planar contacts were discussed. The results of indentation tests on a plate-like assembly of such blocks were presented. The principle of topological interlocking offered a possibility of going down to micro or nanostructured layers once a suitable manufacturing technology was found.
We consider the failure behaviour of a plate assembled from interlocking elements (the so-called osteomorphic blocks) held together by virtue of their geometry and spatial arrangement. As overall failure by crack propagation across the assembly is inhibited by its segmented nature, failure of elements in a random fashion is considered in terms of percolation theory. Overall failure is associated with damage reaching a percolation limit, which is calculated using computer experiments. A new feature of the assembly of interlocked osteomorphic elements as compared to a classical problem of percolation on a square 2-D lattice is the occurrence of avalanches of failures. It is shown that this leads to a significant decrease of the percolation limit, which in our case amounts to about 25% of failed elements. It is further shown that usual scaling laws found in classical percolation theory still apply for the case considered.
Despite the increasing interest in topological interlocking structures made of identical elements, only one type of interlocking brick has been extensively studied so far, with very limited focus on their dynamic behaviour. In this paper, a new design of interlocking brick was proposed, which had a symmetrical geometry with four curved side surfaces to be interlocked with adjacent elements. The dynamic mechanical behavior of the new brick was numerically investigated and compared to that of the existing interlocking brick and the monolithic plate. The deformation patterns and the energy absorption capacity of interlocking structures were also studied. The results showed that the newly designed interlocking brick had intermediate contact forces and much more uniform load and stress distribution during the impact. Moreover, its energy absorption capacity was the largest.
Topologically interlocked material systems are two-dimensional granular crystals created as ordered and adhesion-less assemblies of unit elements of the shape of platonic solids. The assembly resists transverse forces due to the interlocking geometric arrangement of the unit elements. Topologically interlocked material systems yet require an external constraint to provide resistance under the action of external load. Past work considered fixed and passive constraints only. The objective of the present study is to consider active and adaptive external constraints with the goal to achieve variable stiffness and energy absorption characteristics of the topologically interlocked material system through an active control of the in-plane constraint conditions. Experiments and corresponding model analysis are used to demonstrate control of system stiffness over a wide range, including negative stiffness, and energy absorption characteristics. The adaptive characteristics of the topologically interlocked material system are shown to solve conflicting requirements of simultaneously providing energy absorption while keeping loads controlled. Potential applications can be envisioned in smart structure enhanced response characteristics as desired in shock absorption, protective packaging and catching mechanisms.
In this work we present a novel approach to designing responsive structures by segmentation of monolithic plates into an assembly of topologically interlocked building blocks. The particular example considered is an assembly of interlocking osteomorphic blocks. The results of this study demonstrate that the constraining force, which is required to hold the blocks together, can be viewed as a design parameter that governs the bending stiffness and the load bearing capacity of the segmented structure. In the case where the constraining forces are provided laterally using an external frame, the maximum load the assembly can sustain and its stiffness increase linearly with the magnitude of the lateral load applied. Furthermore, we show that the segmented plate with integrated shape memory wires employed as tensioning cables can act as a smart structure that changes its flexural stiffness and load bearing capacity in response to external stimuli, such as heat generated by the switching on and off an electric current.
Vertically interlocking load-spreading unit paving systems offer many economic advantages, among which are the reduction of sub-structure and diminished maintenance costs. The designs that have reached the market have often relied on complex, joinery type connection detailing and, because of this, have never fully achieved their possible economies. The patented G-Block System results from an explor-ation and analysis of solid geometries. Tne close-packing characteristics of tetrahedra have been developed into the G-Block range of blocks and slabs which, when laid, exhibit excellent load distrib-ution characteristics. The system includes an edge block, a reinstatement unit and also a sonhist-icated machine-laying technique. The search for a vertically interlocking paving block has been, for many people in the industry, like the search for the philosospher's stone -a discovery that would turn base metal into gold. Certainly, an effective vertical interlock would offer two immediate advantages over most current systems. First, in improving the lateral load-spreading characteristics of a paved area it would reduce the sub-structure requirement sign-ificantly and thus lower initial capital cost. Second, because of increased stability and resistance to 'punch-in' it would reduce main-tenance costs. There can be little doubt that this would not only affect existinG markets but must, in time, introduce completely new market areas to the concrete block industry. Current practice requires -in the broadest terms -an over-thick surface course on a sub-structure designed to cope with the worst poss-ible condition. It seemed to me that -theo-retically at least -there could be two routes for design rationalisation. First, the sub-structure could be improved to give total sup-port to a block which was substantially reduced in thickness and which was expected to perform simply as a biscuit-like surface. Second, the units or blocks could be designed to have posi-tive structural interdependence, thus allowing for a downgrading of substructure. The first of these options was judged practically unattain-able while the second seemed a direction for fruitful research. Many others have perceived the logic of design development of structural interlock on the vertical axis but, with the benefit of hindsiGht, it is possible to isolate an error of design thinking in previous examples. At a larger scale, in precast concrete buildinG for example, mechanical jointing systems are commonplace apd are usually descendants of traditional joinery techniques -tongue and groove, dovetail, mortice and tenon, etc. In my view, the small scale of most paving block systems precludes the efficient use of this kind of connection technique. The disaavantages of complex interlock can be listed : 1. Weight and size. Naturally, if a block is to have particular constructional detailing on its edges, it tends to become larger and heavier than a non-connectinG block. The economic repercussions are obvious. Not only are handlinG difficulties increased at the factory and on site but, in addition, the surface area of paving per truckload gets smaller. 2. Damage. The more precise the connection detail, the greater the risk of damage to it during handling. 3. Difficulty of installation. It has often been the case that a connection detail that is beautiful in theory demands, on site, the ki~d of care in installation which is either unavailable or expensive. For these reasons we rejected the 'ed~e conn-ection' approach and defined the problem in new, and fairly rigorous terms. We were looking for a block confiGuration which had no 'joinery' type connections, which was easy to manufacture, transport and lay and which would be unlikely to sustain accidental damage in handling. We were looking for a block which would transmit loads laterally and which would close-oack as a fund-amental characteristic of its three-dimensional geometry. It took some time. It was clear that all exist-ing systems were based, topologically, on cubic packin9 -modified and shaned or not -and we felt that further research in this area miGht stimulate slight improvements but was unlikely to produce the second Generation block we were looking for. The tetrahedron provided the key. The tetra-hedron is a solid with four surfaces, each an identical equilateral triangle. It is usually shown as a three-sided pyramid (Figure 1). When the tetrahedron sits on one of its triangular surfaces. as in Fioure 1. then all horizontal sections through it will be triangular. Figure 2 shows the tetrahedron posed on one of its six edges. In this position the top edge and the bottom edge are horizontal, and at right-angles to each other. A horizontal sect-ion taken at mid-heiaht throuah a tetrahedron in this position is a square -the 'equatorial square'. All other horizontal sections are rectangular.
We review the principle of topological interlocking and analyze the properties of the mortarless structures whose design is based on this principle. We concentrate on structures built of osteomorphic blocks — the blocks possessing specially engineered contact surfaces allowing assembling various 2D and 3D structures. These structures are easy to build and can be made demountable. They are flexible, resistant to macroscopic fractures and tolerant to missing blocks. The blocks are kept in place without keys or connectors that are the weakest elements of the conventional interlocking structures. The overall structural integrity of these structures depends on the force imposed by peripheral constraint. The peripheral constraint can be provided in various ways: by an external frame or features of site topography, internal prestressed cables/tendons, or self-weight and is a necessary auxiliary element of the structure. The constraining force also determines the degree of delamination developing between the blocks due to bending and thus controls the overall flexibility of the structure thus becoming a new design parameter.
Economical earthquake-resistant housing is desirable in seismically active rural areas of developing countries. These regions often suffer a significant loss of life during strong ground motion because of lack of seismic-resistant housing. To enable an efficient and cost-effective solution, a new concept of construction was investigated utilising structures consisting of (i) interlocking blocks with relative movability at the block interface and (ii) coconut-fibre rope reinforcement. The interlocking blocks were prepared with coconut fibre reinforced concrete. A mortar-free construction can facilitate more energy dissipation during a seismic event, because of the relative movement at the block interfaces. Four structures were considered: two columns (with and without ropes) and two walls (with and without ropes). This paper reports on the investigation of the in-plane behaviour of the mortar-free structures under different loadings: push over, snap back, impact, harmonic and earthquake loadings. The influence of un-grouted rope reinforcement on the fundamental frequency, damping ratio, induced accelerations, top relative displacement, base shear, overturning moment and block uplift is investigated. The harmonic tests were more accurate in finding the fundamental frequencies of the structures compared to the push over and snap back tests. As expected, the structures with ropes were stiffer than the structures without ropes. The structures with ropes had smaller relative top displacements and block uplifts compared to the structures without ropes. The damping of the structures without ropes was higher than that of the structures with ropes. The damping increased with the amplitude of input motion. The same trend was observed for the maximum overturning moment, uplift and rope tension.
Topologically interlocked materials (TIMs) are a class of materials made by a structured assembly of an array of identically shaped and sized unit elements that are held in a confining framework. The assembly can resist transverse forces in the absence of adhesives between the unit elements. The present study focuses on topologically interlocked materials with cellular unit elements. The resulting materials achieve their properties by a combination of deformation of the individual unit elements and their contact interaction. Drop tower tests were conducted to characterize the mechanical behavior of the cellular TIMs made of an intrinsically brittle base material. The TIMs were found to exhibit perfect softening, independent of the relative density of the cellular units. The analysis of the experiments revealed a positive correlation between strength and toughness in contrast to more conventional materials. An analytical model for the prediction of the observed material behavior is developed. Model predictions are in agreement with experimental data. The implications of the present findings for the design of these novel materials are discussed.
We present a novel approach for designing lightweight sandwich structures by using an assembly of topologically interlocked building blocks as a core of the sandwich. The results of a study in three point bending tests demonstrate a significant increase in maximum deflection before failure and absorbed energy over that of a sandwich with a monolithic core. A novel principle of design of sandwich panels utilizing segmentation of a monolithic core into a set of building blocks with a specially designed shape is proposed. Our investigation shows that segmentation of a monolithic sandwich core made from polyurethane into an assembly of interlocked osteomorphic blocks brings about a remarkable increase in the deflection to failure and in the energy absorption capability of a sandwich panel.
Since its introduction in 2001 [1], the concept of topological interlocking has advanced to reasonable maturity, and various research groups have now adopted it as a promising avenue for developing novel structures and materials with unusual mechanical properties. In this paper, we review the known geometries of building blocks and their arrangements that permit topological interlocking. Their properties relating to stiffness, fracture resistance and damping are discussed on the basis of experimental evidence and modeling results. An outlook to prospective engineering applications is also given.
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