Black Drum Fish Teeth: Built for Crushing Mollusk Shells
Social Science Research Network, 2021
With an exclusive diet of hard-shelled mollusks, the black drum fish (Pogonias Cromis) exhibits o... more With an exclusive diet of hard-shelled mollusks, the black drum fish (Pogonias Cromis) exhibits one of the highest bite forces among extant animals. To understand the structural basis for these integrated functional requirements, here we present the results of a systematic microstructural, chemical, crystallographic, and mechanical analysis of the black drum teeth. The teeth are based on a two-layered enameloid/dentin design. At the microscopic level of the outer enameloid region, Zn-doped hydroxyapatite/fluorapatite crystals and their preferential co-alignment of crystallographic c-axes along the biting direction contribute to the local stiffening, hardening, and toughening of the tooth surface (Er = 126.9 ± 16.3 GPa, H = 5.0 ± 1.4 GPa, and KIc = 1.12 MPa·m1/2). Our analysis also shows that this microstructure promotes local yielding instead of fracture when crushing mollusk shells. At the whole-tooth scale, the unique molar-like teeth, with smooth top surfaces, high density of dentin tubules, enlarged pulp chamber, and special dentin-bone interfacial connections, all contribute to the teeth functional requirements, including confinement of contact compressive stress in the stiff enameloid, enhanced energy absorption in the compliant and tough dentin, reduction of stress/strain concentration in the weakest bone, and controlled failure of the teeth under excessive loads. These results show that the multi-scale structure of black drum teeth is adapted to feed on mollusks.
On the Mechanical Properties of Dual-scale Microlattice of Starfish Ossicles: A Computational Study
Extreme mechanics letters, May 1, 2024
Plants transpiration-inspired antibacterial evaporator with multiscale structure and low vaporization enthalpy for solar steam generation
Nano Energy
Architected Si/C MicroNanostructures with Air Cushion-Inspired Stress Mitigation Strategies for Lithium-Ion Battery Anodes
Architected microlattices for structural and functional applications: Lessons from nature
Due to their low damage tolerance, engineering ceramic foams are often limited to non-structural ... more Due to their low damage tolerance, engineering ceramic foams are often limited to non-structural usages. In this work, we report that stereom, a bioceramic cellular solid (relative density, 0.2–0.4) commonly found in the mineralized skeletal elements of echinoderms (e.g., sea urchin spines), achieves simultaneous high relative strength which approaches the Suquet bound and remarkable energy absorption capability (ca. 17.7 kJ kg−1) through its unique bicontinuous open-cell foam-like microstructure. The high strength is due to the ultra-low stress concentrations within the stereom during loading, resulted from their defect-free cellular morphologies with near-constant surface mean curvatures and negative Gaussian curvatures. Furthermore, the combination of bending-induced microfracture of branches and subsequent local jamming of fractured fragments facilitated by small throat openings in stereom leads to the progressive formation and growth of damage bands with significant microscopic...
The rapidly developing robotics industry demands structures with novel mechanical functions. Trad... more The rapidly developing robotics industry demands structures with novel mechanical functions. Traditional approaches, developing new materials and designing new structures, face two challenges. Highly complex force-displacement functions can hardly be realized and one fabricated structure only has one or limited function. We perform theoretical calculations and FE simulations to demonstrate that the two challenges can be solved by making the mechanical property or geometry of the structure tunable. The mechanical property/geometry tuning approaches are further validated by experimental tests and the results show that multiple different and highly complex objective functions can be achieved accurately. We expect that the proposed tuning approaches will facilitate the development of advanced forms of mechanical metamaterials and a new generation of robotic hands.
This paper presents a mechanically bistable mechanism of the compressed pre-curved beam. A govern... more This paper presents a mechanically bistable mechanism of the compressed pre-curved beam. A governing equation is proposed which can be used to predict and explain the bistability of the compressed pre-curved beam. FE simulations and experimental tests are performed to validate the analytical solution. The beam's unique tunable and asymmetrical potential energy landscape is demonstrated which enables the compressed pre-curved beam to switch its stable position without the need of applying an external force to it. Based on that, a coupled beam element is designed and used as a building block to develop reprogrammable metasurfaces that can be programmed to exhibit different configurations.
Experimental investigation of the temperature effect on the structural response of SG-laminated reinforced glass beams
Engineering Structures, 2010
ABSTRACT To generate high-level redundancy for structural glass beams, a novel concept of laminat... more ABSTRACT To generate high-level redundancy for structural glass beams, a novel concept of laminating a metal reinforcement to a structural glass beam has been developed at Delft University of Technology (TU Delft). This concept makes use of the relatively stiff polymer interlayer material SentryGlas (SG) to bond the metal to the glass. However, due to the visco-elastic properties of the SG, its stiffness varies at different temperature levels. To what extent this temperature dependency has an effect on the structural response of the beam composite has been experimentally investigated in cooperation with Ghent University (UGent) and is the subject of current publication. Two separate series of pull-out tests, to investigate the bond strength, and beam tests, to investigate the post-breakage response, have been conducted at -20, 23 and 60 degrees C. The pull-out tests revealed a high temperature dependency of the bond strength of SG. This temperature dependency also had an effect on the structural response of the beams. However, regardless of temperature level all beams showed high-level plastic response and high redundancy. It is therefore concluded that temperature levels of -20 to 60 degrees C do not endanger the structural safety of SG-laminated reinforced glass beams.
Prediction of effective thermal conductivity of moist porous materials using artificial neural network approach
Building and Environment, 2011
ABSTRACT An artificial neural networks (ANNs) approach is presented for the prediction of effecti... more ABSTRACT An artificial neural networks (ANNs) approach is presented for the prediction of effective thermal conductivity of porous systems filled with different liquids. ANN models are based on feedforward backpropagation network with training functions: Levenberg–Marquardt (LM), conjugate gradient with Fletcher–Reeves updates (CGF), one-step secant (OSS), conjugates gradient with Powell–Beale restarts (CGB), Broyden, Fletcher, Goldfrab and Shanno (BFGS) quasi-Newton (BFG), conjugates gradient with Polak–Ribiere updates (CGP). Training algorithm for neurons and hidden layers for different feedforward backpropagation networks at the uniform threshold function TANSIG-PURELIN are used and run for 1000 epochs. The complex structure encountered in moist porous materials, along with the differences in thermal conductivity of the constituents makes it difficult to predict the effective thermal conductivity accurately. For this reason, artificial neural networks (ANNs) have been utilized in this field. The resultant predictions of effective thermal conductivity (ETC) of moist porous materials by the different models of ANN agree well with the available experimental data.Highlights► An artificial neural network (ANN) is used to predict effective thermal conductivity of moist porous materials. ► The volume fraction of filler and the ratio of thermal conductivity of the constituents are input parameters. ► We have used six training functions TRAINLM, TRAINCGF, TRAINOSS, TRAINCGB, TRAINBFG, and TRAINCGP. ► Better agreement of predicted effective thermal conductivity values is obtained by using ANNs with the experimental results.
Corrigendum ‘Black Drum Fish Teeth: Built for Crushing Mollusk Shells’ [Acta Biomaterialia 137 (2022) 147-161]
Acta Biomaterialia
Lightweight lattice-based skeleton of the sponge Euplectella aspergillum: On the multifunctional design
Journal of the Mechanical Behavior of Biomedical Materials
AFM Manipulation of EGaIn Microdroplets to Generate Controlled, On-Demand Contacts on Molecular Self-Assembled Monolayers
ACS Nano
Multiscale Mechanical Design of the Lightweight, Stiff, and Damage-Tolerant Cuttlebone: A Computational Study
SSRN Electronic Journal
Elastic anisotropy and wave propagation properties of multifunctional hollow sphere foams
Composite Structures
Understanding the multifunctional design of glass skeleton of Euplectella Aspergillum sponge
Bulletin of the American Physical Society, Mar 16, 2021
The role of material architecture to achieve functional hierarchy in the cuticle of the flower beetle, Torynorrhina flammea
Bulletin of the American Physical Society, Mar 16, 2021
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