scholarly journals Mechanical Properties and Weibull Scaling Laws of Unknown Spider Silks

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2938
Author(s):  
Gabriele Greco ◽  
Nicola M. Pugno
Keyword(s):  
Mechanical Properties ◽  
Size Effects ◽  
Spider Silk ◽  
Scaling Laws ◽  
Statistical Investigation ◽  
Strain Rates ◽  
Cupiennius Salei ◽  
Weibull Parameters ◽  
Spider Silks

Spider silks present extraordinary mechanical properties, which have attracted the attention of material scientists in recent decades. In particular, the strength and the toughness of these protein-based materials outperform the ones of many man-made fibers. Unfortunately, despite the huge interest, there is an absence of statistical investigation on the mechanical properties of spider silks and their related size effects due to the length of the fibers. Moreover, several spider silks have never been mechanically tested. Accordingly, in this work, we measured the mechanical properties and computed the Weibull parameters for different spider silks, some of them unknown in the literature. We also measured the mechanical properties at different strain rates for the dragline of the species Cupiennius salei. For the same species, we measured the strength and Weibull parameters at different fiber lengths. In this way, we obtained the spider silk scaling laws directly and according to Weibull’s prediction. Both length and strain rates affect the mechanical properties of spider silk, as rationalized by Weibull’s statistics.

scholarly journals Post-secretion processing influences spider silk performance

2012 ◽  
Vol 9 (75) ◽  
pp. 2479-2487 ◽  
Author(s):  
Sean J. Blamires ◽  
Chung-Lin Wu ◽  
Todd A. Blackledge ◽  
I-Min Tso
Keyword(s):  
Mechanical Properties ◽  
Amino Acid ◽  
Ground State ◽  
Spider Silk ◽  
Mechanical Performance ◽  
Protein Composition ◽  
Compositional Changes ◽  
Spinning Speed ◽  
Spider Silks ◽  
Β Sheet

Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins—MaSp1 predominately contains alanine and glycine and forms strength enhancing β-sheet crystals, while MaSp2 contains proline and forms elastic spirals. Nonetheless, mechanical properties can vary in spider silks without congruent amino acid compositional changes. We predicted that post-secretion processing causes variation in the mechanical performance of wild MA silk independent of protein composition or spinning speed across 10 species of spider. We used supercontraction to remove post-secretion effects and compared the mechanics of silk in this ‘ground state’ with wild native silks. Native silk mechanics varied less among species compared with ‘ground state’ silks. Variability in the mechanics of ‘ground state’ silks was associated with proline composition. However, variability in native silks did not. We attribute interspecific similarities in the mechanical properties of native silks, regardless of amino acid compositions, to glandular processes altering molecular alignment of the proteins prior to extrusion. Such post-secretion processing may enable MA silk to maintain functionality across environments, facilitating its function as a component of an insect-catching web.

scholarly journals Artificial spider silk from ion-doped and twisted core-sheath hydrogel fibres

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuanyuan Dou ◽  
Zhen-Pei Wang ◽  
Wenqian He ◽  
Tianjiao Jia ◽  
Zhuangjian Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Spider Silk ◽  
Water Evaporation ◽  
Damping Capacity ◽  
Impact Reduction ◽  
Ion Doping ◽  
Evaporation Induced Self Assembly ◽  
Spider Silks ◽  
The Impact

AbstractSpider silks show unique combinations of strength, toughness, extensibility, and energy absorption. To date, it has been difficult to obtain spider silk-like mechanical properties using non-protein approaches. Here, we report on an artificial spider silk produced by the water-evaporation-induced self-assembly of hydrogel fibre made from polyacrylic acid and silica nanoparticles. The artificial spider silk consists of hierarchical core-sheath structured hydrogel fibres, which are reinforced by ion doping and twist insertion. The fibre exhibits a tensile strength of 895 MPa and a stretchability of 44.3%, achieving mechanical properties comparable to spider silk. The material also presents a high toughness of 370 MJ m−3 and a damping capacity of 95%. The hydrogel fibre shows only ~1/9 of the impact force of cotton yarn with negligible rebound when used for impact reduction applications. This work opens an avenue towards the fabrication of artificial spider silk with applications in kinetic energy buffering and shock-absorbing.

scholarly journals Mechanical Response of Hollow Metallic Nanolattices: Combining Structural and Material Size Effects

2015 ◽  
Vol 82 (7) ◽  
Author(s):  
L. C. Montemayor ◽  
J. R. Greer
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Relative Density ◽  
Size Effects ◽  
Scaling Laws ◽  
Tube Wall ◽  
Three Dimensional ◽  
Cellular Solids ◽  
Tube Wall Thickness ◽  
Strength And Stiffness

Ordered cellular solids have higher compressive yield strength and stiffness compared to stochastic foams. The mechanical properties of cellular solids depend on their relative density and follow structural scaling laws. These scaling laws assume the mechanical properties of the constituent materials, like modulus and yield strength, to be constant and dictate that equivalent-density cellular solids made from the same material should have identical mechanical properties. We present the fabrication and mechanical properties of three-dimensional hollow gold nanolattices whose compressive responses demonstrate that strength and stiffness vary as a function of geometry and tube wall thickness. All nanolattices had octahedron geometry, a constant relative density, ρ ∼ 5%, a unit cell size of 5–20 μm, and a constant grain size in the Au film of 25–50 nm. Structural effects were explored by increasing the unit cell angle from 30 deg to 60 deg while keeping all other parameters constant; material size effects were probed by varying the tube wall thickness, t, from 200 nm to 635 nm, at a constant relative density and grain size. In situ uniaxial compression experiments revealed an order of magnitude increase in yield stress and modulus in nanolattices with greater lattice angles, and a 150% increase in the yield strength without a concomitant change in modulus in thicker-walled nanolattices for fixed lattice angles. These results imply that independent control of structural and material size effects enables tunability of mechanical properties of three-dimensional architected metamaterials and highlight the importance of material, geometric, and microstructural effects in small-scale mechanics.

The effects of gage length and strain rate on tensile behavior of Kevlar® 29 single filament and yarn

2016 ◽  
Vol 51 (1) ◽  
pp. 109-123 ◽  
Author(s):  
Yunfu Ou ◽  
Deju Zhu ◽  
Mengying Huang ◽  
Hang Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Strain Rate ◽  
Gage Length ◽  
Strain Rates ◽  
Strain Response ◽  
Stress Strain ◽  
Single Filament ◽  
Weibull Parameters ◽  
Structural Scale

The mechanical properties of Kevlar® 29 single filaments and yarns with different gage lengths were investigated by utilizing an MTI miniature tester and an MTS load frame. Single yarns of 25 mm were also tested over four different strain rates using a drop-weight impact system. The experimental results showed that the mechanical properties of Kevlar® 29 are sensitive to gage length, structural size scale, and strain rate. The tensile strength decreased with increasing gage length and the structural scale from fiber to yarn, and increased with increasing strain rate. Weibull analysis was conducted to quantify the degree of variability in tensile strength. The obtained Weibull parameters were then used in an analytical model to simulate the stress–strain response of single yarn. Finally, Weibull parameters of single filaments with other gage lengths and strain rates were also obtained by fitting the stress–strain curves of single yarns with corresponding testing conditions.

Conformational Transition of Regenerated Spider Silk in Water

2013 ◽  
Vol 796 ◽  
pp. 107-111
Author(s):  
Ye Mei Zhang ◽  
Zhi Juan Pan
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Spider Silk ◽  
Conformational Transition ◽  
Ph Value ◽  
Random Coil ◽  
Spider Dragline Silk ◽  
Turn Structure ◽  
Α Helix ◽  
Spider Silks

Spider silks have excellent mechanical properties, which can even compare with some high-performance synthetic materials. Although as reported, the impressive mechanical properties are closely related to the primary amino acid sequence, the conformation that molecular chains form is also an important determinant. In this paper, effects of solvent, pH value, temperature, centrifugation and concentrating on the secondary structure of regenerated Ornithoctonus huwenna spider dragline silk protein aqueous solution were investigated by circular dichroism. Spidroin solutions prepared from different LiBr solutions had a distinct combination of secondary structures. The increasing temperature and concentrating can promote the formation of β-sheet structure. While centrifugation was opposite, which elevate the content of β-turn structure. Circular dichroic spectra quantitatively verified an increased α-helix structure content but a decrease of random coil and β-turn structure content with the increasing of pH value.

scholarly journals A Review on Mechanical Properties of Natural Fibre Reinforced Polymer Composites under Various Strain Rates

2021 ◽  
Vol 5 (5) ◽  
pp. 130
Author(s):  
Tan Ke Khieng ◽  
Sujan Debnath ◽  
Ernest Ting Chaw Liang ◽  
Mahmood Anwar ◽  
Alokesh Pramanik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Polymer Composites ◽  
Stress Transfer ◽  
Natural Fibre ◽  
Transfer Efficiency ◽  
Strain Rates ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Fibre Matrix

With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate dependent due to their viscoelastic nature. Especially for natural fibre reinforced polymer composites (NFPCs) which the involvement of filler has caused rather complex failure mechanisms under different strain rates. Moreover, some uneven micro-sized natural fibres such as bagasse, coir and wood were found often resulting in micro-cracks and voids formation in composites. This paper provides an overview of recent research on the mechanical properties of NFPCs under various loading conditions-different form (tensile, compression, bending) and different strain rates. The literature on characterisation techniques toward different strain rates, composite failure behaviours and current challenges are summarised which have led to the notion of future study trend. The strength of NFPCs is generally found grow proportionally with the strain rate up to a certain degree depending on the fibre-matrix stress-transfer efficiency. The failure modes such as embrittlement and fibre-matrix debonding were often encountered at higher strain rates. The natural filler properties, amount, sizes and polymer matrix types are found to be few key factors affecting the performances of composites under various strain rates whereby optimally adjust these factors could maximise the fibre-matrix stress-transfer efficiency and led to performance increases under various loading strain rates.

Diffraction Crystallite Size Effects on Mechanical Properties of Nanocrystalline (Ti0.8W0.2)C

2021 ◽  
Author(s):  
Chiheb Slama ◽  
Hassen Jaafar ◽  
Amal Karouia ◽  
Mohieddine Abdellaoui
Keyword(s):  
Mechanical Properties ◽  
Crystallite Size ◽  
Size Effects

scholarly journals Microstructural Characterization and Mechanical Properties of Ti-6Al-4V Alloy Subjected to Dynamic Plastic Deformation Achieved by Multipass Hammer Forging with Different Forging Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xiurong Fang ◽  
Jiang Wu ◽  
Xue Ou ◽  
Fuqiang Yang
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
Strain Rates ◽  
Materials Properties ◽  
Forging Process ◽  
Hammer Forging ◽  
Dynamic Plastic Deformation

Dynamic plastic deformation (DPD) achieved by multipass hammer forging is one of the most important metal forming operations to create the excellent materials properties. By using the integrated approaches of optical microscope and scanning electron microscope, the forging temperature effects on the multipass hammer forging process and the forged properties of Ti-6Al-4V alloy were evaluated and the forging samples were controlled with a total height reduction of 50% by multipass strikes from 925°C to 1025°C. The results indicate that the forging temperature has a significant effect on morphology and the volume fraction of primary α phase, and the microstructural homogeneity is enhanced after multipass hammer forging. The alloy slip possibility and strain rates could be improved by multipass strikes, but the marginal efficiency decreases with the increased forging temperature. Besides, a forging process with an initial forging temperature a bit above β transformation and finishing the forging a little below the β transformation is suggested to balance the forging deformation resistance and forged mechanical properties.

scholarly journals Static Mechanical Properties of Expanded Polypropylene Crushable Foam

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 249
Author(s):  
Przemysław Rumianek ◽  
Tomasz Dobosz ◽  
Radosław Nowak ◽  
Piotr Dziewit ◽  
Andrzej Aromiński
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Strain Rate ◽  
Energy Absorption ◽  
Experimental Tests ◽  
Absorption Capacity ◽  
Strain Rates ◽  
Foam Density ◽  
Energy Absorption Capacity ◽  
Closed Cell

Closed-cell expanded polypropylene (EPP) foam is commonly used in car bumpers for the purpose of absorbing energy impacts. Characterization of the foam’s mechanical properties at varying strain rates is essential for selecting the proper material used as a protective structure in dynamic loading application. The aim of the study was to investigate the influence of loading strain rate, material density, and microstructure on compressive strength and energy absorption capacity for closed-cell polymeric foams. We performed quasi-static compressive strength tests with strain rates in the range of 0.2 to 25 mm/s, using a hydraulically controlled material testing system (MTS) for different foam densities in the range 20 g/dm3 to 220 g/dm3. The above tests were carried out as numerical simulation using ABAQUS software. The verification of the properties was carried out on the basis of experimental tests and simulations performed using the finite element method. The method of modelling the structure of the tested sample has an impact on the stress values. Experimental tests were performed for various loads and at various initial temperatures of the tested sample. We found that increasing both the strain rate of loading and foam density raised the compressive strength and energy absorption capacity. Increasing the ambient and tested sample temperature caused a decrease in compressive strength and energy absorption capacity. For the same foam density, differences in foam microstructures were causing differences in strength and energy absorption capacity when testing at the same loading strain rate. To sum up, tuning the microstructure of foams could be used to acquire desired global materials properties. Precise material description extends the possibility of using EPP foams in various applications.

scholarly journals Cribellate thread production as model for spider’s spinneret kinematics

2021 ◽  
Author(s):  
Margret Weissbach ◽  
Marius Neugebauer ◽  
Anna-Christin Joel
Keyword(s):  
Molecular Structure ◽  
Mechanical Properties ◽  
Fibre Type ◽  
Material Science ◽  
Spider Silk ◽  
Functional Unit ◽  
Material Strength ◽  
Spinning Process ◽  
Fibre Spinning ◽  
House Spider

AbstractSpider silk attracts researchers from the most diverse fields, such as material science or medicine. However, still little is known about silk aside from its molecular structure and material strength. Spiders produce many different silks and even join several silk types to one functional unit. In cribellate spiders, a complex multi-fibre system with up to six different silks affects the adherence to the prey. The assembly of these cribellate capture threads influences the mechanical properties as each fibre type absorbs forces specifically. For the interplay of fibres, spinnerets have to move spatially and come into contact with each other at specific points in time. However, spinneret kinematics are not well described though highly sophisticated movements are performed which are in no way inferior to the movements of other flexible appendages. We describe here the kinematics for the spinnerets involved in the cribellate spinning process of the grey house spider, Badumna longinqua, as an example of spinneret kinematics in general. With this information, we set a basis for understanding spinneret kinematics in other spinning processes of spiders and additionally provide inspiration for biomimetic multiple fibre spinning.

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