Modelling and Simulation of Soft Robotic Human Tongue with Improved Motion

There is a huge demand for electronic tongues in the food and pharmaceutical industries for chemical detection and flavor analysis. The lack of availability of robots with electronic tongues has motivated us to investigate, design and simulate a human tongue's complex motions. Human anatomy was studied in detail to modify the standard design of the human tongue, with the addition of embedded chambers at strategic locations, to replicate various 3D motions (rolling, groove, twist, and elongation) of the human tongue necessary for improving the bio-chemical sensing capabilities. The FEM (Finite element method) simulations showed the relation between pressure and deformation range for various kinds of motions in a human tongue, including the mechanical properties from the stress versus strain response.

On the Development of New Test Techniques to Measure the Tensile Response of Materials at High and Ultra-high Strain Rates

Background There is a lack of reliable methods to obtain valid measurements of the tensile response of high performance materials such as fibre composites, ceramics and textile products at high rates of strain. Objective We propose and assess two new test techniques aimed at measuring valid tensile stress versus strain curves at high and ultra-high strain rates. Methods We conduct detailed, non-linear explicit Finite Element (FE) simulations of the transient response of the test apparatus and specimen during the tests and we develop simple analytical models to interpret the test measurements. We consider two test techniques: one based on the split Hopkinson bar apparatus, and suitable for strain rates of up to 1000 /s, and a second technique relying on projectile impact and aimed at measurements at strain rates higher than 1000 /s. Results The simulations are successfully validated using test data at strain rates of order 200 /s and then used to predict the test performance at strain rates up to approximately 5500 /s. We find that both techniques can give valid stress versus strain curves across a wide range of strain rates. Conclusions We identify the limits of both techniques and recommend optimal measurement strategies for dynamic testing of materials with different ductility.

Width Dependent Elastic Properties of Graphene Nanoribbons

The mechanical response of graphene nanoribbons under uniaxial tension, as well as its dependence on the nanoribbon width, is presented by means of numerical simulations. Both armchair and zigzag edged graphene nanoribbons are considered. We discuss results obtained through two different theoretical approaches, viz. density functional methods and molecular dynamics atomistic simulations using empirical force fields especially designed to describe interactions within graphene sheets. Apart from the stress-strain curves, we calculate several elastic parameters, such as the Young’s modulus, the third-order elastic modulus, the intrinsic strength, the fracture strain, and the Poisson’s ratio versus strain, presenting their variation with the width of the nanoribbon.

Effect of Tensile Load on the Mechanical Properties of AlSiC Composite Materials using ANSYS Design Modeller

Aluminium Silicon Carbide (AlSiC) composite materials are used in the electronics industries and other manufacturing companies hence, manufacturing of AlSiC composite materials with the right properties for different applications are vital to most industries. The challenge of testing the same specimens for different properties remains, because most of the tests carried out are destructive. Hence, the use of ANSYS finite element simulation software for the design and analysis of a flat bar specimen. Loads between 3 kN to 21 kN were applied on the specimen since it is within the operating limit of a Universal Tensile Testing Machine (UTTM), while both ends are fixed. The AlSiC composite materials used in this study have a composition of 63 vol% Al (356.2) and 37 vol% SiC and, the resultsshowed that stress was directly proportional to strain. While the calculated Young’s modulus from the stress versus strain plot was approximately 167 GPa for the different tensile loads applied. In addition, the total deformation of the AlSiC composite material increased as the load was increased. Also, the highest deformation of the material was observed around the centre of the test specimen. This is synonymous with the failure observed in practical testing of specimens. Keywords: AlSiC, tensile load, aluminium MMC, stress analysis, deformation, ANSYS

Axial Loading Behaviour of Self-Compacting Concrete-Filled Thin-Walled Steel Tubular Stub Columns

This paper presents an experimental investigation on the mechanical behaviour of self-compacting concrete-filled thin-walled steel tubular (SCCFTST) stub columns loaded in axial compression to failure. Four specimens were tested to study the effect of diameter to wall thickness (D/t) ratios on the ultimate load, failure modes, and ductility of the columns. Confinement of the steel tube to concrete was also addressed. The failure modes, load versus displacement curves, and load versus strain curves were examined in detail. The experimental results showed that the ultimate state is reached when severe local buckling and rupture occurred on the steel tubes, and the concrete near the rupture has been crushed. The columns with larger D/t ratios appeared more local buckling, and its location is more close to the end of the columns. The SCCFTST stub columns with smaller D/t ratios show higher ultimate load and better ductility, and the steel tubes can exert higher confinement to the concrete.

Evaluation of settlement of shallow foundations laid on unsaturated soils

The study presents an experimental and numerical study on an unsaturated, non-plastic and poorly graded sand, originated from Fortaleza-CE, Brazil. The numerical analyses used the Finite Element Method (FEM), were performed using the UNSTRUCT software to simulate the curve stress versus strain, considering the effect of suction on soil stiffness. Characterization and determination of the retention curve were performed through filter paper tests, which were used to determine the stress versus strain curve in a double-oedometer test. Suction was considered constant along the entire test. From the numerical analyses done with UNSTRUCT software presented satisfactory results, especially in the presence of suction profiles, that show the variation of suction along of the depth. It can be concluded that higher suction values (and soil stiffness) generate lower settlements.

Syndecan-1 and Glypican-1 Knockout Alters Body Water Balance and Urine Response to Fluid Challenge in Mice

Syndecan-1 (Sdc-1) and glypican-1 (Gpc-1) are 2 important proteoglycans found in the glycocalyx and believed to govern transvascular distribution of fluid and protein. In this translational study, we assessed Sdc-1 and Gpc-1 knockout (KO) on whole body water balance after an intravenous volume challenge. Sdc-1 and Gpc-1 KO mice had higher starting blood water content versus strain-matched controls. Sdc-1 KO mice exhibited a significantly higher diuretic response (87%; <i>p</i> &#x3c; 0.05), higher excreted volume/infusion volume ratio (<i>p</i> &#x3c; 0.01), higher extravascular/infused ratio, and greater tissue water concentration (60 vs. 52%). Collectively, these suggest differences in kidney response and greater fluid efflux from peripheral vessels. The CD1 strain and Gpc-1 KO had a 2–3-fold larger urine output relative to C57 strain, but Gpc-1 KO reduced the excreted/infused ratio relative to controls (<i>p</i> &#x3c; 0.01) and they maintained plasma dilution longer. Thus, genetic KO of Sdc-1 and Gpc-1 resulted in markedly different phenotypes. This work establishes the feasibility of performing fluid balance studies in mice.