Hyper-Redundant Manipulator Capable of Adjusting Its Non-Uniform Curvature with Discrete Stiffness Distribution

Hyper-redundant manipulators are widely used in minimally invasive surgery because they can navigate through narrow passages in passive compliance with the human body. Although their stability and dexterity have been significantly improved over the years, we need manipulators that can bend with appropriate curvatures and adapt to complex environments. This paper proposes a design principle for a manipulator capable of adjusting its non-uniform curvature and predicting the bending shape. Rigid segments were serially stacked, and elastic fixtures in the form of flat springs were arranged between hinged-slide joint segments. A manipulator with a diameter of 4.5 mm and a length of 28 mm had been fabricated. A model was established to predict the bending shape through minimum potential energy theory, kinematics, and measured stiffnesses of the flat springs. A comparison of the simulation and experimental results indicated an average position error of 3.82% of the endpoints when compared to the total length. With this modification, the manipulator is expected to be widely used in various fields such as small endoscope systems and single-port robot systems.

An Analytical Model for the Uniaxial Tensile Modulus of Plain-Woven Fabric Composites and Its Application and Experimental Validation

With advantages in efficiency and convenience, analytical models using experimental inputs to predict the mechanical properties of plain-woven fabric (PWF) composites are reliable in guaranteeing the composites’ engineering applications. Considering the importance of the aspect above, a new analytical model for predicting the uniaxial tensile modulus of PWF is proposed in this article. The composite yarns are first simplified as the lenticular-shaped cross-sections undulate along arc-composed paths. Force analyses of the yarn segments are then carried out with the internal interactions simplified, and the analytical model is subsequently deduced from the principle of minimum potential energy and Castigliano’s second theorem. The PWF of T300/Cycom970 is chosen as the study object to which the proposed analytical model is applied. Microscopic observations and thermal ablation experiments are conducted on the specimens to obtain the necessary inputs. The uniaxial tensile modulus is calculated and tensile experiments on the laminates are performed to validate the analytical prediction. The small deviation between the experimental and analytical results indicates the feasibility of the proposed analytical model, which has good prospects in validating the effectiveness of the experimentally obtained modeling parameters and guaranteeing the accuracy of mesoscale modeling for the PWF.

A Potential-Induced Transformation in the Double Electrical Layer on the Rhenium Electrode in Alkali Chloride Melts

Structural transformations in the adsorption layer caused by an electric potential are investigated using the experimental data on the capacitance of a double electric layer for a rhenium electrode in molten sodium, potassium and cesium chlorides at 1093 K. Likening the double electric layer to a flat capacitor, as well as the effective length of the shielding of the electrode charge and changes in the charge sign depending on the applied potential are estimated. It is found that near the minimum potential of the capacitance curve, the shielding length decreases proportionally to the square of the potential due to the deformation of the double layer. The deformation reaches critical values at the potentials of −0.65, −0.38 and −0.40 V for the Re|NaCl, Re|KCl and Re|CsCl systems respectively, and decreases sharply at more positive potentials. The analysis of the dependence of the charge density on the electrode revealed the effect of shielding of potential-induced rhenium cations by salt phase anions. The strong Raman-active Re–Cl stretching mode was observed at 292 cm−1. This can be explained by the transfer of anions across the interface resulting in the formation of ordered layers of ion associations (possibly, ReXn(n − 1)−) on a positively charged surface.

Cohesive behaviors of hydrogel under large-scale bridging

It has been recently revealed that large-scale bridging mechanism can be invoked to drastically improve the debonding resistance of hydrogel adhesion, but the optimization of the improvement remains elusive. Aiming at shedding light on the optimization, the present paper investigates the cohesive behaviors of hydrogel under the condition of large-scale bridging in 90-degree peel. A quasi-static model is established based on the principle of minimum potential energy, with the traction-separation law determined from experiments. The model is proved reliable in predicting the force-displacement response and the backing profile up to the peak peel force. Further theoretical analyses indicate that, within the range of interest, the peak peel force decreases with the extended length, increases with the Young's modulus of backing, increases then plateaus with the adhesion length and the thickness and bending stiffness of backing. In addition, the vertical displacement at peak peel force escalates with the extended length, remains mostly constant with varying adhesion length, declines with the Young's modulus of backing, and declines then stabilizes with increasing thickness and bending stiffness of backing. These theoretical insights may help tailor the material properties and geometric parameters for on-demand design of hydrogel adhesion as well as other soft adhesives for biomedicine and engineering.

Appraisal of Rainwater Harvesting in ASCOT Engineering Zabali Campus Baler Aurora

One of the problems encountered by the engineering students and faculty and staff members of Aurora State College of Technology (ASCOT) is the water supply for toilet and urinal flushing. This problem is attributed to the location of the area which is 50m above sea level. The main water source of the campus is the water coming from water falls which requires pipelines that are vulnerable from heavy damage during natural disasters and illegal intrusion. To address the scarcity, rainwater harvesting is considered by the researchers and in this research, the researchers assessed the potential of rainwater harvesting using the roof of an existing building in the area. The result shows that harvesting water from rainfall can become a solution in the scarcity of water in the area. Based on 10-year rainfall data from PAGASA Baler Station Complex which is Located approximately 4.3 km from the location of the study that on average, during December, November and October the amount of rainfall can fulfill the demand of water for toilet and urinal flushing up to 102.54 %, 76.98% and 75.40% respectively. The total area of rainwater collector in this study is about 186.87 square meter. Data also shows that on average, the month of August has the minimum potential of fulfilling the demand water for the area but by increasing the area of collector by 68%, 100% of the demand for this specific purpose maybe met during the driest month of the year

Bending and Buckling Analysis of Functionally Graded Euler–Bernoulli Beam Using Stress-Driven Nonlocal Integral Model with Bi-Helmholtz Kernel

Static bending and elastic buckling of Euler–Bernoulli beam made of functionally graded (FG) materials along thickness direction is studied theoretically using stress-driven integral model with bi-Helmholtz kernel, where the relation between nonlocal stress and strain is expressed as Fredholm type integral equation of the first kind. The differential governing equation and corresponding boundary conditions are derived with the principle of minimum potential energy. Several nominal variables are introduced to simplify differential governing equation, integral constitutive equation and boundary conditions. Laplace transform technique is applied directly to solve integro-differential equations, and the nominal bending deflection and moment are expressed with six unknown constants. The explicit expression for nominal deflection for static bending and nonlinear characteristic equation for the bucking load can be determined with two constitutive constraints and four boundary conditions. The results from this study are validated with those from the existing literature when two nonlocal parameters have same value. The influence of nonlocal parameters on the bending deflection and buckling loads for Euler–Bernoulli beam is investigated numerically. A consistent toughening effect is obtained for stress-driven nonlocal integral model with bi-Helmholtz kernel.

Crystal structure, hydrogen bonds and thermal transformations of superprotonic conductor Cs6(SO4)3(H3PO4)4

Crystals of Cs6(SO4)3(H3PO4)4 belong to the family of alkali metal acid salts that show a high protonic conductivity at relatively low temperatures. Such properties make superprotonic crystals an excellent choice for the study of the influence of the hydrogen subsystem on the physicochemical properties and promising materials for energy-efficient technologies. Single crystals of Cs6(SO4)3(H3PO4)4 were studied by neutron diffraction methods, optical polarization microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Neutron diffraction studies made it possible to determine the positions of all the atoms with high accuracy, including the H atom on a hydrogen bond characterized by a single-minimum potential, to confirm the chemical composition of the Cs6(SO4)3(H3PO4)4 crystals and their cubic symmetry in low- and high-temperature phases, and to draw conclusions about the three-dimensional system of hydrogen bonds, which is fundamentally different in comparison with other superprotonic compounds. Based on the experimental data obtained, crystal transformations with temperature changes are reported, and the stability of the chemical composition is shown.

Effective anti-plane moduli of couple stress composites containing elliptic multi-coated nano-fibers with interfacial damage and variational bounds

Prediction of the anti-plane moduli of solids consisting of a given distribution of unidirectionally aligned elliptic multi-coated fibers with interfacial damage is the focus of this paper. The fibers and their coating layers may be in the order of nano or micro scales. All the constituent phases of the composite are supposed to be described in terms of couple stress elasticity. Accordingly, the bounds for the overall shear moduli of the aforementioned composites are provided by employing the principles of minimum potential and complementary energies. Certain subtleties associated with the elliptic multi-coated fibers for three cases of pure sliding (completely damaged), imperfect (partially damaged), and perfect (undamaged) interface conditions will be discussed. The inherent anisotropy introduced due to the ellipse geometry of the fibers’ cross-sections is addressed. The effects of the ellipse aspect ratio as well as its size, interfacial damage, and rigidity on the effective anti-plane moduli of such composites will be examined.

Modeling and simulation of bonded-type piezoelectric linear motors considering the stress transfer in adhesive layer

This paper provides a general framework for modeling bonded-type piezoelectric linear motors considering the stress transferred by adhesive layer. A three-dimensional static model of stator is first developed by the principle of minimum potential energy and finite element. The stress transferred by adhesive layer could be simulated and analyzed for arbitrary bonding conditions. Basing on the static stress-transfer analysis, a quasi-static stress acted to substrate by piezoelectric elements is assumed and integrated into the substrate dynamic model. A pure mechanical dynamic model is developed for the electromechanical coupling system of stator. Furthermore, the whole-machine dynamic model of motor is presented by incorporating the frictional contact force into the dynamic model of the stator and an analytical model of the mover. Finally, a bonded-type piezoelectric linear motor with V-shaped stator is investigated as an example for simulations and experiments. The methodology presented here for simulating the transferred load of adhesive layer in bonded-type piezoelectric motor as well as for estimating the vibration characteristics of stator and output performances of motor. It is believed that the proposed method would be helpful to design and manufacture the prototypes due to the wider applicability of allowing for irregular geometry and any bonding conditions.