Effect Of Shape Change Research Articles

PENGARUH MODIFIKASI BURITAN SPEED BOAT TERUBUK EXPRESS 6 TERHADAP KECEPATAN KAPAL

Speedboat Terubuk Express is a fast ship that is used as a means of sea transportation to carry passengers with a capacity of 60 people. Because it continues to experience losses, currently the Terubuk Express speedboat is modified by adding capacity and replacing the main drive engine which previously used an outboard engine with 4 x 200 horse power replaced with an internal engine that uses diesel fuel with power 1140 kilowatt. This study aims to determine the effect of stern shape changes and interaction total resistance before and after being modified on the hull to the speed of the ship.In this study several stages were carried out, namely a field survey to obtain the effect of size addition, making a model using Maxsurf 13.0 software, input data and running simulations using Hullspeed 13.01 then analyzing the results which included obstacles and speed.Based on the results of the analysis and calculations showed that the change in stern shape on the express speed boat speed caused L / B to increase by 1.2%, an increase in the comparison of the L / B value could affect the ability of the boat's motion and stability. The total resistance of the ship increased by 1.05% which at a speed of 35 knots before the change in total resistance was 33.5 kN while after the change in the total resistance became 35, 1 kN. Changes to the installed power engine can give a maximum speed of 49 knots with a total barrier of 47.5 kN. Increased speed greatly affects the engine seat and the strength of construction and the location of the longitudinal of bouyancy.

Patterns in Drying Drops Dictated by Curvature-Driven Particle Transport.

Patterns generated by controlled evaporation of droplets containing colloids are dictated by internally generated flows. This advective particle transport is crucial to the efficacy of printing and coating processes and is also an elegant route to the self-assembly of particles. We propose a novel particle transport route, which involves adsorption of particles to the interface and subsequent curvature-driven migration of the particles along the interface. This interface-mediated transport can be exploited to control the distribution of particles in the dried patterns, which we experimentally elucidate by achieving gravity-induced drop shape changes. Our experiments demonstrate that the interplay between the bulk and the interfacial transport leads to strikingly different patterns: while dried aqueous sessile drops of colloidal dispersions produce well known "coffee-rings", dried pendant drops lead to "coffee-eyes". We support our experimental findings using scaling arguments. In previous studies, the effect of gravity-induced change in drop shape on the patterns formed in drying drops has been neglected. However, we show that the structure of the patterns formed by the colloidal particles after solvent evaporation is markedly different when the drops are deformed by gravity.

Deployment and Shape Change of a Tensegrity Structure Using Path-Planning and Feedback Control

Tensegrity structures are pin-jointed assemblies of struts and cables that are held together in a stable state of stress. Shape control is a combination of control-commands with measurements to achieve a desired form. Applying shape control to a near-full-scale deployable tensegrity structure presents a rare opportunity to analytically and experimentally study and control the effects of large shape changes on a closely coupled multi-element system. Simulated cable-length changes provide an initial activation plan to reach an effective sequence for self-stress. Controlling internal forces is more sensitive than controlling movements through cable-length changes; internal force-control is thus a better objective than movement-control for small adjustments to the structure. The deployment of a tensegrity structure in previous work was carried out using predetermined commands. In this paper, two deployment methods and a method for self-stress are presented. The first method uses feedback cycles to increase speed of deployment compared with implementation of empirically predetermined control-commands. The second method consists of three parts starting with a path-planning algorithm that generates search trees at the initial point and the target point using a greedy algorithm to create a deployment trajectory. Collision and overstress avoidance for the deployment trajectory involve checks of boundaries defined by positions of struts and cables. Even actuator deployment followed by commands obtained from a search algorithm results in the successful connection of the structure at midspan. Once deployment at midspan is achieved by either method, a self-stress algorithm is implemented to correct the position and element forces in the structure to the design configuration prior to in-service loading. Modification of deployment control-commands using the feedback method (with twenty cycles) compared with empirically predetermined control-commands successfully provides a more efficient deployment trajectory prior to midspan connection with up to 50% reduction in deployment time. The path-planning method successfully enables deployment and connection at midspan with a further time reduction of 68% compared with the feedback method (with twenty cycles). The feedback control, the path-planning method and the soft-constraint algorithm successfully lead to efficient deployment and preparation for service loading. Advanced computing algorithms have potential to improve the efficiency of complex deployment.

Effect of Shape Change and Angular Orientation of Slot Ends on Vibration Characteristics of Annular Discs

Effect of Shape Change and Angular Orientation of Slot Ends on Vibration Characteristics of Annular Discs

Numerical prediction of wear in SAG mills based on DEM simulations

Wear is a major operating problem for semi-autogenous grinding (SAG) mills. A credible and efficient numerical approach for accurately predicting wear within SAG mills can significantly reduce design time and improve grinding efficiency. In this paper, the 3D simulations were performed using discrete element method (DEM) combined with an erosion model, which is referred to as Shear Impact Energy Model (SIEM), to predict wear within a SAG mill. The approach is quantitively validated against the corresponding experiment reported by other researchers. The results show that the rotation speed significantly affects the wear rate and wear distribution on the liners. In addition, the effects of changes in lifter shape on wear within the SAG mill are also obtained and analyzed. The primary reason for wear on the liners is revealed based on the simulation results: it is the intense collisions between the particles and the liners during the acceleration of the particles in the toe region that cause the severe wear. Finally, the rotation speed and lifter shape are synthetically evaluated from the aspect of wear and energy utilization.

Shape memory composite cellular plan-forms for shape and area morphing

In this paper we demonstrate a two-dimensional deformation mechanism with shape memory alloy (SMA) wire reinforced composite unit cell based plan-form structure which can produce various combinatorial effects of shape change and area change. Active deformation is realized using thermal SMA wire thermoelectric actuators. Compliant topological constructs are arrived at by consider passive and active load path decoupling and sub-optimal shape change and area change. Out-of-plane bending and buckling of the cellular membrane is restricted with the help of first auxiliary rib type stiffeners and later with monolithic elastic thermoplastic fabricated by laser machining. Systematic incorporation of various small-scale deformation features lead to large improvement in actuation efficiency. Structural compliance without and with the actuators are analyzed based on finite element simulation and experimental validation. A super-cell plan-form is characterized which shows interesting possibilities in structural morphing applications. The proposed multi-cell structures have potential applications membrane like structural morphing which can be integrated with transverse load carrying members.

Heat wave probability in the changing climate of the Southwest US

Analyses of observed non-Gaussian daily minimum and maximum temperature probability distribution functions (PDFs) in the Southwest US highlight the importance of variance and warm tail length in determining future heat wave probability. Even if no PDF shape change occurs with climate change, locations with shorter warm tails and/or smaller variance will see a greater increase in heat wave probability, defined as exceedances above the historical 95th percentile threshold, than will long tailed/larger variance distributions. Projections from ten downscaled CMIP5 models show important geospatial differences in the amount of warming expected for a location. However, changes in heat wave probability do not directly follow changes in background warming. Projected changes in heat wave probability are largely explained by a rigid shift of the daily temperature distribution. In some locations where there is more warming, future heat wave probability is buffered somewhat by longer warm tails. In other parts of the Southwest where there is less warming, heat wave probability is relatively enhanced because of shorter tailed PDFs. Effects of PDF shape changes are generally small by comparison to those from a rigid shift, and fall within the range of uncertainty among models in the amount of warming expected by the end of the century.

Effect of Tailoring Martensite Shape and Spatial Distribution on Tensile Deformation Characteristics of Dual Phase Steels

The authors simulated the industrially used continuous annealing conditions to process dual phase (DP) steels by using a custom designed annealing simulator. Sixty-seven percentage of cold rolled steel sheets was subjected to different processing routes, including the conventional continuous annealing line (CAL), intercritical annealing (ICA), and thermal cycling (TC), to investigate the effect of change in volume fraction, shape, and spatial distribution of martensite on tensile deformation characteristics of DP steels. Annealing parameters were derived using commercial software, including thermo-calc, jmat-pro, and dictra. Through selection of appropriate process parameters, the authors found out possibilities of significantly altering the volume fraction, morphology, and grain size distribution of martensite phase. These constituent variations showed a strong influence on tensile properties of DP steels. It was observed that TC route modified the martensite morphology from the typical lath type to in-grain globular/oblong type and significantly reduced the martensite grain size. This route improved the strength–ductility combination from 590 MPa–33% (obtained through CAL route) to 660 MPa–30%. Finally, the underlying mechanisms of crack initiation/void formation, etc., in different DP microstructures were discussed.

Effect of shape change and initial geometry on water diffusivity estimation during drying of gel model systems

The mathematical modeling of simultaneous shrinkage and shape change (deformation) during drying of gel model systems (GMS) was investigated. Developed theory was applied to estimate water diffusivities during drying of GMS (70 °C, air velocity of 2 m/s) shaped as square prisms (9.53 mm × 9.53 mm × 80 mm) and longitudinal sections (quarters and halves) of cylinders (12.7 mm diameter × 140 mm length) by considering the product shrinkage with and without deformation. The contours of transversal product slices, obtained from digital images, were averaged to extract relevant characteristics of the dried samples, whereas compactness and roundness were used to evaluate product deformation. Experimental shape patterns were used to estimate the initial and final mesh matching the real product geometry during simulation via a new algorithm. The obtained results demonstrate that although shrinkage occurs from the beginning of drying, changes in product shape are noticeable only after the free moisture fraction is below 0.3. Water diffusivities estimated considering the shape change of product were in the narrow range of 3.37–3.58 × 10−10 m2/s for studied geometries, and are overestimated in about 6–12% when this phenomenon is not included in drying model. No significant differences were observed in water diffusivity values between studied geometries (p > 0.05).

Numerical investigation of the effect of shape change in graphite crucible during top-seeded solution growth of SiC

In the present work, a combined 2D-3D numerical simulation was performed to study the effect of shape change in the graphite crucible on the heat transfer, flow pattern, mass transport, and electromagnetic field during top seeded solution growth of SiC considering the dissolution of carbon during crystal growth. The graphite crucible shapes at each growth process time were predicted using 2D axisymmetric steady global heat and mass transfer simulations. The crucible geometries obtained for each time step, including the predicted crucible shapes, were used for 3D unsteady simulations. The investigation revealed a significant effect of the shape change of the crucible on the temperature, Lorentz force distribution induced by the radiofrequency heating system, flow pattern, carbon concentration in the solution, and growth rate of SiC.

Energy distribution modulation by mechanical design for electrochemical jet processing techniques

The increasing demand for optimised component surfaces with enhanced chemical and geometric complexity is a key driver in the manufacturing technology required for advanced surface production. Current methodologies cannot create complex surfaces in an efficient and scalable manner in robust engineering materials. Hence, there is a need for advanced manufacturing technologies which overcome this. Current technologies are limited by resolution, geometric flexibility and mode of energy delivery. By addressing the fundamental limitations of electrochemical jetting techniques through modulation of the current density distribution by mechanical design, significant improvements to the electrochemical jet process methods are presented. A simplified 2D stochastic model was developed with the ability to vary current density distribution to assess the effects of nozzle-tip shape changes. The simulation demonstrated that the resultant profile was found to be variable from that of a standard nozzle. These nozzle-tip modifications were then experimentally tested finding a high degree of variance was possible in the machined profile. Improvements such as an increase in side-wall steepness of 162% are achieved over a standard profile, flat bases to the cut profile and a reduction of profile to surface inter-section radius enable the process to be analogous to traditional milling profiles. Since electrode design can be rapidly modified EJP is shown to be a flexible process capable of varied and complex meso-scale profile creation. Innovations presented here in the modulation of resistance in-jet have enabled electrochemical jet processes to become a viable, top-down, single-step method for applying complex surfaces geometries unachievable by other means.

Compaction of granular materials composed of deformable particles

In soft particle materials such as metallic powders the particles can undergo large deformations without rupture. The large elastic or plastic deformations of the particles are expected to strongly affect the mechanical properties of these materials compared to hard particle materials more often considered in research on granular materials. Herein, two numerical approaches are proposed for the simulation of soft granular systems: (i) an implicit formulation of the Material Point Method (MPM) combined with the Contact Dynamics (CD) method to deal with contact interactions, and (i) Bonded Particle Model (BPM), in which each deformable particle is modeled as an aggregate of rigid primary particles using the CD method. These two approaches allow us to simulate the compaction of an assembly of elastic or plastic particles. By analyzing the uniaxial compaction of 2D soft particle packings, we investigate the effects of particle shape change on the stress-strain relationship and volume change behavior as well as the evolution of the microstructure.

Investigation of the Effect of Radiation-Induced Shape Change of Fuel Assemblies on the Temperature Regime and Stress-Strain State of Fuel-Element Cladding

Methods of calculating the temperature regime and stress-strain state of fuel elements in a sodium-cooled BN-600 are presented. Deformation effects and the local azimuthal temperature distribution of fuel elements with wire winding spacing in fuel assemblies are taken into account. The influence of radiation effects on the temperature regime and stress-state of the fuel elements is shown. The maximum stresses are observed in the section with maximum shape change. At run completion, as a result of nonuniform swelling of the cladding material, on the inner fiber of the cladding the compression stresses transform into tensile stresses and repeat the character of the temperature distribution along the cladding perimeter. The maximum inelastic accumulated strains (ec = 1.5%) occur at the point of greatest swelling and high tangential stress.

Study the Performance of a Domestic Refrigerator with Dual-Loop Cycle Flow Condenser and Comparison with Wire-on-Tube Condenser

This paper presents an experimentalinvestigation into the performance of domestic refrigerator system with two different types of condensers, novel design of dual-loop condenser and the conventional condenser.The geometrical configuration considered in this study is representative designing and manufacturing of novel type of dual-loop cycle condenser and compared with typical condenser. The experimentswere conducted with a refrigerator designed to work with HFC134a, under no load and with different loads as (1.5, 3 and 12 litters of water).The results showed that the dual-loop condenser decreases the work done by the compressor by about (1.951% to 5.257%). Also, the effects of shape change of the condenser can be reducing the pressure drop as result of reduction the frictional losswhere can rotate the flow without restriction to the flow in the dual-loop condenser

Microwave drying of spheres: Coupled electromagnetics-multiphase transport modeling with experimentation. Part I: Model development and experimental methodology

To understand the effects of shape, size and property changes in a spherical sample during microwave drying, a fundamentals-based coupled electromagnetics and multiphase porous media model is developed and associated experimental details are described. Microwave drying of different sized spheres is carried out in a domestic microwave oven operating at 10% power level. Maxwell's equations for electromagnetics are solved inside a three dimensional (3D) microwave oven to obtain the electric field distribution inside the oven cavity and the spheres. The drying samples are treated as a porous media consisting of three phases: solid (skeleton), liquid (water) and gas (water vapor and air). Modes of transport for the fluid phases include capillary flow, binary diffusion between vapor and air, gas pressure driven flow and phase change between liquid water and vapor which is spatially distributed. An elaborate experimental system comprising of infrared camera, optical fiber probe and digital balance is built to validate the model in terms of temperature distribution, point temperatures, gas pressure generation and moisture loss from the samples at different times during the drying process. Results, validation, sensitivity analysis and “what-if” scenarios are presented in the companion paper. The work together would provide tremendous benefits when designing and developing microwave drying processes and products through a novel synergy between physics-based modeling and detailed experimentation.

A Couple Approach for a Conjugate Heat Transfer Investigation of the Shape-Change Effects in a Composite Nozzle

To address the conjugate heat transfer problem in complex geometries, a coupling approach based on the local coordinate transformation is developed to evaluate the common wall temperature on non-orthogonal solid–fluid interfaces. The proposed coupling approach is validated and then used to investigate the erosion-induced shape change effects in a composite nozzle. The changes of flow field are evident in terms of the Mach number, temperature, and pressure, especially in the vicinity of erosion steps. The comparison of the wall pressure distribution indicates that the nozzle thrust performance degrades after erosion.

Hyper-dendritic nanoporous zinc foam anodes

The low cost, significant reduction potential and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work, we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1–96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrast to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~88% at full depth-of-discharge (DOD) at various rates indicating a superb rate capability. The rechargeability of Zn0/Zn2+ showed significant capacity retention over 100 cycles at a 40% DOD to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge–discharge cycling and presented superior performance compared with bulk zinc electrodes. A synthetic method turns a problem with plate metal batteries into a path for greater stability and may lead to safer, cheaper batteries. Zinc is more abundant and easier to handle than lithium, but electrodes made from it suffer from shape-change effects that prevent stable cycling. Now, by electrodepositing nanoporous zinc foam onto a traditional current collector, Daniel Steingart from Princeton University in the USA and colleagues have exploited a problem with zinc electrodes — the formation of dendritic crystals that can short-circuit batteries. The team broke convention by deliberately conditioning their zinc electrodes at potentials far from equilibrium. This created a hyper-dendritic network foam that forms with 88% current efficiency and remains stable for over 100 recharge cycles — results superior to those of conventional batteries with non-porous zinc electrodes. The low cost, significant reduction potential and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work, we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1–96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrast to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~88% at full depth-of-discharge (DOD) at various rates indicating a superb rate capability. The rechargeability of Zn0/Zn2+ showed significant capacity retention over 100 cycles at a 40% DOD to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge–discharge cycling and presented superior performance compared with bulk zinc electrodes.

Polymeric Materials as Artificial Muscles: An Overview

The accurate selection of materials and the fine tuning of their properties represent a fundamental aspect in the realization of new active systems able to produce actuating forces, such as artificial muscles. In this regard, exciting opportunities for the design of new advanced systems are offered by materials belonging to the emerging class of functional polymers: exploiting their actuation response, specific devices can be realized. Along this direction, materials showing either shape-memory effect (SME) or shape-change effect (SCE) have been the subject of extensive studies aimed at designing of actuators as artificial muscles. Here, we concisely review active polymers in terms of properties and main applications in artificial muscle design. The main aspects related to material properties in both shape-memory polymers (SMPs) and electroactive polymers (EAPs) are reviewed, based on recent scientific literature. SME in thermally activated SMPs is presented by preliminarily providing a definition that encompasses the new theories regarding their fundamental properties. EAPs are briefly presented, describing the working mechanisms and highlighting the main properties and drawbacks, in view of their application as actuators. For both classes of materials, some key examples of effective application in artificial muscles are offered. The potential in polymer architecture design for the fabrication of actively moving systems is described to give a perspective on the main achievements and new research activities.

Finite element analysis of the tetragonal to monoclinic phase transformation during oxidation of zirconium alloys

Corrosion is a key limiting factor in the degradation of zirconium alloys in light water reactors. Developing a mechanistic understanding of the corrosion process offers a route towards improving safety and efficiency as demand increases for higher burn-up of fuel. Oxides formed on zirconium alloys are composed of both monoclinic and meta-stable tetragonal phases, and are subject to a number of potential mechanical degradation mechanisms. The work presented investigates the link between the tetragonal to monoclinic oxide phase transformation and degradation of the protective character of the oxide layer. To achieve this, Abaqus finite element analysis of the oxide phase transformation has been carried out. Study of the change in transformation strain energy shows how relaxation of oxidation induced stress and fast fracture at the metal–oxide interface could destabilise the tetragonal phase. Central to this is the identification of the transformation variant most likely to form, and understanding why twinning of the transformed grain is likely to occur. Development of transformation strain tensors and analysis of the strain components allows some separation of dilatation and shear effects. Maximum principal stress is used as an indication of fracture in the surrounding oxide layer. Study of the stress distributions shows the way oxide fracture is likely to occur and the differing effects of dilatation and shape change. Comparison with literature provides qualitative validation of the finite element simulations.

Shape memory/change effect in a double network nanocomposite tough hydrogel

In this paper, we present a systematic investigation on the shape memory/change effect in a double network nanocomposite tough hydrogel. Water-content dependency of the response of this hydrogel to heating and wetting by water is confirmed. Since this hydrogel is tough (even after being fully wetted in water) and has a relatively lower swelling ratio, apart from conventional shape memory/change effect as in ordinary hydrogels, additional features have been realized. These features include heating induced shape memory effect utilizing the absorbed water as the transition component, mechano-responsive shape change effect after water wetting and water-induced shape memory effect.