Ashby Method Research Articles

Structural design of a polymer matrix composite ship propeller

This work presents the structural design of a propeller, with its profile established using the OpenProp software for a 5 m long competition catamaran at a speed of 5.5 m/s. The materials selected using the Ashby method were polymer matrix composites, and the chosen manufacturing method was vacuum bagging. The determination of the stacking sequence was initially done using panel theory and the macromechanics of composite materials. The stacking sequence was then optimized using the finite element method with Abaqus CAE. Experimental validation was conducted through instrumented cantilever bending tests on both specimens and the blade. The finite element results showed errors of less than 5% compared to the experimental measurements, thus validating the simulations and allowing the blade to be designed with static safety factors greater than eight under operational service conditions.

Materials selection of non-metallic glasses for planar solid-oxide fuel cell sealants

Solid Oxide Fuel Cells (SOFCs) are emerging as promising solutions for advancing sustainable energy systems, mainly due to their high efficiency and fuel flexibility. The performance of planar SOFCs, distinguished by their high power density, significantly relies on the effectiveness of their seal components. This study applies the Ashby method to systematically identify seal materials that can endure the demanding conditions of SOFC operations, specifically with the target operating temperature of 800 °C, aimed at mitigating operational challenges while maintaining efficiency. We screened potential glass sealants based on their thermal, mechanical, and electrical properties using the SciGlass database and a compiled dataset with 38 new compositions from the last four years. Machine learning models helped predict missing data to refine our selection process. We identified nineteen exceptional glass candidates, including four defining the Pareto front, primarily composed of aluminosilicates and borosilicates enriched with BaO, CaO and SrO, with minor additions of MgO, ZrO, and La2O3. This study offers a valuable resource for researchers and engineers focused on developing high-performance SOFCs, presenting promising non-metallic glass candidates suited for sealant applications at operating temperatures of 800 °C.

Lightweight clad bi-metal conductors for cryogenic applications

Lightweight cryogenic conductors are required for applications in electric propulsion, such as cryogenically-fueled electric airplanes and ships. Clad bi-metal conductors allow to consider certain conductor metals that would not be feasible as a single conductor. This includes materials that are chemically reactive and materials that would not have the right mechanical properties to draw wires. The Ashby method is used to compare material combinations systematically. Manufacturing techniques and applications are also discussed. Copper-clad lithium wire stands out as one of the promising new types of clad bi-metal conductors for cryogenic applications.

Development of thermo-mechanical simulation of WC/Inconel 625 metal matrix composites laser cladding and optimization of process parameters

Laser cladding (LC) of industrial parts with tungsten carbide (WC)/Inconel 625 composite is highly regarded for its unique properties, for applications such as repair and improvement of surface and mechanical properties. In order to achieve high quality cladding, with minimal impact on the metallurgical structure and minimal stress and distortion caused by high local heating and cooling rate, it is necessary to determine the important parameters of the process, evaluate and investigate the effect of each one. Today, the numerical solution of this process can help predict, understand and evaluate the characteristics of the LC, and control and optimize it. In this research, using the thermo-elastoplastic simulation of the WC/Inconel 625 composite cladding process using finite element method (FEM) and the arbitrary Lagrangian-Eulerian (ALE) solution method with moving mesh strategy, the properties of the created coating have been evaluated. The laser is modeled with a moving Goldak double ellipsoidal heat source and the physical and mechanical properties of the temperature-dependent materials are considered. The physical and mechanical properties of the composite were extracted from the role of mixture and Ashby's method, respectively. Using Taguchi's experimental design method, the effect of important process parameters on output parameters such as dilution, cladding geometry, heat and stress have been investigated. Finally, the optimal parameters as well as the relationship between the parameters and each characteristic have been obtained using the linear regression model.

Silolarda Kullanılan Elevatör Kovalarının Maliyet ve Mukavemet Açısından Ashby Metodu ile Optimizasyonu

Silo systems are used to store the bulk grain. In general, they are designed with cylindrical or rectangular shape with steel, concrete, or brick materials. Silos have subsystems for operation such as transportation, aeration, and discharge. Buckets in elevators are one of the major parts of transportation system which carries various kinds of grains. This study aims to select the optimum material for buckets in terms of strength and cost which is suitable for injection molding that are used in different climates. For this purpose, in Çukurova Silo Company, a specific type of bucket which is used for the transportation of 80 Tons of wheat per hour had been analyzed. To choose the suitable materials for buckets that carry grains, advanced material selection technique, which is called as Ashby method, had been applied. ANSYS® Mechanical had been used to find out stresses during the carriage of the grain. Selected materials were ranked with respect to their properties. Some materials had been determined for the usage of production of buckets. Finally, the materials had been compared with respect to the ANSYS® Mechanical results and tested for this specific type of bucket. As results, PA6 with fiber-glass variant had been chosen as optimum material.

Selection of Ti Alloys for Bio‐Implants: An Application of the Ashby Approach with Conflicting Objectives

The aim of the present work is to develop a materials selection strategy for biomedical Ti alloys by combining Ashby's method with a recently published dataset. The selection process concerns mechanical properties such as yield strength, elastic modulus, deformation at rupture, and the cost of the material. Outputs of the selection process point to alloys from both Ti‐Nb and Ti‐Mo systems as viable candidates for joint replacement materials. Additionally, this work discusses the crucial role of certain alloying elements in obtaining high elastic admissible strains, that is, a high yield strength‐to‐modulus ratio. Adding solutes such as Ta, Zr, Sn, Fe, and O is vital to stabilizing the β phase, suppressing the ω phase and increasing mechanical strength. Considering the minimum requirements of a 400 MPa yield strength, and 10% elongation at rupture, the best alloys identified via a multi‐objective optimization approach are Ti‐4.6Mo‐3.3Sn‐1.0Fe‐0.4O, Ti‐22.1Nb‐5Zr‐1.0Fe, and Ti‐20.3Nb‐4.7Ta‐2.5Sn (at%). These compositions present elastic moduli lower than 55 GPa, with an optimal trade‐off between a high elastic admissible strain and low cost. Updated property maps and analyses of conflicting properties are provided to support the conclusions.

Structural Design of Field Plate Load Test Equipment to Determine In situ Bearing Capacity and Settlement of Clayey Soil

The study is to design field-operated plate load test equipment to overcome the problem of predicting bearing capacity and settlement of clayey soil on site using the conventional/traditional methods of short-duration plate load test where a hydraulic jack is used in conducting the test. Ashby's method of material selection was used for the selection of a suitable material for each of the components. The 12 mm thickness was obtained as the minimum safe thickness for the applied load of 500 kg on the lever arm. The I-section frame that support the entire system has sectional modulus of 19.4 cm3 and 4 mm thickness. The equipment will use a lever arm mechanism to conduct an in-situ test that will take long-duration on clay soil where the dissipation of pore water from the clayey soils takes a longer time to complete as against the current conventional method of plate load test that is in use. The equipment will offer several advantages in terms of cost, reliability, portability, authenticity, and user friendly.

Material Selection and Analysis of Torsional Rigidity in Formula Student SAE regulation

The advancement of automotive technology is rapid in this era, as evidenced by the existence of autopilot vehicles that have been developed by a scientist. This progress is balanced with the knowledge that continues to develop in the world of education. Many prestigious automotive competitions are held to be a venue for student creativity and research in developing automotive technology, one of which is the Formula Student SAE. This is the background of a study to develop an engineered electric vehicle chassis, especially in Formula Student. This study aims to produce a chassis design that has torsional rigidity based on the selection of materials that have stiffness, strength, lightweight, and optimization of material cost. The structure of the vehicle was designed following Formula Student SAE regulations. To select material, initial screening was used by the Ashby method which produce 4 material types. Optimum of selecting the material used the Simple Additive Weighting (SAW) method. Meanwhile, chassis with material selected was analyzed by using Solidworks Simulation Education software. The results of this study produced Aluminum Alloys 7075-T6 material and torsional rigidity value of 552.65 x 103 Nmm/degree of chassis, which could achieve the minimum torsional rigidity value set at 500 x 103 Nmm/degree.

Application of a Design for Excellence Methodology for a Wireless Charger Housing in Underwater Environments

A major effort is put into the production of green energy as a countermeasure to climatic changes and sustainability. Thus, the energy industry is currently betting on offshore wind energy, using wind turbines with fixed and floating platforms. This technology can benefit greatly from interventive autonomous underwater vehicles (AUVs) to assist in the maintenance and control of underwater structures. A wireless charger system can extend the time the AUV remains underwater, by allowing it to charge its batteries through a docking station. The present work details the development process of a housing component for a wireless charging system to be implemented in an AUV, addressed as wireless charger housing (WCH), from the concept stage to the final physical verification and operation stage. The wireless charger system prepared in this research aims to improve the longevity of the vehicle mission, without having to return to the surface, by enabling battery charging at a docking station. This product was designed following a design for excellence (DfX) and modular design philosophy, implementing visual scorecards to measure the success of certain design aspects. For an adequate choice of materials, the Ashby method was implemented. The structural performance of the prototypes was validated via a linear static finite element analysis (FEA). These prototypes were further physically verified in a hyperbaric chamber. Results showed that the application of FEA, together with well-defined design goals, enable the WCH optimisation while ensuring up to 75% power efficiency. This methodology produced a system capable of transmitting energy for underwater robotic applications.

Design of mechanically compatible lattice structures cancellous bone fabricated by fused filament fabrication of Z-ABS material

Designing and manufacturing replacement cancellous bone structures by lattice structures and Additive Manufacturing (AM) techniques is an effective method to create lightweight orthopedic implants while ensuring that they are mechanically compatible and their osseointegration ability with the host bone. In this article, we suggest a new design based on three lattice structures from triply periodic minimal surfaces (TPMS) with a different volume porosity to replace cancellous bone based on predicting the mechanical stiffness. To predict the mechanical stiffness, the relationship between the effective modulus of elasticity and different porosity ratios of the lattice structures was determined by using three methods: i) finite element modeling (FEM) simulation, ii) Gibson and Ashby method and iii) a uniaxial compression test after manufacturing the lattice structures by using Fused Filament Fabrication (FFF) Technology. To demonstrate the efficiency of our approach, the comparison of both numerical and experimental results showed that the effect of structure difference and porosity ratio of lattice structures on the mechanical stiffness values effectively match the cancellous bone in terms of elastic modulus and porosity ratio.

Finite element analysis of Ti6Al4V porous structures for low-stiff hip implant application

Solid metallic hip implants have much higher stiffness than the femur bone, causing stress-shielding and subsequent implant loosening. The development of low-stiff implants using metallic porous structures has been reported in the literature. Ti6Al4V alloy is a commonly used biomaterial for hip implants. In this work, Body-Center-Cubic (BCC), Cubic, and Spherical porous structures of four different porosities (82%, 76%, 70%, and 67%) were investigated to establish the range of ideal porosities of Ti6Al4V porous structures that can match the stiffness of the femur bone. The effective mechanical properties have been determined through Finite Element Analysis (FEA) under uniaxial compressive displacement of 0.32 mm. FEA predictions were validated with the analytical calculations obtained using Gibson and Ashby method. The effective mechanical properties of 82%, 76%, 70%, and 67% porous BCC and Cubic structures were found to match the mechanical properties of cortical bone closely. They were also well comparable to the Gibson-Ashby method-based calculations. BCC and Cubic porous structures with 67–82% porosity can mimic the stiffness of the femur bone and are suitable for low-stiff hip implant applications.

Electric Contact Material Selection for Medium and High Voltage DC Circuit Breakers

Medium and high voltage DC grids are increasingly proposed for terrestrial, shipboard and aircraft power systems. However, multi terminal DC networks can only be realized with the development of a DC circuit breaker. Due to the difficulty in breaking DC currents, hybrid circuit breakers—which consist of a non-arcing fast mechanical disconnect switch (FMS) in parallel with a solid state switch—is the most promising solution. The stresses experienced by the electric contacts of FMS are different from those of AC and low voltage DC breakers and disconnect switches. The choice of contact material has a significant impact on the performance of the DC circuit breaker. The Ashby method is used to systematically identify the best suited contact materials by translating the requirements of FMS contacts into objectives and constraints and deriving material indices for each objective. Minimizing power loss, wear and overheating of contacts are identified as the key objectives. The results suggest that copper-based alloys and compounds are more suitable than silver based alloys and compounds and other contact materials.

Materials Selection of Optimized Titanium Alloys for Aircraft Applications

The aim of the present work was to explore the correlation between the physical metallurgy of titanium alloys and its main attributes to select optimized materials for structural aircraft applications in the landing gear beam. The Ashby's method was employed as the materials selection strategy to consolidate and evaluate the data collected from the current literature in a comprehensive and consistent analysis. Landing gear beam materials are mainly β and near-β alloys. Considering the need for high specific strength and fatigue resistance, the best candidate among them was Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe alloy. Finally, a brief discussion of additional aspects related to alloy design, microstructural features and their influence on the mechanical properties is presented.

Seleção de materiais para produtos de tecnologia assistiva

Muitas pessoas convivem com limitações motoras, que impedem a plena realização de atividades cotidianas como a alimentação. O Design Universal e a Tecnologia Assistiva, visam uma interação segura entre o indivíduo e sua refeição, por meio de talheres adaptados. Os materiais dos talheres afetam a percepção dos alimentos, por interações químicas, físicas e mecânicas. Este artigo teve como objetivo, selecionar materiais para talheres adaptados, priorizando a autonomia de pessoas com deficiência. Os procedimentos metodológicos constituem a aplicação de critérios do GODP e Método Ashby. Ao final, foram selecionados, o aço baixa-liga para o talher e PA 12 para a pega.

A Typical Approach in Conceptual and Embodiment Design of Foldable Bicycle

The Conceptual design and Embodiment design are two of the important stages in a typical product design and development process. This study aims at generating different concepts for a foldable bicycle product using a systematic concept generation method and the best generated concepts have been selected using various concept selection methods. It also describes a systemic approach to material selection and FEA justify during embodiment design phase. Various design concepts have been generated from a range of available possible solutions to each product function by morphological matrix which was developed based on functions tree. The Pugh chart and numerical concept selection methods have been employed to select the best concepts that have been generated based on a set of criteria. In the Embodiment design phase, the Ashby method has been used for material selection for the selected design concept. The human comfort has been checked by Digital Human Modeling (DHM) Technology. In addition to the material selection process, the proposed design of the foldable bicycle has also been analyzed for its safety by FEA and Fatigue analysis.

Materials Selection Exercise for Electromagnetic Launcher Rails

Electromagnetic launchers (EML) are currently limited due to rail durability. The rail operating environment consists of large electrical currents, high local temperatures, large electromagnetic loads, and high sliding velocities. The desire to maximize magnetic energy for performance and durability for economic viability are the main objectives in selecting a rail material. A systematic process, often referred to as the Ashby method is used. The three steps include translating the design requirements into objectives and constraints, screening out materials that do not meet basic performance criteria, and ranking material candidates to maximize the objectives. Gouges, grooves, and fracture were identified as the three most life limiting forms of rail damage responsible for durability. Material property tradeoff plots show that magnetic energy and durability are conflicting objectives. A hybrid rail material in the form of a monolayer structure with an electrically conductive substrate and a damage resistant surface layer is the ideal configuration for maximizing the objectives. The results suggest that a conductive substrate, such as copper, is best for maintaining performance by means of magnetic energy and a damage resistant surface material consisting of tungsten, chromium, nickel, or tantalum has the best potential for increasing rail durability.

The immune haemolytic anaemias: a century of exciting progress in understanding.

The immune haemolytic anaemias: a century of exciting progress in understanding.

Materials selection for optimal environmental impact in mechanical design

In engineering design, material selection is carried out in a number of ways. There are many factors affecting material choice for a particular application such as cost, weight and processability, but some of the most important are those of mechanical performance. Many methods exist for optimising parameter values in mechanical design allowing activities such as minimum weight design, design for minimisation of thermal distortion and minimum cost design. These considerations are important but in recent years environmental factors have played an increasing role in the selection of materials and technologies. The inclusion of realistically complex environmental criteria in the design process necessitates the development of methodologies and tools to assist designers. This paper looks at one particular method of material selection in mechanical design: material selection charts by Ashby, and shows how this methodology can be extended to take environmental factors into account. The method for calculating both air and water pollution indices is explained and it is shown how these values may be used to plot charts. By producing material selection charts, along the lines of Ashby's method, which deal with air or water pollution, mechanical design for optimal environmental impact may be structured and accelerated. The limitations of the charts presented in this paper are discussed.

Piezoelectric behavior of wood under combined compression and vibration stresses II: Effect of the deformation of cross-sectional wall of tracheids on changes in piezoelectric voltage in linear-elastic region

This study investigated and clarified the relation between the piezoelectric voltage and microscopic fracture of hinoki (Chamaecyparis obtura Endl.), in particular the deformation of the cross-sectional wall of the tracheid in linear-elastic regions under combined compression and vibration stresses. The piezoelectric voltage-deformation (P-D) curve consisted of a linear region starting from the origin followed by a convex curved region. The linear region of theP-D curve was only about 60% of that of the load-displacement (L-D) curve. By applying combined stresses to a specimen, the cross-sectional walls of the tracheid were deformed mainly at the radial walls. When a tracheid was regarded approximately as a hexagonal prism, the elastic buckling stress of the radial wall was estimated from scanning electron microscope images and our method based on a modification of the Gibson and Ashby method. As a result, it was estimated that the elastic buckling stress was only about 80% of the stress at the proportional limit of theP-D curve. It is found that there are two consecutive regions before the proportional limit of theP-D curve: One is the region up to the spot where the radial cell wall generates the elastic buckling, and the other is the region starting from the end of the aforementioned region up to the proportional limit of theP-D curve.

Sintering diagrams of UO 2

Ashby's method of constructing sintering diagrams has been modified to obtain relative contribution diagrams directly from the computer. It is endeavoured here to study the interplay of sintering variables and mechanisms and determine the factors that affect the participation of mechanisms in UO 2. By studying the physical properties, it emerges that the order of inaccuracies is small in most cases and do not affect the diagrams. On the other hand, even a 10% error in activation energies, which is quite plausible, would make a significant difference to the diagram. The main criticism of Ashby's approach is that the numerous properties and equations used, communicate their inaccuracies to the diagrams and make them unreliable. Our study has considerably reduced the number of factors that need to be refined to make the sintering diagrams more meaningful.