Material Design Methodology Research Articles

Electron work function: an indicative parameter towards a novel material design methodology

Electron work function (EWF) has demonstrated its great promise in materials analysis and design, particularly for single-phase materials, e.g., solute selection for optimal solid-solution strengthening. Such promise is attributed to the correlation of EWF with the atomic bonding and stability, which largely determines material properties. However, engineering materials generally consist of multiple phases. Whether or not the overall EWF of a complex multi-phase material can reflect its properties is unclear. Through investigation on the relationships among EWF, microstructure, mechanical and electrochemical properties of low-carbon steel samples with two-level microstructural inhomogeneity, we demonstrate that the overall EWF does carry the information on integrated electron behavior and overall properties of multiphase alloys. This study makes it achievable to develop “electronic metallurgy”—an electronic based novel alternative methodology for materials design.

Nanoscale element behavior in a continuum.

Patterns in materials are not just decoration but also important for function. In view of this, the dynamics of patterning procedures in materials has been investigated as an important developmental procedure. In this study, nanoscale components in a continuum are traced in terms of natural patterning procedures. Externally applied compressive or extensive forces to an elastic thin sheet commonly induce an orientated lateral line pattern. From a nanoscale element point of view, the dynamics of natural arrangements, forming anisotropic patterns in preference to isotropy, still remains unclear. In this study, new developmental procedures for line patterns are suggested by stimuli-responsive viscoelastic nanocomposite network model systems. Forces originating from an internal source without directional orientation generate lines in preference to isotropic patterns. With repeated, non-oriented (or isotropic) and self-modulated strain variations, stress is accumulated to drive anisotropic orientations and further lines. The anisotropic elemental arrangement is justified by the equilibrium between the short-range attraction and long-range repulsion from a bottom-up viewpoint. This study suggests a new material design methodology that is useful for electrical devices, biomedical devices and other patterned soft condensed matter in conjunction with line patterns typically generated in a broad range of viscoelastic materials.

Material Design Methodology for Optimized Wear-Resistant Thermoplastic-Matrix Composites Based on Polyetheretherketone and Polyphenylene Sulfide.

The main goal of this paper is to design and justify optimized compositions of thermoplastic–matrix wear-resistant composites based on polyetheretherketone (PEEK) and polyphenylene sulfide (PPS). Their mechanical and tribological properties have been specified in the form of bilateral and unilateral limits. For this purpose, a material design methodology has been developed. It has enabled to determine the optimal degrees of filling of the PEEK- and PPS-based composites with carbon microfibers and polytetrafluoroethylene particles. According to the results of tribological tests, the PEEK-based composites have been less damaged on the metal counterpart than the PPS-based samples having the same degree of filling. Most likely, this was due to more uniform permolecular structure and greater elasticity of the matrix. The described methodology is versatile and can be used to design various composites. Its implementation does not impose any limits on the specified properties of the material matrix or the reinforcing inclusions. The initial data on the operational characteristics can be obtained experimentally or numerically. The methodology enables to design the high-strength wear-resistant composites which are able to efficiently operate both in metal–polymer and ceramic–polymer friction units.

Reversible self-bending soft hydrogel microstructures with mechanically optimized designs

A rational design methodology for materials with optimal mechanical properties is a prerequisite for developing programmable soft matter that undergoes structural changes in response to external stimuli. The goals of this study are to experimentally characterize the capabilities of a self-bending reconfigurable microstructure, provide fundamental information in engineering design, and validate simulations of physics-based models. In this study, the self-bending behavior of hydrogel bilayers, composed of an active layer and a passive layer, is investigated experimentally and theoretically. This self-bending is completely reversible and allows the structure to fold and unfold without permanent deformation. Experimentally, the effects of design parameters on the self-bending behavior of the microstructures of hydrogel bilayers are explored by varying the extrinsic geometric variables. The study of finite element method (FEM) simulations shows that the final shape of the bilayer sheet is governed by intrinsic properties, including the elastic modulus and the swelling ratio, and extrinsic geometrical factors, such as the thickness ratio of the bilayer and the aspect ratio of the structure. Therefore, the self-bending behavior of the planar hydrogel bilayer was confirmed by experiments and simulations in which multiple values were assigned for each of the primary design parameters in origami-based engineering.

Computational materials design of negative effective U system in hole-doped chalcopyrite CuFeS2

A general rule of negative effective U(Ueff) system caused by (i) exchange correlation and (ii) charge excitation mechanisms is proposed. Based on the general rule, we perform ab initio electronic structure calculations by generalized gradient approximation (GGA) + U method for hole-doped chalcopyrite CuFeS2 [Cu+(d10)Fe3+(d5)S2−(s2p6)2]. It is found from our calculations that the hole-doped CuFeS2 has the negative Ueff = −0.44 eV, where Ueff ≡ E(N + 1) + E(N − 1) − 2E(N) < 0 and E(N) is the total energy of the hole-doped CuFeS2. The negative Ueff is caused by the charge-excitation in the hole-doped Cu2+(d9) and S−(s2p5), and also caused by the exchange-correlation in the hole-doped Fe4+(d4). The strong attractive electron–electron interaction (Ueff = −0.44 eV ∼ −5000 K) originates from the purely electronic mechanism. The closed shell of the d10 electronic configuration is more stable than the d9 electronic configuration, since the first excited state with the d9s1 electronic configuration and the ground state with the d10 electronic configuration are very close, then these two states repel very strongly through the second order perturbation. Therefore, the spin-polarized total energy curve for the hole-doped CuFeS2 shows the strong upward convexity with N − 1, N and N + 1 electronic configurations leading to the negative Ueff. The hole-doped paramagnetic and metallic CuFeS2 with the negative Ueff may cause a possible high-Tc superconductor (Tc ∼ 1000 K, if 2Δ/kBTc ≈ 10 by assuming a strong coupling regime) because of the strong attractive electron–electron interactions (superconducting gap Δ ≈ |Ueff| ∼ 5000 K). Finally, we propose a new computational materials design methodology to design ultra high-Tc superconductors by using three steps starting from the atomic number only.

Materials genomics: From CALPHAD to flight

Unique depth of scientific knowledge has allowed physical metallurgy to lead the development of a successful computational materials design methodology grounded in a system of fundamental databases. Expansion of the approach to embrace acceleration of the full development and qualification cycle has resulted in the first fully computationally designed and qualified material reaching the flight stage. The example of high-performance alloys provides the template for a general methodology of computational design for all materials.

Genomic materials design: The ferrous frontier

Our unique depth of scientific knowledge has allowed ferrous metallurgy to lead the development of a successful computational materials design methodology grounded in a system of fundamental databases. Expansion of this approach to embrace acceleration of the full development and qualification cycle has resulted in the flight of the first fully computationally designed and qualified material. The example of ferrous alloys provides a template for a general methodology of computational design for all materials.

Particle Packing-Based Material Design Methodology for Pervious Concretes

ACI Materials Journal, V. 109, No. 2, March-April 2012. MS No. M-2010-383.R2 received April 25, 2011, and reviewed under Institute publication policies. Copyright © 2012, American Concrete Institute. All rights reserved, including the making of copies unless permission is obtained from the copyright proprietors. Pertinent discussion including author’s closure, if any, will be published in the January-February 2013 ACI Materials Journal if the discussion is received by October 1, 2012. Particle Packing-Based Material Design Methodology for Pervious Concretes

Composite Design Methodology: Design of Composite Trails for the U.S. Army’s M198 Howitzer, A Case Study

Analysis and design of a fiber reinforced organic composite trail pair for the U.S. Army M198 Howitzer is presented as a case study in composite material design methodology. For this purpose mechanics analysis is performed using the computer program: MIC-MAC composites design and ANSYS 4.4A finite element analysis. The analyses includes composite lamination, material optimization, adhesive bonding, buckling, deflection, stress and failure analysis and validates the practicability of the proposed constant cross-section graphite/epoxy trail. The use of PC based spreadsheet MIC-MAC program, initially, allows efficient and inexpensive evaluation of several alternative designs including different geometries and materials before the finite element program is employed with the few final design choices to rule out failure in stress, deflection and buckling modes. However, superposition principles need to be used to describe the complex loading configuration as a collection of mechanically equivalent individual load modes such as midspan loaded beam, cantilever beam under torsion, in-plane loaded plate etc. in order to be able to utilize the MIC-MAC program initially. Fabrication plans are also proposed for the trail pair.