Building Block Approach Research Articles

Computing the durability of WAAM 18Ni 250 maraging steel specimens

AbstractMIL‐STD 1530D requires that the certification of an aircraft part employ analytical tools that are capable of modeling crack growth. It is further stated that the durability and damage tolerance (DADT) analyses should be based on linear elastic fracture mechanics (LEFM) and follow a building block approach. This paper illustrates the durability analysis required to certify an additively manufactured part by using the examples of durability tests performed on two wire arc additively manufactured (WAAM) 18Ni 250 Maraging steel specimens.

Design allowables of composite laminates: A review

The design and certification process of composite structures relies on the building-block approach, which starts from the mechanical characterization of the material at coupon-level. The certification of composite laminates is thus the first challenge and requires the definition of the design allowables, which are statistically defined as established by the Composite Material Handbook. These quantities are strength or strain values indicated as A- or B-basis and an accurate estimation is needed in order to guarantee the integrity of the structure. Given the statistical nature of material allowables, a high number of experimental tests have to be performed for the full mechanical characterization of a material. Notched and unnotched allowables are determined under different testing conditions and in accordance to the standards specified by American Society for Testing and Materials. Different methodologies are presented in literature and explore the combination of simulation-based solutions supported by test-evidence of a reduced number of coupons. In the recent years, several approaches have been explored in the field of uncertainty quantification and Machine Learning demonstrating to be powerful alternatives to full testing-based or simulation-based solutions. A comprehensive literature review is presented in this contribution among the main solutions for the definition of material allowables. This review demonstrates that simulations supported by a reduced number of tests can reach accurate results and the number of simulations can be further reduced by combining the numerical models with predicting theories.

Proof test methodology for reducing the risk of unvented honeycomb core failures in aerospace structures

The trapped air in unvented honeycomb core and the surrounding environment can induce a pressure differential across the facesheet during launch ascent. Combined with the presence of a defect, the pressure differential across a facesheet in combination with external loads can cause facesheet failure or unstable facesheet debond growth. While honeycomb core venting is the recommended solution, there might be practical limitations in implementing this solution or the possibility that a structure intended to be vented is partially unvented due to manufacturing issues. A methodology for accepting composite sandwich structures for space applications is presented, which heavily relies on the building block approach to characterize the facesheet strength and interfacial fracture toughness. To demonstrate the approach, an allowable flaw size is defined for a hypothetical flight condition using analyses anchored to subscale tests.

Advancing Nursing Science Through Site-Based Clinical Inquiry: Designing Problem Pyramids.

Advancing Nursing Science Through Site-Based Clinical Inquiry: Designing Problem Pyramids.

DESIGN FOR AN ALL-ELECTRIC DESIGN FOR SUPPORT IN INITIAL DESIGN USING THE NETWORK BLOCK APPROACH: A SUBMARINE EXAMPLE

The layout of the Distributed Ship Service Systems (DS3) can be a major constraint both on the location of hull berth unit and of transverse bulkheads, with implications for conducting maintenance and so contribute to submarine Sustainability. This paper proposes a new early-stage ship design (ESSD) approach that would aid the designer to consider DS3 features physically and logically much earlier in the design process. The approach is termed the Network Block Approach and combines the advantages of the UCL 3D physically based ship synthesis Design Building Block (DBB) approach and the network-based approach for distributed ship service systems (DS3) synthesis already proposed for naval combatants. The proposed Network Block Approach enables modelling of individual spaces to locate and zone various DS3 components and take account of hull unit boundaries and major bulkheads. The paper discusses the importance of DS3 routing to warship Sustainability through the complexity of a submarine design example and shows how the proposed approach enables this to be explored in ESSD.

Pre-arranged building block approach for the orthogonal synthesis of an unfolded tetrameric organic-inorganic phosphazane macrocycle.

Inorganic macrocycles remain challenging synthetic targets due to the limited number of strategies reported for their syntheses. Among these species, large fully inorganic cyclodiphosphazane macrocycles have been experimentally and theoretically highlighted as promising candidates for supramolecular chemistry. In contrast, their hybrid organic-inorganic counterparts are lagging behind due to the lack of synthetic routes capable of controlling the size and topological arrangement (i.e., folded vs unfolded) of the target macrocycle, rendering the synthesis of differently sized macrocycles a tedious screening process. Herein, we report-as a proof-of-concept-the combination of pre-arranged building blocks and a two-step synthetic route to rationally enable access a large unfolded tetrameric macrocycle, which is not accessible via conventional synthetic strategies. The obtained macrocycle hybrid cyclodiphosphazane macrocycle, cis-[μ-P(μ-NtBu)]2(μ-p-OC6H4C(O)O)]4[μ-P(μ-NtBu)]2 (4), displays an unfolded open-face cavity area of 110.1 Å2. Preliminary theoretical host-guest studies with the dication [MeNC5H4]22+ suggest compound 4 as a viable candidate for the synthesis of hybrid proto-rotaxanes species based on phosphazane building blocks.

Building block 3D printing based on molecular self-assembly monolayer with self-healing properties

The spontaneous formation of biological substances, such as human organs, are governed by different stimuli driven by complex 3D self-organization protocols at the molecular level. The fundamentals of such molecular self-assembly processes are critical for fabrication of advanced technological components in nature. We propose and experimentally demonstrate a promising 3D printing method with self-healing property based on molecular self-assembly-monolayer principles, which is conceptually different than the existing 3D printing protocols. The proposed molecular building-block approach uses metal ion-mediated continuous self-assembly of organic molecular at liquid–liquid interfaces to create 2D and 3D structures. Using this technique, we directly printed nanosheets and 3D rods using dithiol molecules as building block units.

Application of Building Block Approach on Crashworthiness Design of Composite Vehicular Structures

Application of Building Block Approach on Crashworthiness Design of Composite Vehicular Structures

Assessing the soundness of water governance: lessons learned from applying the 10 Building Blocks Approach

ABSTRACT Sound governance is needed to address water issues, but soundness is a contested concept that should be further specified in societal debates. These debates can benefit from interdisciplinary knowledge. The 10 Building Blocks Approach, a tool developed to generate such knowledge, has been widely applied in research and teaching. In this paper, we draw on the literature and reflect on the experiences of using this approach by elucidating the strengths and weaknesses identified during its applications. Based on our reflections, we propose a revised version of the approach.

Electrospun fiber-based high-performance flexible multi-level micro-structured pressure sensor: Design, development and modelling

• Template-assisted electrospinning is applied to fabricate the multi-level microstructure TPU membranes. • The pressure sensor shows ultralow detection limit, high sensitivity and wide sensing range. • The building block approach is creatively applied in FEA. • The pressure sensors enable real-time human physiological signals. Geometric microengineering is an effective approach to improve the comprehensive performance of pressure sensors. Unfortunately, the design of multi-level microstructure and the development of industrially relevant technology remain challenging. In this study, template-assisted electrospinning is applied to fabricate the multi-level microstructured TPU membranes with both regularly distributed knoll-like microstructures on the surface and randomly distributed fiber-network structures inside, which serve as the active layers of the pressure sensor. The assembled pressure sensor shows exceptional performance, including ultralow detection limit of 0.7 Pa, high sensitivity of 63.93 kPa −1 , a wide sensing range of 0–160 kPa and excellent durability of >10000 cycles. The sensing mechanism is further investigated based on the equivalent circuit diagram analysis and finite element analysis (FEA). In FEA, the building block approach is adopted to simulate the electro-mechanical performance between complex fiber networks. These results reveal that the knoll-like microstructures and fiber-network structures lower the effective elastic modulus and increase the contact points/areas or conductive path upon loading, thereby responsible for the exceptional sensing performance. Real-time monitoring of human physiological signals is demonstrated. The industrial relevance of the template-assisted electrospinning technology for fabricating pressure sensors is highly scalable, thus industrially relevant.

The Roadmap to the ASEAN-EU FTA in the Post-Pandemic Era

Relations between the Association of Southeast Asian Nations (ASEAN) and the European Union (EU) have enriched the multifaceted concept of interregionalism from legal and international relations perspectives. The article argues that the transformative ASEAN-EU frameworks have shaped the Third Interregionalism. Brussels’ building-block approach envisions pathfinder agreements with individual ASEAN states as the basis for the ASEAN-EU FTA, which will help realize the EU’s Indo-Pacific strategy and the ASEAN-EU Strategic Partnership. The designs of the EU’s trade and investment agreements with Singapore and Vietnam are therefore critical. The article assesses core areas such as tariff liberalization and ASEAN cumulative rules of origin, as well as commitments of trade in services and non-tariff barriers in key industries. Contributors to the special issue further analyse cutting-edge issues involving electronic commerce and sustainable development. These on-the-ground insights contribute to a new understanding of ASEAN-EU legal frameworks and evolving interregionalism in the post-pandemic era. ASEAN-EU FTA – CPTPP – Indo-Pacific strategy – Investment Protection – Singapore – RCEP – Sustainable Development – Third Interregionalism – Vietnam

Testing and numerical investigations of hybrid composite for flight control surfaces in manufacturing variability contest

The design and certification of composite structures is based on the building block approach (BBA), following a bottom-up procedure. Starting from the bottom level of Rouchon’s pyramid of test, thousands of coupons need to be produced to determine design allowables and capture manufacturing, geometrical and microstructure variability values. The numerical approach provides desirable data to be confirmed by a reduced testing campaign, especially for the preliminary design process stages and material selection.In this paper a carbon fibers reinforced composite with epoxide resin used for aerospace application has been analyzed, in form of both fabric and unidirectional tape to validate the numerical model considering Salver (of MA Group company) manufacturing process variability data. Hybrid laminates composed of unidirectional plies and woven fabric layers have been tested to pursue a tailored approach based on design guidelines and stress requirements for aircraft flight control surfaces. Benchmarking the experimental-numerical test results allows to assess the statistical reliability of the proposed method.

Virtual Test Approach of Titanium/Composite in Service Repair, Installed on Certified Composite Flap

Virtual test methods can contribute to reducing the great effort for physical tests in the development of composite structure and in particular on the In-service Repair. The present work describes an approach for virtual testing of titanium/composite repair based on the Building Block Approach and the Finite Elements Method. Building on a multitude of physical tests on composite panels and joints, adequate sub-models are developed, validated and the results show that the method used for the substantiation of the generic repairs (GREOs) compared with test results is conservative. This thesis intends to provide a hierarchical virtual testing approach, which enables the prediction of the failure behavior and the strength of composite In-service repairs by means of validated FEM simulation. In particular the objective of this work will be to investigate the damage mechanisms in composite bonded skin/stringer constructions with metallic (titanium) bolted repair under uniaxial (in-plane/out-of-plane) loading conditions as typically experienced by aircraft flap skin panels.

Measurement platform for structural health monitoring application of large scale structures

This paper reports on the development of a software platform for acquiring ultrasonic guided waves for the application of structural health monitoring (SHM) of composite fuselage panels. The focus of the developments has been its application at an industrial scale. As part of the CleanSky2 project developments, the application of SHM has been designed, developed and tested following a building block (BB) approach, from a large number of tests at coupon level to element and sub-component levels each with increasing complexity. Therefore, an SHM measurement platform has been developed and tested at different stages of the BB tests under combined operational and environmental conditions, with different sensor technology and sensor network. The platform is demonstrated to be reliable, user friendly and scalable to large sub-components, with optimized data acquisition and handling protocols.

Electrospinning based on benign solvents: current definitions, implications and strategies

A building block approach, using a variety of benign solvent compositions and additives, offers a continuously developing strategy to render solvent-based electrospinning increasingly sustainable for the generation of polymer nanofibers.

Synthesis and characterization of naphthalene derivatives for two-component heterojunction-based ambipolar field-effect transistors complemented with copper hexadecafluorophthalocyanine (F16CuPc).

In order to develop organic semiconductor materials with good performance, herein, a series of naphthalene derivatives were designed and synthesized by a “building-blocks approach” connected through α-bond, double bond, and triple bond, respectively. Thin-film transistors were fabricated in single-component and two-component modes based on these naphthalene derivatives by combining the F16CuPc as the n-type material. The ambipolar performance was investigated by adjusting the device preparation procedure with the hole and electron mobility of up to 10−2 cm2 V−1 s−1. Furthermore, the electrical performance was also improved to 0.73 cm2 V−1 s−1 using the two-component bilayer configuration.

Strengthening the oral health system in Nigeria: A health systems building block approach.

The present study aimed to describe the building blocks of the oral health system, including the role that the community plays in strengthening the oral health system in Nigeria. This research was a scoping review of the existing literature retrieved from search engines and databases. Thus, we utilised grey literature, peer-reviewed literature, policy documents and websites. The oral health system was analysed using the World Health Organisation's Health systems framework, and we adapted this framework by introducing a seventh block, community participation. We also inserted the links between the oral health service delivery and oral health workforce blocks of the framework to improve the oral health outcomes. More dental clinics are required to improve the availability and accessibility of oral health services. Dental workforce expansion is imperative. This can be approached by training of junior cadre dental professionals and incorporating community health practitioners to deliver basic oral care. There is an unregulated access to medication to treat dental conditions; hence, oral disease treatments need to be included in the country's treatment guidelines to improve standard of care. The government needs to improve on overall health spending and invariably increase oral health care allocation urgently. Furthermore, the country's stewardship of oral health care is hinged on well disseminated and implemented national policies on oral health. The oral health system can achieve its overall goals with community participation, engagement and ownership. Strengthening the oral health system in Nigeria requires urgent attention on each building block and cross-cutting interventions across the system's building blocks. The role of the community will need to be recognised because it is vital in sustaining any organisational change.

Building-block approach to the discovery of Na8Mn2(Ge2Se6)2: A polar chalcogenide exhibiting promising harmonic generation signals with a high laser-induced damage threshold

A new polar quaternary chalcogenide, Na8Mn2(Ge2Se6)2, has been synthesized using the building-block approach by reacting preformed Na6Ge2Se6 and MnCl2 at 750 °C. The structure consists of layers of [Na(1)Mn(Ge2Se6)]3– stacked perpendicular to the c-axis and sodium ions occupying the interlayer space. An indirect bandgap of 1.52 eV has been calculated using density functional theory, which is expectedly underestimated compared to the observed optical bandgap of 1.95 eV derived from diffuse reflectance spectroscopic measurements in the UV/Vis/NIR region. Magnetic measurements confirm the paramagnetic nature of Na8Mn2(Ge2Se6)2 with an experimental magnetic moment of 5.8 μB in good agreement with the theoretical spin only moment of 5.92 μB for high spin Mn2+. Na8Mn2(Ge2Se6)2 exhibits a potentially wide region of transparency in the measured range of 2.5–25 µm. Na8Mn2(Ge2Se6)2 shows a modest second-harmonic generation (SHG) response but with a high laser-induced damage threshold (LIDT) of ~9x AgGaSe2. Third harmonic generation (THG) measurements indicate that Na8Mn2(Ge2Se6)2 displays a high THG coefficient (1.9x AgGaSe2) at λ = 1800 nm.

Development of Red-Emissive Carbon Dots for Bioimaging through a Building Block Approach: Fundamental and Applied Studies.

In recent years, many researchers have struggled to obtain carbon dots (CDs) that possess strong photoluminescence in the red region of light. Success in this area has been limited, although the past few years have brought several promising reports on this topic. The most successful efforts in this area still seem to struggle from a lack of dispersibility/reduced emission in water. This work endeavors to understand the formation process of CDs that do not possess strong performance in an aqueous environment and to improve their capabilities in bioimaging. o-Phenylenediamine (o-PDA) is used along with various precursors in several different solvents (varying acidic and oxidative strengths) to understand the formation process behind the structure leading to red emission that is sensitive to water. These results showed that the combination of acid properties and oxidation is essential for this process, and the important reactions are oligomerization of o-PDA and the crosslinking of these oligomers to form aromatic structural segments of CDs. These CDs are shown to be capable of quantitatively detecting water in organic solvents. Additionally, we have shown that conjugation with transferrin remarkably enhances the biocompatibility of these CDs. Transferrin-conjugated CDs with better biocompatibility were applied to bioimaging studies of neuroblastoma cell lines with N-myc and non-N-myc gene amplification, for the first time. Furthermore, CDs showed versatile bioimaging capability toward a highly aggressive neuroblastoma subgroup of tumors. The importance of creating red-emissive CDs has been well established, and this work is an important step toward understanding their formation and realizing their use in biological systems.

A COMPREHENSIVE APPROACH TO SURVIVABILITY ASSESSMENT IN NAVAL SHIP CONCEPT DESIGN

Alongside deploying weapons and sensors what makes a warship distinct is its survivability, being the measure that enables a warship to survive in a militarily hostile environment. The rising cost of warship procurement, coupled with declining defence budgets, has led to cost cutting, often aimed at aspects, such as survivability, which may be difficult to quantify in a manner that facilitates cost capability trade-offs. Therefore, to meet ever-reducing budgets, in real terms, innovation in both the design process and the design of individual ships is necessary, especially at the crucial early design stages. Computer technology can be utilised to exploit architecturally orientated preliminary design approaches, which have been conceived to explore innovation early in the ship design process and the impact of such issues as survivability. A number of survivability assessment tools currently exist; however, most fail to integrate all the constituent elements of survivability (i.e. susceptibility, vulnerability and recoverability), in that they are unable to balance between the component aspects of survivability. Some of these tools are qualitative and therefore less than ideal in specifying survivability requirements, others are aimed towards the more detailed design stages where implementing changes is heavily constrained or even impractical. This paper presents a survivability assessment approach combining various tools used by UCL and the UK Ministry of Defence, as well as a new approach for recoverability assessment. The proposed method attempts to better integrate and quantify survivability in early stage ship design, which is facilitated by the UCL derived, architecturally focused, design building block approach. The integrated survivability method is demonstrated for a set of naval combatant concept designs and for two replenishment ship studies to test the robustness of the proposed approach.