Manufacturing Considerations Research Articles

Strategies for functionally graded lattice structures derived using topology optimisation for Additive Manufacturing

A number of strategies that enable lattice structures to be derived from Topology Optimisation (TO) results suitable for Additive Manufacturing (AM) are presented. The proposed strategies are evaluated for mechanical performance and assessed for AM specific design related manufacturing considerations. From a manufacturing stand-point, support structure requirement decreases with increased extent of latticing, whereas the design-to-manufacture discrepancies and the processing efforts, both in terms of memory requirements and time, increase. Results from Finite Element (FE) analysis for the two loading scenarios considered: intended loading, and variability in loading, provide insight into the solution optimality and robustness of the design strategies. Lattice strategies that capitalised on TO results were found to be considerably (∼40–50%) superior in terms of specific stiffness when compared to the structures where this was not the case. The Graded strategy was found to be the most desirable from both the design and manufacturing perspective. The presented pros-and-cons for the various proposed design strategies aim to provide insight into their suitability in meeting the challenges faced by the AM design community.

Systematic Development Strategy for Smart Devices Based on Shape-Memory Polymers.

Shape-memory polymers are outstanding “smart” materials, which can perform important geometrical changes, when activated by several types of external stimuli, and which can be applied to several emerging engineering fields, from aerospace applications, to the development of biomedical devices. The fact that several shape-memory polymers can be structured in an additive way is an especially noteworthy advantage, as the development of advanced actuators with complex geometries for improved performance can be achieved, if adequate design and manufacturing considerations are taken into consideration. Present study presents a review of challenges and good practices, leading to a straightforward methodology (or integration of strategies), for the development of “smart” actuators based on shape-memory polymers. The combination of computer-aided design, computer-aided engineering and additive manufacturing technologies is analyzed and applied to the complete development of interesting shape-memory polymer-based actuators. Aspects such as geometrical design and optimization, development of the activation system, selection of the adequate materials and related manufacturing technologies, training of the shape-memory effect, final integration and testing are considered, as key processes of the methodology. Current trends, including the use of low-cost 3D and 4D printing, and main challenges, including process eco-efficiency and biocompatibility, are also discussed and their impact on the proposed methodology is considered.

A novel technique for the design of hybrid composite laminates based on dynamic programming and dynamic tree trimming

This paper proposes a novel technique for the design of hybrid composite laminates. The method explores design space with several implicit decision trees in order to obtain the Pareto front, applying a number of manufacturing and structural considerations. The research is carried out using a parallelized breadth first search algorithm aided by dynamic programming and dynamic tree trimming; as a consequence the searching process is significantly accelerated. This novel procedure is applied to a well-known design case, where it identifies the best carbon-epoxy and glass-epoxy laminate combinations in terms of weight versus cost, and finds the Pareto front with less computational effort than alternative methods used in the past to solve the same problem. Since a full set of feasible solutions is produced with this new methodology, some important conclusions are obtained regarding hybrid laminate design criteria.

The C-Tower project – A composite tower for offshore wind turbines

In this paper the feasibility is demonstrated of replacing the steel tower of an offshore wind turbine by a fibre-reinforced composite structure, with the aim of reducing installation and maintenance costs, and thereby the life cycle cost of the entire turbine. Design considerations regarding tower strength and flexibility, as well as manufacturability considerations, are discussed.

A digital thread approach to support manufacturing-influenced conceptual aircraft design

This paper proposes and demonstrates the integration of manufacturing and production considerations with traditional aircraft design metrics to support affordability-based design. To enable the necessary multi-disciplinary trades, a digital thread approach is proposed that integrates detailed models and analyses. The digital thread refers to linking models from various disciplines through common inputs and data flows with the goal of speeding design time and enabling trades across traditionally isolated disciplines. When used within an overarching design process, the production cost, rate, and efficiencies of non-conventional designs in variable demand environments can be quantified and traded early in the design process. In particular, the methodology is demonstrated using a wingbox design problem such that aircraft performance considerations, production rate, manufacturing cost, and financial planning metrics can be traded within a parametric, visual trade-off environment. The environment, combined with a multi-objective optimization routine, facilitates effective affordability-based tradespace exploration during the early stages of the design of non-traditional aircraft (e.g., those utilizing composite structures) under demand variability. An F-86 Sabre redesigned wingbox using three separate manufacturing concepts is used as a proof-of-concept for this research.

Redesigning a Reaction Control Thruster for Metal-Based Additive Manufacturing: A Case Study in Design for Additive Manufacturing

Prior research has shown that powder-bed fusion (PBF) additive manufacturing (AM) can be used to make functional, end-use components from powdered metallic alloys, such as Inconel® 718 superalloy. However, these end-use components and products are often based on designs developed for more traditional subtractive manufacturing processes and do not take advantage of the unique design freedoms afforded by AM. In this paper, we present a case study involving the redesign of NASA’s existing “pencil” thruster used for spacecraft attitude control. The initial pencil thruster was designed for and manufactured using traditional subtractive methods. The main focus in this paper is to (a) identify the need for and use of both opportunistic and restrictive design for additive manufacturing (DfAM) concepts and considerations in redesigning the thruster for fabrication with PBF AM and (b) compare the resulting DfAM thruster with a parallel development effort redesigning the original thruster to be manufactured more effectively using subtractive manufacturing processes. The results from this case study show how developing end-use AM components using specific DfAM guidelines can significantly reduce manufacturing time and costs while enabling new and novel design geometries.

Operation scheduling of multi-hydraulic press system for energy consumption reduction

Reducing energy consumption is becoming a more and more essential consideration for low carbon manufacturing. In this paper, an operation scheduling approach is proposed for a multi-hydraulic press system to explore the potential on energy saving at system level. In the multi-hydraulic press system, a drive is composed of several motor-pumps and supplies energy to each press according to a given schedule. The scheduling formulation is developed based on power models of the forming process on an individual press. At single press level, models of energy conversion units, including asynchronous motors, piston pumps, hydraulic cylinders, valves and pipes are built by identifying their energy dissipation characteristics. Based on the established model of a single press and scheduling formulation, the energy consumption model and makespan at multi-press level are obtained. In order to balance makespan and energy consumption, the duration of each operation is adjusted by optimizing the configuration of the drive and the schedule of operations. To demonstrate the applicability of the proposed approach, a case study on a four presses system is presented. The results show that this approach is effective in identifying schedules to reduce makespan and total energy consumption during forming processes.

Control architectures for Industrial Additive Manufacturing Systems

As the emergent technologies of Industrial Additive Manufacturing become increasingly employed in commercial manufacturing environments, challenges arise in terms of how resources of the manufacturing system should be marshalled and controlled for sustainable manufacturing. While control architectures are well established for conventional manufacturing, to-date there has been little explicit consideration for Industrial Additive Manufacturing. This article provides redress for this research gap by exploring four feasible control architectures employed in current manufacturing practice. Drawing upon 12 case studies and the operations of three companies, the relative merits, demerits, and challenges for each architecture are explored in terms of changeability criteria for sustainable manufacturing.

Topology optimization with additive manufacturing consideration for vehicle load path development

SummaryTopology optimization has been widely studied and implemented as a powerful conceptual design tool in various engineering applications. However, the result from topology optimization has posed an implementation challenge to engineers because of the complexity of converting obtained solution into computer‐aided design data and then fabricating it into real parts. Over the past few years, the advanced additive manufacturing technology with new materials and higher resolution output capabilities has opened numerous opportunities to fill the gap between topology optimization and product application. In this study, an engineering procedure is presented for the conversion of topology optimization result to ready‐to‐print model for additive manufacturing. The steps of post‐optimization handling are outlined, and the potential practical issues for the additive manufacturing implementation are discussed. A vehicle example for full frontal impact load path development by topology optimization with inertia relief approach is used to exhibit the employed additive manufacturing implementation process with a reduced‐scale part build. The arising implementation issues and needs are examined for future advance of topology optimization and additive manufacturing integration development. Copyright © 2017 John Wiley & Sons, Ltd.

Development of a Low-Cost, Short-Range Radar System to Measure Speed and Distance

The aim of this project consists in designing and implementing a short-range, low-cost K band, continuous wave radar prototype system for industrial applications with the K-LC6 module, capable of measuring distance and radial speed. This article describes all the hardware and software design, manufacture, and implementation considerations of the radar system. To minimize the cost of a potential product for industry, prototype hardware was implemented by using commercial elements. This work also shows the result of experimental tests that permitted characterizing the prototype and verifying measurements of distance and speed of targets in laboratory environments. These tests permitted verification of its operation, obtaining a short-range (from 0.6 to 63 m) frequency modulated - continuous wave radar prototype, capable of measuring speeds up to 9.2 km/h

Heat Transfer and Film Cooling on a Contoured Blade Endwall With Platform Gap Leakage

Turbine blade components in an engine are typically designed with gaps between parts due to manufacturing, assembly, and operational considerations. Coolant is provided to these gaps to limit the ingestion of hot combustion gases. The interaction of the gaps, their leakage flows, and the complex vortical flow at the endwall of a turbine blade can significantly impact endwall heat transfer coefficients and the effectiveness of the leakage flow in providing localized cooling. In particular, a platform gap through the passage, representing the mating interface between adjacent blades in a wheel, has been shown to have a significant effect. Other important turbine blade features present in the engine environment are nonaxisymmetric contouring of the endwall, and an upstream rim seal with a gaspath cavity, which can reduce and increase endwall vortical flow, respectively. To understand the platform gap leakage effect in this environment, measurements of endwall heat transfer, and film cooling effectiveness were performed in a scaled blade cascade with a nonaxisymmetric contour in the passage. A rim seal with a cavity, representing the overlap interface between a stator and rotor, was included upstream of the blades and a nominal purge flowrate of 0.75% of the mainstream was supplied to the rim seal. The results indicated that the endwall heat transfer coefficients increased as the platform gap net leakage increased from 0% to 0.6% of the mainstream flowrate, but net heat flux to the endwall was reduced due to high cooling effectiveness of the leakage flow.

Modular High-rise Construction: An Alternative Building System

Modular construction is a relatively a new form of high-rise construction, which involves the assembly of prefabricated structural modules. In contrast to traditional on-site construction methods, it allows for parallel processes to occur where the modules can be manufactured offsite, before or during preliminary on-site works, and then be transported to the site and assembled progressively. However, modular construction raises some concerns, such as load bearing capacity and structural integrity, in comparison to traditional in-situ construction. Hybrid construction processes may also be required in order to satisfy load capacity requirements, particularly for high-rise buildings. Structural integrity must be fully engineered into the modules during the early design processes and include consideration of manufacturing, handling, transportation and lifting issues as well as their long-term post-assembly integrity. Structural integrity may also need to encompass the capacity to resist seismic forces for buildings constructed in earthquake-prone areas. The purpose of the paper is to specifically examine how the overall structural integrity is maintained through the use of modular construction. Moreover, the main aim of this paper is also to investigate the structural integrity of modular construction specifically for high-rise buildings. Finally, this paper will examine how the panels maintain their structural integrity in the module itself and in the overall structure.

Design Consideration for Additive Manufacturing: Fused Deposition Modelling

Additive Manufacturing (AM) technologies have progressed in the past few years and many of them are now capable of producing functional parts instead of mere prototypes. AM provides a multitude of benefits, especially in design freedom. However, it still lacks industrial relevance because of the absence of comprehensive design rules for AM. Although AM is usually advertised as being the solution for all traditional manufacturing design limitations, the fact is that AM only replaces these limitations with a different set of restrictions. To fully exploit the advantages of AM, it is necessary to understand these limitations and consider them early during the design process. The establishment of design considerations in AM enables parts and process optimization. This paper discusses the design considerations that will lead to optimize part quality. Specifically, the work discusses the Fused Deposition Modeling (FDM) due to its common use and availability. These considerations are drawn from literature and from experiments done by the authors. The experiments done by the authors include an investigation for the influence of elevated service temperature on the performance of FDM PLA parts, benchmarking the capability of FDM to print overhangs and bridges without supports, studying the influence of processing parameters over dimensional accuracy, and the effect of processing parameters on the final FDM samples modulus of elasticity. The work presents a case study investigating the correct clearances for FDM parts and finally a redesign for AM case study of a support bracket originally manufactured using traditional manufacturing methods taking into consideration the design considerations discussed in this paper.

Physical Rigging for Physical Models and Posable Joint Designs Based on Additive Manufacturing Technology

In 3D computer animation, a lot researches illustrated rigging mesh or solid models can be easily converted to articulated characters. Even though these articulated characters can exhibit desired motions in computer, the joints facilitating the motion are not properly designed at all. All rigged joints must be clearly designed with consideration of mobility and manufacturability. In this paper, a physical rigging methodology and a set of joint designs for articulated characters are proposed. The joints can be easily used for both revolute and omnidirectional motion. They also allow a physical character to assume any poses that are within the designed motion range after fabricated by additive manufacturing (AM) technologies. A number of sample designs have been fabricated using two popular AM technologies to demonstrate the effectiveness of the proposed method.

Building parity between brand and generic peptide products: Regulatory and scientific considerations for quality of synthetic peptides

Peptides are a fast growing segment in the pharmaceutical industry. Consequently, the industry and regulatory agencies are increasing their focus on the regulatory path and quality considerations for peptide development and manufacturing. Although most peptides are synthetic, manufactured by solid phase synthesis, nevertheless they are complex molecules with challenging quality and regulatory aspects. This paper provides a structured overview of relevant quality issues for chemically synthesized peptides used as active pharmaceutical ingredients (API) in drug products. It addresses the unique characteristics of peptides pertaining to structural and physicochemical characterization, manufacturing and in process controls, impurities and aggregates arising from manufacturing and storage, along with their potential impact on safety (including immunogenicity) and efficacy of the peptide drug products.

Analytical considerations for cellular therapy manufacturing

Analytical considerations for cellular therapy manufacturing

A statistical analysis of low-stress mechanical properties of warp-knitted fabrics

Fabric hand is an indispensable characteristic for the selection of fabric and product development and the buying consideration for manufacturers and consumers. However, there is little comprehensive work on the hand feel property of warp-knitted fabrics due to the mainstream natural fibers (cotton, wool and silk) and other fabric structures (woven, weft-knitted and nonwoven). The increasing potential for the wide variety of applications and development of warp-knitted fabrics is not only because its fabric hand gives better determination for fabric marketing, but also because it provides extensive scope for fabric performance and appearance. This paper reports an experimental study on the integrated fabric hand behavior of a series of warp-knitted fabrics made for various apparel applications, such as sportswear, lingerie and leisure wear. These 105 fabrics were produced by varying different physical parameters, including fabric weight and fabric thickness. The Kawabata Evaluation System for Fabric (KES-F) was employed to obtain the fabric hand properties (primary hand value and total hand value) related with stiffness, smoothness and softness. All low-stress mechanical properties and fabric hand values from the testing results were used to verify the applicability of the KES-F on warp-knitted fabrics and to analyze the relationships of fabric parameters and hand characteristics. The results indicate that the KES-F is an appropriate tool to measure the hand attributes of warp-knitted samples, and moderate correlations between physical properties and mechanical behavior were found.

Nanomaterial Drug Products: Manufacturing and Analytical Perspectives.

The increasing use of nanotechnology, including nanoparticles, in the preparation of drug products requires both manufacturing and analytical considerations in order to establish the quality metrics suitable for performance and risk assessment. A range of different nanoparticle systems exists including (but not limited to) nano-drugs, nano-additives, and nano-carriers. These systems generally require more complex production and characterization strategies than conventional pharmaceutical dosage forms. The advantage of using nanoparticle systems in pharmaceutical science is that the effective and desired function of the material can be designed through modern manufacturing processes. This paper offers a systematic nomenclature which allows for greater understanding of the drug product under evaluation based on available data from other nanoparticle reports. Analytical considerations of nano-drugs, nano-additives, and nano-carriers and the way in which they are measured are directly connected to quality control. Ultimately, the objective is to consider the entire nano-drug, nano-additive, and nano-carrier product life cycle with respect to its manufacture, use, and eventual fate. The tools and approaches to address the needs of these products exist; it should be the task of the pharmaceutical scientists and those in related disciplines to increase their understanding of nanomedicine and its novel products.

The efficiency of CUSUM schemes for monitoring the coefficient of variation

Continuous surveillance of the coefficient of variation is a quality control issue worthy of consideration in several manufacturing and service‐oriented companies. In this paper, we present a new method to monitor the squared coefficient of variation by means of two one‐sided cumulative sum‐type control charts. We study the run length properties of the proposed charts using a Markov chain approach. Several tables are given in order to show the sensitivity of the proposed charts for different deterministic shift sizes and their performance for the random shift size condition. The results show that the proposed control charts have attractive performance compared with some competing charts and are better in many cases. An illustrative example is discussed on a real dataset. Copyright © 2016 John Wiley & Sons, Ltd.

Mould design and manufacturing considerations of honeycomb biocomposites with transverse fibre direction for aerospace application

Sandwich structures with honeycomb core are known to significantly improve stiffness at lower weight and possess high flexural rigidity. They have found wide applications in aerospace as part of the primary structures, as well as the interior paneling and floors. High performance aluminum and aramid are the typical materials used for the purpose of honeycomb core whereas in other industries, materials such as fibre glass, carbon fibre, Nomex and also Kevlar reinforced with polymer are used. Recently, growing interest in developing composite structures with natural fibre reinforcement has also spurred research in natural fibre honeycomb material. The majority of the researches done, however, have generally emphasized on the usage of random chopped fibre and only a few are reported on development of honeycomb structure using unidirectional fibre as the reinforcement. This is mainly due to its processing difficulties, which often involve several stages to account for the arrangement of fibres and curing. Since the use of unidirectional fibre supports greater strength compared to random chopped fibre, a single-stage process in conjunction with vacuum infusion is suggested with a mould design that supports fibre arrangement in the direction of honeycomb loading.